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GMC V6 and V12 Engines Engine repair and rebuilding

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  #1  
Old February 17th, 2013, 07:35 PM
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Default Oil Leak

Hi everyone,

I have a messy oil leak at the back of my engine. It seems to be coming from the area around the breather tube?? It is very hard to see back there. But the tube seems to come up behind the left head than crosses behind the distributor than up to a hose to the air cleaner.

My oil leak is pretty massive. Mostly going down from about the bottom of heads over the bell housing off the trans. Most of it is to the right side though, some to the left. Mostly seeping. Like the starter is dry, but the block, oil pan, and bell housing are soaked. Not much if any above the bottom of the heads. The clutch and everything inside bell housing are dry.

I believe the head gasket wouldn't leak oil like that without some other obvious problems. I did a R&R on the intake, valve cover's (new gasket's), and cam cover (permatex) last year.

That leads me to the distributor (shouldn't leak much), or the breather tube.
Does anyone know how the breather tube is attached? Is there a gasket, or a fitting that may have failed? Or something else entirely? It seems to me that the tube to the air cleaner is too oily (inside). Maybe a baffle or something?

Any thought's will be appreciated. Thanks. Tim.
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71 C 10 Chev.
71 C 20 Chev.
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  #2  
Old February 17th, 2013, 09:36 PM
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Default Re: Oil Leak

Hey Tim, sounds like maybe you may have twisted a valve cover gasket or it slipped on you when you installed it. That is usually the only place that will produce that much oil. I would pressure wash the areas and run it while keeping an eye out for fresh oil.
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Old July 17th, 2013, 07:20 PM
huntaaar huntaaar is offline
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Default Re: Oil Leak

i recently had this problem and after removing the valve cover gasket i found a solid inch of sludge was hiding in around the lifters and valves. i used a flat head screw driver to chip it off then sucked out what i could with a shopvac. its still pretty dirty. are you saying its safe to pressure wash this area? even while its running?
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Old July 18th, 2013, 06:21 AM
jrmunn jrmunn is offline
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Default Re: Oil Leak

Another possibility to check is whether the breather tube is obstructed. This can cause pressure to build up in the engine and push oil out the dip stick, which then blows back against the rear of the engine and the firewall. I went through the changing valve cover gasket routine a few years ago before finding out that the breather tube "filter" in the line leading to the air cleaner had become clogged.

JRMunn
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Old July 19th, 2013, 03:51 AM
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Default Re: Oil Leak

Sorry, I've been sooo busy. But I did figure things out just unable to get back to reply, then of. course I forgot all about it.
The problem was a couple of things.
First the valve cover gaskets weren't seating right.
They loosened i re tightened them then they leaked more.
So I removed them cleaned everything. Then I re torqued the heads.
Because I read in the service manual that they should be Re torqued every so often. Or when removed. Then adjusted valves again. Re installed valve covers. No more leak.
Also the rubber parts of the breather hose were wasted. So I replaced them and that stopped oil splatter on the Intake manifold.
Conclusion is that most oil leaks are gone. Just a drip now and then.
Tho I was unable to service the breather filter, but I'll try again this winter.
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71 C 10 Chev.
71 C 20 Chev.
and way too many projects sprawled throughout my yard...
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Old July 20th, 2013, 12:52 AM
jrmunn jrmunn is offline
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Default Re: Oil Leak

Tim,

Glad to hear that your leaks are fixed. If you have one of the breather tube filters/screens, I found that it can be cleaned using carburetor cleaner followed by regular cleaning fluid. Keeping an engine clean is a never-ending job. Oil and dirt seem to have a strong attraction to motors and drivetrains.

JRMunn
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