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3.8 Timing Chain

45K views 26 replies 16 participants last post by  JKunlimited07 
#1 ·
I've had a chattering noise coming from the bottom front of my engine now for 3 months... it sounds like a diesel but not in a good way :pissed:
So far I've replaced the water pump, idler pulley, and eliminated the other mounted components like A/C compressor, and power steering.

The only thing left is the timing chain.

I'll be tackling this project in the next week or so and would like to know if anyone has done this yet, and if the 3.8 has a timing chain tensioner.

Any tricks/ advise would be appreciated!



I have the vague Jeep maintenance manual and all the basic appropriate tools including a sprocket puller.

(No more warranty:bawling:)

Thanks!
 
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#2 ·
If that is a picture of a 3.8, then no tensioner. If you want step up to a double roller type chain it shouldn't cost you much more.

Have you checked the oil pump? Depending on the type it could make a racket too.
 
#3 ·
Take the bolt off the cam gear, when you start to pull it the chain will get loose when the gear comes off the cam. When you go to put the new chain on make sure that the cam and crank is in the same position. Put the chain on the crank rod then put in on the cam gear and start to slide it on. Make sure that you are still lined up.


The best way to do this is make sure the motor is top on #1 cylinder.
 
#4 ·
x2, be on TDC compression stroke for cylinder one. Do not turn the engine over after it's there. You'll likely need a gear puller or two to get this done.

The engine ever ingest water? How many miles? Timing chains are usually good for...ohh about 100,000-200,000 miles without problems. (my point being it's pretty unlikely!)
 
#5 ·
The engine ever ingest water? How many miles? Timing chains are usually good for...ohh about 100 said:
I'm at 40k and agree the timing chain is unlikely to be jacked...

Somethin's makin the diesel sound and while the chain cover is off, I plan to measure the oil pump rotors. The oil pump may be the source of the racket. :beer:

The engine has not been abused and has never ingested water.
 
#6 ·
I would say that an oil pump is much more suspect than the timing chain--have NEVER had a timing chain issue on any Jeep in the last 12 years.

I assume you eliminated all the easy stuff first, like exhaust leak, loose bolts on the manifold, etc.?
 
#7 ·
Yup- I'm certain the easy stuff is "out".

After I open the cover, the current plan is to measure chain play, and look at the cover for wear.
Then I'll measure the oil pump rotors (as specified in the maint manual)

Taking a good look inside the oil pan in on the list also...

If the timing chain looks fine- I'm certainly going to leave it alone ;)
 
#9 ·
If your burning oil its not the oil pump doing that.
 
#15 ·
UPDATE

After dissasembling half the engine, I found wear on the inside of my timing chain cover

---This is what I thought the problem was---

According to the service manual, you can have up to 1/8" play in the chain... I had exactly 1/8", so I replaced the chain set.

Then I blended the wear area on the cover to prevent future chain contact.




While I was at it, I replaced the oil pump also ( which measured out OK)

A warranty would have covered this if I had it.....AND if a dealer actually admitted there was a problem.

I was quoted $1,800.00 to look at/ replace the timing chain, and I did it with basic tools and a rental crank puller.

Ten "good" hours in the Garage and $120 bucks :beer:
 
#21 ·
After dissasembling half the engine, I found wear on the inside of my timing chain cover

---This is what I thought the problem was---

According to the service manual, you can have up to 1/8" play in the chain... I had exactly 1/8", so I replaced the chain set.

Then I blended the wear area on the cover to prevent future chain contact.




While I was at it, I replaced the oil pump also ( which measured out OK)

A warranty would have covered this if I had it.....AND if a dealer actually admitted there was a problem.

I was quoted $1,800.00 to look at/ replace the timing chain, and I did it with basic tools and a rental crank puller.

Ten "good" hours in the Garage and $120 bucks :beer:
Where exactly did you find the wear on the timing cover and what do you mean when you say that you "blended" the wear area? Was the oil pump a dealer/Mopar item?

Thanks for this thread, btw.
 
#18 · (Edited)
I realize that I'm bringing this thread back from the dead, but is this how your bad timing chain sounded?

http://youtu.be/vjVFsOZVd6s

I have 50k on mine. I thought it was a lifter at first and pulled the heads and replaced them all with no results. Pulled the pan last week and found this, so I'm thinking I have a dead-ringer.

http://youtu.be/fQfGKHAsIGY
 
#19 ·
That looks like a lot of swap, but here is how to measure the chain and sprockets for wear:

STANDARD PROCEDURE - MEASURING TIMING CHAIN WEAR

1. Position a scale next to timing chain so that any movement of chain may be measured.

2. Position a torque wrench and socket on the camshaft sprocket attaching bolt. Apply force in the direction of crankshaft rotation to take up slack to the following torque:
41 N·m (30 ft. lb.) with cylinder heads installed
20 N·m (15 ft. lb.) with cylinder heads removed

NOTE: With torque applied to the camshaft sprocket bolt, crankshaft should not be permitted to move. It may be necessary to block crankshaft to prevent rotation.

3. Hold a measuring scale along edge of chain links.

4. Apply force in the reverse direction to the following torque:
41 N·m (30 ft. lb.) with cylinder heads installed
20 N·m (15 ft. lb.) with cylinder heads removed

5. Measure amount of sprocket/chain movement.

6. Install a new timing chain and sprockets if movement exceeds 3.175 mm (1/8 in.).
 
#22 · (Edited)
Sonova.....I have the SAME issue. I just bumped a dead
thread about it too!

I took it into the dealer and even spoke with the Service
Manager. They say its a rod.....I say, its as much a rod
as it is the Glow Plugs.

It is the EXACT noise.

EDIT:

Here is my first post.....I deleted it so it wouldn't be posted in two threads:

I hope nobody minds if I bring this back from the dead but....

I'm having this same identical issue. I took it to the Stealership
and they tell me its a ROD! I am having the EXACT noise, exact
scenario. They WILL NOT listen to what I am suggesting.

It only ticks when warm. It ticks only at idle. I have no power loss.
It sounds like a diesel.

I just listened to a VM from the Service Manager and he states:

"I had 4 different techs listen to the tick and we have determined it
was the rod....The #4 rod to be exact." -Exact quote.

So...they have requested ALL of the records for oil changes.
I'm guessing so they can get out of the warranty work.
 
#24 ·
[subscribed]

I have a very similar sound. It has been diagnosed as being bearings in the transmission to a loose cat in the exhaust. But I think this just may be it. I'll try to get a better listen to the front of the engine. Its tough to nail down because it isn't always present.

Similar to as red_smoke stated, it's not common when engine is cold and depending load. Can be duplicated though in second gear by driving with the brake pedal slightly depressed.
 
#25 ·
Cover removal diagram

Like others, I'll apologize in advance for both bring to life an old post but also for posting what may seem like an elementary question. Would anyone be able to provide information for removing the timing chain cover? Pictures, videos, diagrams. I'm looking for bolts and pulleys that need to be removed. I have the oil leak problem that tsb 09-008-07 addresses with the leaking cover causing oil EVERYWHERE. Don't want to just start pulling unnecessary bolts and pulleys.
 
#26 ·
Like others, I'll apologize in advance for both bring to life an old post but also for posting what may seem like an elementary question. Would anyone be able to provide information for removing the timing chain cover? Pictures, videos, diagrams. I'm looking for bolts and pulleys that need to be removed. I have the oil leak problem that tsb 09-008-07 addresses with the leaking cover causing oil EVERYWHERE. Don't want to just start pulling unnecessary bolts and pulleys.
If you haven't started already I have and am doing this procedure on my 07. First drain engine oil; remove serpentine belt and everything it touches including: alternator, power steering pump, AC compressor, belt tensioner, water pump pulley, and vibration dampener pulley; drop the cover that's directly below the flywheel; drop oil pan and it's spacer(?) as a unit; remove lower radiator hose and drain coolant; remove/unplug sensors on cover; unbolt cover and remove with oil sump tube attached. Easy right?... Expect to work for a day or two solid (took me around 5 hours just to get cover removed) and go ahead and replace timing chain assy. as well, you don't really want to do this again.
 
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