Hi there,

I'm currently trying to figure out what is causing my overheating issue that I had a week or so ago and randomly now throughout the week.

1991 Cavalier RS V6 3.1L

About a week ago I was driving around and managed to get stuck in the back alleyway near my house in some snow. At this point I was going in drive and reverse to get out, etc. The night before the outside temperature where I live was around -30 C and when the overheating occurred it was approximately -20 C. During my adventure of trying to dig a path out I noticed steam was starting to appear near my passenger side wheel well. So I took a look under the hood and noticed it was dumping my coolant and steam onto the ground from the reservoir tank. Took a look at the temp gauge on the dash and it was right at the red mark, just touching so I quickly turned off the car.

Later that day I got back to the car and it was cold, added more 50/50 pre-mix coolant to the reservoir, drive about 2 block away, no overheating, nothing different, except it randomly saying that there is low coolant whenever I pressed the gas.

Decided to buy a manual for my car (Haynes manual) as I don't know too much about cars but have been trying to learn more and figured it would help me test things.

So far I've done the following:

- checked for visible leaks (hoses, reservoir tank, etc), none found
- drained coolant, doesn't look much different then the new stuff I got
- replaced thermostat
- replenished with new 50/50 pre-mix coolant
- started car with reservoir cap off to bleed air from cooling system (manual said to do this after draining) until engine starts to get warm
- put cap back on
- drove around for about 10 or so minutes, noticed the temp was starting to rise (again it is still cold out, about -15 C or so at this point) got heat inside the car
- temp gauge started to approach the 3/4 mark, so I pulled over, opened the hood looked around, nothing leaking anywhere, hoses, etc.
- did notice that the radiator fan was not spinning
- turned off the car, walked back home, decided to get the car the next day and then got it home ok without overheating

Today I managed to remove the radiator fan and I tested that by connecting it directly to my car battery. This turned on the fan right away and appears to be working like it should so I re-installed it in the car.

I did some research online too and it seems it could also be a coolant temp sensor or a fan switch / relay. I've checked all of the fuses that are located underneath the driver side dash. Under the hood I sort of see relays (according to what they look like at a parts store) all over the place in random areas in the car, not in one central location and none of them are marked.

I've got no clue what to do next, my $ situation isn't the best right now so I figured I would post on here and see what else I can do besides taking it to a repair shop. Again I'm not the best person to deal with cars but I am trying.

Thanks,

Shaun

 

I am not a specialist but this is what I have learned over the past few years. Since you have "almost" over heated your engine then do this first. Check your oil and see if it looks normal light brown to black or does it look milky? If milky you could have a blown head gasket, or cracked heads. If not, great. The parts of the cooling system that can cause over heating on most cars if very simple: thermostat, water pump, radiator or fan for the radiator. You have checked two of the items, thermostat and fan. The other two are not always easy to check.

Double check the thermostat by boiling water and drop the thermostat in it. It should open on one end of the coiled wire. If it does, then it is good. If not, then it is bad.

I have two Isuzu Rodeo's also that I got on great deals and both of them had bad radiators. About $125 and the problem was solved, but I checked the fan (easiest to check and no money involved), then thermostat first (least expensive), then the other two are more difficult. The water pump usually will make a noise like a coffee can with peebles in it, but not always. The water pump also has a weep hole (a small hole that indicates that the pump has been compromised) and usually will show a little drainage. If you hear or see either of these then replace it.

The radiator is more difficult. I don't know much about radiators but this is what I have experienced. See if it drains at a fast rate when you open the drain valve after removing the radiator cap. If not, then disconnect a hose and check for the same thing. If is looks like it is not flowing at a fast rate then the antifreeze may not be circulating properly. Replace the radiator.

If you replace the water pump or radiator and still have problems, then you only have one item left. I know this is a lot, but let me know how it goes.

 

I agree check your oil to see if you may have blown a head gasket.I would also recheck that fan while it's installed in the car.Hooking it directly to the battery is okay to see if it works but you need to know if the fan turns on when it's supposed to.It should come on when the engine hits a certain temperature,if not maybe it's fan switch,relay,or sensor problem.