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leaking radiator cap

G

gameface87

NAXJA Forum User
Location
Fredericksburg, VA
Hey Guys,

here is what happened:

Yesterday I was dicking around in my front yard trying to see how much flex I can get. After putting my jeep back in the driveway I saw a massive puddle of coolant. Upon further investigation, I saw that coolant was spilling from the radiator cap. The cap is tighten all the way down but some how coolant still comes out. This is my first project and I am learning as I go along. I had replaced the radiator about 2000 miles ago. Any suggestions? I have a 96 xj with a 4.0l HO motor.

thanks in advance
 
New cap is something obvious to try (16 pound without a release lever), but before you do that, be sure that the neck of the radiator isn't cracked, just below where the radiator cap screws down.
 
I would definitely replace the cap. Its cheap insurance against overheating. But while you have the cap off, I would put a cooling system pressure tester on the radiator. Don't pump it up, just put it on. Start the engine and let it get to operating temp. Rev the engine to 2500 rpm or so quickly, then quickly release it. Do that about 10 times. Watch the pressure gauge the whole time to make sure you don't exceed 16psi. If the gauge rises past 16psi under idle conditions or no load (and is not overheating), you most likely have head gasket issues.

Pushing some coolant out after running it hard with high load is pretty normal. If you were just putting around the yard and lost coolant without being overheated, that could mean probable head gasket failure. It is likely the radiator developed a leak from being overpressurized.

Just my buck oh five..
 
I have a similar problem where coolant is leaking out form the cap. But on the 1990 XJ the cap is on the overflow reservoir not the radiator. I was going to try a new cap, but testing the system first sounds like a good idea.
 
There's only one 4.0l, and about 250 shitty radiators that you can use on them...CSF is the only way to go
 
Grimm5577 said:
I have a similar problem where coolant is leaking out form the cap. But on the 1990 XJ the cap is on the overflow reservoir not the radiator. I was going to try a new cap, but testing the system first sounds like a good idea.
Click to expand...


Get the cap from a Volvo for your Renix Jeep. It's a 10224 or 10244. I can't remember.
 
Not that one. It looks like your standard Renix coolant recovery bottle cap except it's green and has a lower profile. It happens to fit the threads better and is rated at a higher pressure.
 
Yes, you got it. Solves a few issues, including if you have a cheapie expansion tank that the threads are crappy on. The thanks really goes to Joe Peters for this.
 
Do i have to worry about the green cap causing too much stress on my cooling system due to it's higher pressure threshold?
 
Great! I just ordered one. Hope it helps. My system seems to work fine, I never over heat but even on small trips it won't hit 200, but it will still have a small leak out of the cap.
 
well sadly the green volvo cap does not fit my overflow tank. The center of the cap does not fit into the neck of the tank. My stock one looks like the gasket is rotted out, so i might just replace that or get another stock.
 
I replaced the cap and it still leaks. So I guess the system is over pressurized. Is there any other casue of this besides a blown head gasket? It started leaking about after about 5 minutes of idleing. PITA. Thanks again!
 
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