I've checked everything!! Still Overheating

[blazzenflamezz24]

ok i just bought a cadillac concours 94 with a 189,000 miles on it. I test drove it twice and let it sit with the a/c on for about 5 to 10 minutes, it never overheated. The first day i was driving it it overheated. So far i have a new radiator, i changed out the thermostat, i even ran it without the thermostat and it still overheated. I was gonna change out the water pump but realized i didnt need to because looked fine, i just need to go back and look to see if there are still fins on the pump itself. I changed the water pump drive belt because it was slipping alot, that still didnt change anything. The car takes about 10 to 15 minutes to overheat. My oil has no water in it, my engine doesnt miss or rock hard, both my fans are coming on when i turn on the a/c. I hope i dont have a crack in the block, but my friend was tellin me it would miss or rock hard, he said i would feel it if it was cracked. And likei said i dont have water in my oil so it shouldnt be the head either. i just have no freakin clue wat is wrong with this thing. Can u guys please help me out here, this is the only car i have. Oh and by the way, i drove my vehicle on the interstate for about 20 to 35 miles and it finally started to overheat, i was surprised it lasted that long. Any help would be greatly appreciated.

[blazzenflamezz24]

oh yea by the way the engine is the 32V NorthStar, just in case ya'll didnt know, but im pretty sure ya'll know

[blazzenflamezz24]

dang i left out the most important thing that i've noticed, the heater core is bypassed, im pretty sure that may have something to do with it, and by the way i checked the fins on the water pump and they are all there, i even turned the car on without the housing and i saw it spinning.

[dan lusher]

Originally Posted by blazzenflamezz24

dang i left out the most important thing that i've noticed, the heater core is bypassed, im pretty sure that may have something to do with it, and by the way i checked the fins on the water pump and they are all there, i even turned the car on without the housing and i saw it spinning.

Have you checked the return hose from the reaiator as if the spring is rusted out the hose will suck flat and not allow water to circulate. Dan

[blazzenflamezz24]

wow i finally got a response woo hoo. Yea i did check that, the spring is fine, i did tryi to pull it out to examine it and the spring broke in the middle, but that was just yesterday. Now i was wondering, the 2 hoses that go to the heater core are combined so that the heater core is bypassed. I notice that those 2 combined hoses get real hott before any other of the coolant hoses do,. The thing in front of my radiator which looks almost identical to the radiator, what is that? someone told me that the part in front of my radiator works with it to cool the system and they said that may be stopped up. Does any of that sound right to you? Thanx guys

[curtis73]

When you had the thermostat out, did you notice any crap or corrosion in the block? With 185k I'd consider that. Maybe there just isn't effective heat transfer from the block to the water.

Keep in mind that its still possible for a head gasket or crack to leak even if there's no water in the oil. It can be leaking straight to the ground or into something else. Usually, though a leak that is big enough to cause overheating would be pretty noticable.

First major thing I would do and this sounds dumb, but disconnect the neg battery cable overnight. Its possible (but unlikely) that the PCM is operating under an incorrect spark map and resetting the computer might help. Kinda like instead of asking why your PC won't print to an HP deskjet, just restart and 9 times out of 10 it will do the trick. Check the timing, too and see if its within spec. Its possible, too that someone was in there with Tuner Cat and rewrote some of the flash memory stuff in a quest for more power. After that I might start checking for proper operation of the EFI sensors to see if some parameter isn't being properly reported allowing an abnormal spark. I guess it wouldn't hurt anything (except your wallet) to replace the pump.

Oooh, Oooh. I just thought of something else. I think Northstars have the thermostat that has the extra stick-down part. Normal stats just look like a UFO, but some have a "plunger" that goes down into the bypass passage. I used a standard UFO stat in my Caddy 500 and it overheated because it was easier for the flow to go through the bypass than past the stat to the rad. I replaced it with the "plunger type" and it was alot better. You would remember that from when you installed yours.

[Genopsyde]

the fans come on with the A/C cuz they're supposed to, they're also supposed to come on at a specific temp. close to 200, run it up to that temp, and see if the fans kick on when they're supposed to, make sure you keep the a/c off tho, if not, then your problem lies there, if they still come on, i'm clueless.

[ricardoliveira]

I already found the mistake in my vw. A few weeks ago i replaced a tube from the radiator circuit. In that operation i replaced and cleaned the radiator... and i made i mistake, i didnt "bleed" the radiator well, so it gained air... and air prevents the coolant to get into touch with the termostat, so the 1st fan velocity didnt worked... i looked in the net and come with a solution, i already did it and now its working well.

1 - warm the car to the middle temperature without the cap that covers the coolant resovoir.
2 - And now the trick... turn on the heat on the car to maximum... the coolant will run through the tubes to warm the air to warm the veihucle interior, and you will see bubles in the resovoir... after a few minutes until it stops give some gas to the car... just a little to bring the air up. turn off the car.
3 - with a key, unscrew the termostat until it comes a little water, as soon you see water, screw it again. cover with the cap the resovoir and try it out.

For me did work, try to find in google.com HOW TO CLEAN CAR RADIATOR

I just hope i dont have a leek in somewhere else, because if i have the air will enter again and bring back the problem. tomorrow i will try it again to see if it is ok.

Try this and give me your result to [email protected]

Hasta la bista.... and pass this solution to others............................................ ...

[modification_inc]

Originally Posted by blazzenflamezz24

wow i finally got a response woo hoo. Yea i did check that, the spring is fine, i did tryi to pull it out to examine it and the spring broke in the middle, but that was just yesterday. Now i was wondering, the 2 hoses that go to the heater core are combined so that the heater core is bypassed. I notice that those 2 combined hoses get real hott before any other of the coolant hoses do,. The thing in front of my radiator which looks almost identical to the radiator, what is that? someone told me that the part in front of my radiator works with it to cool the system and they said that may be stopped up. Does any of that sound right to you? Thanx guys

The radiator in the front of the other one is the a/c condenser but take a look at the fins the ones on my truck were full of mud after a little offroadin that coused an overheat on mine.Also try to hook up your heater core... you never know.

[jeeperphil]

I hope you don't have the problem I have. It only takes one time for a northstar to overheat and destroy the motor. northstars are made of aluminum. It doesn't hold up to heat well. when a northstar overheats the steam inside the motor puts too much pressure on the head bolts and pulls them out of the block, stripping the aluminum threads. 4000 bucks to fix if you can find anybody to do it, i can't. the dealer says best thing to do is buy hole new drive unit (engine, trans complete) for about 10000 bucks. NOT INSTALLED YET. There are litterally thousands of service bulletins about this but caddy refuses to admit theres a problem. 6-7 dealers say service depts everywhere hate this engine but caddy wont drop it. always drive with the temp showing on info center to avoid this.