Engine Overheating

[kingjaydub]

I've got a V8 '87 Cutlass Supreme and it overheated so I replaced the thermostat, replaced the gasket and flushed the cooling system. It still overheats, so I checked the radiator and both hoses are hot, so I assume the radiator isn't blocked. The heat works and both lines to the heater core are hot, so I assume the water pump is working. I pulled the thermostat and boiled it to make sure it was working correctly. The first time it overheated, the radiator cap flew off, so I thought maybe the vent wasn't working correctly, so I replaced that too.

When it overheats, the reservoir fills and starts to boil. I hear a click a few minutes later (which I assume is the thermostat) and it stops boiling within seconds.
I do not see leaks in the radiator or anywhere else and the oil looks fine and isn't milky.

Anyone have any clue what could be causing it to overheat?

 

[ERIC87442]

will it overheat if you drive down the highway or just sitting still or all the time? if its only when your sitting still i would check the fan clutch.

 

[kingjaydub]

I let it run outside for over a half hour today and it didn't overheat, so I took it for a spin around the neighborhood and it overheated within 2-3 minutes. Sometimes when it overheats, just pulling over (but with the engine still running to check for leaks) it gets cool enough for the temp light to turn off.

 

[ERIC87442]

it is possible to have a bad head gasket and not have water in your oil, im sure u would notice this but is there alot of white smoke out your tail pipe? does it run rough at all?

 

[anakputa]

Check for coolant flow. The water pump may have the fins rotten off.

 

[megaladon6]

Check for coolant flow. The water pump may have the fins rotten off.

X2
how did the old coolant look when you dumped it?

 

[monte olrac]

X3 on the flow, remove your radiator cap start your car and let it get up to operating temp. when the thermostat open you should notice the coolant moving through the cap or romove your thermostat an look for the same result with out the warm up.

 

[kingjaydub]

When I first start the car I see a very little amount of white smoke come out of the exhaust that goes away within a few seconds.

As for the water pump; I started the car with the radiator cap removed. When the thermostat opened the coolant level dropped, but did not appear to be flowing. I'm assuming it would be a real obvious flow. The old coolant looked to be fine, but now I'm thinking it's the water pump.

Side note: I was doing some research last night and read that a bad catalytic converter could cause an engine to overheat. I had never heard of this before, but I did get the emissions done on the car 2-3 months ago and they had a really hard time getting it to pass and said that it may not pass next time (which isn't a problem, because by the time it needs it again it'll be an antique and won't need an emissions test). Anyway, how common is this problem?

Thanks everyone.

 

[anakputa]

A plugged cat would slow the car down. If you have white smoke upon start and coolant loss. That could be signs of a headgasket. Get a block checker and see if you have HydroCarbons in the exhaust.

 

[monte olrac]

When I first start the car I see a very little amount of white smoke come out of the exhaust that goes away within a few seconds.

As for the water pump; I started the car with the radiator cap removed. When the thermostat opened the coolant level dropped, but did not appear to be flowing. I'm assuming it would be a real obvious flow. The old coolant looked to be fine, but now I'm thinking it's the water pump.

Try revving the enging a little bit to, you should see coolant coming out of the tubes when that coolant level drops, if you don't it probally the water pump