3.1 Chevy Lumina has me stumped..................

I'm trying to figure out what's wrong with a friends car for him...... Here goes......
95 Lumina - 3.1 MPFI - 101,000 miles on the clock, appears to be pumping
exhaust into the cooling system.
When the engines cold it has 165 - 170 PSI compression in all six. As soon as the engine gets warm it starts pumping all it's coolant into the bottle. This starts happening before the engine reaches its normal operating temp. after the thermostat opens, the temp continues rising until it pins the gauge and pumps all the coolant into the bottle. The fans work and we've tried 3 thermostats, that's not the problem. The upper radiator hose is getting smoking hot when the thermostat opens, at about mid temp gauge. I just got the engine smoking hot and did a hot compression check. Again, all holes at 165 - 175. I was figuring it was a cracked head which would pump exhaust into the cooling system after the head got hot enough to expand and allow a crack to open up, and then seal when cool, BUT, good compression seems to be proving me wrong. A burnt head gasket would have the problem cold as well as hot I would assume....... I'm pretty sure it's compression in the cooling system as I put my Stant radiator pressure tester on and started it up cold. Just as the thermostat opened the pressure gauge started rising until it pinned. This car is well cared for and belongs to a good friend who can't afford to throw money at it until it's fixed. In other words, it needs to be fixed right the first time. Can someone point me in the right direction ?????
Thanks Brian...........
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Are you checking the compression with all the plugs out or just removing one plug at a time?
You must remove all the plugs and to check the compression. Sorry if you knew that!
Jim Smith

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Here goes......

pumping exhaust into the cooling

soon as the engine gets warm

happening before the engine reaches

continues rising until it pins the

we've tried 3 thermostats,

hot when the thermostat opens,

hot compression check. Again,

would pump exhaust into the

crack to open up, and then seal

burnt head gasket would have the

it's compression in the cooling

cold. Just as the thermostat

well cared for and belongs to

In other words, it needs to

direction ?????

Bad head gasket. It doesn't take much to cause a problem. Consider it takes just 12-15 pounds of pressure to open that cap. Go buy some test strips to test for presence of combustion products in the coolant.
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Wouldn't a head gasket act up cold as well as hot ?????? If it's burned through it should pressurize the cooling system when first started. Also, why isn't anything showing up on a compression test ???? I would think it would..........
Thanks.............
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wrote:

As
test
burned through it should

anything showing up on a

May not be burned through enough to open up when cold. It may just move enough out of place enough to cause problems when warmed up. As for the compression test since it only takes a few pounds of pressure to cause problems it may be in a cylinder that would normally show 160 and is now showing only 150 because it is bleeding off 10 pounds of pressure. If you have access to a leak down tester run that and see if you get bubbles in the radiator then. You may have caught a gasket that is just starting to fail.
Steve W.
-
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Brian wrote:

if u have a Cracked Head / Block, The Crack Closes somewhat with the Engine COLD, The Crack will open farther when it is warm or Hot.
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Nope, not always.

The thermostat is in the way and there's likely to be an air pocket at the top of the coolant space in the block from the last time the engine was run.

Because compression pressure is lower than combustion pressure.
Two ways you can try to determine which cylinder is the culprit; 1) take the thermostat out, re-install the housing with gasket and refill the cooling system. Remove all 6 spark plugs. Do your compression test and watch the coolant level at the radiator cap opening, the leaking cylinder when working to pump the cylinder against the compression gauge should cause the coolant level to change visibly. You may even see bubbles. if the leak is bad enough, you'll get a coolant bath.
2) Do a cylinder leak down test on each cylinder, watch the coolant level at the radiator cap opening, you'll see bubbles or a rise in coolant level when you're on the leaking cylinder. Again, if the leak is bad enough, you'll get a bath....
but before you get too carried away, are you certain that the impeller on the water pump is intact?
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What you have is a blown head gasket.............. Don't just fix that though, those aluminum heads usually will get warped when the head gasket blows from all the heat, so I would be looking for a good used 3.1 in the junk yard.

Here goes......

exhaust into the cooling

soon as the engine gets warm

before the engine reaches

rising until it pins the

tried 3 thermostats,

when the thermostat opens,

compression check. Again,

pump exhaust into the

to open up, and then seal

head gasket would have the

compression in the cooling

cold. Just as the thermostat

well cared for and belongs to

other words, it needs to

direction ?????

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"" wrote: > I'm trying to figure out what's wrong with a friends car for > him...... Here goes...... > > 95 Lumina - 3.1 MPFI - 101,000 miles on the clock, appears > to be pumping exhaust into the cooling > system. > > When the engines cold it has 165 - 170 PSI compression in all > six. As soon as the engine gets warm > it starts pumping all it's coolant into the bottle. This > starts happening before the engine reaches > its normal operating temp. after the thermostat opens, the > temp continues rising until it pins the > gauge and pumps all the coolant into the bottle. The fans > work and we've tried 3 thermostats, > that's not the problem. The upper radiator hose is getting > smoking hot when the thermostat opens, > at about mid temp gauge. I just got the engine smoking hot > and did a hot compression check. Again, > all holes at 165 - 175. I was figuring it was a cracked head > which would pump exhaust into the > cooling system after the head got hot enough to expand and > allow a crack to open up, and then seal > when cool, BUT, good compression seems to be proving me > wrong. A burnt head gasket would have the > problem cold as well as hot I would assume....... I'm pretty > sure it's compression in the cooling > system as I put my Stant radiator pressure tester on and > started it up cold. Just as the thermostat > opened the pressure gauge started rising until it pinned. > This car is well cared for and belongs to > a good friend who can't afford to throw money at it until it's > fixed. In other words, it needs to > be fixed right the first time. Can someone point me in the > right direction ????? > > Thanks > Brian...........
The only known way exhaust gas can get into the cooling system is by way of a blown head gasket or cracked cylinder wall or cracked head
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Get the headgaskets fixed.
Brian wrote:

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I have a 90 Lumina in my garage with a 3.1 that I would sell cheap if you are in or near Wisconsin. It needs a lot of work but the motor and trans are fine. Phillip Wolf
I Hate Spam wrote:

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