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Mike6

Loud ticking noise coming from top of engine

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And to think all I wanted was a car with a bit of street cred to see me into my dottage. Didnt mind a bit of work but the so and so has never ran that well in the two years I have owned her ( and insurance is now due - 28% increase through Adrian Flux). Having now stripped out the cams and having to drill out a couple of TORX heads which stripped it seems the shattered cam follower has completey buggered the cam itself and the casing has damaged the valve spring retainer and damaged the valve stem as well.

It now looks like a complete engine strip to assess what further damage has been done, could have been - hitting the piston crown for all I know. Biting the bullet but thoroughly depressed about how a cam follower could have done so much damage and why it went in the first place. And I have never driven the car that fast in the first place.

On a brighter note it seems that the exhaust manifilod will be easier to remove with the cams off and the few pints of a very strong ale I have just consummed at Wetherspoons with my son has dulled my depression (sorry bi polar disorder).

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Why on earth did I say it looked like it wouldn't be that difficult to remove the exhaust manifold. Hours of cursing, drinking tea and then more cursing over a few days (I work short hours) has finally seen the nuts undone but I have left a couple on so I could call it a day and have a Radox bath and try and straighten out bits of my body which seem to have set in different positions.

When I looked at my accomplishment it didn't amount to more than a few bits in a spray can lid but tomorrow I may at last make some meaningful progress.

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keep at it Mike, will be worth it on the drive after! at least with the engine out you can inspect for any other issues and resolve them now (rather than putting it back and taking it out again for an oil seal!)

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Made significant progress over the last few days. Exhaust manifold with turbo attached came out nicely in situ. Carbs with all the bits came out ok and the cylinder head pulled without much problem. Would have expected the head nuts to have been torgued but they didnt have much resistance.

Piston crown looked ok but oily so no damage. Felt around the piston liner and there is a small lip near the top on each bore indicating some wear but it was not significant so maybe the liners are ok or not??. The head all looked ok with no burning or damage. Pulled a few exhaust valves before calling it a day and there was a fair amount of coke build up but not affecting movement of the valve. Put the valves minus the spring back into the head and there is some sideways movement possibly indicating new guides are required and explaining the oil getting in. Not sure how much movements is normal. Any thoughts???

Will eventually post some pics when I fathom out the technology

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Still cleaning up the sticky, gooey mess of a cylinder head and notice that the head gasket looks like it has seem better days. It has 'Coopers Gaskets' stamped on it. Is this a Lotus part or some sort of hybrid which might indicated that at some stage in its life someone has meddled. It does seem a fairly thick gasket, not sure how thick the right part is.

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Took the cylinder head to a recommended auto engineering firm and they said the exhaust valves were very sloppy in the guides. They demonstrated with the inlet valve where you get a popping if you pull them out by hand. This is a likely area where oil has been getting into the cylinders. They are fitting phospor bronze K-liners into the worn guides rather than trying to pull the old guides out (an accepted form of repair), skimming the head, cleaning everything up including the innards of the head and checking each valve for flatness and machining where necessary.

All for £180 plus vat. I call that good value but of course non of this fixes the original problem.

Now decided to strip the bottom end, overhaul the oil pump and water pump and probably pull out the petrol tanks to investigate that smell which oddly seems to have gone since the cam follower shattered.

Expect the car back in play in a few years time at the speed I work - should be fairly rare by then and worth at least £50 more than I paid.

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Be very careful when skimming the head!

I had 2 different machinists put a trapezoidal taper into my head surface when they didn't set it up properly!

There are no even regular surfaces on the head to mount it square and level, even with the cam towers attached.

In order to fix my taper, I had to design a fixture to hold the cams parallel to the machining table, therefore machining the head parallel to the cams.

I found a shop that let me machine my head myself, using their machine, for free! Using my fixture. That finally fixed the problem that the first machinist had caused.

PICT0300.JPG

PICT0303.JPG

My head was actually tapered .005" from end to end and across the short axis as well, so I sloped down and to the right!

PICT0311.JPG

Edited by Vulcan Grey

Travis

Vulcan Grey 89SE

My Lotus Photo and Projects Album

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Mike

I suggest that you impress on the engineering co that they should try to skim the head by the absolute minimum as too much will significantly inrease the compression ratio and in extremes lead to piston to valve contact.

Increased comp ratio will potentially lead to more knock

John

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Now I am getting worried again and its probably too late the job will have been done. I do remember the company saying it would cost a bit more than normal to set the head up due to its shape so I can only trust them. They are a reputable motor engineers so I guess they will have experienced this before. Surely Lotus cannot be the only motor company to have such a head arrangement/configuration..

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Compression ratio is not an issue any more.

The max allowable limit for the head is .018" removed.

But the original head gasket is obsolete and was replaced by the composite Goetze gasket, which is .020" taller than the original gasket.

But the Esprit 907 and 910 head is unusual that the cams are not part of the head, and there are no flat surfaces except two small pads on the ends, and those don't constrain all the degrees of freedom...


Travis

Vulcan Grey 89SE

My Lotus Photo and Projects Album

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Thanks Travis

Just been looking through the service notes and they say that if the head has been machined then a thicker gasket is available and should be used. However if the gasket you mention is thicker than the original then there is no problem. However the gasket I have removed is made by 'Coopers'. which I dont think is original so has the head already been machined and fitted with a thicker gasket. So much to worry about, just wish I was an engineer.

Didnt leave the cams with the engineers, if that would have made any difference so hope it doesnt come back banana shaped

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The coopers gasket is actually the original fitment. I assume its a silver metal finish on either side? You can still find them advertised as NOS but the Goetz seems easier to use and as Travis said benefits from being a little thicker to compensatefor a skimmed head - especially as you have no idea how many times its been skimmed.... Should really be done with cam carriers bolted in place, and I would only get it done if it needs it.

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Thanks everyone. Will ring the engineers first thing but suspect they have done the skimming. If not I will get them to cancel. After all its got nothing to do with the original problem.

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Good news, managed to get hold of the engineers before they skimmed the head - now cancelled since it wasnt a problem in the first place. Cheers everyone

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Mike, has the head been checked for flatness? It may still require skimming as aluminium heads 'relax' in use.

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No I didnt ask them that as they are probably getting fed up with me ringing them. When they have done the other work I will ask for this to be checked before picking up

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