Locost82
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| posted on 7/9/05 at 03:50 PM |
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Head Gasket query
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?
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Danozeman
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| posted on 7/9/05 at 03:52 PM |
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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]
Dan
Built the purple peril!! Let the modifications begin!!
http://www.eastangliankitcars.co.uk
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Locost82
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| posted on 7/9/05 at 03:58 PM |
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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!!
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jollygreengiant
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| posted on 7/9/05 at 04:15 PM |
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what engine is it, make & size?
Beware of the Goldfish in the tulip mines. The ONLY defence against them is smoking peanut butter sandwiches.
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GParkes
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| posted on 7/9/05 at 05:29 PM |
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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
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Locost82
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| posted on 7/9/05 at 05:40 PM |
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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!!
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britishtrident
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| posted on 7/9/05 at 07:11 PM |
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Oil and water temp up to temp before the engine was shutdown ?
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Locost82
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 posted on 12/9/05 at 10:24 AM |
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NIGHTMARE
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!
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NS Dev
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| posted on 12/9/05 at 11:09 AM |
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sounds like the head is cracked to me
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omega 24 v6
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| posted on 12/9/05 at 11:35 AM |
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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.
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Peteff
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| posted on 12/9/05 at 12:32 PM |
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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.
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
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Locost82
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| posted on 14/9/05 at 09:03 AM |
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Eureka!!
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??
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NS Dev
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| posted on 14/9/05 at 12:02 PM |
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..............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!
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Locost82
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| posted on 14/9/05 at 01:38 PM |
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Is a dye penetrant check something I could do myself or is it an engineering firm job?
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David Jenkins
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| posted on 14/9/05 at 01:47 PM |
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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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rusty nuts
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| posted on 14/9/05 at 05:58 PM |
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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 ?
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NS Dev
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| posted on 15/9/05 at 08:00 AM |
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quote:
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
Knew I had seen a few cracked but couldn't remember where they went! Cheers.
You can do dye penetrant diy, just buy some dye and developer sprays, they are very cheap. Having said that, as David said, you will probably be able
to see a crack anyway if you clean the head thoroughly and inspect it carefully.
I always keep some dye penetrant handy though, good to check cranks with it to avoid things like this happening!!!:
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MikeR
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| posted on 15/9/05 at 05:04 PM |
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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 
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crbrlfrost
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| posted on 15/9/05 at 05:07 PM |
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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.
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