: Overheating



Rafterd
02-08-08, 08:31 PM
OK, hears the dead horse again. I have searched this sight but recieved to many hits to read them all. My 98 STS
120k miles, just started getting hot yesterday. I brought it home let it cool, then checked the water. Held about a quart. I looked everything over, then started it and drove into town, about 10 miles. I noticed the heat guage at 2oclock position. It never goes past 12 oclock. I stopped at a service station and looked it over again. NO LEAKS. The top radiator hose was HOT. The lower was COLD. I turned on the heater, cold air. OK, thats easy, thermostat is stuck. I just replaced it about 6 months ago, but I'll change it again. Changed it again. Left the radiator cap off to watch the water level. When it warmed to the 12 oclock position, I heard a gurgle then the water level went down in the tank. I added about 1 more gallon and it seemed to be enough. I checked the heater, HOT air. Let it run for about 30 minutes, guage still at 12 oclock and hot heater. I put the radiator cap on and drove down the road about 1 mile and the heat guage was at 2:30 oclock position and the heater was COLD!!! I shut it off let it cool and took it home. Almost like the water is not circulating. New water pump belt and tensioner. Why is the heater cold when I know the engine is hot? Is the radiator cap being on causing the 15 psi to build then starts the leaking headgaskets?? Why is the heater hot when the cap is off??

I give up.
Thanks in advance for any help
Bill

JC316
02-08-08, 08:47 PM
I would check that thermostat again, it's possible that it isn't opening. I once went through THREE alternators in one day because the parts house got a bad shipment. It's also possible that you have a clogged radiator.

carnut
02-08-08, 09:46 PM
I think you have an air pocket. I do what you do when refilling but when the level drops, I raise the idle to approx 1500 then top off the cooling system at that RPM. ( sometimes easier with a friends help)While I'm refilling, the heater is set to 90 degrees as well. The raised idle and heater on high help purge air from the system. Also there's no mention of the radiator fan off or on at this time? The fan should turn on at approx 219 F or 95C. Do you know how to run diagnostics to monitor the coolant temp? It should be somewhat stable between 85 to 95C.

Rafterd
02-09-08, 09:48 AM
Ok how do I purge the air? The fans will run with the a/c on, but I forgot to check with the engine at operating temp. No I don't know how to run diagnostics to monitor engine temp.

Thanks again.
Bill

carnut
02-09-08, 12:08 PM
As I described, with the engine cold remove cap, let it idle till level drops then raise idle and top off. Best money you can spend is on a factory service manual. This car has a very easy diagnostics system already in it. You just need to know how to access it. Got my manuals on EBAY for 25.00 3 months ago.

JimD
02-09-08, 01:10 PM
Ok how do I purge the air? The fans will run with the a/c on, but I forgot to check with the engine at operating temp. No I don't know how to run diagnostics to monitor engine temp.

Thanks again.
Bill
Air purge is automatic. You should check for coolant flow at the rubber hose that attaches to the surge tank at the top. If there is no coolant flow when you pull that hose off, there is a blockage somewhere. And the most likely blockage location is at the hollow bolt screwed into the crossover just above the water pump.

Here is how you display trouble codes.
http://www.cadillacforums.com/forums/cadillac-tech-tips/55172-how-pull-codes-got-codes-warning.html

Your model does not have the option to display coolant temperate in degrees. There is a picture of mine somewhere with measured temperatures Photoshoped onto the gauge picture. If I can find it, I willl direct you to it.

JimD
02-09-08, 05:41 PM
....There is a picture of mine somewhere with measured temperatures Photoshoped onto the gauge picture. If I can find it, I willl direct you to it.Here is the temperature gauge picture. This will be very close for owners of '98 to '04 Sevilles and '00 to '05 Devilles.

http://s70.photobucket.com/albums/i101/JimDphotobucket/?action=view&current=Smallertempguagewithnumbers.jpg

(Yes Ms Smith, I can spell temperature.)

carnut
02-09-08, 08:59 PM
JimD, are you saying that within diagnostics you cannt display coolant temp in celcius? on this year of car.

JimD
02-09-08, 09:39 PM
JimD, are you saying that within diagnostics you cannt display coolant temp in celcius? on this year of car.
Yes. But display of temperature in "C" or "F" is not a factor.

What I am saying is the original poster, with a 1998 Seville, does not have the option to display (on the DIC) coolant temperature in numbers.

Rafterd
02-09-08, 10:00 PM
OK, the fans DO come on with the temp guage in the 12oclock position. But the heater is still cold. I go to Auto Zone and get a new water pump and rent the tool to install it. When removing the old one, the "bell" that is on the impellers was gone. You could see where the weld spots were, so I know at one time it had one. Now It's gone. The old pump was in very poor condition. I install the new pump and gaskets and flush the cooling system with clean water. After filling, I let it run to operating temp. It doesn't get hot. But the heater is still cold. I put the cap on and drive about 1 mile and already the temp is rising. Being pissed off now, I floor it to go home, this thing will RUN, and notice the temp goes down. Strange.I slow down it gets hot. I stomp it again and it cools off?????
The heater is still cold. I park it at home about 10 minutes start it up, the heater is hot. car is not overheating. I go back down the road heater goes cold and temp rises. I wonder is it really hot? so I let it go. It is really HOT!! Bring it home and park it. Could the radiator be stopped up and why all of a sudden?? The heater being cold tells something. The water is not circulating, but why??

HELP
Bill

LCLCLC
02-10-08, 01:46 AM
Are you saying part of the water pump was broken off and MISSING????

If so, I would think this missing part is inside the motor and blocking water flow.

If this is not what you are saying, that there is no missing part, then if you are having to add coolant every time the motor gets hot - I think you have blown head gasket.

Rafterd
02-10-08, 09:30 AM
Yes part of the waterpump is missing. But it is to big to go anywhere unless it broke into pieces then the impeller would be destroyed. I think it came off, made noise, and someone took it out.

Bill

carnut
02-10-08, 02:59 PM
Did you verify the surge tank hose mentioned on earlier post is flowing? did you fill the system at a fast idle? Still sounds like air in system.

carnut
02-10-08, 04:37 PM
You could go to a radiator shop and they can verify combustion gases in the exhaust to determine possible blown head gasket.

Rafterd
02-10-08, 04:43 PM
That is most likely the next step. I can run it in the driveway for almost an hour and it is fine. I can go down the road and it gets hotter. But I can keep the rpm at 3000 or higher and it cools off. Strange. The heater blowing cold air means the water in not circulating. Don't know why.

Bill

Ranger
02-10-08, 09:00 PM
Did you check the purge line as JimD suggested?

Rafterd
02-10-08, 09:16 PM
MAN!!! That is one of the thing I was going to do today and forgot. The brakes went out on my dumptruck and I spent the rest of the day fixing them. I will do it tomorow.

Bill

Rafterd
02-11-08, 06:06 PM
Ok, took upper hose off. Engine cold, started and ran till opreating temp was reached. No water ever came out of the hose. Now what???

Bill

JimD
02-11-08, 06:09 PM
See Post #6.

Rafterd
02-11-08, 07:33 PM
I for the life of me can't find the hollow bolt above the waterpump. Do I need to remove it, or pull the waterpump? I'll do whatever. I have my FSM here and still can't find it.

Bill

JimD
02-11-08, 07:46 PM
You should be able to see the piece of 3/8" rubber hose that is the other end of the hose to the coolant reservoir. The water pump end of that hose is attached to a hollow bolt that is threaded into the coolant crossover.

Rafterd
02-11-08, 08:08 PM
OK right next to the upper radiator hose? The top hose from the surge tank goes into a pipe that goes under the throttle body and around then connects to another hose to the hollow bolt. I took that hose off and blew through it and it is the same hose. I will take out the hollow bolt next.

Thank you very much
Bill

Ranger
02-11-08, 08:44 PM
Just clean it out with a wire or compressed air.

JimD
02-11-08, 09:13 PM
OK right next to the upper radiator hose? The top hose from the surge tank goes into a pipe that goes under the throttle body and around then connects to another hose to the hollow bolt. I took that hose off and blew through it and it is the same hose. I will take out the hollow bolt next.

Thank you very much
Bill
You got it....

On your engine, that coolant line passes through the throttle body on the way to the reservoir.

Rafterd
02-11-08, 09:17 PM
OK Got it!! That thing was stopped up 3 days after it left the showroom!! Had to drill it out looks to be about 3/16 hole. OK now heater is hot. Still does'nt fix the original problem, but narrows it down. If I pressure check the cooling system, will that tell me if it is the headgaskets??

Thank you guys so much
Bill

Ranger
02-11-08, 09:31 PM
Not unless they are leaking so bad that coolant is leaking into the cylinders when parked. You have to do a cylinder pressure test to check the head gaskets.

Rafterd
02-12-08, 09:23 PM
Am not losing any water. Drove it today, and drove about 15 miles before it started getting hot. And it does it instantly, as if something is blocking the flow, and just as fast it goes back to normal. Since cleaning the purge line, the heater works perfect. Since it was stopped up, and the water pump was rusty, I am now wondering about the radiator. I'm sure the size of the radiator is barley marginal, so any restriction at all would be to much. I will go get a test kit to check for exhaust gas in the coolant.

Bill

Ranger
02-12-08, 09:31 PM
I would guess that if the radiator was clogged, the temperature would stay up rather than fluctuate.

carnut
02-12-08, 11:17 PM
Whatever happened to the missing piece to the water pump impeller?

97Concours1
02-13-08, 05:01 AM
Could be a sticking thermostat. I think I've got one in a van that I have. It started sticking after I added aluminum stop leak to the system. Sometimes out of the blue it will start to over heat and then quickly drop back to the correct operating temperature. I'm guessing the stop leak got into the thermostat and gunked it up.

Rafterd
02-13-08, 06:40 PM
Whatever happened to the missing piece to the water pump impeller?


I wish I knew for sure. Went to NAPA today and bought a "block test kit" for 50 bucks. Am going to test it right now.

Bill

Rafterd
02-13-08, 07:56 PM
Well the water turned YELLOW. So either it is pregnant or there is exhaust gas in the cooling system. I don't think it is pregnant. Well the dealership quoted a price of $2127.75 for a gasket job, minus the inserts which I furnish. So I am going to think about it. The car has only one scratch, a door ding on the passenger door, the interior looks brand new, new tires, and is very sharp. I really like the car so I may fix it.
Thanks for all your help.

Bill

JimD
02-13-08, 08:22 PM
Well the water turned YELLOW. So either it is pregnant or there is exhaust gas in the cooling system. I don't think it is pregnant....I really like the car so I may fix it.
Thanks for all your help.

Bill

Sorry to hear the results. But I don't have a clue how reliable the pregnancy test is. I would be tempted to apply shop air pressure to each cylinder in turn with the valves closed to see if you get air bubbles in the reservoir. That is a 100% reliable test but it takes time and effort.

I raise the point because you mentioned earlier that you have not been losing coolant. Coolant loss, without external leaks, is another head gasket heads-up, which you do not have.

If in fact you have a failed gasket, the price you were given is more than reasonable. I would ask the service manager how many timesert-head gasket repairs they have done. Chances are in a town the size of Stephenville, you know someone who knows someone. Know what I mean?

Rafterd
02-13-08, 10:07 PM
Gota point Jim. That is one thing that bugs me. One day it was fine, the next it is not. I have been dealing with this dealership for 15 years and always got a good deal. But I'll go ask and see. I know several of the mechanics and there's none better.
Well now I have a block tester that has abot 30 more test left and don't know what to do with it.

Bill

Rafterd
02-23-08, 05:38 PM
Still not satisfied it's headgaskets. Took it today and tore it apart again. Could not find the missing water pump piece. Put back together minus the thermostat. Only made it worst. I guess that what it is. Found another dealer that does from 3-5 per month and he will do it for $3000 with a 12/ 12 warranty so i guess he gets the job.

Bill