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pickled_asparagus 01-21-2012 03:25 AM

GM 3.1L Cooling issues and cooling fan
Ok, so I've been having trouble understanding what's going on here. Vehicle is a 1995 Olds Cutlass Ciera SL 3.1L. Normal operating temp is the guage at 1/2. Lately it's been creeping up to almost 3/4 when I'm at 65-70 mph. So far, I've replaced the heater core (box was full of coolant and it smelled in the car), and just finished fixing the leaking lower intake gaskets today using the steel fel-pro ones (FUN!!). Head gaskets seemed fine, no cylinder pressure in the radiator or coolant in the oil/vice versa. New T-stat also. I'm assuming all the air bubbles are out (maybe not?) but the heat blows warm for the most part. Does anyone know the proper "bleeding" procedure for these?

Also, When is the cooling fan supposed to come on? It seems like I let the car idle forever and the fan never kicked on. I do live in Wisconsin and it's 10 degrees outside but I would think the fan would kick on. At idle, temp is fine and stays steady at 1/2. Does the fan ever come on on the freeway or is it only at idle/slow speeds? Like I said, the car never really overheats, but i dont ever remember it running like this. Any help would be greatly appreciated!


LATECH 01-21-2012 01:40 PM

Fan runs when required by engine temp. It usually switches on at about 225-230 farenheidt. This is normal. Also if you turn on the AC the fan will run , and IIRC that one will have 2 speeds and is dependant on condenser pressure. But forget that for now, If your moving down the freeway at 60 mph the airflow at the radiator is good enough that even on an 85-90 degree day the fan wont run, but when at Idle, when there is no airflow the fan should activate. Usually about 3/4 gauge is where it will come on, however gauges arent allways accurate.
You could have a trapped air bubble in the system. There are 2 air bleeds I think, one at the bypass and one on the top outlet.I have in the past , pulled a heater hose off and filled through it to be sure all the air was bleed out, just to speed up the process.Chances are by now , if you have driven it and it has cooled down, all you will need to do is add some tothe expansion tank(what the rad cap goes on to) and you will probably be good to go.
I would check the atual temp of the water at the water outlet verses the reading on the gauge to be sure it is reading correctly, then you will know for sure.
You can check the coolant temp with a good data scanner, look at live data stream, and watch it. I have an extra coolant sensor in my tool box that I use , i plug it in to the cars harness, then turn on the key and look at the coolant temp. ThenI hit it with a bic lighter or propane torch, watch the temp go up and wait for it to hit 235 ish, usually by then it will send a cooling fan request and the fans kick on. Takes a lot of time waiting for it to warm up out of the equation, and if the car has a defective sensor the motor is still cold enough to work on. :thumbup:

pickled_asparagus 01-23-2012 11:42 PM

Thanks so much for the help! Ok, I tried turning the AC on full blast (ambient temp outside was 12 degrees) and neither fan came on...does that mean I have a bad fan relay or something? (the 10a fuse in the fusebox looks good) Driving around town it seems fine, however On the freeway is where it starts to get alittle warm. Up to 60-65 its ok, but 70+ the temp guage wanders almost to 3/4 (and it's winter!).....I don't recall it doing this before. I did just have a new trans put in as well....could the trans running hot and using the internal cooler in the radiator be an issue (fluid is full)? I noticed the lower radiator hose is warm (not hot). At this point I'm alittle perplexed!

Do the air bubbles just take a while to get rid of? I bled the little valve on the water pump and the other one by the thermostat housing when I first got it back together. Everytime I've checked it since then, the radiators full with the expansion tank at the hot level when warm.

Of course, maybe there's nothing wrong and I'm being too picky....Normally, I dont buy cars unless theyre 25 years old or older (broke my rule for this one and look what happened!!), so to me, 220 is getting alittle warm.... does this newer stuff just run hotter?

1990fordLTD 01-24-2012 01:23 AM

210 ish is when my fan kicks on....1996 Grand Prix with the same 3100 motor.

LATECH 01-24-2012 05:13 PM

Sounds like your radiator is really plugged up.Look in the end with the cap off. Check the tube openings inside,if they are covered with a white crusty looking crud, then it is plugged.
To confirm the pluggage, if the engine is good and warm,stop the car and open the hood, if the radiator feels cold at the bottom and kinda warmer toward the top , it is plugged,it should be pretty warm to the touch if the water is flowing through it well. No need to guess, just feel it to see.A cold radiator is a plugged radiator
BTW, if the AC was turned on, the fan may not kick on as it comes on according to head pressure, which will be real low on cold days.That is why it didnt come on.

T-bucket23 01-24-2012 07:29 PM

If the A/C is on I think the fans should run. You could have a defective fan or relay. If they are not turning they can actually deter air flow. I would test the fan with a couple jumper leads or remove the fan relay and jump the 30 to the 87A terminal in the relay socket. This should force the fan on. As Latech said your radiator may be partially plugged as well.
I would test the function of the fan first and go from there.

mario1212 05-20-2013 11:59 PM

i have 2004 oldsmobile silhouette my coolin fan turn on let if i driving on the city the cooling fan turn on 3/4 but if i driving on the freeway the temperatur stay on 1/2 i drive for 1 or 3 hour or more the tempreratur stay on 1/2 but wend i come of the freeway the temperatur go to 3/4 and back to 1/2 can you help me please

LATECH 05-21-2013 04:45 PM

mario....first you need to slow down on your thinking and type more complete/coherent sentences so we can understand them.
I think I can decipher your post anyhow.
Moving along at freeway speed, the temp gauge stays at 1/2 right?
this is normal on your van.
When you get off the freeway and are in city traffic , the gauge moves up to about 3/4 then back down ... correct?
This is also normal. When your gauge is at 3/4 you should stop and look under the hood with the engine running and you should be able to see the fan running, which will cool the temp back to 1/2 gauge.
All normal

mario1212 05-21-2013 05:59 PM


Moving along at freeway speed, the temp gauge stays at 1/2 right?


2 When you get off the freeway and are in city traffic , the gauge moves up to about 3/4 then back down ... correct?



LATECH 05-21-2013 06:03 PM

Yes , system is operating normally Mario.
BTW when you type in capitol letters it is the equivalent of yelling.
If you are Gilbert Godfried I understand LOL :D
Just sayin :evil:

mario1212 05-21-2013 06:35 PM

thank you latech and sorry for the capitol letters
I did not know that
thank you .:)

LATECH 05-21-2013 06:46 PM

Its all good .:D

Aaron-71 10-14-2013 12:43 PM

I don't normally like to bring up old threads, but I could really use some assistance with this one...

I've got a cooling issue with my 3.1L 1996 cutlass supreme.

Any opinions/comments are welcomed cause this one has me stumped.

Things I've checked/changed out:

1) NEW Coolant temp sensor
2) NEW Thermostat - I know it works cause I put it in boiling water and it opened
3) NEW Head gasket set installed + NEW Fel-pro Lower Intake Manifold Gasket (problem-solver stainless steel set) installed.
4) NEW oil pump drive shaft gasket + cleaned & rtv'ed around the top flange to help seal it
5) Checked fan relays, they all work
6) checked for radiator blockages by pouring water down rad with different ends undone each time - no blockages.
7) hot air blows hot.
8) A/C blows cold
**** 9) A/C fan will not turn on if A/C is turned on (passenger side fan)
**** 10) Driver-side fan will not kick in until the car hits the red zone on the temp gauge.

All of these things were done to try and solve my overheating (gauge pings to red zone) issues with my car. I've changed out the dex-cool coolant for green stuff and I'm still getting overheating issues. I've bled a lot of air out the system...

Anyone have any suggestions on things to check next? I've done a lot of work to the car, and put it all back together only to find out that the issue still remains...

Aaron-71 10-14-2013 01:53 PM

Couldn't edit my last post... Double post!

Started the car and checked the radiator after the car tried to overheat again and found that the bottom of the radiator is cool and the top is warmer (closer to the temp of everything else on the top end of the engine).

Blocked radiator?

I checked it with a garden hose and it had water coming out of it at all ends (still installed in the car test only).

I didn't mention in my last post that I have also changed out my water pump because it was bad/leaking.

LATECH 10-14-2013 04:47 PM

If the heater blows good hot air , then the water pump is circulating water.
Hot top hose and cold bottom hose means nocirculation of coolant through the radiator
SO...that leaves the thermostat not opening or a plugged radiator. My bet is the radiator, but I would still re check the t stat before spending any cha ching on a radiator.
Radiator is probably plugged with block sealer from someone trying to fix the head gaskets with a mechanic in a can.

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