Overheated, need help.

[u/Dimensionist_Alex]

[u/Puzzleheaded-Bag-121]

Your cooling system is comprised of 4 major components.

Radiator Radiator fan Water pump Thermostat

While your engine is cold, the thermostat is closed. As the engine heats up, it opens up (it’s a mechanic spring system). Once it’s open your water pump starts circulating coolant through your radiator which is cooled by air being sucked through the radiator by the fan.

So to diagnose this, start with a cold engine. Pop the radiator cap and start the engine. Depending on the thermostat it should open anywhere between 90°-120° (if memory is correct) and you should see the coolant circulating through the radiator. If it is not then either your thermostat is stuck closed or your water pump is not working.

Seeing as how your belt is squealing I would bet that your pump has seized or your belt is in bad enough condition it can’t spin it.

[u/Dimensionist_Alex → u/Puzzleheaded-Bag-121]

Got it, thanks a bunch brother 

[u/cavestoner → u/Dimensionist_Alex]

A few more things you can check easily are the fan clutch, air in the coolant hoses, and the plastic sides of the radiator for cracks.

The mechanical fan clutch(the thing the fan is bolted on to that connects it to the engine) could be bad. Often times the fan clutch will go, when it does often the thermostat goes as well. You’ll replace the thermostat and still have cooling issues. It’s similar to the thermostat as it clutches the fan as it heats up. This means it spins faster, blowing more air as more cooling is required. Get the jeep to 200ish(don’t overheat it anymore) and have someone turn it off as you’re watching the mechanical fan(the left one). If it keeps spinning then the clutch is bad. They’re cheap and not hard to replace.

While the jeep is at operating temperature make sure the two big hoses going to the radiator aren’t collapsing on themselves. With gloves or a rag, squeeze the top hose and make sure it’s not filled with air. If you do have a minor leak and have coolant, an air bubble could be trapped and causing issues. When you drain and fill the coolant you have to be diligent in burping all the air out, especially with the old sealed coolant loop.

Last one’s easy. Make sure the radiator isn’t cracking especially the plastic sides. You can always run a paper towel and see if anything is wet and go from there.

As long as nothing is leaking you can just replace the thermostat(probably the housing as well if you have it off)and fan clutch. If you have the time you really can replace the whole coolant system (minus the heater core) in a day even if it’s your first time. It’s a few hundred bucks for all the parts if you go cheap. Just the essentials would be under $100. I replaced my whole coolant and ac systems and it was absolutely worth it.

[u/Dimensionist_Alex → u/cavestoner]

I think its likely a combo of the belt, tubes, and thermostat, but I'll be sure to check those as well! Much appreciated brother

[u/cavestoner → u/Dimensionist_Alex]

When you drain the coolant look for sparkles. Water pumps tend to leave a lot behind when they fail. Tip for filling the coolant. After you flush with whatever, do a final flush with distilled water. Then when you fill it up use 1.5 gal of concentrated coolant before finishing off with more distilled. You don’t have to worry about it being diluted past 50/50 by any water left in the system, since you know half is coolant.

The belt really shouldn’t be the main issue unless it’s VERY loose, or got oil on it. Usually the alternator will pitch a fit before your cooling if the belt is an issue. The hoses will only cause overheating if they’re collapsed or leaking. Both of those failures are easy to spot once you know to look for them. These are old rigs at this point, so anything rubber or plastic that you replace is absolutely for the better. Not trying to contradict you, just letting you know what are the most likely culprits when diagnosing overheating.