Need some help diagnosing warm engine only, rpm dependent engine rattle 96' FZJ80 (1 Viewer)

[M0untaineer]

Howdy guys- could really use some help diagnosing a warm engine only (only when at normal operating temp 190+), RPM dependent (around 1265 and 2200 rpm), ONLY when in DRIVE, engine rattling that seems to be coming from the front (bumper side) of the engine...no decrease in engine performance, spark plugs pulled and look normal (no pre-ignition signs), using a little oil (about normal for this engine), coolant normal.

I've included a video of the sound at 1265 rpm...as soon as you go above or below, the rattling noise abates... no obvious heat shield rattling detected...I have gotten P420 codes before, but doesn't seem localized to the cats...seems to be coming directly from engine front...Bobby at CruiserCo was kind enough to take a look and said he thought it might be dieseling...seems like classic dieseling involves wanting to run after shutting off though? Any thoughts guys?

 

[fjfodee]

Was this a progression or an all of a sudden type thing?

 

[M0untaineer]

Was this a progression or an all of a sudden type thing?

I guess I'd have to say kinda all the sudden...although the higher RPM rattle around 2200 or so RPM is fairly recent and it seems to be getting worse (more pronounced)...

 

[fjfodee]

Wish I had an answer Eli. Can you pinpoint whether it's coming from the front or up top?

 

[M0untaineer]

Thanks...Really hard to tell Mark...I'm thinking front if I had to pin it down...I wanted to see if anyone could help rule out pre-ignition...I would think the spark plugs would show some signs of that if that were the culprit right? I'm kinda wondering if it might be something to do with the timing chain, but I would think you'd hear that sound even when in neutral/park...Idler Pulley?

 

[fjfodee]

Before you get too involved, get a mechanic stethoscope or a stick of brake line tubing (works pretty good) and try to find exactly where it's coming from. Start simple and go from there.

Edit: Just saw your post in the 80's section. Seafoam is dang good stuff...

 

[M0untaineer]

Before you get too involved, get a mechanic stethoscope or a stick of brake line tubing (works pretty good) and try to find exactly where it's coming from. Start simple and go from there.

Edit: Just saw your post in the 80's section. Seafoam is dang good stuff...

Thanks Mark...do you recommend it being added only to fuel or to oil or both?

I'm also gonna try thicker oil...been runnin Rotella T6 5w-40 for awile and wonder if that will make any difference compared to some regular 10w-30

 

[fjfodee]

Thanks Mark...do you recommend it being added only to fuel or to oil or both?

I'm also gonna try thicker oil...been runnin Rotella T6 5w-40 for awile and wonder if that will make any difference compared to some regular 10w-30

I've never used it in oil, but know plenty who have. Would be worth a shot. I would try 10w30 as well.

 

[M0untaineer]

Ok...10W-30...no change whatsoever...gonna check/adjust timing next I think...

 

[YotaJosh]

From what I heard the other day, I'd pull the valve cover and check the valve clearances.

It's a regular maintenance interval adjustment:
Valve Adjustment 1FZ-FE - WHEN????

 

[M0untaineer]

From what I heard the other day, I'd pull the valve cover and check the valve clearances.

It's a regular maintenance interval adjustment:
Valve Adjustment 1FZ-FE - WHEN????

Thanks Josh.

 

[Bama4door]

I wonder if a valve guide or spring is worn/damged and one of the valves is floating freely inside. I would take the cover off and see what you can find. Hopefully it's just the clearances out of spec.

 

[M0untaineer]

I wonder if a valve guide or spring is worn/damged and one of the valves is floating freely inside. I would take the cover off and see what you can find. Hopefully it's just the clearances out of spec.

Thanks Cole- That's a possibility for sure...in talking with my Dad today, I kinda wonder if it's drivetrain related however since it will only produce the sound when in gear...however, the fact that it only does it once the engine gets warm makes me think that it's originating from the engine...

 

[fjfodee]

Have you isolated the noise yet?

 

[M0untaineer]

Have you isolated the noise yet?

Thanks Mark...

No, no joy just yet- I'm waiting on my timing light to come in from Amazon tomorrow...gonna check that, then remove belts....


So far I've:
1. Pulled Spark Plugs- All appeared normal (not overly cleaned as with Head Gasket failure or damaged as with pre-detonation)
2. Changed the oil to conventional high mileage 10W30 from the synthetic Rotella T6 5W40 and it definitely ran a little smoother and seems to be consuming less oil.
3. Ran 2 cans of Seafoam in gasoline
4. Ran a tank of 93 Octane

It seems to me that the noise is a bit quieter, but may just be wishful thinking....it is still there for sure at the same 1265 rpm range...It seems to me that the higher RPM range may have quieted down a little...really hard to tell though since I was driving on the highway with rainy and windy conditions that mask the noise...

Gonna see what the timing check yields...was gonna just take it in and get it checked, but auto shop wanted $90+ for something that I'm sure I can easily do with a $33 dollar tool, a youtube video and an hour of time...

I also ordered some Redline SL-1 fuel system cleaner that folks seem to swear by (I guess it has a high concentration of PEA (polyether amines) which seem to be the way to go to help clean out carbon deposits...

So far people have suggested that it could be:

1. Pre-detonation
2. Dieseling
3. Valves (adjustment or spring)
4. Idler Pulley
5. Heat Shields or Cats (I've had P0420 codes before, which makes me somewhat suspicious of this one, but the noise seems isolated to the very front/top of the engine)
6. Timing chain guides
7. Dirty/blocked fuel injectors
8. Torque converter/transmission related- Why would it only occur when engine is warm is this was the case?

With daily driving this thing to Little Rock 3-4 times a week now, I'm more concerned with figuring this out

 

[Bama4door]

Have you had someone hold the rom at the 1265 while you check under and around the truck to rule out the cat/shield or TC/trans?

Hope you can get it figured out soon!

 

[fjfodee]

From the sound of the video it kinda sounds like timing. But the circumstances don't add up for that, IMO.

Back in my mini truck days I've heard timing chains sound similar (slack in chain, worn guides/tensioner). Most common was on start up, but I've experienced this at a certain driving rpm. However, that was usually more of a rapping noise that was always the same tempo. Yours sounds more sporadic if I heard correctly.

Doesn't really sound like valve lash. That usually has more of a solid tapping sound. Yours sounds more...hollow...I guess, like advanced timing.

I would think that you would hear it hot or cold, load or no load, if it were injectors.

I've only heard torque converter issues once, and it was similar in sound. I don't believe that is the issue here though. Come to think of it, I believe it was actually a cracked flex plate that was the problem.

Being warm makes me think worn part....tolerances getting opened up. What I'm not sure of is the need for load to produce the sound.

I think you're on the right track. Start simple. If timing checks out, pull the belts and rotate any thing that can by hand.

Just wondering....how did you make the video if it only does it in "D"?

 

[M0untaineer]

From the sound of the video it kinda sounds like timing. But the circumstances don't add up for that, IMO.

Back in my mini truck days I've heard timing chains sound similar (slack in chain, worn guides/tensioner). Most common was on start up, but I've experienced this at a certain driving rpm. However, that was usually more of a rapping noise that was always the same tempo. Yours sounds more sporadic if I heard correctly.

Doesn't really sound like valve lash. That usually has more of a solid tapping sound. Yours sounds more...hollow...I guess, like advanced timing.

I would think that you would hear it hot or cold, load or no load, if it were injectors.

I've only heard torque converter issues once, and it was similar in sound. I don't believe that is the issue here though. Come to think of it, I believe it was actually a cracked flex plate that was the problem.

Being warm makes me think worn part....tolerances getting opened up. What I'm not sure of is the need for load to produce the sound.

I think you're on the right track. Start simple. If timing checks out, pull the belts and rotate any thing that can by hand.

Just wondering....how did you make the video if it only does it in "D"?

Thanks Mark- I definitely appreciate the second look. I'm gonna mess with the timing on Wednesday probably and see what that yields...

Had to enlist the wife's help making the video...foot on brake and pedal down on throttle...probably not the greatest for the drivetrain.

 

[M0untaineer]

Have you had someone hold the rom at the 1265 while you check under and around the truck to rule out the cat/shield or TC/trans?

Hope you can get it figured out soon!

Thanks Cole...since its in Drive to produce sound, kinda limited on crawling around.

 

[M0untaineer]

Ok...checked the timing today...was right at 3 deg BTDC...per the advice of some on the forum, adjusted it to about 6 deg BTDC...gonna see how that does for a little while...

Will remove belts and check that out on Wednesday...