Caravan Valve Stem Seal/Timing Belt Installation Notes
If your vehicle has a 3.0 liter Mitsubishi V-6, and smokes at idle or startup but not while cruising, you may be able to fix it yourself for under $200.
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Table of Contents
[Table of Contents]
- My wife and I bought my in-laws' 1988 Dodge Caravan with
108,000 miles on it. It was using oil, and visibly smoking when
idling. On our trip across the country with the vehicle, it used
about a quart every 900 miles or so. In Los Angeles city traffic,
I'd guess the consumption increased to a quart every 500 miles.
This makes sense to me: if the valve stem seals were at fault,
then they'd lose the most oil during highest intake manifold
vacuum - during idle and off-throttle engine braking. With the
throttle butterfly slammed shut, the vacuum gets high enough
to draw a significant amount of air (and oil) from inside the
head and past the valve stem seals, stems and guides. When accelerating
from a traffic light after a couple minute stop, our Caravan
consistently left a nice blue ghost of itself. There was never
visible smoke during cruise.
- When we initially considered buying the minivan from my in-laws,
I considered entire engine fixes. I found a very impressive shop
in Burbank, California which "remanufactured" engines.
They had been a jobber machine shop for years, doing work for
other shops that pulled engines out of customer cars - they decided
to do the whole thing themselves. They're adamant to point out
that "remanufacturing" is not "rebuilding."
Their procedures are thorough: for example, they magnaflux and
shot-peen the crank and rods as a matter of course. Most impressive,
they invited potential customers to visit the facility. I took
a friend who also does his own automotive work, knowing he'd
also enjoy the tour and might also be a potential customer for
an commercial engine rebuild. I was convinced of the shop's integrity
after the tour and discussion with the "guide." Their
facility was immaculate and huge. Bottom line: for a "turnkey"
job, where the customer drops off the vehicle and picks it up
in about a week, a 3 liter Mistubishi V-6 Caravan will run you
about $2800. This includes a 36 month, 36,000 mile warranty,
which also covers removal/installation. If I chose to do the
engine pulling myself, and drop off the long block, they'd charge
about $1800, warranting the engine only for 12 months, 12,000
- I'm a hobbyist mechanic. For various reasons, I haven't had
anyone work on a vehicle I owned (except air conditioning work)
in 15 years. I'm not sure this was ever fun - when I was in automobile
competition, it was sort of part of the pursuit. Today, I enjoy
it much less - but I still feel I can do most automotive diagnostics
and repair better than any mechanic I could hope to find. Doing
It Yourself has risks - and you must suffer a severe
lack of information and resources. But if you're reading this,
you probably accept these truths.
- I figured that I'd save about $1000 for each large step I
was willing to take. One for pulling/installing the engine; one
if I did the engine disassembly/reassembly. I figured I'd still
be in for the remaining odd $800 for parts and machine work.
I rebuilt the engine in my '73 Porsche 914 autocross vehicle
fifteen years ago, but that was with available tutelage from
a certified Porsche mechanic. I'd worry quite a bit about those
inevitable "forgotten" steps if I did an engine unsupervised.
- After several months of research, I discovered that two other
personal acquaintances who also had 1988 Chrysler minivans
with the Mitsubishi 3.0 liter V-6, with very similar symptoms.
One of them hired a garage to replace their valve stem seals,
and claimed that the oil consumption was cured. Most compelling,
I found a Web
page detailing this very job for this very engine within
10 minutes of surfing. As much as anything, I was convinced that
just replacing the valve stem seals was the Way To Go.
- This job took me four days. If I'd had all the information
I'm including here, it would've taken me two. Today I could do
it in one, maybe as quickly as eight hours. But you couldn't
pay me enough to do it for money. I'm a freelancer, so
I do justify home auto repair as money in our pocket.
About this Document
[Table of Contents]
- I started this as notes to myself, after the job was done. I'm writing this
from memory, so don't use it as a literal procedural text. I can't guarantee
completeness. If something is unclear, please email me at the address at the
bottom of this page. (Please: no general automotive questions - I'm not an
expert, this was just a solution I deduced to one problem.) If you
obtain the other manuals listed below, I hope this can fill in their omissions.
I spent many hours over several months in research and contemplation on this
project. I recommend you make a similar commitment.
- I really wanted to spare someone else any grief that I could
by passing along my experience. For many years, I've wanted to
be able to share this kind of information with others. Today's
public popularity of the Internet provides a vehicle for that
[Table of Contents]
- I used Haynes (Part Number
1231) and Chrysler factory manuals (P/N 31-370-8005 and 31-370-8006,)
and an account by Keith
Vickers of an in-vehicle valve stem seal replacement for
a Mitsubishi 3.0 liter minivan found on the Web at http://www.allpar.com/mopar/3fix.html.
The Haynes manual, since it's targeted at DIYers, actually details
the process of doing valve stem seal replacement with the engine
still in the vehicle. However, it refers the reader to a section
of the manual for the 2.2 liter four-cylinder variant of the
minivan. The Chrysler manuals don't mention the in-vehicle seal
- Some of this reference info was actually bad - at least incomplete.
Which is why I'm posting this document.
Special Tools I Used for the Job
[Table of Contents]
- K-D (In-vehicle) Valve Spring Compressor - Part# 3271; actually
a repackaged "E-Z Squeeze #2995" compressor, also resold
by a couple of other companies - the K-D 3271 came with an interchangeable
longer "arm" for longer springs - which I thought was
worth having around for $5 more; $40
- The K-D was the _shortest overall_ compressor of five in-vehicle
compressors available at the tool store I shopped.
- Nylon Strap Wrench (almost didn't work - had to spray Vibration
Damper and wrench strap with 3M 77 Adhesive Spray - see text
- A 3/8" drive inch-pound torque wrench (for rocker shaft
- A 1/2" drive foot-pound torque wrench
- 1" long 3/8" drive extension - it would have been
nearly impossible to remove the power steering pump bolts without
it (inserted with a 15mm socket through the holes thoughtfully
made into the pulley) because of clearance problems
- 22mm 1/2" drive socket (for turning the engine)
- Air compressor to hold valves closed during valve spring
removal and valve stem seal installation
- must produce at least 100 psi, but doesn't need a lot of
- Spark Plug Adaptor for pressurizing cylinders
- get one which incorporates a short hose - you'll have problems
reaching the holes otherwise
- many cylinder compression test kits incorporate the very
part you need - with spark plug threads at one end, and a male
quick-connect air fitting at the other; this is what I used
- I built a body board to lie on to work on the rear cylinders.
At the rear, it was supported at the height of the radiator support
- the front simply rested on the radiator support and overhung
the engine as needed. A foam pad kept my chest from aching. It
was worth it. The few times that I worked on the rear cylinders
without the board, my legs and back complained. The board
also served nicely as a work surface when I wasn't using it as
a body board - I'd just slide it over toward the battery end
of the compartment. I used a 1" x 12", about five feet
long, and built a wooden structure on the top of a two-foot ladder
to match the radiator support height.
[Table of Contents]
- Valve Stem Seals: Chrysler P/N MD197467* - $3.85 each [12
- *the parts fellow at the Dodge dealer where I shop knocked
them down to this price from a quoted $4.62 each
- Rocker Cover Gaskets: P/N MD120091* - $12.00 each [2 reqd]
- Timing Belt**: P/N MD100679 - $45.00 (optional)
- **This isn't necessary for the task, but because of complications,
I had to get this deep into the engine, so it was just practical
to replace the belt.
- *I think the "MD" in the part numbers must be Mitsubishi
- Intake Manifold Gaskets - $21.00 (intake and exhaust)
- I ended up buying a set of intake/exhaust manifold gaskets
at a Pep Boys. I didn't really want the exhaust gaskets
- when the counter guy asked if I wanted "the set,"
I was thinking of the gasket for the intake plenum - which I
didn't end up getting at all. I never used the exhaust gaskets.
- Permatex High Temp RTV #101 gasket material
- It's necessary in installing the valve cover gaskets and
sealing the cam end caps.
[Table of Contents]
- Checking for Fallen Guides
- Of all the references I used, only Keith
Vickers' Web account suggested the possibility that in some
cases, the valve guides themselves may have slipped down
into the head. In these cases, the seals bottom on the head rather
than seating on the guides. Apparently this condition necessitates
removal of the head. Keith
Vickers suggested inspecting all the guides before beginning
the operation, because it'd be pointless to continue in this
condition. The front head is fairly easy to inspect: just pull
the hose off the PCV valve, pull the plug wires from the harness
and loosen the valve cover's two 12mm bolts. Removing the rear
valve cover requires removal of the alternator, and it's awkward
to work in the back of the engine compartment over the manifold/intake
plenum. Thankfully, our valve guides seemed perfectly normal.
- Once you've determined that your valve guides haven't
slipped down into your head(s,) you can begin the operation.
- Preparing for Cylinder Head Access
- Pull the air conditioner belt andthe serpentine belt.
- Pull the air cleaner assembly. It's attached to the rear
head with two bolts through steel straps.
- Pull the alternator. I suppose you could actually leave it
connected to its harness and rest it out of the way near the
brake master cylinder. I completely disconnected it. It's held
in place by a pivot bolt and nut which is very visible, and another
anchor bolt toward the firewall end of the alternator, head towards
the passenger front wheel. I did not remove the alternator
bracket - it didn't create an interference problem that I noticed.
- Removing Intake Plenum and Manifold
- I'd say that it's necessary to remove the intake plenum
and manifold. Even if you found a really short spring
compressor which fit between the intake valves and the intake
runners, the ease of access to the rear head without the intake
parts is worth the effort. Furthermore, the sludge I found in
our EGR plumbing was also inside the intake plenum where
the EGR pipe hooked in, so it'd be easier to clean that out off-vehicle.
Here's what I recall of removing the intake:
- This necessitated the removal of several vacuum hoses. I
didn't have to label anything. Sizes of hoses and unique angles
were adequate. I also had to pull several sensor connectors -
no problems there. Throttle and cruise control cables had to
come off the throttle body bellcrank. Then I removed the throttle
cable bracket from the intake plenum. At the driver's end, toward
the rear of the plenum, the EGR pipe is a 5/8" O.D. steel
pipe which connects to a flange at the plenum and another flange
at the EGR valve itself. The plenum came off with a little sideward
tap from a hammer and a block of wood. Now the plenum came free
of the car.
- Before pulling the intake manifold off, I pulled the injector
harness connector at the rear of the intake manifold. I chose
not to disconnect the fuel lines from the injector rails,
or to remove the rails or injectors from the manifold. This spared
me from depressurizing the fuel system. After removing the nuts
and bolts from the manifold, I tapped downward on the top surfaces
of the manifold with a rubber mallet. The manifold came free
with a couple of taps. The manifold-to-head gasket did tear in
a couple of places, but I'd planned on buying a new gasket anyway.
(Don't expect to find a manifold-to-intake plenum gasket at a
non-factory place. I didn't actually try, but I wouldn't count
on it. Ours survived intact.) I gently folded the manifold on
its three fuel system hoses backward so that it rested upside
down on a pad over the passenger fender.
- Removing Valve Covers and Rocker Assemblies
- Now that the intake's out of the way, you can pull the valve
cover(s) (if you didn't already have them off for the guide inspection.)
- *NOTE: Remember to stuff rags into the oil return passages
cast into the heads, to prevent small parts from dropping through
during the following operations.
- *NOTE: When removing the rocker shaft assemblies, it is likely
that one or more of the hydraulic lash adjusters will fall out
of the rocker arms. These 7/16" diameter, 3/4" long
steel lozenges are recessed into the valve end of the rocker
arms, and are only retained by oil viscosity. When they fall,
the adjusters are easily retrieved from beneath the cam (the
typical place they'll fall) or other cavity with a magnetic parts
retriever. Upon reinstallation, dip them into grease to stick
them in the rockers during handling. Keith
Vickers' Web account suggests securing the adjusters to the
rocker arms with wire twist ties. Would've been a pretty good
idea, if I'd remembered.
- Getting the rocker shaft assemblies on and off was a pain.
Because some of the valves and rockers are open and thus under
compression, the rocker shaft assemblybolts must be removed a
quarter turn at a time. Each of the eight bolts takes many of
these quarter turns to remove. Because of my own errors (detailed
later) I ended up removing and installing the rocker assemblies
some five times (twice in front, thrice on the rear head.) I
made the mistake of following a manual's instructions and removed
all the bolts before removing the cam assembly. Mistake. The
bolts should stay in the assembly during removal, temporary
storage, and installation. Otherwise, the springs between the
rocker arms will push the cam bearing bosses and rocker arms
off the rocker shafts. You'll be faced with many separate pieces,
which the factory manual points out must be reassembled
in the same order.
- Place the removed rocker assemblies on a clean surface (a
sheet of newspaper will soak up some of the oil which will drain
from the assembly.) If you can set them on their sides, you might
avoid having either the bolts or adjuster fall out. It proved
useful to go ahead and stick the adjusters in the rockers with
grease to keep them in place while they're set aside.
- Carefully remove the two rearmost bolts (furthest from the
pulley) and the associated cam bearing cap from the rocker assembly.
The endmost springs and rocker arms will threaten to spring off,
so be advised. Now reinstall the cap on the head. Without it,
the free end of the cam can be levered into the air when the
engine is turned, possibly slipping off the pulley and resulting
in loss of crank-to-cam synchronization. I should know - this
happened to me! (more about that later)
- Compressing/Removing the Valve Springs
- I did the front valve stem seals first, because they were
easier, and I hoped to learn some technique before proceeding
to the awkward rear head.
- I'd intended to use a technique for holding the valves in
place I read in the Haynes manual - stuffing the cylinder with
nylon rope instead of using compressed air. If I could have done
that, it would've saved me some grief - more about that later.
As it turned out, I couldn't get access to the spark plug holes
to stuff the rope. Because of a sheet metal heat shield between
the exhaust manifold and the spark plugs, I couldn't get my fingers
within 4 inches of a plug hole. Pushing a rope across a four
inch gap to stuff a cylinder is less than practical. So I went
with the traditional method of using compressed air.
- (*NOTE: because of the 4 inch access problem, you'll want
to use a spark plug/air compressor device that uses a piece of
flexible hose. It'd be really difficult to use some of the spark
plug/air adapters which are solid metal)
- The preferred technique for pressurizing the cylinders is
- rotate the engine by hand to TDC for the current cylinder;
this will require either using a probe in spark plug hole or
using the distributor position (provided the distributor hasn't
been removed; now rotate the engine slightly past TDC,
so that it's on the downward part of a stroke; then secure the
ratchet on the crank so that it prevents rotation of the engine
in the forward direction (clockwise as viewed from the pulley
end); if the ratchet handle is long enough, you can rest/clamp
it on the passenger-side halfshaft
- *NOTE: the reason for doing this step is to provide some
insurance that the valve won't drop completely into the head
in case of accident or malpractice - I don't actually know
that it'll keep the valve from falling past the end of the guide
- the consequence of that occurring is removal of the
cylinder head; which would be BAD
- Here's where a semi-disaster occurred:
- I thought I realized at this point why one account
I'd read didn't worry about keeping the engine from turning when
pressurizing the cylinders: since the rockers are removed from
the head, it wouldn't seem to matter whether the engine was at
TDC for that cylinder or not. The valves will always be closed,
in any crank position.
- However, I'd completely missed the argument that keeping
the current piston near TDC might save a valve from falling through,
so I chose to let the engine turn. I was very lucky that I dropped
no valves. You probably shouldn't take the same risk.
- The bigger problem was the unsupported cam problem, mentioned
at the end of "Removing Valve Covers and Rocker Assemblies,"
above: the cam bearing caps are part of the rocker shaft assemblies
recently removed. When the rocker shaft assemblies are out of
a head, the cams are merely resting on the lower bearing surfaces
and a seal around the shaft between the cam pulleys and the inside
of the head. Every time I connected the compressor air supply
to the spark plug adapter (without concerning myself with the
current cylinder's position,) the engine would spin a partial
turn until that piston was at BDC. A couple of times, the non-pulley
end of the cam violently lurched two or three inches up off the
head, levering itself on the front seal. This was really distressing.
On the front head, I was so disturbed by this that I removed
the top cam bearing cap from the end of the rocker shaft assembly(this
was before I figured out that I could leave all the bolts in
the rocker assembly) and bolted it in place at the rear end of
the cam. (In fact, Keith
Vickers did suggest this very procedure, which I'd
forgotten by time I was working on the engine. Just goes to show
that I shouldn't trust my memory. Perhaps yours serves you better.)
Later, I would attribute losing a couple of teeth's worth of
cam timing to these incidents. I would eventually reset the cam/crank
timing by manually tilting up the rear end of the cam and slipping
the belt off the pulley. I don't know what kind of damage these
abuses did to the front cam seals.
- Do this at your own risk: If you're willing to forgo the
insurance of leaving the piston at TDC to keep a valve from dropping,
or just believe that having the cylinder at TDC wouldn't help
anyway, here's a method that would save you from locating TDC
and restraining the crank's turning for every cylinder. If you
could put a socket and breaker bar on the crank pulley bolt and
clamp the breaker bar to something (the halfshaft is convenient
in the Caravan) to prevent its turning in either direction,
that would work. You would want to wedge something between the
inner fender and the breaker bar to make sure it didn't slip
off the bolt head. It's critical that you prevent rotation
in either direction, since any given piston might be either
before or after TDC, and you couldn't predict the
direction of rotation.
- *CAUTION: If the engine does move under 100+psi of
air pressure while there is a tool connected to the crank, you
could injure yourself or damage part of the vehicle.
- You could leave this rig in place for the duration of the
valve stem seal work, as there's no reason to rotate the engine
during the procedure (if you're not trying to catch falling valves.)
- If you have a manual transmission, you can avoid all these
engine-securing procedures, and simply leave the vehicle in gear
and set wheel chocks and parking brake.
- Compressing Valve Springs and Replacing Seals
- The K/D compressor worked well. I could only grab a little
less than two thirds of the spring, which was a little disappointing
at first. Compressing two-thirds of a spring left a little more
than 1/4" of clearance. But it proved adequate, requiring
a "special technique." Almost none of the top spring
retainers released easily from the valve stem keepers. I tried
banging on the spring compressor with my hand - this worked on
the first intake valve. But the exhaust valve was really stubborn.
I could bang so hard that it'd pop the exhaust valve open, even
against 100psi from the compressor. The system I eventually worked
out was this: stuff a little piece of rag or paper towel on top
of the top of the valve, between the arms of the compressor,
to catch any keepers that might shoot out when they release (one
of mine did, in fact, do this - leading to a prolonged search
about the engine compartment - the towel trick was developed
at this point.) Then I'd place a small drift somewhere on the
top of the retainer and tap lightly with a hammer. Eventually
the spring assembly would drop to the head, and I'd remove the
keepers with a magnet. Now I could slip the spring off the valve.
- *CAUTION: It's critical at this point that you not lose air
pressure from the compressor. Likewise, a hard enough tap on
the top of the valve stem might pop it loose, even with air pressure.
If you drop the valve into the head, and you haven't left the
piston at TDC, it'd be really ugly. Again, I don't know that
a piston at TDC would catch the valve high enough to leave
the stem accessible. Nor do I know if a valve could be recovered
without removing the head.
- The Haynes manual suggests at this point that you slip a
rubber band around the valve stem (small nylon wire tires fit
well into the keeper grooves,) so that you can de-pressurize
the cylinder and check the valve by hand for straightness and
guide condition. If you aren't going to check these, you
can just leave the air compressor connected and go on to installing
the new seals.
- The old valve stem seals I removed with a pair of slip-joint
pliers. They require a little effort to remove. Be careful: it's
easy to slip off, and potentially nick a valve stem. Go slowly
and twist the seal back and forth around the guide, with constant
upward tension. The seals often release suddenly, so keep your
face clear of the pliers (especially while you're bent over the
engine working on the rear head.) Now choose a tool to help tap
down the new seals. I used a 1/4" drive 1/2" deep socket.
It should fit around the narrow part of the stem seal without
touching the top of the soft seal, and evenly contact the top
of the metal shell. It's important not to damage the narrow part
of the seal or its little spring.
- *CAUTION! It is CRUCIAL that the socket (or whatever tool
you use) not touch the top of the valve stem. Test fit your proposed
tool on the new seal and on the bare valve stem and guide. You'll
be tapping on this with a hammer - if the socket came into contact
with the top of the valve stem during the tapping, you might
tap the valve into the head, despite the compressed air. That
would be BAD.
- To install the new seal, oil the stems with fresh engine
oil, and slide the seal down until it contacts the guide.
- (One account I read said that the new seals should come with
some kind of installation sleeve that slips over the grooves
in the valve stem, to prevent damage to the new seals. I received
no such sleeves, and only noticed this in print after
the job was done [notice a trend here?] For what it's worth,
most manuals merely mention oiling the stem before installing
the new seal.)
- Press down as much as you can with your fingers. Now slip
the socket carefully over the valve stem until it rests on the
seal. Tap on the socket with a rubber mallet until the seal bottoms
on the guide.
- Valve Spring Reassembly
- Put a glob of white grease on the keepers during reassembly
to stick them in place on the valve stem during reassembly. Use
a magnetic retriever whenever possible to keep from dropping
parts. Make sure the keepers seat when you uncompress the springs.
- Final Reassembly
I'm going to wimp out and hope that you can figure out
most of the reassembly yourself. Here are some notes:
- Remove the end cam bearing cap from the head and carefully
reassemble it with the rest of the rocker shaft assembly. The
bolts will hold the endmost rockers, springs and bearing cap
in place while you move the assembly back to the head.
- Put a 3/8" long, 1/16" strip of Permatex High-Temp
RTV (oxygen-sensor safe) at the corners where the round seals
or bearing caps meet the flat machined surface to which the valve
- Place the rocker shaft assembly on the head, being careful
not to knick any cam bearing surfaces. It might take some wiggling
to seat the assembly. I felt the gaps between the cam bearing
caps and bosses with my fingers to determine whether it was going
together symmetrically. Now thread the eight rocker shaft bolts
with your fingers until they just contact the cam caps. It's
important again to run them down equally to prevent bending or
breaking the rocker shafts. It's only important that the bolts
progress an even depth into the head, even though the
loads on the individual bolts during tightening are very
different (because some of the valves will be open.) They'll
finally be torqued very lightly, so be gentle with a ratchet
as you get close to seating the bolts.
- Tighten rocker shaft bolts in several steps, to a final torque
of 180 inch-pounds. Work from the ends of the shafts toward the
[Table of Contents]
- There's no single timing reference mark on the crank which
is easily identifiable as TDC. There are three notches
in the multi-v crank pulley (serpentine belt) closest to the
front of the engine, but none are distinct. Through experimentation,
I determined that one was probably TDC. At that time I thought
that there were four notches. The notches apparently serve
as references for some sort of "magnetic" diagnostic
sensor mentioned in the factory manual. One of them is, I guess,
also TDC. I say "I guess," because when I had the whole
front of the engine open to replace the timing belt (and find
out once and for all where TDC was) that I thought the
existing notch was a couple of degrees off when using the actual
TDC crank mark (under all the pulleys and vibration damper.)
One of the notches also provides the only mark that I've found
to reference with a timing light. There is a stamped gauge
calibrated in degrees (BTDC) which would indicate that (one of
the) notches is the appropriate index. I beat a divot in the
multi-v pulley with a centerpunch, so at least I'll be able to
find TDC in the future without fishing around in a spark plug
hole or taking apart half the engine.
- NOW, after the fact - here's how to establish Compression
TDC (provided the distributor-to-cam-to-crank relationship hasn't
- Remove the distributor cap; look inside - *IMPORTANT: the
contacts inside don't line up with the sockets for the
ignition wires on the outside of the cap; THIS IS CRITICAL: determine
which of the inside contacts goes to the number one cylinder
(located on the passenger side closest to the firewall); make
a mark on top of the uncovered distibutor housing which is directly
under the number one contact INSIDE the cap. On our engine, the
#1 contact was slightly rearward of pointing at the driver's
(left) side of the car.
- Remove the front (nearest the radiator) cam pulley cover;
it takes three 10mm bolts, the bottom one is long; you can now
see the reference mark for the cam on the engine-front (pulley
end) side of the cam pulley - it's a "v" shaped mark
pointing toward a tooth on the pulley - it's probably got a dab
of yellowish-white paint on it; there's a reference notch at
about 11 o'clock on the stamped steel pulley guard (the rear
cam's reference mark is at around 1 o'clock in a cast piece)
- With the coil wire and battery disconnected, put a 22mm socket
on a 2 inch long 1/2" drive extension on a long-handled
ratchet (a flex-head works well); set it to turn clockwise; put
it on the bolt in the center of the crank pulley (it's much easier
to get past the A/C hoses if the top radiator hose is off, but
it requires draining some coolant - which is pretty easy in the
Caravan, its radiator has a stopcock.)
- Now turn the engine clockwise (I did this a lot with the
spark plugs still in; it's harder to turn, but it's a
serious bitch to remove/install the rear plugs); every two revolutions
of the engine, the cams and distributor turn once. That is: the
crank to cam ratio is 1:2 and the crank to distributor ratio
is 1:2. When the cam marks get close to their tell-tales, watch
the rear crank pulley for the next notch to come around. When
the crank notch lines up under the "0" mark on the
degree indicator, the cam indicators are on their tell-tales,
and the distributor rotor is pointed directly at the #1 cylinder
contact, the engine is at "compression" TDC
(there is an exhaust TDC as well, every other engine revolution
- where the cam indices are 180 degrees from their reference
- If you've lost distributor timing because the engine
was moved when the distributor was out of the engine, and you're
confident that you have maintained cam-to-crank timing, then
you could do the crank and cam marks only and put the
distributor in so that its rotor points at the "inside"
[Table of Contents]
I'm really not sure now if what I thought went wrong
at the end of day two ever went wrong. Here's the week:
- Day 1, Monday 5/6/96: started taking apart engine, discovered
that there was much more to disassemble than either the manuals
or Internet account suggested, including:
- The alternator must be removed to allow rear valve cover
- After seeing five "in-vehicle" valve spring compressors
in the store, I can't really imagine what compressor would
fit between the intake valves and the underside of the intake
manifold runners. I ended up removing the intake plenum and manifold
- removing all ancillary connections to the manifold but leaving
the injectors installed and the fuel lines connected; this required
new intake manifold gaskets and cleaning the old gasket faces;
as a result of removing the manifold, I think that rear head
access for doing the stem seals was substantially improved.
However, I ended up removing/installing the rocker assemblies
several times with the manifold re-installed with little difficulty.
- One of the things you'll have to remove from the intake manifold
is the metal pipe connecting the EGR valve to the intake plenum.
On our engine, the EGR pipe was nearly plugged with a thick black
goo. I suspect that this is engine oil passing out of the exhaust
system (which is why you're doing this job) re-ingested through
the intake. It took a bit of doing, but I swabbed this pipe out
with lacquer thinner on several pieces of rag tied to a piece
of cord. I fished a piece of bailing wire through the pipe to
thread the cord through.
- Additionally, the intake plenum, intake manifold, and the
inside of the throttle butterfly were coated in black crud. I
chose not to pull apart the intake plenum halves - it looked
like more of a problem to re-seal the halves than any problem
caused by the crud. The inside of the nipple on the intake plenum
where the EGR pipe attaches was nearly gooed shut, too. You'll
have to pull the throttle body off the intake plenum to fish
the hole clean. The intake valves were kinda sooty, too, but
I deemed that unnecessarily difficult as well. Suit yourself.
Here's why I had to retime the cam:
- Doing the actual valve spring seals wasn't too bad, considering
the rest of the operation.
- My most critical mistake was misinterpretation of the distributor
diagram and instructions from the factory manual. The diagram
illustrates that the contact points inside the distributor
cap are not aligned beneath their corresponding plug wire. However,
both the contact points and the plug wire connections are numbered.
The manual should have labeled the distinction between contact
point (spark gap from rotor) and the place where the plug wires
plug into the distributor. I must admit, I'd never considered
distributor caps that weren't "straight through," from
inside to out - and I can't figure out why they've done that
here. So even though I'd seen the diagram a number of times,
every time I tried to position the ignition rotor "directly
beneath the contact for number one cylinder," I was nowhere
near correct. Which probably means that I lost at least a whole
day's work (or re-work) of the cam timing because I thought I
was doing the ignition timing correctly.
- So I got through the front seals on Day 1, and left the other
half and engine reassembly for Day 2.
- I'm pretty certain that the first time that I fully assembled
the engine on the eve of day two, the cam timing was probably
off. The starter turned the engine over at what sounded like
a much greater speed than normal. And with less strain. I suspect
that there were no cylinders compressing at all - both cams out
of time. I'm less certain about the retiming I did later that
day. It sounded better when I tried to start, but still didn't
run. I may in fact have gotten the valve/cam timing right and
still didn't know that my ignition timing was wrong.
- So Day 3 was kinda short, as I was weary and muscle-sore.
I spent a couple of hours under the hood, mostly looking for
a timing mark on a crank pulley that I'd missed. No such luck.
In retrospect, I'd successfully found the correct of three possible
notches in the block-most pulley by probing the number one spark
plug hole with a coathanger wire and turning the engine by hand.
But at that point, I was convinced that there was no actual
visible TDC mark, and thought that I was having to depend on
my own devices. So I unnecessarily removed: the front engine
mount; mounting plate; A/C idler pulley assembly; serpentine
idler pulley assembly; and the two bolts mounting the power steering
pump to the mounting plate. Not to mention replacing the timing
belt - the old one looked flawless. I looked in my in-laws' old
service records and found no mention of timing belt work. Perhaps
the previous owners had done a replacement.
- After a couple of hours on Day 3, I decided that I'd take
a break for the remainder of the day (Days 1 and 2 were 12-15
hours long.) I decided that the only way to approach the cam
timing problem was to take the passenger engine mount parts off
and treat it as a timing belt change. I decided that it was sensible
to go ahead and put in a new timing belt, even though
the old belt appeared healthy - as much as I could see it with
the cam gear covers removed. I knew that with both crank pulleys
removed and the vibration damper removed, I'd be able to see
the crank TDC mark for certain.
- So on Day 4, I started afresh as a timing belt job. It was
a good call, in that I didn't have to look at the cam/rocker
assemblies again. It proved a bit tedious, but not as bad as
the timing belts had been on our two 2.2 liter Dodge Shelbys.
- Wednesday evening (Day 3,) I dropped by a friend's house
and borrowed his timing light and a two-sided steering wheel
- I began Day 4 by shopping for a tool to hold the crank while
breaking loose the 110 ft/lb 22mm bolt holding the pulleys/damper.
At a local tool store, I looked for a "chain wrench"
as suggested by the Haynes manual. But chain wrenches are plumbing
things, and a chain wrench big enough to fit around an 8"
diameter has a handle three feet long, weighs around 70 pounds,
and costs well over a hundred dollars. I considered getting motorcycle
chain and modifying a smaller wrench, but the "smaller"
wrenches were still over $60. After much deliberation, I picked
an aluminum handled thing with a nylon strap long enough for
a foot diameter object for $27. I also picked up a cheesy set
of metric six-point 1/2" drive impact sockets. The only
1/2" metric sockets that I owned were 12-point, and I figured
this was no time to round off a nut.
- To get access to the lower front end of the engine, you'll
need to remove the right front wheel and the plastic inner fender
liner; support the corner of the vehicle securely on jackstand(s)
- you'll also need a floor jack to support the engine separately
when you remove the engine mount
- The strap wrench worked, but not initially. In retrospect,
it might've been more reliable to buy two imported chain locking
pliers (Vise-Grip knock-offs) and link them together to get the
overall diameter. They were only $10 each, so it would've been
cheaper than the strap wrench. The strap wrench slipped on the
smooth outer surface of the vibration damper. Deciding that I
couldn't return it at this point (the fabric strap was pretty
grimy,) I took a chance: after cleaning the damper's circumference
with lacquer thinner, I sprayed both the damper and the inner
surface of the strap with 3M 77 Adhesive Spray. After a few minutes
of drying, I stuck the strap to the damper, tied the remaining
strap to the handle to hold it in place, and laid the handle
of strap wrench on the passenger-side halfshaft to hold it. I
popped a new 22mm six-point socket on my breaker bar, and went
for it. It took some effort, but sure enough, the bolt broke
loose. A borrowed steering wheel puller (a two-armed affair)
did the trick on pulling the damper.
- Once the damper was off, the crank TDC mark was indeed visible.
(During reassembly, I banged my own punch mark on the multi-v
pulley to identify which of the three notches was TDC.) It took
a bit of work to remove the parts to access the timing belt:
- A/C idler pulley assembly*
- serpentine idler pulley assembly
- engine mount (after supporting the engine on a floor jack)
the bottom nut on the engine mount is awkward to access, and
is torqued to around 80 ft/lbs; I've had to remove these on all
three of our vehicles, and I always use a swivel-headed 1/2"
drive ratchet and a socket and reached under the mount from above
If you had a very long 1/2" extension (I don't,) it might
be easier from below in the wheelwell
- A/C compressor*
- A/C compressor mount* (the A/C compressor mount was pinched
against the engine mounting plate, prohibiting removal its removal)
- engine mounting plate* (and the tricky through-the-pulley
15mm bolts holding the power steering pump to the plate)
- the lower timing belt cover (plastic)
- *note: when reinstalling these parts, the bolts for the A/C
idler pulley assembly must be at least started before tightening
the A/C compressor mount; it might be prudent to tighten the
engine mounting plate bolts afterwards, as well
- The preceding procedure probably wouldn't have been so hard
if I'd expected to remove the A/C compressor and mount - they
weren't mentioned in manuals. I had a bit of trouble removing
the big stamped steel engine mounting plate once it was free
- this was remedied by jacking up the engine a little to allow
it to clear the mounting boss on the body.
[Table of Contents]
- This started as just a valve stem seal replacement. It turned
into a timing belt change. It was a pretty unpleasant experience,
taking far longer and requiring much more effort than I'd hoped.
- It's only been a matter of days so far, but we've seen no
visible smoking from the exhaust. The engine runs smoothly and
- Update 3/25/97: 10 months and 20,000 miles later, still no
smoke. The Caravan uses around a quart of oil every 3,000 miles
- probably unchanged since doing the valve stem seals. Mind you,
the rest of the engine has 128,000 miles. I'm pretty happy about
that. And as things go, I can't really remember how tough this
was to do. I'm only reading now from my own document, while preparing
it for Web posting, how much trouble I had. C'est la vie.
Ellsworth's Other Pages
(Please: no general automotive questions
- I'm not an expert, this was just an account of my own Do-It-Yourself experience
in trying to solve one problem.)
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Go to David Zatz' expansive AllPar - Chrysler Enthusiast's Site for more tech help and Mopar hobby info.