I figured I would get some opinions before I started throwing money at it. The coolant is boiling on my 99 xj and I’m struggling to figure out why. It does not leak anywhere other than out the overflow once it gets hot. The motor just had a head gasket put in, the radiator is only a few months old. And the radiator cap is brand new. Motor runs great and does not get over just slightly above 210 in temp on the gauge at least so far. I have not ran it hard since I obviously do not want to make anything worse. Less than 50 miles since the head gasket replacement which I’m very confident was done correctly by a an awesome mechanic I know.

 

Was this an issue before the head gasket was done?

 

What type of brand new radiator cap was used? Generic? OEM/Mopar?

 

No it was not. I found a water hole a little too deep and sunk the jeep and filled it with water. That was reason for head gasket needing replacement

 

I bought a generic duralast cap. I still have the original one that seemed fine I suppose I could put the old cap back on and see if it helps.

 

That is a good idea.

 

What year vehicle?

 

He mentioned 99.

 

New thermostat?

New water pump?

Shroud installed?

 

Well I put the old cap back on and it didn’t seem to make a difference really. Maybe a very small improvement but still isn’t how it should be

 

I’m thinking those are about the last two things I can think of to try and replace. The fan shroud has not existed in the time I’ve owned the vehicle. A previous owner broke it at some point.

 

Have you checked the A/C condenser and radiator to see if it fins got plugged up when you went into the water ? and how is your fan clutch working also look at the e fan .

 

I sprayed the condenser and radiator out really well with power washer and it seemed pretty clean. I have the electric fan wired up to be switched by hand and I usually run it all the time when I’m wheeling to keep things cool. I usually don’t ever have the need to run the e fan just cruising down the road since it’s getting lots of air.

 

The other thing I was wondering is do you have enough coolant , to much water will let it boil over . Did the head get resurfaced ?

 

Did the head and block get checked for cracks? If you leave the cap off and run it cold, are you getting bubbles at the radiator neck?