Clacking Noise from LH Head

[Mark S]

Would really appreciate some advice as I'm sure I'm not the first with this noise.

I have finally got around to investigating a LH head noise that has been slowly getting worse over the last couple of years. It started off as a faint tick and has now developed into a noticeable clack that can be heard from inside the car. I couldn't locate with accuracy but sounds like from the cam box around the middle of the LH head. I've looked for an exhaust manifold leak but found nothing.

I should have started with compression test but I didn't. The engine has been running fine.

Tappet gaps all ok.

Today I've removed the cam and buckets hoping to find a worn or cracked bucket but they all look reasonably ok. A little rubbed on the sides in the middle and the odd scratch that can be felt with a finger nail but nowhere near the wear of the old ones (barrel shaped) that I replaced around 10k ago when I rebuilt the engine. None are particularly loose or rocking in their bores either. I could fit new buckets but can't see the wear on any of the existing ones causing the noise.

I've pushed all the valves with my thumbs and all springs feel to provide the same resistance so don't think one has broken.

I really don't want to go much deeper unless I have to. The heads were a pig to get off last time and it's all watertight.

If I put it back together and run without the cam cover to see if I can pinpoint where the noise is coming from or stop it, will it throw a lot if oil around from the cam chain?

The heads have been skimmed and the block decked to clean it up so valve clearance could be a bit tight but it ran fine for 8k miles and I don't take the engine above 5000 rpm. If a valve was very slightly bent causing a slightly sticky valve would this cause this noise. I have an endoscope so could look inside for witness marks.

Would a loose valve guide make a noise all the time hot and cold?

The loudest noise from the engine used to be from the distributor turning. I can't live with this clacking as it spoils the car and is worrying. Any ideas or advice would be gratefully received.

[barkerwilliams]

To be honest you really need to track the noise down.

I would first check exhaust manifold gaskets for leaks, these leave sooty stains on themanifold and can be seen, or hold a strip of paper and feel for draughts from the escaping gases.

Then blow £6 on a stethoscope such as https://www.ebay.co.uk/itm/2PC-AUTOM...EAAMXQYwFRg7Sj

(no connection)

It is really amazing how you can track noises with a stethoscope, but pleae dont start just fitting parts on the off chance they might sort the problem. Track the noise down and only fix the one problem you have.

Alan

[Motorsport Micky]

Typical noise for some worn cam followers, take off the rocker gear and check the cam follower condition and measurements against the cam follower bored diameters to see if you can identify.

Micky

[Stagdad]

Are you absolutely sure its not the head to exhaust manifold gasket blow. I had the exact same type of noise. I was convinced it was machanical until i put my hand down around the exhaust manifold and could feel it blowing after it got too bad to live with. Try pulling the HT leads off one by one. I pulled the injector plug off mine because its injected and when i got to No7 the noise stopped thats when i started feeling around the gasket. I was sure it was a loose valve guide by the sound.

[Mark S]

I was convinced it was a cam bucket or spring but on inspection all looks good.
I did nave a feel around the manifold and couldn't find anything but maybe need to look underneath a bit closer. The centre gasket does look a bit narrow in places. I re-built with exhaust gaskets but there weren't any fitted when I bought the car. Were they fitted originally? I'll try disconnecting plug leads in that area as well.
I've ordered a stethoscope and will get the cam back in and have a better look and listen.
Thanks for the advice so far. Any more thoughts appreciated.

[022Dave]

I had a similar problem some years ago. I cured it by having the tubular headers planed flat on a large milling machine, so that they mated correctly with the head face. I don't have gaskets fitted, just used exhaust sealant.

Dave

[flying farmer]

I would measure the cam buckets while they are out, there should be no measurable wear after 10,000 miles.

If there is wear around the middle, even 1 or 2 thou you have problems.

My P reg Stag had this trouble on the RH head which went away after its engine rebuild following jackshaft seizure. When it started clacking again after a few thousand miles I found one follower in particular had measurable wear around the middle.

The fundamental problem was that the cam follower bores were embedded with abrasive material and the only fix was to have the cam follower bores machined for oversize buckets on the one head and this has stopped the problem re-occurring.

The fact you said your original followers were very worn makes me suspect this may be the problem in this case.

Neil

[Mark S]

The original buckets were worn (76000 miles) but the wear was top and bottom. And they weren't making this much noise. I'll measure them up but putting them side to side I can't see daylight. TBH if £40 for a new set of buckets and 2 or 3 hours work every 10000 miles results in a quiet engine I'd be happy.
Are bucket tops thicknesses fairly consistent (I haven't mixed up the valve order) or will I be back to changing shims to correct clearances if I fit new ones. More of a pain with the head on the engine.
Are LD buckets any higher quality or are they all from the same manufacturer whoever supplies them?.

[flying farmer]

I suspect the buckets are all from the same manufacturer.

The tops do vary in thickness, it can be useful if you have a micrometer to measure old and new and try and get at least some of them the same to make the re shimming job easier.

I use this approach to try and reduce the number of new shims I buy, particularly if it is a size that isn't available. Sometimes you can find one that is a thou thicker or thinner that allows you to keep another valve within its 2 thou tolerance.

Neil

[Mark S]

Well, I've looked at the buckets and checked them with a micrometer. All the same diameter and no perceptible wear. The first two pictures are of No.6, Pic 1 with flash, Pic.2 without. The wear doesn't look anywhere hear as bad to the naked eye but No.6 is the only one with the ridge, (which can barely be felt with a finger nail).

The wear patterns on the others are all similar to this with a ring around the middle towards the top and another near the bottom. I really can't see this making the noise I'm experiencing.

All oiled up and back in their bores, no wobble, all turn smoothly with the same resistance.

Is it worth replacing No.6 bucket?

A quick feel under the exhaust manifold but no black fingers. I'll need to get it up on ramps to get a look once its back together.

[flying farmer]

No 6 doesn't look good, doesn't look like it has been turning in its bore.

For that matter the picture of no 7 looks like it has a wear mark made by the cam on the upper surface and it also looks like it hasn't been turning.

If they are not turning you will get uneven wear patterns and noise, I had this with my last engine and ended up changing all 8 cam buckets on one head, though one was such a tight fit I had to use a good second hand one and selectively fit the rest.

Neil