Cadillac Deville over heating problem

[joshdude85]

This car started over heating two weeks after i bought it. I brought it in to Lentz auto and they told me it was the water pump...tuffys auto center was cheapest to replace. I got it done (only because u need a special tool to do it and no one around here will let u rent it)*$100* to buy. After they did it the thing ran as good as new. Week later over heated again. Filled it with fluid cause it was low and got it home...took it back. They said there was air in the system and now its running fine. Tryed to drive it 120miles made it about 30 and overheated again. Put fluid in it let it run with cap off and got all the air out and it got me back home. Brought it back AGAIN and they told me the only thing it could be is the head gasket. They SAID they chemical tested it and it was bad. I have been letting it sit for a whle now and decided to look at it with my dad. Ran it...filled the fluids after we took the thermostat out(by cutting everything off but the alluminum top with seal)turned it off after temp was raising. Let it cool down a bit checked level...was full. Took off top hose going from radiator to motor.... It was cold by the way and now pressure... blew threw it into the radiator and fluid came out from where it meets the engine. So we figured no circulation...So i brought it to tuffys and told them its gotta be the waterpump again. They checked it...drove it said it runs rough and its been over heated to many times and its the head gasket. He also said that there was a coolant leak and he fixed it. It was one of the heater hoses comming from the engine into the firewall. So now the top hose has pressure and is getting hot. The top and bottom of the radiator is getting hot...never used to. The heat works again. But when ur driving it thew town the temp stays arround 190 and 210 for a while untill you drive a little faster and cost down hill. Then it starts to go to 233 ..thats when i figured out.. if u park the car and tap the gas to get the rpm's higher the engine temp will go down...drastically. 233 to 197
Some one has to know what the deal is??
I will reply with the electrical problems later but this is my biggest consern. Although i can drive it at least now.

but for the head gasket
-No milky oil
-No fluids comming from exhaust
-Runs great
it does have a misfire but it had before..i replaced the spark plug and it was fine...now the comp says cylinder 2 it was on the other side last time. If it is the head gasket...how common is it for both sides to go out?

HELP!

[DFBonnett]

Put a new 195 deg OEM or Stant stat back in. Don't buy a cheapie. Top off the coolant. Pressure test for leaks and repair as needed. Drive it normally for a few days, checking the coolant level each day. If you don't lose any coolant, it is unlikely a head gasket has blown.
Are the cooling fans coming on around 225 deg?

[joshdude85]

Yes the fans are comming on. There isnt a thermostat in it right now, do i really need one if the heat is still comming on regardless? I drove it today and it seems to be running fine but i have yet to attempt to drive it on the highway cause im afraid i will get stranded.

But i will check for coolant leaks today cause it was full last time i looked at it.

[83cutlass]

What Year and engine do you have. A quick peek at your Public Profile shows you own a 1998 DeVille so I'll assume thats it.
If they ran the chemical test (we call it a block test) and it failed then you have a head gasket failure(more likely) or a cracked block(less likely). I work in a Cadillac dealer and I can tell you that from your description of your problems it sure sounds like a head gasket failure. Its not uncommon for the threads in the aluminum block to pull out which loosens the tension on the headgasket and causes the failure. There is a special tool kit out in the Cadillac dealerships to repair the threads in the block. They are called Time-Serts and they are simular to Helicoils but 10 times stronger/better. Head gasket repair on a Northstar V8 is expensive (like $2000 - $3000). It requires engine removal to do. Another option is to just have a used engine installed.

[joshdude85]

I might be wrong but dont they have to take the engine somewhat apart to run a block test?
Yesterday i took it out and drove it and tryed something new...when i drive it in second gear(automatic) and run it at about 35-40 mph the temp went down from 242 to 188-190? Does anyone elts have any other ideas OTHER THEN HEADGASKET? this car runs fine exhaust smells normal....you can smell coolant though i noticed when u turn it off after driving it for a while. Heat still cutting out when temp goes up. *no thermostat in this car*

[caddydaddy]

Check that the waterpump belt isn't slipping. If the temp goes down when the RPMs go up, it could be a slipping belt not giving enough flow. Check that the tensioner is working ok.

[DFBonnett]

Originally Posted by joshdude85

...you can smell coolant though i noticed when u turn it off after driving it for a while.

Where are you smelling the coolant? Inside? Front of car? Behind car?

[83cutlass]

The block test I'm talking about can be purchased at NAPA for $50. Here's how it works. You put this blue liquid in the plastic tube, place the tube cone end in the radiator neck or on your Cadillac, the reservoir, and use the squeeze bulb to draw in air up into the blue liquid while the engine runs. If combustionn gas is present the the liquid turns yellowish. Sometimes they'll turn yellow right away, sometimes you need to load the engine a little or rev it up to push a little combustion gas into the cooling system.

[caddydaddy]

I've used that block tester before. I didn't know what you were talking about at first either. It is very easy to use! I'd also recommend the hydrocarbon test before thinking of spending the money on a headgasket replacement.
On my Deville, it turned out to not be the headgasket that was leaking, so that saved me time and money!

[83cutlass]

I've had plenty of Northstars run normal, no smoke but have a headgasket failure. They don't all just blow out huge. Other possible problems could be a plugged up radiator.

[96DEVILLE]

I Have A 99 Deville With Same Problem. I Changed The Water Pump Twice, W/p Belt. The Tool Was Under $20 At Auto Zone.... Changed Thumistate Twice ,ran It Without One For A While, New Hoeses. No Help!! My Car Runs Hot When I Drive Up A Incline... This Was Last Summer. I Stopped Driving It For A Few Months. While Trying To Find Problem... This Past Winter I Started To Driver It Again And Had No Overheating Problems Car Run Grate For The Last 4 Months...... How That To Weather Is Getting Warmer..when It Hits 70 Deg. Out Side My Car Run Hot Again ????? If It Is A Head Gasket Why Does It Run Good In Cold Weather ??? If I Find My Problem I WILL Let You Know....or If Anyone Has Any Advice Plaese Responed.. Good Luck...

[joshdude85]

the belt thing sounds promissing. the radiator cant be pluged if i can blow threw it....i will check belt. I also noticed the two hoses going from the passanger side seem odd cause one is hot and the other is not. Are these going to the heater core?

[83cutlass]

Originally Posted by joshdude85

the belt thing sounds promissing. the radiator cant be pluged if i can blow threw it....i will check belt. I also noticed the two hoses going from the passanger side seem odd cause one is hot and the other is not. Are these going to the heater core?

That doesn't really mean anything, you could have a few rows plugged which will reduce the radiator's cooling abilty and still blow through it. The two hoses do go to the heater core. Does your heater work? Because it sounds like your heater core might be plugged. You can back flush the heater core to fix that problem.

[joshdude85]

heat does work although there is no thermostat in this car and when the temp climbs higher the heat cuts out. But when u get it at a higher rpm...put in neutral and hold has petal down slightly...the heat kicks back on?

[fisherboyz 99devil]

I'm having a similar problem my heatercoil went out an my car started overheatin asap so I by-passed the heatercoil an it still overheated so I changed the thermostat I changed the waterpump an its still gettin hot. the oil is still the same an runs good I don't think its the heads cuz as soon as the heatercoil went out the car got hot I jus don't think the heads would go outthat fast sum body help!!