• Hi Guest!
    You can help ensure that British Car Forum (BCF) continues to provide a great place to engage in the British car hobby! If you find BCF a beneficial community, please consider supporting our efforts with a subscription.
    There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Subscribers don't see this gawd-aweful banner
Tips
Tips

Disconcerting engine noise, please help if you can.

Share this page

shortsguy1 said:
... being a good mechanical engineer is rather different than being a good mechanic ...
Click to expand...

I've always suspected as much, given how the engineers sometimes locate the critical, failure-prone components and routine maintenance items in the most hard-to-get-to places (and now, they cover everything with massive slabs of plastic; I reckon they figure the 'modern' car buyer would be severely traumatized by having to look at a naked manifold).
 
Last edited:
Hi All-
I just wanted to give an update to this thread, as I got new information from the mechanic (Russ Thompson) today. He changed out everything directly under the valve cover and the noise unfortunately persists. So even though the rockers, pushrods, etc all showed damage, the damage was not the cause of the engine noise. Russ saw the vertical scratching in cylinder 4 and feels that it may be a faulty wrist pin connecting to a piston in cylinder 4. I posted a picture earlier in this thread of some vertical scratching in cylinder 5, so maybe some error was made in installing/fitting the pistons. I was going through the records for the car and its last engine rebuild occurred in 1997/1998 and ended up costing around $8K. Since then, the car has driven 4000 miles. Russ plans to measure the camshaft and remove the head to figure out the next steps, but he feels a complete overhaul may be necessary. The engine has good compression, starts easy, runs great, doesn't burn oil, etc etc., but may have a fatal flaw which requires a complete redo of its internals.

I will post again when Russ shares any more info. Thanks for all your previous help and advice.
 
I am sorry to hear about the magnitude of the problems with your car. For what its worth your car is in good hands. Russ Thompson is an honest guy and a very competent mechanic. He has done a considerable amount of work for many members of the Austin Healey Association of Southern California, including myself. Good luck and let us know what you learn.

Jeff
 
Same problem. Same sort of noise.

I managed a valve adjustment last night and a compression test.

7 out of 12 valves had clearances below 0.12 with some down to 0.09. none of them had gaps larger than 0.12. So I reset them all to 0.12 as per he factory settings.
Question; What's the theory behind having larger gaps? Some have suggested 0.15.

Compression values (psi), measure after the valve clearances had been adjusted, were as follows, with cylinder '1' being the front cylinder:
160, 150, 150, 140, 150, 155
Question; What might be the reason behind cylinder 1 being higher than all the others? When I first measured it I got 167 but the second time only 160. The fourth cylinder is clearly the lowest so I'm keen to understand why.

I managed to get the engine started too after the adjustments but the noise was still there. Could it be a loose or worn tappet? As with ShortsGuy1, I think I'm, rapidly reaching the end of my mechanical understanding and ability to fix it in my garage even if I could diagnose the issue.

Still, if anyone has any suggestions I'd love to hear them.

Cheers

Bobby
 
Possibly piston pin causing noise. Piston slap. He might follow up on 4. Lower compression on second check could be due to less oil in cylinder on dry check. #4 just might have broken oiling or compression ring. Might not have been specs on ring gap?? All speculation. I just rebuilt a Jag engine that had 500 miles on it and the shop that rebuilt it before me had it a yr. and really screwed it up.
 
Shortsguy,
Any update on the diagnosis? I am very interested in what you determine to be root cause as my engine is making similar noises.
 
IF Russ can not find the problem it does not exist. He is an old friend of mine.:encouragement:
 
FWIW the only noise the normally extremely quiet C series engines make is if the camshaft is worn or the rocker shaft (far less likely).

Big ends eventually go and oil pumps wear worse than average. Low oil pressure if this happens.

Pistons will only rattle if there's too much skirt clearance or if they've seized, which is unlikely unless water was lost.

I've just had to rebuild my engine twice because I couldn't get bead blasting grit out of the oilways. In the end we had to drill out all the blanking plugs, chemically clean the block and then a conventional wash twice. I didn't blast it and I never would, but it taught me that they're difficult to clean out well and they won't last long if they aren't.
 
Bead blasting the engine - I unintentionally sand blasted mine- direct from having a rebore and a crank shaft regrind- loaded the parts onto a trailer and drove over to Bill Rawles' place for a camshaft bearing installation - when I got there everything was covered in sand - My good friend who was helping me with his trailer had shifted a load of sand in it two days before so there was plenty left in the bottom to coat the parts.

Still, about a half a day and a good work out with some special cleaner and brushes, that Bill had solved the problem and I have done over 4000 miles in it now. I was also fortunate in that we removed the little brass ' throttles' in the oilways of the crank shaft which made cleaning easier.

:cheers:

Bob
 
It had got into the main galleries on mine and no amount of cleaning chemicals and pressure washers would shift it, so we removed every blanking plug and after chemical dipping, bottle brushed it through, or rather Paul Hurley did it for me. He's in Bath and one of the best we've used. Not cheap, but superb workmanship.
 
Hi Everyone-
Thanks for showing interest in the vehicle. Russ tried changing parts on the valve train (where you may recall there was insufficient oil because of rocker holes being closed which weren't meant to be closed), but could not get rid of the noise. So he took off the head and found that two of pistons were rubbing the sides of the cylinders, and feels that it was this that was making the noise. He feels that the car must have overheated at some point and messed up the clearance between the pistons and cylinders. Perhaps even the clearance was not correct from the outset (recall the rebuild had other issues like wire brush bristles abandoned inside the engine).

I know the prior owner and I don't think the car ever officially boiled over, but I do know that it ran very hot. On the drive from the prior owner's house to my mom's house to deliver the car, he had to pull over as the engine got way too hot (230 or thereabouts if I recall). So maybe some deformation occurred due to prolonged running hot. Russ found massive (1" thick) deposits stuck in some cooling passages (sorry, I don't know exactly where) which he had to chip out at great effort. He says that the quantity of deposits indicate that they hadn't been addressed since the car was new. Even though the rebuild was quite recent in miles (though not years), he did not feel all those deposits could come from the time since the last rebuild. So basically, the engine had an internal cooling problem which wasn't addressed when the engine was rebuilt a while ago.

Since much of the engine is relatively "new", I guess a lot of it can be reused with only polishing (like the cam and crank). It will be re-bored and need new pistons. His is also installing a higher capacity radiator and a better fan (it still had the originals).

Unfortunately, it will still be a few months before he is done, but I am sure he is doing his best. Both he and his machine shop are in demand, so things go a bit slower than perhaps ideal.

Thanks again for your interest.
 
shortsguy1 said:
Hi Everyone-
Thanks for showing interest in the vehicle. Russ tried changing parts on the valve train (where you may recall there was insufficient oil because of rocker holes being closed which weren't meant to be closed), but could not get rid of the noise. So he took off the head and found that two of pistons were rubbing the sides of the cylinders, and feels that it was this that was making the noise. He feels that the car must have overheated at some point and messed up the clearance between the pistons and cylinders. Perhaps even the clearance was not correct from the outset (recall the rebuild had other issues like wire brush bristles abandoned inside the engine).

I know the prior owner and I don't think the car ever officially boiled over, but I do know that it ran very hot. On the drive from the prior owner's house to my mom's house to deliver the car, he had to pull over as the engine got way too hot (230 or thereabouts if I recall). So maybe some deformation occurred due to prolonged running hot. Russ found massive (1" thick) deposits stuck in some cooling passages (sorry, I don't know exactly where) which he had to chip out at great effort. He says that the quantity of deposits indicate that they hadn't been addressed since the car was new. Even though the rebuild was quite recent in miles (though not years), he did not feel all those deposits could come from the time since the last rebuild. So basically, the engine had an internal cooling problem which wasn't addressed when the engine was rebuilt a while ago.

Since much of the engine is relatively "new", I guess a lot of it can be reused with only polishing (like the cam and crank). It will be re-bored and need new pistons. His is also installing a higher capacity radiator and a better fan (it still had the originals).

Unfortunately, it will still be a few months before he is done, but I am sure he is doing his best. Both he and his machine shop are in demand, so things go a bit slower than perhaps ideal.

Thanks again for your interest.
Click to expand...
can he check the tops of the Pistons to see if there's pieces of rings embedded there?
 
I have asked Russ to hold onto all the pieces for me. If there is anything interesting in the carnage, I will definitely post photos. But he didn't mention anything about damage to the piston tops, so I doubt that was part of what transpired. I will definitely post again when I learn more, but it may be a while.
 
I have the same problem with my 65 BJ8. Tried everything including replacing the tappets and rocker shafts. Even
used a flapper wheel to reface the rocker arms. I tracked it down to #3 rocker arm. Setting it to .008 instead of .014
made it "almost" go away. I spoke to a camshaft designer and he told me that Carroll Shelby said you do
what you have to do. I most likely have a worn cam lobe. Runs great, still ticks a little bit, but the solids always did.
Just my true story
 
This may be of help, My dad was a mechanic and when he had a tappet that was noisy( usually caused by wear of the tappet face in an "under cut" way and the feeler gauge does not go into the under cut section) he would check each tappet with a feeler gauge while the engine was running at idle until the offending tappet noise would reduce or in some cases disappear, When this was ascertained He then adjusted this tappet until the noise was just audible. He also would check the distance the push rod was going thru just to check the cam follower was not sticking. Also a broken valve spring can cause a noisy tappet Hope this helps Saltiga
 
Back
Top