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6V92 oil leaks from rear of the head? 16 Aug 2014 19:41 #147342

  • theroadbossman
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Hi all,
Many of you have had years of experience on servie & repair of 92 Detroits, so I am trying to take a shortcut and ask if there is a more than common reason why I might see oil at the back of both cylinder heads about where the heads meet the block on the lower back corner.

I have cleaned the engine down twice and have not even done any miles yet, just running in the drive while doing other stuff, and it is annoying leaks that have been there for a while i would say (by the oil spotting all over the back bumper). Can't see any other leaks on the engine at all.

If you can give me the places to look, that would be a great start.

Identifying the point of leak is one thing, fixing it properly is another; first things first :)

Thanks all,
Brett
Austral Tourmaster with 6V92T mechanical

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Re: 6V92 oil leaks from rear of the head? 16 Aug 2014 20:45 #147343

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and ask if there is a more than common reason why I might see oil at the back of both cylinder heads about where the heads meet the block on the lower back corner.


Its a Detroit.. They leak.. Wasn't that a factory setting.. :D

I would hazard a guess that its leaking around the perimeter seal of the head.
There is a continuous square section 'o' ring that sits in a groove in the deck.
I have seen them fitted with the corners cut and turned out in the groove, with a dob of silastic on them. The ones I have had apart, fitted that way, generally leak..
If that is the case.. Heads off Ol Mate, that will fix it.

Pritty hard to diagnose something you can't see.

chocs 8-)

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Re: 6V92 oil leaks from rear of the head? 16 Aug 2014 20:54 #147344

  • theroadbossman
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Thanks Chocs, I have wiped it and wiped it and it seems to be exactly like you have suggested - but my 55 year old head has trouble digesting taking the heads off for an oil leak.
Sounds like it will be a job :(
Austral Tourmaster with 6V92T mechanical

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Re: 6V92 oil leaks from rear of the head? 16 Aug 2014 21:04 #147345

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Yes, it is very annoying to strip so much for so little.
That's about all that comes to mind though..

Everyone seems to have a secret recipe for putting them together so as to keep the oil in...

I think the biggest secret is, they must be clean at the point of assembly.
A wipe with a rag 2 days before the head goes on, usually doesn't cut it..

Wait till she needs a kit and give it a birthday then...

chocs 8-)

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Re: 6V92 oil leaks from rear of the head? 16 Aug 2014 22:10 #147346

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.....i'll hope to bring on a bit of a chat here and say that it's more than likely blowby (compression pressure passing the piston rings entering the crankcase) that's the root cause of any oil leaking problem with a GM....?????

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Re: 6V92 oil leaks from rear of the head? 16 Aug 2014 22:22 #147347

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.....i'll hope to bring on a bit of a chat here and say that it's more than likely blowby (compression pressure passing the piston rings entering the crankcase) that's the root cause of any oil leaking problem with a GM....?????


That theory is worthy of discussion

chocs 8-)

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Re: 6V92 oil leaks from rear of the head? 17 Aug 2014 03:45 #147348

  • BillyP
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Mate,
personally i would not be pullin any thing apart till you know EXACTLY where its comin from.

This means a good clean down & runnin it with your head stuck right in there to try & spot the source.

you might have to do that more than once to find it , but knowin where the problem lies first up is the

way to go. ....................Billy........................
I came into this world with nothing & still have most of it..........

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Re: 6V92 oil leaks from rear of the head? 17 Aug 2014 09:15 #147349

  • theroadbossman
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Yeah Billy, that is what I am seeking at the moment, and I'm thinking of doing exactly that. Clean it all down again spotlessly, start and run and watch.
But to be honest I wasn't looking for any more info than for example "hey, have a look at the blower boot - they all leak".
I'll do the clean and watch thing and see if I can actually pinpoint the leak - stay tuned and thanks to you all! ;)
Austral Tourmaster with 6V92T mechanical

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Re: 6V92 oil leaks from rear of the head? 17 Aug 2014 10:08 #147350

  • Swishy
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RBMan
Gudday M8

normally the rocker covers do all the leak n
if the RC R ovr tightend they can distort the covers and the rust prevent n oil weepz out
any oil leaks R pushed 2 D rear of the beast by the coolin fan
May B u got a leak up above the 'V' in D valley n it is run n back n down the heads

pure gesstim8 on my part

LOL
cya
OF ALL THE THINGS EYE MISS ................. EYE MISS MY MIND THE MOST

There's more WORTH in KENWORTH

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Re: 6V92 oil leaks from rear of the head? 17 Aug 2014 11:38 #147351

  • geoffb
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Fix that reckon it will find some where else :-[ :-[

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