GM 3100 bad head gasket??? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

69heavychevy · 03-14-2013, 10:14 PM

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?

Z16 · 03-15-2013, 01:54 PM

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

69heavychevy · 03-16-2013, 01:39 AM

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.

Z16 · 03-16-2013, 10:51 AM

Read again, I said milky COOLANT. It's quite common not to have milky oil.

**GruntMoanCough** · 03-16-2013, 09:29 PM

Quote:

Originally Posted by 69heavychevy

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.

68C15 · 03-17-2013, 12:46 AM

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.

03-15-2013, 01:54 PM	#2
Z16 Registered User Join Date: Mar 2001 Location: Medicine Hat, Alberta, Canada Posts: 1,509	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 __________________ 98 GMC Sierra Ex Cab, cowl hood, Euro LED lights, 30 bar billet, Whipple Supercharged 350 Vortec: Forged flattops, E-Tec aluminum heads, Comp Cam, Scat crank and rods, Granatelli Mass air flow, Headers, Flowmaster exhaust , Complete MSD Ignition, Custom Tuning, intake spacer , ported throttle body, AC Delco port injection upgrade, Roller Rockers, Power Pulleys. Gear Vendors Overdrive. Soon to hit a dyno. 2/4 drop(for now). 95 Chevy S-10 Ex Cab 4.3 5 Speed 2/3 drop, Euro lights, billet grill, More to come. The Daily Driver

03-16-2013, 01:39 AM	#3
69heavychevy Registered User Join Date: Jan 2007 Location: Garland,TX Posts: 431	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. __________________ 80 C10 SWB Step Side - 350 w/ vortec heads, TH350, 12-bolt 3.73

03-16-2013, 10:51 AM	#4
Z16 Registered User Join Date: Mar 2001 Location: Medicine Hat, Alberta, Canada Posts: 1,509	Re: GM 3100 bad head gasket??? Read again, I said milky COOLANT. It's quite common not to have milky oil. __________________ 98 GMC Sierra Ex Cab, cowl hood, Euro LED lights, 30 bar billet, Whipple Supercharged 350 Vortec: Forged flattops, E-Tec aluminum heads, Comp Cam, Scat crank and rods, Granatelli Mass air flow, Headers, Flowmaster exhaust , Complete MSD Ignition, Custom Tuning, intake spacer , ported throttle body, AC Delco port injection upgrade, Roller Rockers, Power Pulleys. Gear Vendors Overdrive. Soon to hit a dyno. 2/4 drop(for now). 95 Chevy S-10 Ex Cab 4.3 5 Speed 2/3 drop, Euro lights, billet grill, More to come. The Daily Driver

03-17-2013, 12:46 AM	#6
68C15 blood type; Retumbo Join Date: Jan 2004 Location: next to my reloading bench Posts: 10,269	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. __________________ Man rule #77...if you own a 67 stepside with a caddy 472 you will never be in danger of loosing you man card

03-14-2013, 10:14 PM	#1
69heavychevy Registered User Join Date: Jan 2007 Location: Garland,TX Posts: 431	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? __________________ 80 C10 SWB Step Side - 350 w/ vortec heads, TH350, 12-bolt 3.73



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