Top end clatter - diagnosis help please!

[Hugo]

It's a new or rebuilt head, isn't it? Few hundred miles I think he said? And #2 valve in that hole comes out ok for gap? So that suggests there's nothing wrong with the head?
Certainly agree not to grind valve tip or shim - that would be dealing with a symptom of the problem rather than the problem itself.

[christopher storey]

I think that the first thing to do is to obtain a new valve and see whether that produces a shim requirement within the normal range. I agree with all who think this is a case of a stretched valve

As far as Hugo's objection to that is concerned on the basis of his thesis that no gap = no noise, as I pointed out near the beginning of this discussion , once there is no gap, the sound of the valve hitting the seat is telegraphed via tappet and camshaft , and also the fact of no clearance may be inducing rocking of the tappet in the bore

It is also worth checking that the tappet has not "barrelled" , which is a very common problem, albeit usually with higher mileages. Barrelling is a very definite source of noise

[mgcjag]

All very wise words Christopher, as usual... Steve

[andrewh]

I think that the first thing to do is to obtain a new valve and see whether that produces a shim requirement within the normal range. I agree with all who think this is a case of a stretched valve

As far as Hugo's objection to that is concerned on the basis of his thesis that no gap = no noise, as I pointed out near the beginning of this discussion , once there is no gap, the sound of the valve hitting the seat is telegraphed via tappet and camshaft , and also the fact of no clearance may be inducing rocking of the tappet in the bore

It is also worth checking that the tappet has not "barrelled" , which is a very common problem, albeit usually with higher mileages. Barrelling is a very definite source of noise

Makes perfect sense to me as well Christopher. I don't think you need very much to not be correct for it to make a right old noise. Just think of the noise of the loose buckets hitting the camshaft when that occurs.

[kingzetts]

Further update.

Moving only the valve between the 1 & 2 location does NOT move the lack of clearance to #2, it stays at #1. So it is not the valve. Neither is it the tappet - same test.

Here's where it gets interesting;

With everything in its original spot, #1 has <0.002 clearance, #2 has 0.016
With the upper spring seats only swapped, #1 = 0.007, #2 = 0.015
With upper seats and collets swapped, #1 = 0.017, #2 = <0.002

So it seems that the spring retainer and collets from #1 are the culprit, and are allowing the top of the retainer to sit sufficiently above the normal position to cause the tappet to ride on the top of the spring retainer, rather than the shim/valve stem.

So the obvious next step is a replacement spring retainer and collets.

What leaves me baffled is if I really correctly measured a normal clearance on #1 when I fitted the head, how the spring seat and collets could have distorted in use, and how this would cause noise. I suppose that if this analysis is correct, there would be a gap between valve stem tip and shim/tappet and when the cam opens the valve, that gap would close and maybe that's the different noise.

Still rather puzzling. Off to order a new spring retainer and collets

[Geoff Green]

Check the length of the valves. I think one has the end shortened keeping the valve away from the shim.

[Hugo]

Further update.
.....So it seems that the spring retainer and collets from #1 are the culprit, and are allowing the top of the retainer to sit sufficiently above the normal position to cause the tappet to ride on the top of the spring retainer, rather than the shim/valve stem.

So the obvious next step is a replacement spring retainer and collets. :

What I would do is take both valves out & just sit the collets & top collar on there, then measure how much of the valve tip is poking out of each. The discrepancy, if that is where it lies, should be obvious.
I have seen exactly this happen on a K series engine in a Rover 200 VI that I bought. It had been put together at some point in the past with the collets incorrectly seated, and one of them had fallen out. Miraculously it did not drop a valve, but it did wear the internal taper in the collet. I bought it with a blown head gasket - and when I stripped it down I found an 'extra' collet lying in the head under all the valve gear. I figured somebody had just dropped it when assembling it some time in the past, easily done as they are tiny. But when I put the head back together I noticed that one of the collets was sitting noticeably higher than the others. Like yourself, I couldn't figure out why, but closer inspection revealed that it had obviously been running for some time with one collet missing, and this had caused the collar to tip over and wear the internal taper.

Yours is a replacement head, isn't it? You don't have any old cam followers or collars, do you?

It's very early in the morning here in sunny Florida & I shall digest the rest of your article in detail when my brain is a bit more awake.

[Hugo]

As far as Hugo's objection to that is concerned on the basis of his thesis that no gap = no noise, as I pointed out near the beginning of this discussion , once there is no gap, the sound of the valve hitting the seat is telegraphed via tappet and camshaft , .....

Nah. Sorry. I see what you mean, and I hate to disagree with you, but I still don't buy it. Valves don't 'slam' into the seat, they are lowered gently by the ramp on the cam. In any case I think he had a couple of thou gap. Even with no gap there's going to be a cushion of oil between the cam follower & the cam to soak up any noise that is 'telegraphed'. That is not going to cause the kind of noise that is going to catch your attention when you're belting down the Autoroute in France.
I don't like being a party-pooper but we haven't pinned this down yet.

[64etype]

Along the lines of Hugo's remarks...with the valve installed the top edge of the shim should always be above the top of the retainer...and it should sit directly on the top of the valve stem (physical contact). So, you should be able to rock the shim slightly in it's depression in the retainer when placed into the recess. If these criteria are not met (with shims within the specified range of thickness), it points to several potential problems.

[kingzetts]

What my measurements imply is that the spring retainer is sitting too high on the valve stem, so that there is a gap between the underside of the shim and the tip of the valve stem despite the shim being seated in its recess in the spring retainer.

This has a couple of consequences. First, although there is no clearance between cam and tappet, there is clearance between shim and stem. So there's a noise source. Second, as the cam lobe presses down on the tappet, the spring retainer will be pushed down until shim meets valve stem. This will loosen the collets causing movement and potentially wear, as well as another noise source when the collets are reseated fully on the way back up.

That's my current thinking. I have no explanation for why the retainer and collets got to that state in the first place. Unsatisfying, but the next step is new collets and retainer. If that restores proper clearance, the head will go back on and we shall see if the noise has gone.......

[Hugo]

That makes sense - so you end up with too little clearance between cam follower and cam, but too much between cam follower and valve. Although how it could have happened is something I wouldn't like to guess at. As I said, I have seen this on a Rover K series, but that had been running for some time with only one collet holding the valve in, so that explains how the taper in the collar got worn.
Yours doesn't have a crack or something silly, does it?

[64etype]

What my measurements imply is that the spring retainer is sitting too high on the valve stem, so that there is a gap between the underside of the shim and the tip of the valve stem despite the shim being seated in its recess in the spring retainer.

As suggested earlier, it could also imply a valve was topped excessively. That said, it doesn't explain the measurements when you moved the retainers, although it's not clear what you did with the shims during that check.. Did the shim pass the wiggle/rock check when initially installed?

[kingzetts]

It's not the valve, otherwise moving just the valves between #1 and #2 would move the issue which it doesn't.

The shims remained with their respective valves. Only the retainers and collets were moved. I did not specifically check whether the shims rocked on the valve tips - but the measurements seem to me to paint a clear picture of the issue being the retainer sitting far too high and opening up a gap between shim and valve tip.

[Hugo]

I'm with you all the way. The only mystery is how? If you take #1 valve out & just stick the collets & collar on there while it's in your hand you might be able to see what's what. I assume it's the internal taper in the collar that has opened up, but unless you have a crack, or maybe one of the collets has broken up (which you would have noticed by now) it's difficult to imagine how this could happen.
Just one thought - is it possible that you dislodged one of the collets when revving it, & it sat there cocked over until it enlarged the hole in the collar? Clutching at straws really. If this were the case you'd expect it to be a recognised issue when racing.
Or indeed maybe the collets weren't seated properly when it was assembled - in fact that's more likely. You wouldn't know anything about it till it wore the collar so much that it (the collar) rose up & pushed the cam follower away from the valve, which is what made the noise. That's where my money is going.
A lot of work but you're lucky it's minimal damage & not catastrophic.

[kingzetts]

To wrap up this saga.....

I obtained a replacement spring retainer and collets. These were guaranteed NOS original Jaguar items. The picture shows the replacement item on the left and the one removed from my head on the right.



Clearly the NOS item is rather thicker towards the narrow end and does not have the tapering section of the one from my head. No obvious reason why this would cause a problem, as the collets sit inside not outside - but I decided to replace all 6 inlet spring retainers and collets pairs as a precaution. Got standard clearances on all valves with no issues.

Head is now refitted and fired the engine up this afternoon. The noise, which was previously audible instantly from cold start, is now GONE!

So, it seems like there was something wrong with that one retainer, or something was assembled wrong during initial assembly at the head builders which subsequently caused deformation of the retainer in service - but I cannot say exactly what.

Just happy the noise has gone and the problem did not lead to more substantial damage.

[288gto]

Glad you actually got to the what and why of the problem. There is nothing worse than fixing something but not really knowing what had gone wrong.

Did Barratts themselves build the head or was it outsourced by them?
How do you stand in terms of warranty and costs incurred?


Simon

[kingzetts]

I believe the head buildup was outsourced.

Barratts supplied all the parts I needed, including the retainers and tappets, a set of cam bearings (precautionary, not actually necessary), gaskets, consumables etc FOC without me having to ask. I'm entirely happy with how they have supported me in the issue. - If I had paid a garage to fit the head originally and then had to pay again for it to be R&R'd I may have expected a contribution to those costs, but the question did not arise as I do this sort of thing myself for fun anyway.

They asked for the duff retainer to be sent back to them (which I've done), so they can investigate further.

[288gto]

That's excellent service John. At least you're back on the road with confidence the clearances are all as they should be.

Simon

[Hugo]

So it was just one odd collar? It's not going to wear like that so I would guess it is a part for another engine that crept in there somehow without anybody noticing. Does that makes sense?