Please...anyone With Info!?!


LVC Member
Aug 5, 2005
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my car is STILL overheating..

i have a 4.6L 93 caddy STS

this is what ive done so far.....

replaced: radiator (visteon), waterpump (nappa), thermostat (nappa), lower hose, bleeder hose, coolant flush twice, even in the thermostat housing replaced the gasket.

the car holds pressure. the fans work when the engine runs. have new v belt on waterpump and serpentine. no leaks.

my mechanic checked the head gasket and its fine. the computer always says check coolant though.

im out of ideas... he is had the car for 2 days now and is now going to outside help with his mechanic friends.

help, what else could it be? there isnt a secondary waterpump is there? I mean, i have changed EVERY PART IN THE COOLANT SYSTEM!

im outa ideas and running low on money.

im thinking i shoulda went ford for the cash im wasting.... *owned*
A couple years ago, Jay Leno pointed out how the mechanics couldn't get 1 of his 2 old Lambo Miura's to stop overheating (Rear engine V-12 super cars). He figured out himself that if you put the back wheels about 3 feet in the air and open a valve in one of the water lines, that was the only way to get all the air out of the system. The high-priced LA Lambo mechs didn't know it.

IMHO you either have air trapped in it, or you have air being sucked in somewhere. It's a thought... I've always filled my other cars with the radiator cap off and the engine running, then topped off the expansion tank, but you can't do that with a northstar, can you??

Best of luck!
I've got a question. You are saying that it's overheating. are you SURE that it's overheating,or is your gauge telling you that?If it's saying that it's hot and it's not, it may be a temp sensor or something.If it is getting hot, then it may be air trapped as lhheston said.
Fill the radiator with the cap off and engine running, squeeze the hoses as your filling to get all the air out.Leave the cap off until it starts overflowing.(That'll tell you that it's circulating.)
With all that you've changed, water circulation shouldn't be a problem,but, don't assume that the thermostat works just because it's new.Anymore, you can't get good parts.
yea...its bubbling hot in the engine when the computer says its 260 then, turn off engine, hot , and beeps...

i can hear the coolant in the tank boiling. when i squeeze the lower rad. hose, and then let it go, the pump is sucking coolant.

as with the first reply, what valve would i shunt water out of? I have run the cap off before and it squirted out coolant when the temp read 235. So its doing everything normal cars do....

As for lifting it 3 feet in the if you say what valve, hell ill try anything once, but i dont think its that.

But the coolant isnt leaking either, and if it was sucking/blowing out air, then the coolant would escape, wouldnt it?...
but the computer tells me coolant low, and it doesnt go anywhere? i checked my oil, nadda... so im at a loss.
You got heat? Did you check that end of things? (The Heater Core)
the car blows air out when i put on heater to 90 degree max. is that what you mean joey?
Is your surge tank cap sealing or could it not be on right? Did you refill with the proper mix of 50% distilled water and 50% Dexcool antifreeze? Check purge line(water pump to surge tank), is it plugged. Are your cooling fans operating? I pray its not a blown head gasket.
Its the head gasket.

my mechanic tested everything and told me its the h.g. 1400 bucks to fix or just replace the engine + the labor.

Its weird because the engine only has 130,000 miles and is not giving the signs of head gasket. I.e: white smoke or leaks.

im sick of cadillac! they make crap if its already needing an engine at 130K.
I seen the old lady that used to drive this caddy i i know it wasnt raced or abused by performing.

GM = Crap. i shoulda stuck with toyota or ford.... god im pissed.

im looking into rebuilts or used...but the rebuilt longs are around 1200-2600 bucks... and the shorts are 800-1500.

used ones are 600-1000... but god wadda sham... not to mention that almost 80% of the sites ive looked into DONT SERVICE OR SELL V-8 NORTHSTAR 4.6L!!!

The car not being raced or abused is good but was the coolant changed at 5 years or 100k? and if so was the bars leak sealant tablets or powder added to the system? Did you check out Ebay-motors for an engine?
HappyMofo said:
im sick of cadillac! they make crap if its already needing an engine at 130K. I seen the old lady that used to drive this caddy i i know it wasnt raced or abused by performing.

Everything I've read about the NorthStar indicates THAT to be a BIG Problem.
Not that racing would have helped, but not driving the engine hard has caused
many build up issues. The suggest WOT frequently helps this engine. Doesn't seem to be the cuase for overheating though... I'm totally confused as to why they're indicating HG for the overheat!!!!! The HG is usually what goes from overheating... So if your still overheating, replacing this HG doesn't seem to me like it will fix the problem...?
Did the mechanic do a cylinder pressure test? I ask because you(Happymofo) state that the first time he checked it, it was fine.
A poorly functioning radiator cap is one of the most often overlooked items on a typical vehicle.

A radiator cap is designed to let your cooling system increase its operating pressure and hold it at its designed limit, yet bleed off any excess pressure so that the cooling system does become damaged by over-pressurization. A weak cap can cause your system to loose pressure at a much lower than normal level, severely reducing the cooling ability, and also causing you to lose coolant through evaporation. I know you mentioned you replaced the radiator... But check if the cap is funtioning.... I know it sounds simple, but Geez... We're at the end of the rope here.....
I second it. He's right a radiator cap thats not sealing right will cause that problem. A $10 fix.
'i can hear the coolant in the tank boiling. when i squeeze the lower rad. hose, and then let it go, the pump is sucking coolant.'

The lower radiator hose should have a coiled peice of wire in it to keep it from colapsing when the coolant pump pulls a vacuum on it. You should not be able to squeeze it. Do I need to tell you that if the lower rad hose calapses at highway rpm, the engine will overheat? Is that when it overheats?

I worked on a Camaro once that overheated at highway speed, but not at lower speed. The lower air dam had been knocked off. With the air dam missing air was not being forced through the rad as per design.

If you have a blown head gasket you would be losing coolant and/or have occasional hydrolock on startup and/or one or two clean spark plugs when the rest have normal carbon buildup and/or chocolate milkshake looking oil on the dipstick or the inside of the 710 cap and/or a sweat smell of hot coolant at the tailpipe.

hope this helps

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