Noisy tappet

[DaveEFI]

I recently fitted some Stage 1? heads bought secondhand off Ebay to my SD1 - they appeared to be in perfect condition. Measured the height and they were to the figures given here for composite gaskets. Fitted them and omitted the outside row of bolts. Everything is fine - apart from one noisy tappet. Mainly noticeable at idle, and worse when cold.
The cam and tappets are fairly new, and I'd hate to have to replace them.

The original heads with steel gaskets had never been skimmed. The rocker gear seemed to be excellent, and both of them and the pushrods were replaced in the original positions.

[softdash3.9]

Have you taken the car out for a good run since fitting?

I assume the heads were clean before you fitted them?

Did you change the oil/filter?

My Nova SR use to tell me it needed servicing as the cam followers would rattle from cold, even though I used to service it within the service limit!!!.

My wife's Saab turbo had a noisy cam follower, after taking the cam cover off and inspecting the cam/followers I found nothing amiss, took the car out for a good thrash, and the follower quietened down, that was @ two years ago, never done it since.

Does seem a little odd as you have used all the original rocker gear!

[DaveEFI]

Yes - it had a good blast up to the SD1 national meeting at the BMC spares day at Peterborough. Thinking as you did I waited until it had a decent run before posting.

It hasn't had an oil change - I do it once a year and it is due shortly.

There was an approx 5 thou difference between the new heads - but this was within the tolerance given here.

[JC.]

Did you drain the oil out of the tappets before setting them up?
If not, tollerances might be set a bit wide?

You could always go the adjustable pushrod route...

[DaveEFI]

Did you drain the oil out of the tappets before setting them up?
If not, tollerances might be set a bit wide?

You could always go the adjustable pushrod route...

Setting them up? They were never removed. And I wasn't aware there was such a thing.

Thought the whole idea of hydraulic tappets was they are self adjusting? Assuming everything is within tolerance.

[mgbv8]

while you had the top off it would have been worth draining the lifters and checking the pre loads when it went back together.

But as the pre load tolerance is pretty big I wouldnt have expected a problem myself if just doing a head swap.


Maybe it isnt actually a lifter at all. It could just be a leaking exhaust manifold gasket. Its very common for folk to mistake a blowing flange gasket for a noisy tappet. The noise is worst when cold, but as the gasket, head and manifold flanges heat up they expand and seal the leak off a bit so the noise gets quieter ??

For this I use a bit of garden hose as a stethoscope. Let the engine idle and stick the hose down near the manifold flanges with the other end stuck lightly into your lug hole. Have a practice by using the hose to listen to things in the home like the washing machine or run it around a drill that is running so you get a feel for how it can pick up localised sounds that you cant hear with your ears alone as background noise from other sources can drown these out.

Or you could just try going over all the exhaust manifold flange bolts and nipping them up again as the engine has now been through several heat cycles and see if that improves things??

[DaveEFI]

The noise was there from initial start-up - so I doubt it is an exhaust leak.

I didn't check pre-load since I didn't think it was necessary unless things like head height etc were non standard.

[JSF55]

You could remove the noisey side rocker cover and start it up and with an old set of feeler gauges push them under the rocker and find which one is giving the problem, altho finding it still means fixing it !

[DEVONMAN]

Hi Dave,

Some suggestions based on the fact that only the heads were changed,

- One of the new heads has a valve set lower than the rest.
- the new heads have stronger or double valve springs which is now showing up a lifter that is bleeding down slightly due to additional force.

If it turns out to be a lifter then I have in the past obtained a new lifter from the same supplier and swopped the internals into the existing outer case and this worked for me and saved the cam/lifter replacement.

Cheers
Denis

[DaveEFI]

Hi Dave,

Some suggestions based on the fact that only the heads were changed,

- One of the new heads has a valve set lower than the rest.
- the new heads have stronger or double valve springs which is now showing up a lifter that is bleeding down slightly due to additional force.

If it turns out to be a lifter then I have in the past obtained a new lifter from the same supplier and swopped the internals into the existing outer case and this worked for me and saved the cam/lifter replacement.

Cheers
Denis

The spec of the heads doesn't mention stronger springs. I could easily run a straight edge along the valve stem tops after removing the rockers - what sort of tolerance would you expect?

Excellent idea about replacing the internals.

[mgbv8]

The noise was there from initial start-up - so I doubt it is an exhaust leak.

Thats when its worst!
At cold start. Then as things warm up it tends to soften a little.

[DEVONMAN]

Assuming you will check out Perry's suggestion about an exhaust leak with a piece of garden hose in your ear.

The factory installed height for the valves is 47.63mm (1.9")
I dont know what the factory preload on the followers is but it must be between 20 - 60 thou. Say 40 Thou.
For a minimum of 20 thou, a 20 thou max low tolerance on the valve height should just be ok to keep some preload.

Comparing a low valve height to the others with a straight edge of course assumes the others are correct.

Good luck

Cheers Denis