: 2000 Deville Overheated losing coolant.

07-28-10, 06:04 PM
Just bought a cadillac deville(126k miles) despite the owner said it overheated once on him and he replaced some part and it hadnt happened since then. Also, the pre- owner said some ppl looked at it and it might just need a thermostat replaced. Coolant was full at time of purchase
Well 3 days into owning it was driving home, and temp went all the way up and overheated, so i pulled over and found out there was no coolant in the bottle. Next day I filled up the dexcool coolant and bought a head gasket repair liquid(bars leaks head gasket fix) and added that to the radiator as it instructed.
Then drove it to work today and back(40 miles total), then checked the coolant bottle and it is about a half inch below full, was at full last night, so im a little worried its ganna run out and overheat again.
Could a bad thermostat result in losing coolant?
FYI: check engine light on: Heater core bank 2 sensor 1(both codes were something like that)
Dash displays: Change engine oil, Check coolant level

Cant smell any coolant
No coolant in exhaust, no white smoke to the best of my knowledge
No spills on driveway; i dont think there is a leak

WHERE is my coolant going?
could it have leaked into the oil?

Im hoping its not the head gasket but it might be the case
i have very limited funds, college student.
What should I do, get a cylinder compression test? does that need to be done on every cylinder i assume? How much does this cost apprx?

What are the other possibilities?

How much am i looking at to replace head gasket if its the problem?
Im am mechanical engineering student used to work at a used car dealership and quite "hands on" type, could i replace said head gasket myself with normal tools including torque wrench?
Sorry im sure this is a repeat but it takes forever to find any info in here

07-28-10, 10:33 PM
Snake oil repairs in a bottle WILL NOT work.

It does not sound good. Northstars do not put coolant in the oil when the head gaskets fail and you won't see any steam in the early stages. Best thing you can do is get a block test kit and test the air in the surge tank for exhaust gases.

If the gaskets have failed you need to drop the drivetrain out the bottom. The head bolt holes need to be drilled and tapped for inserts or studs (http://www.northstarperformance.com). Prices vary depending on if it is a DIY, dealer, independent. Jake at the link provided or someone we can recommend depending on your location.

08-04-10, 08:05 PM
I FEEL your pain!!! I am just finishing a engine change out on a 03 which is almost the same as yours. The origninal engine did the same thing as your, the coolant disappeared. They take ALOT of time (24 hours work time so far) but are not too brutal. It is best to take the whole cradle out the bottom, struts included. You will have too realing it, bleed the brakes and recharge the A/C.
Money wise.... well thats another story The BEST way is to install a set of Jake's studs but you have tear the engine the whole way down, have the heads checked for cracks ETC. have the studs installed by a good shop, replace the top end gaskets ETC, All that = lots of cash. The cheap way is find a low milage engine for cheap and install it yourself. This, however, is no guarentee that it wont happen again, but the 2000-2003 have a little better track record as far as there head gaskets go, as least better than the late 90's any way.

Good luck

08-04-10, 10:07 PM
karlskaddy, That coolant reservoir is supposed to be half full, engine cold. No more than that. If the coolant is too full or topped up it simply blows out the pressure cap relief as the engine warms and coolant expands: normal action.

Look at the "FULL COLD" legend and arrow molded into the side of the reservoir. Check the purge line for flow: Remove the pressure cap, cold, and remove the purge line from the nipple on the upper reservoir side. Hold the line in the reservoir neck and have an assistant start the car at idle. The line should spit a few bubbles then emit a slow, steady coolant flow. If it doesn't, clean the line, the tank nipple, and the hollow bolt nipple at the water pump housing.

Get that Bar's Leaks stuff out of the system before you really screw something up !!!

A complete DIY head gasket and stud job will cost about $1750 - $2,000 and will take a full, busy 3-day weekend of wrenching with a lot more tools than just a torque wrench. You remove the entire drivetrain and lift the car off of it - it doesn't come out the top, and you'll need a GM/Helm Factory Service Manual or a subscription to www.alldatadiy.com

08-06-10, 12:10 AM
..........but the 2000-2003 have a little better track record as far as there head gaskets go, as least better than the late 90's any way.

Good luckHmm, you did the repair on a 2003 and he has a 2000 that needs the repair. Surprising that you believe the '00-up are actually not as prone as the older ones. Time tells everything.

08-06-10, 08:48 AM
I said a little better not trouble free. I decided this via the poll and reading thru this tread and counting 2000-2003 v. late 90's and down. without the studs it's still a crapshoot, I just got lucky with a low milage motor for cheap that came with a parts and labor warrenty.

08-06-10, 02:01 PM
Here's some links:




08-12-10, 02:10 PM
Hmm, you did the repair on a 2003 and he has a 2000 that needs the repair. Surprising that you believe the '00-up are actually not as prone as the older ones. Time tells everything.

I agree with Destroyer that the N* engines are prone to HG problems, and nothing was ever done that totally addressed the underlying design flaws. I believe anyone who owns or plans to buy a high mileage N* car should expect the HG to go. I disagree with Destroyer's contention that it makes all N* engined car's pieces of crap that aren't repairing when the HG go. In that area, I agree with Jake, who I think feels that if the car is otherwise good, it doesn't make sense to send it to the scrap heap over a $2-3,000 repair. Sure, it kinda sucks, but if you already own and like the car, it's still cheaper than buying another car.

Have we ever heard of any of the closed deck design N* (only found on RWD models, I believe) head gasket's failing?