newbee here problem with 01 montana cooling system

I just bought a 2001 pontiac montana from a private owner 132,000 miles i drove it for another 3000 miles then van starts overheating first drain the coolant, replaced bleeded it and seems to work for a few more weeks. then car stars overheating again. i replaced the sensor, thermostat 2x , replaced radiator but still having the same problem. not showing any signs of leaking coolant or loosing any coolant. but i saw the infamous milky substance in my oil cap. and also a lot of air is coming out when i bleed it. and even if i bleed and let all the air out until its coolant that is coming out from the bleeders after a few minutes of driving it will overheat again. and also to add after i bleed it i will get a good heat inside the van but after awhile it will vanished again and van start overheating again. please help me what might be the problem?

I just bought a 2001 pontiac montana from a private owner 132,000 miles i drove it for another 3000 miles then van starts overheating first drain the coolant, replaced bleeded it and seems to work for a few more weeks. then car stars overheating again. i replaced the sensor, thermostat 2x , replaced radiator but still having the same problem. not showing any signs of leaking coolant or loosing any coolant. but i saw the infamous milky substance in my oil cap. and also a lot of air is coming out when i bleed it. and even if i bleed and let all the air out until its coolant that is coming out from the bleeders after a few minutes of driving it will overheat again. and also to add after i bleed it i will get a good heat inside the van but after awhile it will vanished again and van start overheating again. please help me what might be the problem?
Sounds like a leaking head gasket. You can go out to her early in the morning when she's cold, pop the hood and feel the radiator hose. It should be soft. Start it up and feel the radiator hose again. It should get hard slowly as it warms up. If it gets hard too quickly, the system is being pressurized by a leaking head gasket.

I'm not pointing fingers, or blaming you, but it seems like you threw a lot of parts ($$) at it when a simple combustion gas test would have confirmed that the head gaskets are leaking. That is probably the reason for the original owner selling it. If you decide to do the job yourself it's not too expensive, just time consuming.

Sounds like a leaking head gasket. You can go out to her early in the morning when she's cold, pop the hood and feel the radiator hose. It should be soft. Start it up and feel the radiator hose again. It should get hard slowly as it warms up. If it gets hard too quickly, the system is being pressurized by a leaking head gasket.

actually one more thing that i noticed the gauge actually doesn't go up towards the red line until the thermostat opens. then once it reaches the thermostat operating temperature it will keep going up to 3/4 of the gauge. and when i start seeing this happening i pull over then start bleeding the valves. and actually yesterday when i drove it the van's engine was not even that hot yet but the gauge was already on the 3/4. so if this is really a blown head gasket will the be easy to replaced? do i actually need to lift the engine out of the vehicle to do this?

thanks for all your help!

I'm not pointing fingers, or blaming you, but it seems like you threw a lot of parts ($$) at it when a simple combustion gas test would have confirmed that the head gaskets are leaking. That is probably the reason for the original owner selling it. If you decide to do the job yourself it's not too expensive, just time consuming.


actually one more thing that i noticed the gauge actually doesn't go up towards the red line until the thermostat opens. then once it reaches the thermostat operating temperature it will keep going up to 3/4 of the gauge. and when i start seeing this happening i pull over then start bleeding the valves. and actually yesterday when i drove it the van's engine was not even that hot yet but the gauge was already on the 3/4. so if this is really a blown head gasket will the be easy to replaced? do i actually need to lift the engine out of the vehicle to do this? and also i'm not a mechanic i was just doing it by myself following instructions from haynes manual.

thanks!

do i actually need to lift the engine out of the vehicle to do this? and also i'm not a mechanic i was just doing it by myself following instructions from haynes manual.

thanks!

I don't think so. If it's the forward head, it will be alot easier than the back one, but you should be able to do it while still in the vehicle.

I don't think so. If it's the forward head, it will be alot easier than the back one, but you should be able to do it while still in the vehicle.

thanks for that info.. one more thing to add. i actually drove the van ;ast saturday and when i got home i checked the radiator to check how much coolant is in there. i can see some coolant right below the filler neck so i decided to add some more. when i start filling it up it starts sucking in the coolant and i was hearing like a burping sound. then goes down again way below where it was the first time. then i added some more. it will sit there for a litlle while then it starts going down. then i started the engine then i reaized a lot of white smoke is coming out of the exhaust and it was like a cloud. check the bottom of the car and realized all the coolant that was disapearing from the radiator was going to the exhaust. what will be the problem this time now? please help...

and realized all the coolant that was disapearing from the radiator was going to the exhaust. what will be the problem this time now? please help...

Probably your intake manifold gasket is leaking and needs to be replaced.

To replace the head &/or intake gaskets, I'd take the GM mini-van to a professional auto shop. The reason is, they also inspect (and if needed, replace) all related parts as well. Also... To recommend the heads be "plained - shaved" down. Thus, ensuring they are perfectly flat - to properly seat on the new gaskets. Many DIY repair folks don't plain the heads and within 3-4 months later, their vehicle needs another intake &/or head gasket replacement job. The extra $200 (or so) to plain the heads (to ensure perfectly flat) is worth it - so I've been told.

After you get its head &/or gaskets replaced, I'd recommend the install of aux ATV LPD (Low Pressure Drop) cooler as well. An LPD cooler rated to pull attached 5,000 lbs trailer. Even if your GM mini-van never pulls a trailer, my tranny mechanic recommends all GM mini-vans have an additional aux ATF cooler installed. By default, their stock transmissions run hot. With aux ATF cooler, it helps eliminate extra "tax" on its main cooling system as well. Thus, positive benefit on its antifreeze cooling system as well.

If/when the Intake Gasket blows on our 2003 3.4L engine (in our "run about" vehicle), I'll be getting a professional auto shop to repair it. Especially since our "run about" has ZERO rust. And, its low miles/kms as well. Thus, worth fixing - if its head &/or intake gasket blew today.

Hope this helps as well...

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