my van started over hearting yesterday... its always ran a little hot...
it was low on water. I filled it and as soon as i started the van, the water came out the over flow.

did some testing, changed the thermastat. filled system, and it still runs hot.
the system has very good pressure but some is filling up with air. it hard to explain.... as soon i start it, it pumps water into the overflow, then appears to pump air into the overflow. in 5 minutes theres not enough water to cool the van.

i unhooked the hot side to the radiator to see if the old thermastst was opening, water slowly started pushing out when it got hot. same thing with the new one. i dont know how fast it's suposed to flow at, but my buick was a lot more than that.

i dont get how the system gets so much air in it so quickly after i fill and bleed it. how is pumping air into the overflow if there was no air to start with.... :banghead:

at idle with the cap off, water just jumps out the cap... even when cold...

whats going on, what should i check... is there a certain way to install the T-stat? anyone know where to get a service manual online?

Do you have a coolant system tester? If you are getting some extreme pressure you may have a blown head gasket, What color is your exhuast smoke?

exhaust is clear, i dont have a tester. but when i drive it, but under full throtle, it purs like a bird. if i have a blown gasket, why isnt it in the oil? i've filled the system about 10 times, eachtime takes about 1/4 to 1/2 gallon. that water cant just dissappear. it has to be coming out the overflow, i just changed the cap. it only starts to go out the over flow when its warm/hot. not cold. it idles very smoothly until it get hot, then its rough but on the throttle smooths it back out.

You may be losing the coolant through a faulty intake manifold gasket. The 3.4L are known for bad IMGs. Be very carefuly if the van is overheating. It is very easy to blow the head gasket. Unfortunately, I know from experience.

im afraid im starting to think the head gasket has blow betweent the combustion chamber and the water gallies in the head, thus pumping hing pressure and air into the water system, this in turno pushes water out the overflow....

so, a compression revield a bad head gasket. started with #6, red 120psi cold, 60warm. #4 185psi, #2 120pis warm. back to #6, unhooked the guage and water shoots a tremendous amount every reverulition.

is possible to change the head gasket while the motor is still in the van? what would be the cheapest fix? i dont think i have the capibilities to pull the motor from under, will it come out the top?

You have a crack in the head - period.

Not sure how much of a job this is but it took my mechanic a days work to replace the Dome gasket and Head gasket. I paid a visit when he was doing in and the engine was still in the van.
Total cost was around 1100$ for the job but it's better doing that then having a busted engine. Apparently the dome gaskets are due on these around 120k or so, after that they start to leak. Mine was and you could notice it around the upper part of the motor in areas where water can accumulate. We also had a smell of coolant (which I don't think you have).

well, i don't know what to do.... i don't have nay money and the van is verry nice and clean but i think it has a low resale value. maybe i'll get lucky and only have to change the front head gasket. i havent comp tested the rear yet...

well, i don't know what to do.... i don't have nay money and the van is verry nice and clean but i think it has a low resale value. maybe i'll get lucky and only have to change the front head gasket. i havent comp tested the rear yet...

Well, one thing you can't do is replace just the one head gasket. Well, you could, but that would be pretty pointless since the gaskets come in a kit with everything you need for both heads (about $120 for the kit).
The job is big, but straight forward to do--no problems and plenty of room in the engine compartment once you remove the top engine mounts and roll the engine forward. The hardest part is getting the ignition packs off the rear of the engine--once that's done you have room to reach back in there and pull off the exhaust manifolds.

this job will take a complete novice maybe 4 days working about 4 hours a day. I wouldn't do it without a manual and plenty of advance research (read this forum for eveyone elses experience). You will need a torque wrench and a crow's foot wrench (10mm for the intake manifold). $120 bucks in parts and 4 days labor. Its not worth geting rid of the car over, or if it is, I'll buy it from you :grinno:

John

Today I started tearing her down, Spent four hours.

I'm at the point where i pulled the LIM off and need to remove the rockerarms. But there's a hurricane headed toward me...

Whats a crows foot and what do i need it for?

A crow's foot wrench looks like this: http://buy1.snapon.com/catalog/item.asp?P65=&tool=&item_ID=1211&group_ID=147&store=snapon-store&dir=catalog
and you need one--10mm--to get at the two bolts under the sides of the LIM. There are 8 bolts total, 4 straight down the top and 4 on the sides. Two of the side bolts are covered up by the lim itself. You can do the one under the air intake without too much trouble, but the left side by the power steering pump mount is just a pain. Getting them out isn't the real issue; its torquing them back down correctly after you're done that's tricky. I have done three LIM jobs now and the crow's foot wrench I got for the 3rd one is the way to do it.
John