Could a stretched timing chain be causing a gutless engine?

Pcleaners2

TJ Enthusiast
Original poster
Joined
Jun 23, 2017
Messages
494
Location
Pacifica, CA, United States
Hey guys in another thread I started was scratching my head about my gutless 4.0 5 speed 4.88geared tj. While it’s probable it could be a bad cat or o2(no codes) I noticed my timing chain is super loose. Kinda almost ridiculously loose.
Could this be the cause of my gutless TJ. 141k Miles
I pulled the oil pan off and noticed this while in process of rear main seal for 3rd time. And I also see a groove in crankshaft where rear main seal is. I don’t feel anything with my fingernail really though. Maybe that’s why it always leaks.!
 
Download your year of the FSM, it has a recommended way to check if your timing chain is stretched beyond acceptable tolerances. There’s little reason to guess on this one.

I think symptoms of that being bad though are typically more in the realm of the cam and crank position sensors being off and related codes (out of sync, random stalling, etc).

https://wranglertjforum.com/threads...ice-manuals-fsm-technical-documentation.4618/
 
Download your year of the FSM, it has a recommended way to check if your timing chain is stretched beyond acceptable tolerances. There’s little reason to guess on this one.

I think symptoms of that being bad though are typically more in the realm of the cam and crank position sensors being off and related codes (out of sync, random stalling, etc).

https://wranglertjforum.com/threads...ice-manuals-fsm-technical-documentation.4618/
So you think the TC slack moving about an inch might be because of cam and crank sensors ? I don’t have any codes at all
 
So you think the TC slack moving about an inch might be because of cam and crank sensors ? I don’t have any codes at all

No, I meant to say the issues in a stretched timing chain seem to often be associated with cam/crank related codes. But an inch does seem substantial, I think the FSM suggests 1/2” as the upper bound. Seems like that could cause any number of issues!
 
No, I meant to say the issues in a stretched timing chain seem to often be associated with cam/crank related codes. But an inch does seem substantial, I think the FSM suggests 1/2” as the upper bound. Seems like that could cause any number of issues!
I c
Yeah it’s crazy at just 141k
It’s well more than 1/2” lol
 
My 4.0 started making some horrible noises about a year ago. I have a thread on here going through my thought process to find the source of the noise. I pulled the valve cover & inspected the bottom end. Then dropped the oil pan. The timing chain was visible and easy to see that it was loose, like an inch or more of play. I thought I'd found the problem & started pulling the grill and radiator to get to the timing cover. My buddy came over about this time and slid under the Jeep. He noticed that the #1 cylinder rod would click if you tried to move it. At that point I knew we were pulling the engine rather than just the timing cover.
In the end the loose chain didn't cause any marks to the guide or cover.... nothing. And that bearing was trashed. I replaced them both but the loose chain didn't cause any problems.
 
My 4.0 started making some horrible noises about a year ago. I have a thread on here going through my thought process to find the source of the noise. I pulled the valve cover & inspected the bottom end. Then dropped the oil pan. The timing chain was visible and easy to see that it was loose, like an inch or more of play. I thought I'd found the problem & started pulling the grill and radiator to get to the timing cover. My buddy came over about this time and slid under the Jeep. He noticed that the #1 cylinder rod would click if you tried to move it. At that point I knew we were pulling the engine rather than just the timing cover.
In the end the loose chain didn't cause any marks to the guide or cover.... nothing. And that bearing was trashed. I replaced them both but the loose chain didn't cause any problems.
Your saying that my Stretched chain isn’t causing the sluggish throttle? I have pretty much thought of everything and my compression is 135-157 roughly. I figured this might be causing an issue with my timing and causing slower response
 
Your saying that my Stretched chain isn’t causing the sluggish throttle? I have pretty much thought of everything and my compression is 135-157 roughly. I figured this might be causing an issue with my timing and causing slower response
I'm saying that after dismantling my engine, the loose timing chain was not giving me any problems. Power was fine. I'd be surprised if it was yours either.
In your case, it seems like you could check/monitor the timing with an ODBII tuner app.
 
The timing chain isn't known for that problem, it usually has no problems making it until it's time for an engine overhaul. I'd suspect something else like a partially plugged catalytic converter, especially since it happens whether the engine is hot or cold.
 
  • Like
Reactions: rasband
The timing chain isn't known for that problem, it usually has no problems making it until it's time for an engine overhaul. I'd suspect something else like a partially plugged catalytic converter, especially since it happens whether the engine is hot or cold.
I removed the cats
They look great (visually atleast- not to say there isn’t an issue )
 
You can also do a crappy test of the catalytic converters by pulling the upstream oxygen sensors and driving. It will throw a CEL and be quite loud, as you've essentially straight piped the engine. But if you get a lot of power back, then you can suspect an exhaust issue.