Knock or clunk on shut down 67S

Lyndon302 · 08:29 PM

Most of the time I shut my engine down I get a clunk or a knock. It's quite high pitched. It's as it stops and under compression it loads the engine backwards. It's coming from the rear of the engine. First I thought it was the cam tensioners. But now I'm not so sure. I've done the top end recently Inc pistons and barrels. and had two sets of tensioners in it.
I have done about 3000 miles in this car since I have it. Always done it. Top end done about 1000 Miles ago. Car runs strong and good oil pressure. Zero leaks. Drive and forget or ??
Lyndon

stownsen914 · 12-28-2020, 05:23 AM

Can you post a sound clip?

Lyndon302 · 01-05-2021, 08:25 PM

Ok here it is.
Lyndon
https://youtu.be/fCKNQtDRV5U

dannobee · 01-09-2021, 02:03 PM

Try it with the clutch pedal in and the trans in any gear to eliminate gearbox clatter and see if it makes any difference at all.

Did you happen to check intermediate gear backlash when you had it apart?

Lyndon302 · 01-09-2021, 02:07 PM

No I never checked the backlash. I never had the cases apart ?
I will check clutch / trans but it's definitely coming from the chain area at the rear of the engine.
Lyndon

Henry Schmidt · Henry Schmidt's Garage

Quote:

Originally Posted by Lyndon302

Most of the time I shut my engine down I get a clunk or a knock. It's quite high pitched. It's as it stops and under compression it loads the engine backwards. It's coming from the rear of the engine. First I thought it was the cam tensioners. But now I'm not so sure. I've done the top end recently Inc pistons and barrels. and had two sets of tensioners in it.
I have done about 3000 miles in this car since I have it. Always done it. Top end done about 1000 Miles ago. Car runs strong and good oil pressure. Zero leaks. Drive and forget or ??
Lyndon

Check for metal in the oil. If the engine is eating itself, tear it apart. No metal you're probably OK to drive it until it gets worse, if ever.

Just a thought: your intermediate shaft end play (trust) is determined by the steel cover on the engine beneath the crank pulley. If the end play has gotten excessive, it could make that kind of clunk/ knock.
Sometimes you'll find that the intermediate shaft end has worn into the plate. You can surface it, check for appropriate trust (shims for adjustment and bob's your uncle. I have a shim kit with gaskets in stock.

That said: you are the builder and must be responsible for determining the severity of the noise.

Lyndon302 · 01-10-2021, 01:31 PM

My oil change had some aluminium in the filter. When I get home I will take a pic of it. This car is new to me.
When I did the top end at one point the chain on one side ( can't remember ) had worn into the chain housing. It looked like an old issue as when I pulled it apart the chains and tensioners were ok. I then after my top end job had some noisy cam chain tensioners. So I have replaced them. I think the aluminium is a residue of this. ??
I can't think what else would be aluminium. But what is on the filter concerns me.
Pics to come
Lyndon

Lyndon302 · 01-10-2021, 04:09 PM

http://forums.pelicanparts.com/911-engine-rebuilding-forum/295556-intermediate-shaft-end-play-2-0-a.html
This sounds so much like it. I get a clunk when rocking it. I best see if I can access out. Had all this apart with the new chains setting the alignment. It did have a shim and two gaskets I think.
Lyndon

Lyndon302 · 01-10-2021, 08:33 PM

Ok my oil filter. ??
Looks worse now I'm looking at it a second time.
Lyndon

stownsen914 · 01-11-2021, 07:01 AM

That's a little more than I'd want to see. Any of it respond to a magnet?

Henry Schmidt · Henry Schmidt's Garage

Too much debris for me to feel comfortable.

Lyndon302 · 01-11-2021, 11:33 AM

Any thoughts on what it is.
It's all aluminium.???
Lyndon

ahh911 · 01-12-2021, 08:12 AM

Quote:

Originally Posted by Lyndon302

Ok here it is.
Lyndon
https://youtu.be/fCKNQtDRV5U

Lyndon,

Listening to your video I can hear the same clunk on the first startup at 17sec just as you start it up. Didn't make the sound on the second startup.

Phil

stownsen914 · 11:26 AM

I have my 3.5L race engine apart due to finding small amounts of aluminum in the filter. Wasn't making any noises, and was running great. But it made me uncomfortable. When I got it apart, I found the aluminum intermediate shaft gear significantly pitted. I assume that was causing the aluminum in the filter. No idea how much longer it would have lasted before it would've been a problem, but I'm sure glad it didn't fail catastrophically.

Lyndon302 · 01-12-2021, 11:25 AM

I engaged the starter to long. So I believe that's the noise.
But I will listen again. I will get a better video.
Lyndon

Lyndon302 · 01-12-2021, 03:57 PM

Ok I'm surprised. About 600kms on this filter with new oil after my oil change which revealed all that aluminium.
It's spotless. Both sides ??
I guess just drive it and for piece of mind remove it and cut it open In about 1000kms.
I would like to do 5 or 6 K on this expense oil I have in it.
Thoughts Lyndon

Lyndon302 · 01-13-2021, 07:05 PM

Ok the intermediate shaft is .9 mm proud.
I have measure what I had
2 gaskets and 1 shim with a total of 1.9 mm so I have 1 mm or 40 clearance.
Specs are .08 to .12mm
My shim is .2mm and gaskets when installed are .85 mm
So I will fit a gasket and shim to give me 1.05 mm with a clearance of .105mm
Let's see if the knock stops.
When the engine is wound backwards it come out so I hoping on shut down when it comes up to compression and reverses a tad it's knocking this plate.
Lyndon

ajwans · 01-14-2021, 06:10 PM

I would be concerned if that dimension changed. I'm sure they don't have that play coming from the factory. I feel like a bottom end inspection is in your future.

One thing I notice is that those gaskets are not original. Whoever installed with those gaskets didn't measure the backlash or the original paper gaskets (901 105 198 03). The paper gaskets are pretty thin and you are supposed to order the shim at the correct thickness (0.1mm - 0.5mm in 0.05mm increments) to make the clearance.

If you install with only 1 gasket I expect you will leak here.

andy

Lyndon302 · 01-14-2021, 06:13 PM

I've three bonded the shim to the plate and gasket between shim and crankcase. All good no leaks.
Yes it's a concern but I'm hoping two thick gaskets are the issue not wear ?
Lyndon

Lyndon302 · 01-14-2021, 06:24 PM

If some one knows the thickness of the original gaskets I can work on 2 of them plus my .2mm shim and it being .9 mm proud. With those numbers I can work on how far out it may be ?
Lyndon