: 95 eldorado Northstar over heats



MoMo 70 Formula
02-22-04, 05:15 PM
This is some background:
headgasket replaced
waterpump replaced
radiator replaced
Cooling fans works

At idle the engine reaches 219-221 degrees (according to gauges)
and it won't stop there if I would keep it at idle for longer.

Now if i Drive the car @50mph in drive the gauges shows about 212 degrees
If I then shift down to 3rd gear and drive it @50mph the temp drops to about 201-203 degrees (where it should be right?)
If I let the car idle and then raise the rpm to 2000-2500rpms it will still keep on getting hotter.

Does anybody have any idea of what might be the problem here?
First I thought that there may be a restriction somewhere in the cooling system.. But raising the rpm at idle doesn't help, it will still overheat..
And the fans work?!?!?

Any tips or ideas are appreciated.

Thank You
Matt

Lawrence
02-22-04, 06:09 PM
Some quick thoughts.

<At idle the engine reaches 219-221 degrees (according to gauges)
and it won't stop there if I would keep it at idle for longer>
Very normal. The fans come on at just under 230

<Now if i Drive the car @50mph in drive the gauges shows about 212 degrees
If I then shift down to 3rd gear and drive it @50mph the temp drops to about 201-203 degrees (where it should be right?)>
212, also normal. A little high maybe. What is the outside temp? The fact that engine rpm lowers the temp shows good cooling system perfermance.

<If I let the car idle and then raise the rpm to 2000-2500rpms it will still keep on getting hotter.>
Normal. The faster a motor turns the more heat it makes. Especially apparent at idle (car not moving). Because of the electric fans the motor temp will increase to the temp at which the fans come on to cool it.

<But raising the rpm at idle doesn't help, it will still overheat..>
Normal. Higher rpm with the car still will make more heat. Again the electric fans. The old direct drive fans could cool better with the rpm elevated, but electric fans don't know the rpm, only temp.

It seem like its OK. Maybe 212 is a little high on the road. I would probably do a thorough cooling system check/maitanence.

First pull the small top hose (not the overflow hode right next to the cap) from the "coolant overflow tank, COFT", run engine to check for good flow. Slide it back on, don't over-tighten.

Pull the bottom hose from the "COFT", same as above.

On drivers side, pull the small hose that goes through the motor lift bracket, same as above.

Carefully check that the water pump drive belt on the end of the front valve cover is tight and that the tensioner has free movement. Also look for belt glazing.

If all looks good, drain the anti-freeze using the drain plug. A pain to get at. Easier if you move the fan off to the side and disconnect the lower hose. Out counter-clockwise.

Pull and check (or replace) thermostat. Be sure to use a 180 stat.

Remove "COFT" tank from car and wash and rinse inside thoroughly. install.

Disconnect lower rad hose at the motor and put in 3-6 cooling system tablets. Get them at a Cadillac dealer. About $7. Fill system with 50/50 mix of distilled water whatever antifreeze was in it (green or orange)

With a garden hose or better a hot high pressure spray. or better yet both, thoroughly clean/spray/wash the radiator fins. At the front your be spraying through the AC condensor (which needs done too) to get to it so be careful not to damage the delicate fins. A little time here goes a long way.

BeelzeBob
02-22-04, 08:30 PM
This is some background:
headgasket replaced
waterpump replaced
radiator replaced
Cooling fans works

At idle the engine reaches 219-221 degrees (according to gauges)
and it won't stop there if I would keep it at idle for longer.

Now if i Drive the car @50mph in drive the gauges shows about 212 degrees
If I then shift down to 3rd gear and drive it @50mph the temp drops to about 201-203 degrees (where it should be right?)
If I let the car idle and then raise the rpm to 2000-2500rpms it will still keep on getting hotter.

Does anybody have any idea of what might be the problem here?
First I thought that there may be a restriction somewhere in the cooling system.. But raising the rpm at idle doesn't help, it will still overheat..
And the fans work?!?!?

Any tips or ideas are appreciated.


Thank You
Matt



What exactly do you think is abnormal with the above....??? Sounds perfectly fine and it is operating as designed....

220 is NOT hot. The cooling fans will not even turn on until the temp gets to 225 or 230......

The cooling fans are controlled by engine coolant temp AND the demand of the AC compressor. Since the AC condensor needs constant airflow over it the fans will come on regardless of coolant temp if the AC is on (control in AUTO or DEF) and the compressor is cycling. If the AC is in OFF or ECON such that the AC compressor will not come on there is no demand on the AC system so the cooling fans do NOT need to work to keep airflow over the condensor...sooo....they will only come on when the coolant gets to about 225 or a little higher. Perfectly normal.

Electric fan cars act different from cars with engine driven fans. With engine driven fans there is always some air flow even at low RPM or if the clutch fan is not engaged. With electric fans the fans are either on or off....and they don't turn on unless the coolant gets above 225. Perfectly normal.

Realize that the cooling sytem will operate between 210 and 245 under normal conditions. This is expected and fine. The system will stay in control and not boil all the way to 265 F....if you have fresh 50/50 coolant/distilled water and a properly operating pressure cap. At 15 PSI with the 50/50 mix 265 is the boiling point so unless the system is getting to 250-255 there is no reason at all to worry about anything.

You are trying to fix something that is NOT broke.

MoMo 70 Formula
02-22-04, 09:46 PM
Thank you both for your answers.
I realize now that I have been a fool to believe that an new engine like the Northstar would operate closer to the temp of my old 1970 Pontiac 455CUI engine which is around 200-205.

Thanks again!
I guess I was trying to fix something that wasn't broke.:banghead:
Well at least i got some good answers and learned something new:)