Need cooling help: 2.5 runs over 220 degrees

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f4u5t

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Jun 4, 2020
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Bristol, Va
well, ive replace everything BUT the radiator, so im looking for one of those now, any suggestions for a daily driver 2.5, not a rock crawler monster so I dont need anything crazy....
So far ive bypassed the heater core, removed the thermostat, new water pump, yet it still runs over 220, on a 80 degree day....
 
I haven't had this problem yet but expect it will happen, it seems to be common. When I rebuilt my 2.4L I had the machine shop replace the engine block drain plug because it was rusted in place. You may have sediment in the block but I'm not sure that's the cause in your case.

Air in the head/block seems to be a very common issue. It's recommended (by others, not in the shop manual) to raise the front end when filling the system. I drove mine up on ramps so the air goes towards the cap. I even started the engine without the cap until it warmed up and found lots of air burbing out the top.

The proper Jeep thermostat should have a small hole in the flange with a loose rivet in it and should be oriented so that hole is in the top side when installed. This might help allow some trapped air come out as you fill the system but it takes a long time.

If the rubber on the radiator cap looks worn it may need to be replaced too. Are you losing coolant? It may be boiling out.

The last thing may be to have someone flush the radiator.

Cap with rivet.

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so the thermostat i removed (195) was stuck open, the one I replaced it with (180 ) neither had that hole, And i did find the block had air trapped....I have since removed the thermostat altogether, and ensure the water is full by removing the temp sensor and allowing water to come out that....
Im not sure about the plug on the block, ill have to research where that is...
today i plan to get some "flush" from the autoparts store and run that for a bit, then dump it again - before i just replace the Rad.
 
I had luck with another car using the Prestone radiator flush. I think it says for heavily contaminated systems leave it in longer so I ran it for two days in the system. It did work.

The original block plug have a female 8mm square plug (If I recall correctly) I changed it out to a regular plug I can get a wrench on.

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When you say runs over 220, what does that mean? My temp gauge regularly gets up to about 230 on super hot days, but it never goes beyond that. This is normal and nothing to be alarmed about. I take it yours is getting much hotter?
 
Which brings to mind the coolant temp sensor probe. There's two, the front one on the water pump is for the ECM to keep your engine running smooth and the rear one by the last head bolt on the left (Drivers) side with a single wire. That back one is for your gauge cluster.

They are different but can be tested with an ohm meter for resistance. I tested mine at 82 degrees F and it showed 7820 ohms.

Here is the chart from the Jeep FSM for different temperatures.

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Hope this is fixed by now. I had the same problem. It ended up being a bad fan clutch. If you are overheating make sure not to overlook that as well. From the interwebs:

"To confirm the diagnosis, start with this simple test: Spin the fan as hard as you can on an engine that has not been started that day. If the fan rotates more than five times, you can bet the clutch is bad. You should feel some resistance and the fan may spin up to three times, depending on the ambient temperature."
 
I know this is an after the fact posting, but I think a lot of us have been through this.
I went down this rabbit hole myself with a 2.5, turned out to be the Gauge sender.
Wasn't running hot in stock form, but I wanted to get rid of the prop and that ridiculous fan shroud.
The radiator had a bad case of the Crusteeze anyway, so I bought a matched aluminum radiator and fan unit from Champion.
Well, that turned into a "while I'm there event", t-stat, all hoses, water pump, belt and as I know now, just the ECM sender.
The entire cooling system was new with the exception of the heater core.
O'Reilly's gave me the wrong t-stat 180 vs 195 that it's supposed to have, still ran 210+ according to the gauge.
The ECM was not happy about the 180 and it threw codes left and right.
Changed the Gauge sender that I did NOT know it had and put in the proper t-stat, now she's happy as a clam.
After a 5 hour trail ride last weekend, never got close to the 210 mark, no codes, not even a hiccup or a fart.
 
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