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Discussion Starter · #1 ·
I just purchased a 95 YJ with 2.5L and 5speed, gonna be my future project but for now daily driver. Anyway engine seems to be running a bit hot on the highway. Is this normal for the little 4banger. I was thinking of changing the thermostat, maybe the rad is gone, could be just the gage. Anybody had any experience with the YJ running hot?

91 YJ Islander
Lots of Plans, Little $$$$

13,432 Posts
How hot is hot? Nope, like any engine, it should be regulated to a specific working temp by the cooling system. It shouldn't run ho, espically a fuel injected vehicle. Thier enging heat specifications are very narrow.

You've identified good places to start looking for the problem. A thermostat is a place good start. It's cheap... and the heart valve of the system. Don't forget about the water pump. Get a prestone Chemical back flush kit and back flush the engine. This should get some of the crud and scale out of the block. Once you do this you know that what ever was in the block... it's also in the radiator. You may want to remove it and have it rodded, or re-cored. Also, don;t neglect to put in the correct ratio of anti-freeze to water. If you don't the boil temp will lower and this could be the cause for the heating.

Don't forget that mechanical and fuel problems can cause an engine to run hot. If the engine's running lean, or too far advanced it will run hot. If the cat converter is plugging, or the muffler's collapsed the backpressure build up and lack of exit for hot exaust gasses will add to the engine heat and loss of power. It could be even something as simple as a bad radiator cap.

Good luck.

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