Thermo opening late - V6

[dustyd63]

My '99 Alero has about 95k on it now and has learned a new trick - overheating and boiling all of the antifreeze out of the tank.

At first it wasn't overheating - just blowing, so I replaced the tank cap, thinking that maybe it was shot and not holding pressure
.
About two days after that, the thermostat starts to not open once in a while, and then it quickly progresses into opening late every time - usually the needle was up to 3/4 before it would open... meanwhile, there's no heat until it opens and it's wintertime right now. Very cold.

To remedy this problem, I replaced the thermomstat Wed. night. Now, only a couple days later, however, it's opening late again (needle at 2/3 or so) and blowing all of the antifreeze.

I'm really getting sick of a sweet smelling car. Too much burning antifreeze (although I guess it's better than oil).

I'm not sure what else I'm overlooking - Ideas??

Thanks!!

[mrmike]

Did you check to see if your lower intake manifold gasket is leaking? Because I had trouble with overheating and the sweet smell when mine was leaking.

[dustyd63]

I don't seem to have a problem with any leakage. There is no evidence outside the engine (except on everything surrounding the blow-off hose) and the oil level is close enough to normal that it doesn't seem to be leaking to the inside.

I'm now thinking the water pump for one main reason... my heat. If the engine starts to overheat, all of a sudden I have no heat in the car - it's like all pressure through the core is gone. As soon as something kicks, though, the operating temp goes back to normal and I have heat again - pretty much instantaneously for both.

Granted, I havn't heard of a water pump coming and going - normally, don't they just leave and never come back? But I've had enough other really quirky suff happen on this car that I'm seriously considering it.

[steve-o]

could be air trapped into the coolant system, make sure your the coolant levels are ok.

[dustyd63]

Yeah... That's what it was at first, but now parts are failing. I fill the coolant tank up and drive into work (10 mi or so) to get rid of air, but it still acts up on the way home.

[olds2race]

Did you check to make sure you have the right thermostat? When you get a thermostat from the parts store they just give you whatever their computer tells them. most thermostats have a number stamped on them that tells you at what temp they will open. you may have one that opens at a hotter temp then what the car needs. Also make sure that the system IS holding presure. sometimes the coolant tank will develope a seam leak that will not aloow it to presurize properly until it gets too hot.

[billytheman1188]

I am having the same problem, its the lower intake manifold. My stepdad put my car up on ramps, looked under the car and saw a leak, but yeai had the same problems as you, its the infamous LIM leak, im getting it fixed thursday, TRY NOT TO DRIVE YOUR CAR TOO MUCH with the leak.

[Redog]

I concur with everybody else

You either have "the Leak" or the wrong thromo

[dustyd63]

The thermostat is set for 195 degrees, so that shouldn't be a problem.

I already checked for leaks and didn't see any, but I'll look again. I'm sure that if it's dumping tanks of coolant that I'd have seen it, though.

It's currently sitting... The cooling is completely shot - doesn't work at all. I'll have to fix this before I can drive it again - which means tonight.

Thanks for all the input!