Just rebuilt the Locost racing engine, and I've run it for around an hour so far.

Did a precautionary oil change and noticed the dreaded MILKY SLUDGE in the rocker cover gasket.

Initial thoughts were that the head gasket (new with the rebuild) had failed or the head was warped. Head off, gasket looks fine, head and block fine too.

Could it be CONDENSATION?

If so, can I reuse the head gaskett?

Did u wash the head out then u did it? Water in it somewhere?

Not advisable to re use the gasket.

[Edited on 7/9/05 by Danozeman]

I gave the block and sump a really good clean, but I'm pretty sure there was no water hiding anywhere as the block was turned over regularly during the rebuild and the sump was washed out with petrol.

The head wasn't touched, and there was no yogurt in the rocker cover before the build!

Confused!!

what engine is it, make & size?

Hi

Did you clean out the head bolt holes in the block before reasembly? It sounds like a thorough rebuild so I expect you did.

It can be a problem if oil gets into the threads and the bolts don't torque up properly meaning the head is not as tight as it should be, then the oil and water can mix. Depending on your engine building knowledge it can be difficult to see if the gasket has been breached or not.

I would make sure you can srew the head bolts in without the cylinder head on using your fingers right up to the end.

Don't reuse the old gasket!

Gavin

Cheers for all the advice

I'm convinced there's nothing wrong with the block or head, and the gaskett looks 'like new', hence the confusion.

I'm getting another gasket tomorrow to try again, and I'm racing at Brands this weekend whether it's cured or not!!

Oil and water temp up to temp before the engine was shutdown ?

Had an absolute nightmare over the weekend.

Refitted the cylinder head with a new gasket and noticed water flowing UP A VALVE STEM onto the top of the head. And this was 15 hours before a race!

Had the head skimmed (all I had time to do) and refitted the head with another new gasket. This time water rushing up a pushrod tube onto the top of the head, and then down into the sump. Emulsified the new oil in about 5 minutes.

Result: 2 missed races and engine in bits again!!

I'm now working on another bottom end (have most of the parts ready to go) so I can bolt the head onto that and see whether it cures the prtoblem. If it does it must have been the block, if not it must be the head. Either way I'll know, don't care which, just need to know!

sounds like the head is cracked to me

check you have'nt put in a cyl head bolt while there was oil in the threaded hole. You can crack the block casing with the resulting hydraulic forces.

Have you got the gasket the right way up? I have seen some that are very similar either side up but expose oil and water galleries.

I was chatting through the problem with my dad last night. At the end of the previous race there were NO indications of water in the oil, despite running for 45 minutes after any damage would have occurred.

The problem came to light after the rebuild and seemed to get worse AFTER I had the head skimmed. The threads were cleaned both times before the head was fitted.

If the block was cracked, I'd have expected the symptoms to be the same before and after the head was skimmed. The block has been decked in the past.

This led us to conclude that the head bolts could be bottoming out in their threads before the head was pulled down correctly. As far as I know the head bolts are standard.

This would:
Give indications of correct torquing
Leave a gap between the head and the block
Get worse when the head was skimmed.

Tonight I'm going to torque the head down without a gasket and see if there is any space between the head and the head of the bolts.

I'll let you know what I find, but I have never shortened the bolts despite there being quite a bit of head/block removal over the years!

Anybody had experience of this??

..............going back to my previous post!

have you checked to see if the HEAD is cracked!

very common on crossflow heads. Quick dye penetrant check may save you countless head gasket sets!

Is a dye penetrant check something I could do myself or is it an engineering firm job?

The usual place for a x-flow head to crack is at the narrow piece between cylinders 2 and 3 - there's a waterway just below and there's not much metal there. On the heads where I've seen this, the crack has been easily visible.

The usual causes are removing or tightening the head bolts in the wrong sequence, or not doing it in easy stages.

I hope this isn't the problem, as fixing it is very difficult - not impossible, but probably uneconomical.

rgds,
David

Would it be worth just removing one head bolt at a time and putting on a thick washer? then retorque. 20mins work and no head gasket replacement. If bolts have not been clamping gasket it may be reusable ?

quote:

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Originally posted by David Jenkins
The usual place for a x-flow head to crack is at the narrow piece between cylinders 2 and 3 - there's a waterway just below and there's not much metal there. On the heads where I've seen this, the crack has been easily visible.

The usual causes are removing or tightening the head bolts in the wrong sequence, or not doing it in easy stages.

I hope this isn't the problem, as fixing it is very difficult - not impossible, but probably uneconomical.

rgds,
David

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can't see out wrong with that crank - might have a slight amount of 'bow' in it but looks fine.........

of course the fact i can SEE the crank might indicate another problem

Wow, thats an impressive picture. Anyway, I would stay away from shortening the bolts and use a hardened washer if possible. Wouldn't want to mess up the temper of the head bolts.