Yet another guy with timing chain issues

[81eagle]

I did timing chains on my '01 and was very satisfied the results.....for about 250mi. The engine started making a rattling sound when warm at idle. The noise continues even off idle and worst at about 2000rpm. I installed a mechanical oil psi gauge to verify oil pres was not the problem. It holds about 20lbs at idle warm and instantly hits 40+ off idle. It jumps to 55+ at cold start. I pulled the belt off to verify it wasn't an accessory causing the noise. It wasn't.

I pulled the engine to verify cam timing and no slipped sprockets. All OK. I noticed that when barring the engine over the rear cassette flops open and closed. Like the tensioner doesn't hold enough pressure on it to maintain tension. The engine also when being barred over has resistance from compression, then goes free just briefly, and this is when the cassette flops. The front cassette does not do this. You can also see where the cassette has contacted the head from the flopping action.

I feel this is my problem. I used shop air to blow into oil passage that feeds the tensioner and it is clear straight to the filter base. No restrictions found.

The engine ran absolutely flawless for those first 200mi. Any input?

This is not my daily driver yet so I am not seriously rushed to complete. I just don't want to remove the engine a 3rd time if possible. THX

 

[boominXplorer]

What brand timing components did you use? The tensioners compressing when manually turning the engine over is normal.

 

[81eagle]

What brand timing components did you use? The tensioners compressing when manually turning the engine over is normal.

It was the Cloyes set. So the tensioner loading and unloading is normal when barring the engine over? Is it due to valve spring pressures sort of causing the cam to speed up/slow down briefly? And hey, thanks for the response!

 

[boominXplorer]

Yes it's just from the cams jumping between the lobes. I recently saw a chain break one of the links and wreck the front chain guide until it finally broke so take a good look at everything.

 

[81eagle]

Yes it's just from the cams jumping between the lobes. I recently saw a chain break one of the links and wreck the front chain guide until it finally broke so take a good look at everything.

Everything looks DOBA (Dead On Balls Accurate). Can you think of anything else that may cause the sound? So just to verify, the cassette moving in and out is normal. Why does the front look rock solid? Just how the engineering worked out with the valve spring arrangement?

 

[81eagle]

Has anyone had issues with the Cloyes set? I should also point out that this is a 4x4 truck, but the engine does not have a balance shaft. Not sure if that makes any difference.

 

[81eagle]

Here is a video of the issue. I am having a hard time wrapping my head around the engine jumping forward. Wouldn't other cylinders be coming up on TDC and buffering the jump ahead? This feels like my dirtbike when you are trying to find TDC before the hard kick. With a single cylinder engine it makes sense, but with 6cylinders it doesn't. I am about to go back in with the engine, and I want to be absolutely sure this is normal. Thanks man.

 

[81eagle]

Well, I put the engine back in and it ran great! For another 250mi. This time I said the hell with it and decided to let it develop. It's hard to fix what isn't broken. Well it made 300mi and died just as I was coming from work one day and I coasted into the drive. I pushed it into the garage and pulled it a 3rd time. Totally disgusted it has sat on an engine stand for about 9mo. Today I pulled the intake and valve covers and found the left timing chain is broken. Getting ready to pull the damper now, and the timing cover. OH BOY!!! What is waiting for me on the inside!? I will be very angry if it is NOT my fault. If there are no signs of an installation mishap, I will be rather annoyed with the Cloyes timing set. Time to put that CAT failure analysis training to use.