valve gear noise

[YellowS4DHC]

I can hear a lot of noise emanating from the head on my TC; you can hear it inside the car and outside from several feet away. It is loudest when cold at low oil pressure (idle). The noise is not the result of a loose timing chain or excessive valve clearances .

I looked through the archives and began to suspect my followers and sleeves. I pulled the cam cover and cams and inspected the tappets (followers) and found them with minimal wear and no barrel shape or ovality.

I didn't pull the head so I couldn't measure the sleeve diameters, however I could insert a 2 mil (.002") feeler gauge in the gap between the follower and sleeve on all eight valves.

The measured gap clearly shows my sleeve IDs are worn, but it sure seems like a lot of noise for a clearance of only .002". Is it reasonable to conclude this is the source of the noise I'm hearing? Any thoughts on this are appreciated.

regards
Rick


'72 Europa TC
'69 Elan S4 DHC
'67 S800 Coupe
'57 T1 Speedster

[rgh0]

It could be the followers rocking in the sleeves like you say. This is normally a light tapping noise and it is rare for all of them to wear the same and knock at the same time so will normally come from only one or two of the 8 followers, listen with your ear to a screw driver on the cover to see if you can locate the noise more specifically . It also tends to be worse when the engine is hot and the oil thinner as the cold thick oils damps the movement better between the follower and sleeve which is inconsistent with your observations.

It may also be piston slap due one or more worn pistons. This tends to be a heavier tapping sound and it is worse when the engine is cold as the pistons expand and close up the clearances when they are hot.

cheers
Rohan

[YellowS4DHC]

thanks Rohan, I was hoping to catch your attention.

The noise I'm hearing is hard to place. I used a piece of plastic tubing to try to locate the source but didn't get any strong indication except when placing the end of the hose near the lower left side of the head near the exhaust ports. I wasn't picking up any strong indication from the top of the cam cover which confounds me.

The tapping noise is loud, but light in tone suggesting a relatively small mass is involved. I would think piston slap would be a heavier, duller sound. Also, the tapping frequency at low RPM (at idle) suggests multiple sources - it's hard to believe all this racket could come from a single piston at 800 RPM but then......

It seems louder when the engine is cold, but as I rethink it, I'm not sure. I usually sit and let the car warm up before I drive off, so when the engine's cold I have no road noise or exhaust to deal with. Conversely, when the engine is warm I'm at speed and have road noise and engine exhaust that could be masking the tapping sound making it seem less loud but really only harder to differentiate.

I'm only guessing, but I suspect when the PO rebuilt the engine, he replaced the followers and either ignored the sleeves altogether or replaced them and honed them to an incorrect diameter. I'm thinking of buying some of the oversized followers that Dave Bean sells (std dia + .001") and see if that makes a difference. If nothing else, it would at least help diagnose the problem.

regards
Rick


'72 Europa TC
'69 Elan S4 DHC
'67 S800 Coupe
'57 T1 Speedster

[rgh0]

Another thing to check is for a leak at the exhaust manifold to head joints. A leak hear can produce a tapping noise, which would be near the location you describe

cheers
Rohan

[nigelrbfurness]

I would suspect a little-end bush or loose gudgeon pin, especially as it's louder at start up. I've had several of those over the years and the symptoms are very much as you describe.

Nigel F.

[LCRJ]

Hi all,
My friend also has the completely same situation on his TC.
The unexpected tapping noise only appear for about 10-20seconds
when the engine is cold and at low RPM (warming-up).
Probably the noise come from the exhaust ports.
Incidentally, He starting the engine once in one or two weeks.
also it has high lift cam like QED420 with big valves and a little bit high CR.
Will this have any relation?
But He sometimes followed two days to start the engine does not occur at that time.
His engine just rebuilt and running in around 1000mile now.
I did not hear the tapping noise until quite recently.
So I worry about this problem, is this common?
What will be a problem? Is there any solution?
Any advice would be appreciated.
Thank you.
Hiro
P.S
I think the steady valve noise a little bit louder than other standard engine.
I did make sure a leak at the exhaust manifold to head joints and re-joints other exhaust point.
Then the steady valve noise became small clearly.

[ianf]

I also suspect exhaust gaskets, my car started by knocking and then sounded like a steam engine, 3 of the 4 gaskets had blown - it's a cheap fix if that is your problem!

Cheers,

Ian

[Quart Meg Miles]

Hiro, I think you are describing the effects of oil draining from the working parts. As you say, if he restarts after a couple of days it is fine and quiet. But give it a week or two for the oil to drain out and there isn't anything to cushion the engine noise from tappets and bearings until the oil circulates again. (Sorry I missed your post earlier).