Gradual overheating mostly stock

B

BWAHitman

Senior Delegate
Joined
Jul 5, 2004
I own an 87 GN larger compressor and injectors. 48k stored and clean. cooling system clean! new 160 stat. new hoses. origional rad. normaly runs 180deg. when ambiant goes over 80deg it slowly creeps up to 220. ac stock and affectects temp rise faster. coolant flows through rad. cooling fan functions properly. any sugestions ????????? Tom
 
Sounds like a nice low mile car. Just because you see it swirl doesnt mean its flowing good.

Get a turkey baster or equiv and pull out some antifreeze until you can see 3 or 4 rows of flus in the core. Of course do this when its the engine and such are cold

Visual inspect those if there is ANY crud, if any I would take action/new radiator/recore.

While its at that level start the car and monitor tstat opening and rev the engine once the tstat is open and see how the flow is through the core.
It should BLAST through the flus if not you need a new water pump. Alsio, verify your fan is coming on at right temp.
 
I agree. Check the condition of the radiator. If that seems fine then see if you can find a leak down tester to use. At least this way you can rule out it being a head gasket. I have found head gaskets blowing even on cars with as low miles as yours does is still pretty common. I am not saying this is what the problem is but it helps to rule out a head gasket. Also on a side note it helps bleed the air out of the system if you drill a small 3/16" hole in the top of your thermostat.
 
Thanks

Thanks for the info ! rad looks clean BUT that can be deceiving. I will check flow as advised and take out a loan for a new rad ! Ha Ha Thanks again
 
Did you check between radiator and condenser. If they start clogging up with crap it will heat up. I just did a 2000 corvette. Driving it normal it would go to 248degrees. At idle it would sit at 215 degrees. Another shop installed a waterpump and thermostat and it still was getting hot. I pulled the radiator and you could only see through maybe 30% of it:eek: I powerwashed it out and reinstalled the same radiator. After cleaning radiator I drove it for an hour and it never went over 207 degrees. check it just to make sure. I hope this helps
 
My car was doing the exact same thing last summer. I changed the hoses, thermostat and pump and flushed the radiator a few times and it got a little better but still got up to 210 with the ac on in 85 degree temps. I got the f-body radiator at the end of the summer and today I drove it in 95 degree heat with the ac on max and it only got up to 200 while stuck in traffic. When I was driving it would drop to 175 and if I got up to 55 it would go in the 160's. I still have the factory fan on my car as well. A guy at the radiator shop told me that if a car sits a lot it will have silica drop out. Basically sediment will settle and clog the radiator. My closest radiator shop is 50 miles away so I didn't waste my time I just went to Auto Zone and bought the f-body aluminum one for 100 bucks. There isn't a engine oil cooler in it but you can get and aftermarket one fairly cheap and run new hoses or just take the sandwich plate off and run without it.
 
when its warm check the bottom 4 inches and see if it is colder than the top. mine was 1/2 clogged solid
 
be sure

Be sure to confirm accuracy of your gauge- And I highly reccommend the F-body radiator swap. dropped my average temp by 20 degrees!
 
Also look for any corrosion on the radiator on the outside. My original developed some very light crusty spots near the bottom. They were pin hole leaks. No fluid was missing but it was losing pressure.
 
BWAHitman said:
I own an 87 GN larger compressor and injectors. 48k stored and clean. cooling system clean! new 160 stat. new hoses. origional rad. normaly runs 180deg. when ambiant goes over 80deg it slowly creeps up to 220. ac stock and affectects temp rise faster. coolant flows through rad. cooling fan functions properly. any sugestions ????????? Tom
Click to expand...

There is NO way a 25 year old radiator is not over 1/2 plugged up from the bottom tubes up. Only way you will see this is to remove a side tank.

The original radiators were marginal at best when new, and that was obvious here during the summer in the desert.

Have seen this happen on 10 year old GN's back in the 90's. You only see the above normal temps in the hotter weather.

Do the smart thing and replace the core or complete radiator. :smile:
 
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