: overheats sometimes

The Punisher
04-17-05, 01:56 PM
Can some one please tell me why my 94 seville sls has no apparent signs of a head gasket proble(no oil in the water , no water in the oil no rough running)
and it overheats. I've changed the radiator,thermosta,waterpump,. The cooling fans comes on at about 223 degrees which is what mitchell on demand says its supposed to. if i fill the system drive for a little while then let the car cool and top the system off i can can drive for about 1 and a half hours before she starts to climb to 250 if i'm driving and the temp goes to 235 or 240 if i accelerate or if at a stop i put the car in neutral and accelerate up to 3000 rpm the temp goes down to 214 210 and sometimes lower as if its a flow problem not a headgasket problem it was a head gasket problem wouldnt the car temp rise even if irev to 3000 rpm someone said the gasket could be leaking at the exhaust port and the exhaust gases is heatin the water this argument is very true and possible in most cases but why would the temp go down if the engine is reved to 3000 rpm or more if that was the case the hot exhaust gases should heat the water even more. i'm frustrated with this car, this is my first and last caddy

04-17-05, 04:53 PM
Whoa, hold on a minute there. You bought an 11 year old car that has this problem and you're so frustrated with it that it's your first and last Caddy? You're disappointed for some other reason, then, not because of this problem. Anyway, this is probably easily solved. If the fans are coming on at the right time, you knocked that one out already. If you changed the radiator, water pump, and thermostat, you probably paid a whole lot for that stuff, and that's why you're peeved. I've got news for you: Your mechanic sucks. Are there any combustion byproducts in the coolant? It sounds like the vapor vent line is plugged up, maybe because somebody put the coolant supplement in the surge tank rather than the radiator hose. Search the forums for vapor vent line and you'll find lots of good information from Bbobynski about how to check and clear it. You also posted about vapor lock, and I think that's right on target. Clear the vapor vent line and there will be no more such problem. Unfortunately, that won't get your money back for the pump, thermostat, radiator, and all that coolant, labor, etc., but maybe you'll be able to enjoy your Cadillac.

Good luck, and fire your mechanic right away.

04-17-05, 07:31 PM
Check the water pump tensioner. Remove the belt, and move it back and forth, as you put some oil (*not* WD40) on the pivot. Be careful not to drip any on the pulley itself or the belt.

04-17-05, 08:39 PM
I'll add that whoever told you water in the oil and/or rough running must be present if you have a head gasket leak is WRONG...and not just on Caddy's.

You need a cyl pressure test done to verify the head gasket integrity.

Everything the other guys told you is correct...it is 11 years old, no matter how well it looks. It could still be something fairly simple.

04-20-05, 11:15 AM
Mine did the same thing off and on for a months and I couldn't figure out what was wrong...once I found out that it was a misconception that oil would be in the water if the gasket was blown.. i started looking a little deeper in to it... and found a discoloration in a few of the cylinders on the back side where the sparkplugs are from where antifreeze was dripping down from the heads in to the cylinders...car still ran ok over all because the N* is put together so well that it would keep going even with one gasket blown...you may not be able to tell with one blown... but that doesn't mean its not... and definitely doesn't mean the car is crap!!! If you lived near me.. I would take it off your hands...lol