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Low/fluctuating oil pressure gauge and spiking temps at idle

Memorial Day week and I am trying to finally fix all my automotive woes…

I have a 1998 Jeep Cherokee L6 4.0 Liter automatic with 223,000 miles.

The oil pressure usually runs around 1/8-1/4 when driving around town and now I am getting temperature spikes. I had the coolant and water pump replaced last fall when I was having similar idling issues then. My coolant isn’t a perfect green color–it is a little bit grey, but it is full. I cleaned the entire throttle body last January, cleaned the IAC today, and redid the NSS this week (not that this probably matters, just being thorough in my explanation).

It seems to happen worst on hot days (of course) when idling in traffic for a few minutes and makes the air conditioned air run warmer than it should.

Is this a busted radiator? The mechanic said I did not have a leak when I had him check last week.

Any ideas (especially cheap or DIY ones!) would be greatly appreciated.



I believe at least one of the problems is the driver’s-side fan behind the radiator. It isn’t kicking on as the car overheats to cool the engine…How can I tell if this is a fault in the fan or an electrical problem like a relay or some switch like the water temp switch or the ECM itself etc?

Thanks for taking the time to read this.


Turn on the A/C. if both fans come on, it’s not the fan.

That’s what I mean; when I have the A/C on full blast, the plastic fan on the driver’s side never runs no matter how hot it gets. It isn’t the relay; I tried a new one and it didn’t fix the problem. So have I narrowed it down then to the coolant sensor or the fan itself, or could it be something else like the ECM or something?


Fixed it! It was the coolant sensor. 20 bucks to fix. Easy. No fan required.