2.5 running warm at driving speeds

jeepjoe43

YJ Enthusiast
Lifetime Supporting Member
Joined
Dec 4, 2020
Messages
926
Location
Black Canyon City, AZ 85324
Hi folks,
I've been jeepin for 30 years but I'm new to the YJ.
Had mine for about 3 years now putting less than 100 miles on it as a driveability issue cropped up after lifting it then an electrical Gremlin reared it's head.
My question is this; is it normal for a YJ to run with the guage indicating 210?
It did it on or off road with the factory cooling set-up, and it does it now at driving speeds, 45-50mph with a completely new set-up (haven't had the new off road yet).
The Entire cooling system has been replaced, correct reverse rotation pump, New 3 row aluminum radiator w/shroud and electric fan, hoses, thermostat and sender, still 210.
At idle it will go up to 210 and then drop to the first mark and stay there. Once on the road it goes up to 210 and stays there, never seen it over that mark.
The fan is on a toggle switch, not a thermo-switch.
Could the guage just be out of calibration? VDO did make the guage packages for the YJ, but It is 30 years old.
Any ideas?


For those who might be interested, my Gremlin was the motor breifly cutting out on every bump in the road, but I found the SOB.
Stressed voltage supply wire to the coil plug, I broke it changing the coil and didn't even know it, no problems since repairing it.
 
I've read two different opinions about making sure there's no air in the engine's cooling system. Some say the air will naturally flow out into the overflow system while others say no, there's a problem and you need to raise the front end higher to burp the trapped air out. If air is trapped the engine will run hot.
 
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I thought that too, especially with the lower radiator hose having that bump to clear the diff, filling it cold it would take more coolant when I pushed it down.
The coolant fluid capacity is 9 quarts or 2.25 gallons and that is almost exactly how much it took, maybe a little more.
I have thoroughly burped the system, still 210. Going to verify temps today with an IR temp gun to check the accuracy of the gauge. I'm suspect of the gauge because it just does not act like a hot motor, not that 210 is overheating, but that's not my happy place.
I used to have Flatfender with a 175hp, 2.0L Pinto motor that NEVER went over 170 with a crappy old Datsun radiator/w electric fan.
Just seems bizarre to me that a 125hp wind up motor would run that warm with my cooling system, radiator's supposed to be good to 300hp.
 
Update; it's the gauge.
After running it up to 210, I put the IR Gun to the motor couldn't find any spot hotter than 185 with exception of the exhaust manifold.
I can live with that..
 
If you're happy, then no problem, but I think surface temps lag internal temps I would troubleshoot a little more. What is the condition of the coolant temp sensor? You can test it with an Ohm-Meter, but I like to immerse it in a cup of boiling water to verify the sensor and the gauge. How old and what temp range thermostat is installed? 195°F? If you remove the thermostat, you can place in one of your wive's cooking pans on the stove and observe the water temp when the valve starts to open. Also, what brand coolant do you use? Mix ratio? Any chance a section of the radiator exterior is clogged with mud/debris? That one got me once.
 
The entire cooling system is new, I discovered the thermostat was the wrong temp, and that I only replaced the ECM sensor.
Today I replaced the gauge sensor and thermostat, just to discover the t-stat slipped when I reinstalled the housing, but I didn't have time to correct it...More to come.
2 steps forward 1 step back has been the rule EVERY step of the way with this project.

JEEP

Just Empty Every Pocket
 
Just got back from a great trail ride, and not a single hiccup from the jeep.
Running at proper temperature, no stumbling or codes, for lack of a better description, she ran perfect.
Probably was the temp gauge sending unit, never came close to 210 all day, just the way it should be.
Even after taking out the 180 t-stat and putting in a 195.
First good day I've had with her in years! It was a GOOD day, like the ones I remember.
i hope she stays that way, I'm tired of hunting Gremlins, and I've invested too much to give up.