Timing chain noise?

[Hot Air Beast]

I am trying to isolate what could be possibly causing this noise.

I have an engine knock which gets progressively worse as rpm rises. Noise is worst at above 3000 rpm.

Does not appear to be wrist pin as wrist pin noise is twice the rpm and my noise is not.

Does not appear to be rod/main as I could not isolate the cylinder by removing spark plug wires one at a time and revving the engine - noise remains regardless of load being removed.

Brake stand - revved to about 1300 rpm and noise was gone.

Pulled dust cover and poked/prodded flex plate and checked torque on convertor bolts - all OK

Noise started in late march - drove car 1600 miles at about 65 mile per hour and noise got no worse or better.

A friend who builds 900 hp engines for fun, listened to the noise with a stethoscope last night and is of the opinion that it is the timing chain hitting the tensioner or the cover.

Please give a listen and chime in with your opinion.

Oops - how can I upload an MP4 video file?

 

[EVIL]

Easiest way to upload video is post on YouTube and post link on here.

Has the chain been changed?

D

 

[Hot Air Beast]

Easiest way to upload video is post on YouTube and post link on here.

Has the chain been changed?

D

Thanks, I'll try that. Chain and gears were changed in 2008 (1984 GN)

 

[Hot Air Beast]

try this - first time I ever uploaded to you tube!

 

[TURBOELKY]

Whatever that is it sounds terrible.
Sounds more like a rod knock or piston slap. Idk

 

[ek02]

I would unbolt the converter and slide it back and take a look where the fltwheel bolts to the crank for cracks. Run the engine with the converter disconnected also. If the noise is still there, pull the pan and see what is in it. It's hard to tell what it is from a video, but it sounds bad enough to be a spun rod bearing. They don't always change when you short the cylinders out if it's spun. I hope it's just a cracked flywheel.

 

[Hot Air Beast]

I appreciate all the comments. I would think it to be a bearing, however; it hasn't gotten worse in over 1600 miles of driving and doesn't have as heavy a sound as other bad rod bearings I have heard.

So none of you have ever had a timing chain banging on the tensioner or cover issue, huh?

 

[machinegun]

for giggles have you removed all the drive belts to see if the issue goes away?

 

[Hot Air Beast]

So far I have only removed the AC belt - soon I will remove the alternator/water pump belt. The the power steering.

Will post results.

 

[earlbrown]

I would drop the pan, see what's in there and go from there.

If the chain was replaced in 08 with a parts store chain (or a not-expensive double roller) it's probably time again.

If it was replaced with a double roller AND a tentioner, you'll find the plastic part of the thentioner in the oil pan and the metal part banging against the chain.

 

[Hot Air Beast]

I would drop the pan, see what's in there and go from there.

If the chain was replaced in 08 with a parts store chain (or a not-expensive double roller) it's probably time again.

If it was replaced with a double roller AND a tentioner, you'll find the plastic part of the thentioner in the oil pan and the metal part banging against the chain.

You might well be right. First I am going to eliminate a worn water pump. Just curious - I didn't think I could actually remove the pan completely on a 1984. I have also heard that I could if I remove the torque converter dust cover and drop the crossover exhaust pipe - any clues here?

 

[Hot Air Beast]

Another fact I haven't mentioned is that the noise began a day or so after a local garage in Bonita Springs Florida swapped the intake manifold because of a crack and leaking coolant. There are no moving parts in the intake but who knows - strange things always happen to me. Maybe the wrong pan gasket was used and it is hitting something????

 

[Hot Air Beast]

Another thing I forgot - oil pressure hot at idle is 22 psi and the oil pressure sending unit and electric connector are new as of late March 2016.

Ask me any questions you might think of - who knows what else I have forgotten to mention.

 

[TURBOELKY]

have you ever thought about converting to an 86-87 set up? If something is wrong mechanically that is going to cause need for a rebuild, might be a good idea. Car looks like it's in good shape just from what little I see in the video.

 

[earlbrown]

Since you had the intake R&R'd I'm wondering how much antifreeze you might have in the oil pan. That's not good.

I don't have a hotair car but I know for a fact you can pull the crossover and oil pan on an intercooled car. I have to imagine there's the same amount of room down there.


If something was hitting the pan, you'd know it! From what I could tell minus the wind noise, the frequency was too fast for a bottom end noise. And it seemed too deep to be a broken rockershaft.

Plus you wouldn't get 1600 miles out of a broken shaft, they curl right up and lose a cylinder.

 

[EVIL]

Have you check the oil for metal?

D

 

[Hot Air Beast]

I am the second owner and bought the car in 1988. I have kept it stock all the way. it is in reasonable shape. Raised the body a few years back to replace all body/frame rail cushions. Runs tight. Over 400,000 kms (240,000 miles) and I was really happy until March 2016. Don't really want to try and replicate an '87.

I was running Royal Purple on the ride home from Florida and switched to Rotella T 15W40 when i got home. No coolant in the oil. Visually checked the oil and ran a magnet through it. No sign of metal. Should have cut the oil filter in half but didn't think of it - so sad.

I tend to agree with Earl - probably not bottom end.

i intend to start it up without any belts, just long enough to hear noise still there or not. If noise still there then it is not likely water pump or power steering. Have already eliminated A/C bearing.

Still leaning towards timing chain/gears.

Thanks again to all of you. It has spurred me to search the board and learn from others. the timing chain replacement document from Eric is a good read - just wish there was a document like this for 84-85 so I wouldn't have to read between the lines.

 

[Hot Air Beast]

The chain and gears installed in 08 were GM OEM and that was about 80,000 miles ago.

 

[earlbrown]

80K and 8 years... It's time for the next swap.

 

[jayp57]

If it is the chain if you put a long screwdriver against the cover and to your ear you will know....I also agree to unbolt the converter and run it. The flexplate could be a cheap fix.