LT1-LT4 Modifications 1993-97 Gen II Small Block V8

MLS head gasket leak?

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Old 02-07-2011, 10:54 AM
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Default MLS head gasket leak?

Been trying to find an oil leak for the longest time, when I finally found where it was coming from I couldn't believe it. The driver's side head gasket looks like it's leaking oil. I really don't understand how oil can leak from a LT1 head without contaminating coolant first, or blowing the head gasket out completely. I'm running MLS head gaskets with ARP bolts and didn't cut any corners when I rebuilt the top end so I'm really wondering if it couldn't be an intake corner. Could it be the intake? Or should I get new head gaskets on the way?
Old 02-07-2011, 12:37 PM
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Compression and leakdown test will tell you more. Before you tear it apart, make sure it's a head gasket issue.
Old 02-07-2011, 12:46 PM
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It could be leaking oil out of the head gasket and have no problems indicated by a leakdown or compression test. When the oil is pumped through the lifters, then pushrods and on to the rockers the oil has to go somewhere. There are to drain holes in the head, one in front and one in back for oil to return into the block and flow back to the oil pan. First question I want to ask is...were the head and deck machined for a MLS gasket? If they were, you have an unfortunate situation that should be corrected by installing a new gasket. If not then you have your answer, as well as a possible condition that a leakdown or compression test would find (loss of cylinder pressure due to inadequate sealing). Either way if it truly is the head gasket (make sure it' not the intake or valve cover) then it sounds like you're head is coming off.....
Old 02-07-2011, 07:32 PM
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Motor passed compression test, no leakdown yet. The block has been decked to zero, and the heads have been surfaced. I'm really thinking the intake is leaking from the front corner. I honestly don't see why the head gasket would leak oil without blowing. The oil that flows from the head to the block isn't under any pressure so I'm thinking the head gasket situation is extremly unlikely. I'm going to start with the intake, and see where it goes.
Old 02-08-2011, 08:05 AM
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Originally Posted by 09jyounger
I really don't understand how oil can leak from a LT1 head without contaminating coolant first...
It can't. Oil does not pass from the head to the block through the headgasket. If you see oil on the outside of the head then aim higher, like the valve cover gaskets.
Old 02-08-2011, 01:51 PM
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Originally Posted by SS RRR
It can't. Oil does not pass from the head to the block through the headgasket. If you see oil on the outside of the head then aim higher, like the valve cover gaskets.
Exactly what I did last night. Pulled the valve covers off and put on new gaskets. I haven't had time to check yet if the leak has improved or not. Plan on doing that tonight when I get off work. I've got intake gaskets on hand just in case. Anyone know the torque procedure for the intake? My manual is currently across town and I don't feel like going sledding through the 6 inches of snow we got we today
Old 02-08-2011, 04:57 PM
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http://shbox.com/ci/intake_sequence.jpg
Old 02-08-2011, 06:49 PM
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I agree with SSRRR. I doubt its the head gasket especially if its coming from the front.
Old 02-09-2011, 01:22 PM
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Well we confirmed that it isn't the head gasket last night, thank god, but we still haven't found the leak. The front of the intake SEEMS sealed, but it's coming off and getting resealed tonight. SS RRR, thank you for the link. I'll keep everyone updated as I make progress.
Old 02-13-2011, 03:31 AM
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Well pulled the intake off and found out the back of the intake was leaking. I resealed the intake, drove the car around tonight only to find oil was still on the side of the block. I checked the oil level and it was full. Now here's where the light bulb turns on; my power steering is low . My original theory of the leak coming from the block, and dripping on the k member was wrong, because everything is dry, except the power steering knuckle, and the side of the block. It looks like loose lines, so nothing major. I'll pull them off and inspect and reinstall them tomorrow. Thanks to everyone for the advice, help, and support
Old 02-13-2011, 10:29 AM
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Congrats, you found the #1 cause of LT1 oil leaks.



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