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

Leak Down Testing

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Old 06-04-2011, 04:09 PM
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Default Leak Down Testing

Fresh rebuild, first oil change had chocolate milk colored oil. Perhaps there was condensation build up in the sitting motor or the machine shop didnt assemble correctly.

I have suspicions of a bad head gasket. From what I understand, I should do a leak down test.

Is there a guide somewhere? Any other tests I should do.

Thanks!
Old 06-05-2011, 04:30 AM
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How did it run, how do the plugs look, did it smoke, is there oil in the intake, or in the coolant? What makes you suspect a head gasket other than the oil, what did the "fresh rebuild" consist of? As far as a leak down test Google/ Youtube is your friend! More info will probably net you more responses.
Old 06-05-2011, 10:44 AM
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For the cooling system right? Its simple doesn't really warrant a write up. But as suggested go on youtube and look it up. Your only other option is a compression test of the cylinders. More of a PITA.

Drain your coolant, let it sit a day or two and see if an oil puddle forms on top of it like mine Just because the coolant looks good with the cap off doesn't mean anything
Old 06-05-2011, 02:41 PM
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Originally Posted by 96LT1355Z28
How did it run, how do the plugs look, did it smoke, is there oil in the intake, or in the coolant? What makes you suspect a head gasket other than the oil, what did the "fresh rebuild" consist of? As far as a leak down test Google/ Youtube is your friend! More info will probably net you more responses.
I pulled the motor, did a LE2 head/cam package with all the usual maintenace stuff - reground crank, new rods, pistons, freeze plugs, oil pump, bearings, etc.

I haven't pulled the plugs. There looks to be a tiny bit of white smoke, but not a ton. Can't really see it outside, but if its in the garage with exhaust facing the inside you can see it kinda accumulating and flowing out the open bay door.

I didn't see any oil in the coolant, which I swapped out when I replaced the distributor this past weekend. I havent looked in the intake either.

I thought chocolate milk colored oil was a tell tale blown head gasket sign.
Old 06-05-2011, 02:52 PM
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Originally Posted by LarsV8
There looks to be a tiny bit of white smoke,

I thought chocolate milk colored oil was a tell tale blown head gasket sign.
The white smoke is another confirmation, it'll only get worse. Stick a camera or buddy behind it if you're still running it to see.

The milk oil is the tell tale sign but you should have other symptoms to, as stated one or more of your plugs will be showing signs. The white smoke is another. Your coolant can also be discolored.

Hows it running? Not over heating? Are you loosing any coolant?
Old 06-05-2011, 02:57 PM
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Seems to be running okay, although I am not sure what normal is since this is a fresh rebuild on a high powered car. I don't run it long enough to overheat because I read the water in the oil can ruin bearings.

Will this work?

http://www.youtube.com/watch?v=QA7KV...yer_detailpage

Last edited by LarsV8; 06-05-2011 at 03:03 PM.
Old 06-05-2011, 03:02 PM
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If you just changed the oil / coolant or both no! This is how i was going to go about it until i read up on it. It'll effect the results having fresh oil/coolant in it. It reads some chemical reaction mojo or such that'll be in the coolant after cycling for awhile.

Rent the Cooling system pressure test from autozone and see how that works. Mine failed quick
Old 06-05-2011, 03:06 PM
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Will do, thanks man!
Old 06-05-2011, 06:23 PM
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Got the pressure tester from Autozone.

Pumped it up to 15 PSI and I had some leaking on top hose where it connects to the intermediary pipe with the bleeder screw. Tightened it up and stopped the leak there.

Started up the car and it idle for 2 minutes. Pressure increased to 18 PSI and held constant for two minutes.

I still feel like something is not right.
Old 06-05-2011, 06:40 PM
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I know the feeling, mine failed the pressure test but is still running strong, no smoke or over heating. Maybe i'll dump the oil again soon on mine but for as far as your engine maybe do the same, like you said just condensation maybe?

Someone else with some more know how might able to suggest something else. Good luck.



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