: 97 ETC overheating



bobvondutch
05-17-04, 11:55 PM
Hi fellas: I'm new to this site, and would appreciate any info. I have a 97 Eldorado ETC, 78000 miles. Last year, I wanted to see just how good this thing ran, had it up to 105, and overheated. Was going uphill, under load at the time. Managed to limp home, only overheated uphill under load. Changed the thermostat, thought I had the problem licked. Didn't run it over the winter (that's what beaters are for!). Took it out yesterday, ran it for 40 miles total. Jumped on it a few times, seemed OK. Was coming up a long hill, got on it to 90, slowed to 60, back to 80, looking good. Was at a normal 60 uphill under load, temp gage started climbing again. Pulled over, left it run. Whole underside of passenger side was coated, so it's building pressure and blowing out the overflow. Gage was at 3/4, started down the road, fairly level, some slight hills, and gage dropped back to 1/2 and ran OK last 5 miles. I'm thinking a) plugged system or b) bad thermostat again or c) water pump slipping or d) head gasket leakage. Doesn't overheat on levels/slight hills, only steep hills under load. Any thoughts would be appreciated!! I haven't looked yet, but is the water pump on the back side driven by a belt? Could it slip? HELP!!! and thanks.

BeelzeBob
05-18-04, 12:08 AM
Hi fellas: I'm new to this site, and would appreciate any info. I have a 97 Eldorado ETC, 78000 miles. Last year, I wanted to see just how good this thing ran, had it up to 105, and overheated. Was going uphill, under load at the time. Managed to limp home, only overheated uphill under load. Changed the thermostat, thought I had the problem licked. Didn't run it over the winter (that's what beaters are for!). Took it out yesterday, ran it for 40 miles total. Jumped on it a few times, seemed OK. Was coming up a long hill, got on it to 90, slowed to 60, back to 80, looking good. Was at a normal 60 uphill under load, temp gage started climbing again. Pulled over, left it run. Whole underside of passenger side was coated, so it's building pressure and blowing out the overflow. Gage was at 3/4, started down the road, fairly level, some slight hills, and gage dropped back to 1/2 and ran OK last 5 miles. I'm thinking a) plugged system or b) bad thermostat again or c) water pump slipping or d) head gasket leakage. Doesn't overheat on levels/slight hills, only steep hills under load. Any thoughts would be appreciated!! I haven't looked yet, but is the water pump on the back side driven by a belt? Could it slip? HELP!!! and thanks.


Lots in the archives on this subject.... use the search feature on the toolbar for the forum and search on "overheating" or "coolant" or things like that and read up...

You kind of answered your own question, though. The water pump drive many be slipping. Can't diagnose over the internet. You'll have to check the water pump drive belt and tensioner yourself. It is very easy to access and check.

Also, check the coolant concentration very carefully with a refractometer. If the coolant is not 50/50 (good to -40 ) it can cause overheating as a lower concentration of coolant will boil prematurely and cause what you describe. Only way to find out is to check it. Don't trust a simple float style hydrometer as they are woefully inaccurate.

There are numerous posts on head gaskets if you search the archives for "head gaskets" should you start leaning in that direction.

bobvondutch
05-18-04, 05:19 PM
Just a note: I removed the covers today, looked at the belt/tensioner. The belt still has the GM insignia and factory numbers: I find it hard to believe that it would still have numbers after 7+ years. Anyhow, tensioner is intact, seems to have good tension, belt has no cracks on ribs. Water pump seems to be original: no evidence of any changes made. I brought some coolant into work to check mix, will let you know what the number is but I think it's high in favor of antifreeze, which I believe raises the boiling point. Any ideas what to check or do next? I'm fairly adept with tools: should I just put a new water pump in? Should I have the system flushed and refilled? Should I also put in a new thermostat again? Should I have it pressure checked? Since the problem only occurs uphill under the load of the car and my chunky behind, I find it hard to believe that it could be head gasket associated - I would think that the overheating would occur under any normal conditions. Anyhow, please point me in the right direction, thanks.

bobvondutch
05-18-04, 08:04 PM
OK, update time. I brought the coolant into work, best refractometer I could find here only measured up to 30%. So I'm SOL there. Any other ideas??

BIGGUN
05-19-04, 02:43 AM
My 96 was overheating the same way. My problem ended up being a head gasket that I'm in the process of changing.

I figured my problem out by laying the overflow hose out in the open and brake torqueing by holding the brake and feathering the gas. At around 1800-2000 RPM water was flying everywhere.

I guess when I was loading up the engine with hard acceleration or hill climbing the combustion was blowing thru the gasket and forcing antifreeze out of the overflow til it finally over heated.

Good luck with yours.

Let us know what it was and how it worked out.

Kevin

zonie77
05-19-04, 03:22 AM
Several people had the problem show up up first under load, which makes sense if the gasket is not "blown" but just starting to leak.

You should do a compression test or preferably a pressure test of the cylinders.

The first one I did was intermittent and we wasted some time and money diagnosing. It acted like a cooling system problem at first and responded to a new thermostat and radiator for a while. They only helped and the next long trip caused the car to overheat again!

Do the compression/pressure tests and see if any of the cyl are low. We had two low and it was bad head gaskets.Another test is to crank the engine without starting it(disco plug wires) and see if the water in the tank pulses with the engine cranking. A sign of pressure blowing into the cooling system. This pulsing will be noticeable on one or two cyl.

If it is head gaskets take a look at this thread...

http://cadillacforums.com/forums/showthread.php?t=5052

mcowden
05-19-04, 02:58 PM
Maybe it sounds ridiculous, but if it's blowing out the overflow, have you checked or replaced the cap? Perhaps the spring is weak. If nothing else, it's easier than compression tests and cheaper than a new head gasket.

The water pump belt probably does still have the printing on the back side because the back side never comes into contact with a pulley like the serpentine belt does. I replaced my belt and tensioner about a year ago and the printing is still visible.

Good luck! :cool:

BeelzeBob
05-19-04, 03:12 PM
You need to check the coolant concentration and the cap for proper sealing and operation.


The belt might still be slipping...look at the belt grooves completely around the perimeter of the belt to make sure that they are not excessively worn or missing in an area. Light checking is OK but cracks, missing chunks, etc... warrant a replacement belt on the water pump drive.

It is fairly easy to pressurize each combustion chamber with shop air thru the spark plug port to check the head gaskets. 120 PSI shop air into each chamber using an old spark plug shell as an adapter and watch the cooling system for bubbling from air leakage into the coolant.