1998 4.0 Overheating. Too much coolant?

D

Domant22

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Joined
Apr 24, 2020
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6
Location
NY
Hi all, my brother and I recently replaced the oil pan gasket, oil pan, and rear main seal. Today was the first time we have driven it since and it began to overheat. Turns out my brother filled the coolant reservoir way past the “FULL” mark at some point. On the way home the Jeep began to overheat and looks like coolant was coming from the radiator cap. Would all the extra coolant cause this to happen?

TIA
 
Extra coolant wouldn't cause that. Is the radiator cap screwed all the way down? Does it have the correct 18 psi pressure rating? Did you do anything to the cooling system so it would need to be burped of trapped air?
 
Nothing else was done to it besides coolant in the reservoir. Radiator cap is 18 psi and is on correctly. What’s the best way to check for trapped air? Really scratching my head here
 
What do you mean by "overheat"?
Water expanding, bubbling over with normal temperatures
is not the same as
temperature climbing above 220+, then water vapor coming out.
 
Park your Jeep on a slight hill so that the radiator fill is the highest point. Run the engine with the cap off till it is up to temp and you have heat inside the vehicle. You should see some bubbles come out if air is trapped. Refill as necessary.
 
Wtrask said:
Park your Jeep on a slight hill so that the radiator fill is the highest point. Run the engine with the cap off till it is up to temp and you have heat inside the vehicle. You should see some bubbles come out if air is trapped. Refill as necessary.
Click to expand...

This. Keep an eye on your temp gauge to make sure it's not overheating, but this is the best way to get air out of a 2.5/4.0. Also, I'd recommend one of these:

OEMTOOLS 87009 No-Spill Coolant Funnel Kit, Near Universal Fitment, Translucent, 15 Piece Set

3cb-308d6ed24a78.__CR0,0,2479,2479_PT0_SX300_V1___.jpg


They make the job much easier, and I think they also help keep air out of the system. I've never had to burp my TJ or XJ using this kit.
 
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