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Old 03-14-2013, 09:14 PM   #1
69heavychevy
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GM 3100 bad head gasket???

Hey guys,
I wanted to get some input on a car I'm working on 2001 Chevy Lumina 3.1. The car was puffing out steady white smoke so right away I figured bad head gasket. I check the oil and its clean, no signs of water contamination. I check the coolant in the reservoir and it looks like mud. I crank the car up with the radiator cap off and right of the bat its shooting coolant out through the filler neck. I go ahead and do a block test and the tester fluid turns a light yellow. Everything points to it being a bad head gasket but why is there no coolant mixing with the oil? Also will a bad lower intake manifold gasket cause all the symptoms of a bad head gasket?
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Old 03-15-2013, 12:54 PM   #2
Z16
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Re: GM 3100 bad head gasket???

If it's intake, there wouldn't be pressure in the cooling system. That means combustion pressure is getting into the coolant. Oil can suck in from under the intake during the intake stroke, so that explains the milky coolant. 3.1s are known for cracked heads as well, but with oil in the coolant, I would say head gasket. With oil getting in the coolant, I would say there's a good chance of the head being warped as well. I believe the spec on a 3.1 is .002" warp, but I like to resurface every time I do head gaskets. Only other cause would be a cracked block, but highly unlikely
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Old 03-16-2013, 12:39 AM   #3
69heavychevy
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Re: GM 3100 bad head gasket???

Z16, I don't have milky oil. That's what's confusing. I have all the symptoms of a bad head gasket, but my oil is clean with absolutely no signs of coolant contamination.
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Old 03-16-2013, 09:51 AM   #4
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Re: GM 3100 bad head gasket???

Read again, I said milky COOLANT. It's quite common not to have milky oil.
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Old 03-16-2013, 08:29 PM   #5
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Re: GM 3100 bad head gasket???

Quote:
Originally Posted by 69heavychevy View Post
Also will a bad lower intake manifold gasket cause all the symptoms of a bad head gasket?
Very common on these engines. Usually around 180,000 km (100,000 + miles).
The ones I have seen, leak coolant at the right front corner (looking at the engine) above the starter.
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Old 03-16-2013, 11:46 PM   #6
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Re: GM 3100 bad head gasket???

most likely the oily coolant is from a bad intake gasket and you also have a bad head gasket. I usually find them blown on the corner of the block by cylinder #1. sometimes I find the block eroded away.
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