Thread: Big trouble with my new car!

I bought a 1999 Grand prix GT last week with my daughter. She will be using the car. That was the plan anyway.
When we got the car, it looked like it was leaking oil at the valvecovers and perhaps at the lower intake manifold gasket. I decided since I has a couple days off, I'd go ahead and change out the lower and upper manifold gaskets, new upper manifold plenum, plugs, wires, etc.

Anyway, I got everything back together and wanted to flush the dexcool out and replace with green.

Here's where it gets ugly. While filling and flushing the radiator, I was finding some signs of oil, little pieces of sludge in the radiator. I was hoping is was from a previous leaky intake gasket. I had the thermostat out and was running the engine when all of a sudden it seemed to begin to boil over and was shooting water out of the radiator. I have never seen this before from any car. The cooing system was full and the temp gauge was below the 210 mark, but that seemed hot for a car with no thermostat.

So what do think? Did I screw up the intake job? Or do I have a head gasket issue. I'm upset that I didn't drive the car more before working on it. I barely drove it before I tore it down so I can't say if it had this problem before.

Give it to me straight.

Checking the dipstick is a good start.

You need to bleed the air from the cooling system. There is a small valve on top of the thermostat housing that you open up to let the air out. Once you get a steady stream of coolant from it then you should be good.

As far as the sludge, that is most likely from the old leaking LIM gaskets and old Dexcool. Might be a good idea to backflush the heater core as well if there is a lot in it.

The headgaskets almost NEVER go on these motors, even if overheated for long periods of time.

My question is this- When you replaced the LIM gaskets did you dump a quart of oil into the lifter valley and let it drain down into the pan and then change the oil and filter BEFORE you fired it back up? You should have done this, then let it run for about 10-15 min, then change the oil and filter again w/ your chosen brand and call it good. This will ensure that any coolant that made it down into the oil from the work does not damage the bearings and cause them to spin, thus toasting the motor.

Thanks for the replies!! The oil is perfect, I changed it out about a half hour before this all happened. clean and right at the full mark.

I just went out and ran it again, here's what happened.

I started it up and filled the radiator with water, it didn't take much, maybe a gallon at the most.
I watched as it ran, it was bubbling slowly at the radiator cap opening, which I left open the entire time.
I should note that the bubbles didn't smell like exhaust.
It acted normal for about 15 minutes as it was warming up. There is no thermostat in the engine right now.
I rev'd the motor a bit and could see the water flowing in the radiator.
the temp kept climbing and once the temp gauge hit about 190 it boiled over. Water began flowing out of the radiator cap hole. I shut off the engine and it really overflowed! The cooling fans never turned on...

So, What is the problem? Is it simply overheating because the fans aren't coming on? Its running pretty good actually... I may have overreacted.

Yes the heat was on and blowing warm air. Like I said, it didn't start overflowing until the temp gauge read around 190, What temp is it supposed to run? Should I try flushing with a chemical flushing product? Maybe my temp sender is suspect...I didn't think of it at the time, but I can shoot some temps with my IR temp gun.

Originally Posted by 98GPGT2D

Airlock.

My 98 GP GT did the same thing. Luckily, I wrench for a living and knew what was going on.
I put a jack under the front of the car and raised it up getting the rad cap up above the motor a little higher, giving the air a better chance to rise. There is also a BLED SCREW on the thermostat housing that needs to be opened up while filling. A cooling system funnel is a big help too. They work great when bleeding the cooling system.


Jay

Wow, i really hope you're right...I did use the bleeder and had water coming out of it.

Thanks for the suggestions. I did not fill from the thermostat housing. Perhaps it is not filling properly and the temp sensor is not giving proper readings. I won't be able to work on it again until this evening.

When I said shooting, here's what it does. Once it got hot, the water just began to spill over the lip, in a constant flow. When I shut the engine off at that point, it shoots much more water out momentarily then with the water level down at that point, I can still hear it bubbling in the radiator.

And no, the fans never ran.

Bill! Thanks you so much for the reassuring words. I will go ahead and finish my flushing, refill with the green, and reinstall the thermostat this evening and let everyone know how it goes.

Also, I do like beer, but it's 6am!!! I need to go to work today!