Car 1990 GTA 305 5 speed.
This has now happened a couple of times this year. Again yesterday. I live in the low hills above Riverside Ca. I went to lunch with friends downtown. About 1000 feet lower.
The temp indicated about 200 degrees with the ac on and 85 degrees out. Perfect going downhill. Returning home a couple of hours later. Outside temp 96 degrees.
Going uphill car temp went up to 220 and climbed to about 240. AC was on but was not very cool. The climb back up is pretty steep.I'm guessing maybe an bubble that moves around? I will be doing a burping this weekend.

Any guesses or advice is greatly appreciated.

Bob

 

What speed were you traveling? What type of fan do you have? Is engine stock? Mileage on car? When was coolant serviced last? How does it operate normally in stop and go driving? How does it operate on highway (non-stop speeds above 45)?

Cars tend to operate hotter going up hill due to load. I had a 97 Transport that would get real hot going up mountain passes at highway speeds. I would usually turn off AC to help some. If it was slower speed up hill I would actually turn on the AC to bring electric fan on sooner (not sure if that is correct to do).

If it has been awhile since you replaced coolant, maybe flush the system.

 

Hi Thanks for answering.

Speed was in town and about 45 mph. Had more stop and go going to lunch.
Stock 305 as far as I know.
One thing I did not mention originally is yesterday morning I simple greened and hosed the rad and AC rad.

Normal operating temp is around 215 all the time. Maybe 220 if going a little slower, in town or getting in traffic on the freeway.

Dual fans both which were on. Milage is 101,000 or close to that.

Coolant and thermostat both have less than 1000 miles on them.
I have not done a engine flush since I bought the car about 10 years ago or about 6000 miles.
Maybe I should dump the coolant if the burping does not work.

Then this brings up the next question. What is the best way to a flush and what agent to use?

†hanks again and any other ideas would be greatly appreciated.

Bob

 

Is your front air dam in place?

If it starts to climb over 220 you should turn the AC off and turn on the heater. This will help cool it down. I know it doesn't seem like much from 220 to 240 but that much extra temp in your OIL will drop you approximately a full weight in viscosity and pulling hills like that is high, high load. That should be avoided if at all possible. If you drop from a 30 to a 20 and are heavily loading the engine, a little detonation is all it takes to damage a rod bearing.

GD

 

Air Dam is in place a little beat up but it should be doing what it is supposed to do.

Will do on the AC.

Thanks

Bob

 

If it was mine, I would flush the coolant system. That many miles it's not going to hurt. I am going to do our 84 this summer. It has pretty new coolant, radiator and pump. When I did that I tried to run hose water through it. New coolant discolored pretty fast, so I did not get it good enough.

Temps seem high to me, but I am in MT and we don't get temps you do. On my 95, highway speed my gauge stays on 195. Under 45 it will cycle with the fans. Both fans do not come on until about 220 unless AC is on. It will sometimes go some higher but drops right away. When I was commenting to my friend (GM mechanic in the 90's) about the high temp, he said don't worry about it, it is designed to work that way. And it has for the 13 years I have owned it.

Your gauges may not be spot on accurate which as I have read on 3rd Gen is common.

 

Thanks again
Im going to do the burping this morning . It is going to be in the triple digits till next week, like 115 on Tuesday, (summer is here). Will see if that helps.
Have you used any of the system cleaners? Used to use prestone cleaner but there are more out there,

Bob

 

if your worried about trapped air, drill 2 or 3, 1/8" holes on the edges of the thermostat. it will burp any trapped air out and lets a small amount of coolant to always circulate.
i've found "water wetter" to be good for a 10 degree drop in temps.
https://www.redlineoil.com/product.aspx?pid=74&pcid=10

 

Thanks. I will add the drilling of holes as a project "most soonest". I do use water wetter and hopefully it is helping.

Update on burping. I did the procedure that I found here on third gen. Adding coolant in a small amount twice. Topped up the Rad. and overflow tank. Took a test drive to the same place as the other day with same condition but nor as hot. Have to out later in the day this weekend. Anyway the car stayed about 200 going down hill and coming back up it went up to about 215 going 45. At about 50 it dropped some maybe 210.
For today i would call it a success at least till I can test it when it is over 100 out.
In the garage tested with the laser temp gauge at the thermostat housing I was getting 208 average with the motor running.
On to the the project

Bob

 

Amsoil has a product called Coolant Booster that beats the Redline product in independent testing. Basically the same price. You only need half the bottle for a 3rd gen running glycol mix. Lots of my customers run this with plain water for the track (Glycol not allowed on the track).

http://www.amsoil.com/shop/by-produc...coolant-boost/

GD

 

Have you looked between the radiator and AC condensor? Have seen leaves and trash actually build up in there halfway to the top. No way for that stuff to get in there, it just does. Just a thought.....

 

Update
Only a few leaves and whatnot between the Radiator and condenser. But there is alway a but. I noticed what appeared to be hair sticking out between the fins of the condenser. It looked enough to block air flow.
Not wanting to pull the radiator at this time, I scrounged though my drip system parts and made a water wand. Just small enough to fit between the devices with the fans loose and radiator pulled back. Blasted water through both and put it back together.
Went for a drive with the AC on. Temp on the gauge stayed about 215 then going up to 220 or slightly above. Driving up the hills and lugging the engine it went up to maybe 225 or 230. Pulled into the garage and lifted the hood and shot a laser beam on the upper thermostat housing and got a 218 reading. Hopefully this is it.
Will take it out tomorrow when it is hot out.
Today 88 degrees. Try to get out when it is over 90.

 

If you do a drain and flush make sure you take out the drain plugs (not the freeze plugs...there's one per side, just above the oil pan rail there pipe thread) I took mine out awhile ago and one side nothing came out, I had to fish around with a clothes hanger to break up the goop in there...mine was Allen head, but some are 1/4" drive...a short extention fits perfectly....I had to use heat and a breaker bar to get mine out but it was worth it...it solved an overheating prob...just make sure to get all the goop out