K Series Rattle

[RogerB]

Thanks Revilla for your super prompt response That all makes sense and gives me the confidence to proceed.

[Geoff Brown]

Maybe a 'one off thing' but I found that when my vernier arrows aligned to enable the fitting of the locking block the lower marks did not exactly align though the timing of my 1.6K was spot on. I did learn that some of the lower marks were not that accurately applied during manufacture?

[revilla]

Yes that's true, and to be hones even if you get all the marks aligned it doesn't mean the cams are times correctly, there are manufacturing quality issues with the drilling of the roll pin holes in the ends of the cams too. It's all a bit sloppy. On a VVC engine it's even worse by the time you get to the back pulleys. When I've timed the cams properly on VVC engines using offset dowels (we can't use Verniers) I've sometimes had to slip the pulleys by a whole tooth and paint new timing marks to get close enough to correct with dowels.

[Englishmaninwales]

I found the VVC can have awful timing marks and concluded that offset dowels were necessary, but never bothered.

[RogerB]

Back to consult with my learned friends. Referring to the rattle recorded in post 16 I now have the head off and all valves removed. They are however single valve springs and all appear in perfect condition. Everything else looks in good order with the top end and cylinder bores in good condition.

I guess the next stage is to remove the sump, although the sound did appear to be coming from the top end, specifically No 4 exhaust manifold.

Other Qs are:

1. Recommendations as to refitting valve stem collets as these are fiddly to remove with the aid of a magnetised screw driver.

2. There appears to be a spacer shim stuck to the underside of the cylinder head. However I assume this is just the MLS head gasket coming apart when the head was lifted.

[SLR No.77]

Re 1, wipe a small amount of grease onto the rebate in the valve stem, then use a screwdriver with a small dab of grease on the end, the grease can be used to pick up the collet to fit it in place. The grease on the stem will hold the collet in place while you position the second one.

Stu.

[revilla]

1) Grease! Compress the valve spring, put a bit of grease around the end of the valve. A slightly magnetic screwdriver is useful put I put a little blob of grease on the end of the screwdriver too. Stick the collet in the grease on the screwdriver, offer it up and stick it into the grease on the valve. Surface tension will hold it in place. It takes some practice aiming the depth correctly but you get your eye in by the time you've done a few.

When you release the compressor, a) check it feels right as you release it, that give you a clue as to whether the collets locked in place or fell out as they sometimes do! b) Check afterwards that you can see both collets in place, you may need to wipe any grease away with a cloth, and probably best not to look straight on at the valve until you're sure, you don't want it popping loose and firing anything towards your eye. c) Once they're all on, put the head face down (use newspaper or something to give a soft surface and make sure it's supported along the sides so the valves have some clearance, I tend to use a folding Workmate type bench so the valves sit over the open gap in the middle). Then using something soft, give the end of each valve a few sharp blows to bounce the valve a bit, this will make sure everything is settled and nothing can come out afterwards (e.g. use a bit of wood, I use the wooden shaft of a valve grinding stick, and a mallet)

2) The standard MLS gaskets normally come with a separate shim layer. This has a black PTFE or similar coating that bonds to the head when it gets hot. You'll need to remove the old shim and clean the head face to remove any old shim coating. Red grade Scotch Brite is quite effective without being too aggressive.

[revilla]

Stu, posts crossed - you managed to say it in a lot fewer words :)

[RogerB]

Thanks again, all good stuff. 

However any thoughts on what I can investigate further whilst opened up.

Grasping at straws. I'm going to measure the comparative length of the valve springs and under compression with two pushing together in a vice.

[garybee]

Your original description sounds like how I would describe pinking.  Does it happen mostly under load?

edit: forgot there was a video.

[revilla]

I don't thing the springs will lose their tone. If they're not obviously broken, just measure their free lengths and compare them to the specs in the overhaul manual (which I don't have to hand right now).

 

If something was rattling it should he quite obvious when you find it.

[revilla]

I've just listened again to your video. It's going to be obvious when you find it, it's not exactly just a little rattle, is it?

All the cam lobes look OK? None of the lifters look oddly marked on the tops (as though there was a lot of lash and they've taken a hammering).

Before taking the bottom end apart ... See if you can get a look inside the bellhousing through the clutch arm hole. There's nothing that looks loose or broken about the clutch cover plate or anything is there? No foreign bodies in there (I'm mostly think gravel, or possibly even a cover bolt dropped out). The release bearing isn't coming apart?

It doesn't sound like piston slap or knocking rod bearings to me but at the same time it sounds too "fast" to be top end. It can be deceptive where the noise is coming from.

Now the head is off, do the cylinder bores look OK?

[RogerB]

Spring free lengths range from 40 mm to 40.7 and these two pushed together reduced to 30.7 and 40.3. Unfortunately the Haynes manual just says to compare this to a new spring. Also I'm not sure if mine will be standard as it pushes out 190 BHP On the rollers.

However there doesn't seem to be much discrepancy there.

I don't think it's pinking as I only hear it with the car stopped at tickover and with increasing the revs off load.

I used to get pinking in my TR6 many years ago and that was quite different.

[revilla]

@Garybee there was a video lost back in the mists of the early pages of the thread - does this ring any bells with you https://youtu.be/vnKmuNow6f4. I don't think pinking, it's very mechanical.

[garybee]

Ta fellas, I had just read the OP again and forgotten the rest as it's been a while.  Watched the video and agree, extremely unlikely to be pinking.  I remember ruling that out before now 

 

It's not rhythmic enough to be a high pressure exhaust leak.  I remember expecting to see something light bouncing around when the cam cover was removed.

[revilla]

Has anyone got experience of what an engine sounds like with the early stages of the typical K Series piston failure mode ... when the first ring land separates from the piston? I doubt it's that, not enough scope for movement to make that kind of rattle, but just wondering. It really does sound like something loose and rattling around inside.

[RogerB]

Cam lobes are unmarked, cam followers look good with just some concentric circles mostly towards the centre ( I guess these rotate in their guides) Liner bores look good still with visible crosshatching .

There has always been a lower frequency rattle from the clutch which disappears with the clutch depressed. I can't see much down the clutch arm opening. However the arm does rattle about in all directions. The higher frequency sound remains with the arm held steady.

[MADMALC]

Hi Roger, Malcolm here. I am totally confused that removing the head has not revealed the issue.

For those kind enough to post I have personally listened to the noise via a screwdriver and the 'rattle' is/was clearly coming from the the specific valve area previously identified. When the screwdriver was positioned even slightly away from this valve the noise was clearly reduced. I am baffled that the issue is not now obvious.

I do not know if this engine is still on hydraulic lifters or has solid lifters. For those more skilled than us, is there any scope for issues with the lifter system on this valve that would/could give rise to the localised noise? Other than this I will gracefully retire defeated.

Good luck with this Roger, we may see you later in the year when we visit C&E.

 

[revilla]

At 190bhp (I think you said) I'm guessing it's probably on hydraulic lifters? In which case the only thing I can think of that might make that kind of noise specifically from the lifters would be if one of the lifters was collapsing leaving a lot of lash. I would expect it would leave telltale changes on the lifter though, but maybe only after rubbing like that for some time. I would suggest trying to see if you could compress any of the lifters to see if they were soft and spongy, the problem is you would really need to do that before stripping the head as it's likely that they will have drained down and taken in some air now. If you don't find anything else it might be worth using new lifters when you rebuild it as a precaution; you don't want to get it all back together then find you have a last lifter after all. If it is on mechanical lifters very little of this is relevant.

[RogerB]

Mechanical lifters I'm afraid chaps. As Malcolm said the noise was clearest on No 4 exhaust manifold. And all pointed to a broken valve spring. I was poking around the manifold to see if it was something silly with that last night, but nothing.

I'm now considering taking the engine out to look in the bell housing. Is this feasable with the head off? And complete with gearbox or split at the bell housing which has the dry sump saddle tank.

[revilla]

Yes feasible to take the engine out with the head off. I'd leave the gearbox and bellhousing in place (you can support the bellhousing with a big ratchet strap around the chassis rails) and just lift the block out.

Be careful though. With the head off you really must avoid turning the crankshaft. The liners seal to the block with a Hylomar type sealant. The seal can be quite fragile and if the crank turns, the liners can lift. If that happens you've got to remove the affected pistons, rods and liners and re-seal. The good news is that in most cases, as soon as you take the head bolt load off the block, it usually distorts enough to seize the crank, but not always. There's a good chance of something catching or dragging the flywheel as you remove it, turning the crank.

You really need to clamp the liners down for safety while working on it. You can make liner clamps from aluminium spacer tubes and big washers that slip over the head bolts. I've got some made up of you want to borrow them. I'll need them back in a few weeks but not urgently.

[revilla]

I sent the video to a friend and ex-member (Mankee Cheng). His comments were that the noise sounded fairly tinny, which made him think it was probably something on the exhaust system. Reading back over the thread it looks like you checked that all the exhaust headers were secure. But could there be any rattling in a joint, maybe header to collector? Mankee also said he once had a similar noise from a lambda sensor bung that had come loose, hidden underneath the exhaust heat wrap. The lambda bung is probably in header No 4. If that was vibrating and rattling in its hole, the noise would indeed sound like it was coming from a similar place. I had a header pipe rattling in the collector once and it didn't sound that dissimilar. I'd have a very close look at the exhaust system before pulling anything further apart. Hollow pipes can make sound echo and resonate and appear to coming from a location quite far from the actual source.

[RogerB]

Spot on, the lamda bung hidden under the heat wrap.

Thanks so much for all the help.

[revilla]

You mean that was it? It was loose and rattling?

[SM25T]

What an anticlimax after 8 pages !