Moto1

I finally replaced all my A/C gear on my 84 and while I was at it I replaced my radiator as well. I noticed that the car would reach around 225 and climb in traffic with the A/C on. Turn the A/C off and temp would go down to around 200. The other day I noticed a little Antifreeze on the floor and it turned out to be the water pump weep hole. I just replaced the thermostat and the water pump and I'm in the process of "burping" the system right now. Anyhow, at what tempature should I become nervous about overheating, or better yet, what tempatures do your vettes normally see on a 100 degree day with the A/C on?

Jon Hekking

I don't know about an 84, but my 93 gets up to 240 in traffic, which according to GM is still normal as the secondary cooling fan doesn't kick in until 238 degrees.

kalister1

The 93 secondary cooling fan comes on with the AC. The first car I ever drove that runs cooler with the AC on.

floridamale

Yesterday 90+* out AC on in town traffic 216* 87 L98 180* T-stant Hwy running 188* Now that being said I just changed out the intake gasket last week and I'm running mostly on water right now wanted to check for leaks before I re-filled with coolant.

harley 1951

I tried a lot of things to make my 85 run cooler. Still ran 225/ 210 in town. Had new belt,hoses, and thermostat put on and flushed system twice and car now runs 215 in town/ 200 highway - oil temp 6-8 degrees warmer. Acceptable to me. Just gotta remember front end is closed so in town it's gonna be hotter.

xCCTer

Perfectly normal.

Jon Hekking

According to the GM spec book, yes the secondary comes on with the AC or when the temp hits 238 degrees, read it from my friends service manual who is a service tech for GM...........

Moto1

Thanks for the responses. I have replaced everything related to the cooling system with the exception of the heater core. I know there isn't any air flow when in traffic, but it seems like an instinct to get excited when your'e over 200 degrees and you don't know when it will quit rising. I know that if you park the car when the temp is at 225 that it is going to jump another 20 degress since the fan is off. I guess Il'l have to live with it....

SunCr

Your '84 should run cooler with the a/c on as the system is designed to maintain a gas temp that averages 120 to 140 degrees at the condensor. In order to do that, the fan has to run longer and come on even before the thermostat opens. A weak radiator, with the load of the a/c system, will often give you the problems you are seeing - but - since you've replaced it, you need to check out the a/c system. If never serviced or serviced improperly, it's probably backed up. Check operating pressures with a manifold gage set and note the pressure the fan is coming on at. Also, make sure the shroud/lower valence is intact - it should be running around the thermostat at cruise a/c on or off.

xCCTer

If I just happen to be parking the '88 when it's at the top of the cycle (228*), I just wait another minute for the fan to bring it back down to 215* before I shut it off.

Pointless I know, but...

Moto1

All the A/C is new. Compressor, accumulator, hoses, etc. head pressure is ok as well. Just about everything on the car is new. Just got back from checking on a C3. Probably about to let this one go.

SunCr

If it's all new and charged right, then it's an air flow problem - damaged shroud; valence - make sure something isn't sucking the voltage out of the system slowing down the fan.

jhammons01

Those temps may be considered "ok" by some....

That Water pump leaking is your notice to start shopping around. That thing could go at any time now....and on the '84 it is a Beotch to replace...they hooked everything to the four studs that hold the WP in place.

After you fully service your cooling system...

My coolant system is completely stock. I replaced the water pump, thermostat and radiator with NEW components last summer.

I cleaned out between the condenser and radiator and I keep it clean by pulling the cowling off every now and again. I cut the cowling so that the holes that the hoses go through are now slots. I only need to take the ~20 screws out of the top and lift it off to see the trash in there. I use the cordless drill and a nut driver set from Target to make the screw removal a very quick process.

I've flushed my system ~6 times and yet it still turns ruddy brown within days. there must have been a sh!tload of corrosion in there. Each time I do it, I pull the over flow bottle and take it to the sink where I can clean all that rust out of the bottom.

Stop and go city streets


A few moments later about 3 miles on the Freeway


don't ask about the Oil pressure gauge and the Average.....yes the battery was going dead and resetting the computer and yes the Oil pressure sending unit should be changed.......but that is another thread.

jhammons01

To answer your question...the day mine hit 250°....I shut it down and let it cool....it wasn't too long later that the WP went out and then not too much later the radiator split.

coincidence? I think not.

Moto1

I thought about cutting slots in the upper shield but changed my mind. I cleaned everything from the shroud to the nose when I put a new rack and pinion in a few months back. My fluid is green and there wasn't any sign of debris or rust when I replaced the radiator nor when I changed the water pump. I probably need to drive it around with the air off and monitor the temp to see if it is the compressor loading the engine too much. I had an issue once before with a firebird that when the compressor was changed, I over charged the refrigerent (stay away from that cheap charging hose with the gauge) and apparently this placed too much pressure on the compressor which caused the engine to run harder to keep it turning which caused the car to run hot. A lesson was learned! I will keep at it and post what I find. I enjoy driving the car but I hate missing the scenery from staring at the gauges like I'm at the track.

AstroMan1

I have a 1984, it usually runs at least 200 around town. Really a little more. That's without the AC and 80 degree temps. The first day I got mine the fan quit working and I didn't know it, came off the highway and pulled into a drive-thru and it completely overheated, up to 260. I was lucky nothing blew. Got that fixed but I still worry about overheating all the time. I think 240 is too hot.

dchoran

Whoa - I just bought an '84 C4.

Is this normal operating conditions in the city:

45 oil pressure 240 oil temp 233 coolant temp

Manual says idiot lights don't go off until 299 oil / 255 coolant.

THANKS Dave H Appleton, WI

pologreen1

it's kind of high. They do run hotter, but not all should. alot of people have old coolant, and clogged radiators, etc

example today a guy bought my dads 86, and I know the temps never got over 180 unless in real bad traffic, today he called, because it over heated. I checked temp, flushed raditaor, new coolant, etc and traced it to the fan relay not working. now back to normal.

dchoran

OK - bought mine two weeks ago - previous owner maintained it flawlessly -new water pump, regular flushings, etc.... he even had it into the GM dealer because he thought it was running warm/hot - they said everything was "normal".

So is it safe to say 233F is OK or should I "find the problem"???

Maybe this particular stock '84 runs hot since it was built in June 1983???

jfb

GM says to shut the car off and let the engine cool down if the coolant temp gets to 260 F. I think this is because 50% antifreeze at 15 psi boils at 265 F. Even 260 F will not harm anything in your engine, but boiling antifreeze will lose coolant out the overflow and low antifreeze can cause very high head temperatures (no coolant in the heads) if you keep driving the car.
Your primary fan will come on at 228 F and if you have the auxilliary fan, it comes on at 238 F. When the fan comes on you should see that the coolant temp drop in temp. You needn't be concerned about your coolant temps in 100 F ambient with the A/C on until the coolant temp reaches 260 F.