Sons 1990 XJ running hot

Cbrianroll

Cbrianroll

TJ Enthusiast
Supporting Member
Joined
Mar 27, 2023
Messages
123
Location
Washington
Hi all, since you guys know so much maybe you can help with this. He’s had it a couple weeks and it gets pretty hot. Haven’t really dUg into it much yet but are now. Going to pull thermostat and make sure it’s workin. wanted To check the radiator cap but there isn’t one. Is the overflow cap a simililar design that can go bad?

Thanks
 
This is very vague but I suppose I would start by making sure the radiator is full. Then I would start inspecting the overall health of the cooling system and when the last time it's had an overhaul was.
 
Sorry for the vagueness but this is step one so far. He just told me about it, so the troubleshooting begins, and I suck at troubleshooting. It had a lot of older maintenance papers with it, it had sat for a few years, but run to keep it from rotting.
I thought I read that the xj 4.0 ran hot ish, 230 approx. But It has overflowed out of the overflow. The overflow has a cap, it appears to have a spring so I assume it is pressurized?
the radiator does not have cap on it like my tj. Unless I really pulled a rookie move and didn’t see it. He is working right now so I can’t look around for a bit.
Is there a good order you all would recommend for diagnosing? I figured thermostat first, then water pump, then coolant flush/ pull radiator to inspect.
 
Has it got an electric fan? I’m thinking it does, so first I’d confirm if that fan is running. If it’s got air conditioning the fan should come on with the ac. Even if it doesn’t, the fan should be coming on when the engine is warm. I would also think it should run at 210° just like our Jeeps. Six cylinder right? Pics under the hood would be great!
 
Make very sure the fan clutch and aux electric fans are doing their job. Best thing I did with my 90 was to put a newer radiator in there and get rid of that whole pressure bottle BS.
 
Sorry, it does have one clutch fan on the pump and another electric one that does turn on with the ac.
I’ll have him run it tonite to confirm it kicks on when no ac is on.
 
Here’s a few pics
IMG_8460.jpeg


IMG_8461.jpeg


IMG_8462.jpeg
 
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