• Welcome to the new NAXJA Forum! If your password does not work, please use "Forgot your password?" link on the log-in page. Please feel free to reach out to [email protected] if we can provide any assistance.

XJ coolant overflow after engine is shut off

Stant is the only one to buy! No, quick relaese caps either.
 
FWIW, I'm in the "try another cap" crowd. Had this happen on other vehicles including my '88.
 
So This issue still is not resolved. I did not purchase another cap because when I pressure test the system with a pressure tester, the pressure basically drops like a stone, so I know that the system is not holding pressure from some other point besides the cap. BUT there is no coolant coming out anywhere when the XJ is running or with the pressure test cap on (even pumped up past 20psi). I even sprayed all coolant lines, mating points and radiator with soapy water to look for air escaping and there was nothing. The oil is clean of coolant and the compression and leak-down tests were performed and everything was great, it was even across the cylinders and held fine. Like I stated before, the XJ runs and drives fine. Never overheats, idles perfect, oil pressure is spot on, the mechanical fan and e-fan work as they should (even with the A/C on). The only issue is that coolant randomly boils and comes out of the overflow tank after the XJ is turned off.

Where do I go from here?
 
Did ever do a sniff etr test it sounds like a cracked head.
 
RCP Phx said:
Did ever do a sniff etr test it sounds like a cracked head.
Click to expand...

Not specifically. There are no signs of a cracked head, the compression is good, the oil pressure is good, there is no visible coolant in the oil, it doesn't seem to be loosing any coolant and it is not blowing any white smoke, I would think that the head was ok.
 
JMA_2001XJ said:
Not specifically. There are no signs of a cracked head, the compression is good, the oil pressure is good, there is no visible coolant in the oil, it doesn't seem to be loosing any coolant and it is not blowing any white smoke, I would think that the head was ok.
Click to expand...

You say that a coolant system pressure test fails, but the engine is not loosing coolant during driving. Both can't be true. Are you sure the pressure tester is not defective? And keep in mind that hot water evaporates. A cracked water passageway into the valve space may not result in water in the oil.
 
A crack into the chamber will cause all the symptoms you describe with no noticeable coolant loss
 
maxbraketorque said:
You say that a coolant system pressure test fails, but the engine is not loosing coolant during driving. Both can't be true. Are you sure the pressure tester is not defective? And keep in mind that hot water evaporates. A cracked water passageway into the valve space may not result in water in the oil.
Click to expand...

It is my buddy's pressure tester, he is a mechanic and uses it all the time. I guess that it is possible it could be broken but it looks like it is pretty new and in good condition. He is not the type to not know if something is broken.

How would I know if there is a cracked passageway? Is there a test?
 
JMA_2001XJ said:
It is my buddy's pressure tester, he is a mechanic and uses it all the time. I guess that it is possible it could be broken but it looks like it is pretty new and in good condition. He is not the type to not know if something is broken.

How would I know if there is a cracked passageway? Is there a test?
Click to expand...

Are you sure that your XJ is not loosing coolant when driving? But even if it looses a little, I'm not sure its a big deal. My heater core has been leaking for two years, but it never caused a post-shutdown boil-over. I would think that a pretty significant leak is needed.
 
I got the test kit to see if there is any exhaust gas in the coolant and there is NONE. I did the test three times, twice from the radiator and once from the radiator overflow tank. I pulled vacuum from the line running down the passenger side engine bay. Plenty of flow and bubbles in the test chamber but never changed from blue. I have been driving it all week in this hot NY weather with the AC (blowing clod) and the temp has always been perfect and it did not boil over once. I still have no freaking idea what could cause this sporadically. With help from you all and two different mechanic friends no one seems to have any real idea what the problem is.
 
Have you done a dye check, you may have a pump starting to fail causing cavitation.
 
JMA_2001XJ said:
I got the test kit to see if there is any exhaust gas in the coolant and there is NONE. I did the test three times, twice from the radiator and once from the radiator overflow tank. I pulled vacuum from the line running down the passenger side engine bay. Plenty of flow and bubbles in the test chamber but never changed from blue. I have been driving it all week in this hot NY weather with the AC (blowing clod) and the temp has always been perfect and it did not boil over once. I still have no freaking idea what could cause this sporadically. With help from you all and two different mechanic friends no one seems to have any real idea what the problem is.
Click to expand...

Have you assessed whether there is any correlation to the kinds of driving being done before parking? Or whether it correlates to parking over a cooler area (garage) or over hot asphalt? Have you check the boiling point of your coolant? I guess you still haven't tried a different cap?
 
I had the same issue in NY in the summer a few years ago, I replaced the fan clutch and it solved the issue. Even though it spins it doesn't mean it's okay.
 
You must log in or register to reply here.

Similar threads

D
1996 4.0 No Crank, Starter Works When Jumped
2
Replies
20
Views
312
DirtySouthXJ
D
J
2001 4.0L issues
Replies
15
Views
276
Saudade
Saudade
S
Issues flushing dirty coolant
2
Replies
29
Views
4K
fenns7
F
Z
1990 renix electrical issues
Replies
3
Views
92
cruiser54
C
V
High temp woes
2
Replies
21
Views
427
Vitzaa
V
Back
Top