Air Pockets In Cooling System??

[sr1206]

I have a 1997 Park Avenue Ultra and it keeps getting way too hot. I've seen it get up to 260 degrees. I put in a new thermostat and that didn't work, so I thought there might have been some air in the system from when I changed the thermostat. I took off the radiator cap (when it cooled down) and let the car run and I saw air coming to the surface. I let it run until I didn't see any more air coming up. That fixed the problem temporarily. So I then changed the radiator cap. That didn't work either. Anyone know why I'm getting air in there? I'm also not losing any coolant which doesn't make sense to me. I'm stumped.

[ZiggyPA]

It may be a leaking head gasket...

[punxsymd]

Have the intake gasket checked for a leak. 3.8 engines crack the intake at the EGR ports. If this happens the coolant will probably burn off and never hit the ground. It could also be going in the base pan via the intake gasket or head gasket. If not, put car on ramps and repeat the bleed proceedure that you have already done. Sometimes you have to get the radiator up higher than the rest of the cooling system.

[HotZ28]

Originally Posted by sr1206

I have a 1997 Park Avenue Ultra and it keeps getting way too hot. I've seen it get up to 260 degrees. I put in a new thermostat and that didn't work, so I thought there might have been some air in the system from when I changed the thermostat. I took off the radiator cap (when it cooled down) and let the car run and I saw air coming to the surface. I let it run until I didn't see any more air coming up. That fixed the problem temporarily. So I then changed the radiator cap. That didn't work either. Anyone know why I'm getting air in there? I'm also not losing any coolant which doesn't make sense to me. I'm stumped.

Are both fans coming on? Blown head gaskets are very unusual on this engine, however if that were the problem, it can be detected with a cooling system pressure test.

Originally Posted by punxsymd

Have the intake gasket checked for a leak. 3.8 engines crack the intake at the EGR ports. If this happens the coolant will probably burn off and never hit the ground. It could also be going in the base pan via the intake gasket or head gasket. If not, put car on ramps and repeat the bleed proceedure that you have already done. Sometimes you have to get the radiator up higher than the rest of the cooling system.

In an effort to clarify the above, according to the OP, his car is an Ultra; so therefore it has an all aluminum intake and not subject to EGR burn out like the plastic intakes on the standard VIN-K engine. In addition, the EGR burn out usually is found on the inside of the intake; so therefore, when it does burn through, it will ingest coolant into the UIM and there will not be any visible external leaks.

After draining & flushing the cooling system, follow the bleed & filling procedure below.

1) While cold, fill the radiator with coolant to the top of fill neck.
2) Start engine & let it idle until coolant level drops, then fill to neck again.
3) Let the engine warm until thermostat releases (you can see & feel when this happens)
4) Open throttle to about 2000 RPM, you should see the coolant level drop, then add coolant once again to top of the neck and install the radiator cap. (Do not allow RPM to drop while doing this).
5) With cap on, let the engine reach full operating temperature. Open the bleed screw on top of the thermostat housing to bleed any residual air out. Once it quits burping air and you see only coolant, close the bleed screw.
6) Fill the overflow reservoir to the HOT level. When the engine cools down, it will suck coolant into the radiator until completely full. After the engine cools overnight, if the overflow reservoir level drops below the COLD level, add some more coolant to bring it back up to the proper level. Keep an eye on the reservoir level for several weeks & fill to proper level if needed.

[sr1206]

Thanks for the advice everyone.