Strange antifreeze leak

See if you can help me with this one.

In early June I installed a new 3 core CSF radiator into my 96' auto trans 4.0l XJ. This worked great for a while, but then I developed a transmission fluid leak from the lower trans line where it connected to the radiator.
I replaced both the upper and lower trans lines, and presto, no more leaks.

However, in the process of removing the old lower trans line quick connect fitting I slightly deformed the lower coolant hose connection on the radiator itself. This caused some leaks because the coolant hose didn't seal properly.
To fix this leak I reamed out the metal fitting as round as I could get it, then spread high temp (copper colored) RTV gasket maker of the outside of the fitting, and reconnected the coolant hose. This seemed to solve the problem, and my temps remained in the correct place. (190 degrees)

Now for the kicker - its still leaking, but only after I park it and let it sit for a while. And its not just a few drips either, its a big puddle. (1.5x1.5 feet) The leak is still coming from the very front drivers side. I have narrowed it down to the radiator cap or the lower coolant hose, but I'm leaning toward it being the radiator cap. Has anyone ever experienced a similar issue? I couldnt find anything on this or any other site that matched my problem.

Buy a new cap and see what happens....still have problems then get the cooling system leak checked;any repair shop should have a tester to pressurize the cooling system to check for leaks. If it flunks, you may have busted the solder connection on the lower radiator hose connection. I would think you could trace the leak after a shut down since it seems to be a significant amount lost.

mike
00XJ

It's not just water?

No, its not water. I dont run my a/c, so it isn't condensation. Also, its 'slippery'.

Its difficult to trace the leak because it is never leaking right after I shut down, and because the cap is directly over the hose I can't tell which is leaking. My best guess is that the coolant is boiling out of the radiator cap. Is this feasible? Would sufficent heat be retained by the block after shutdown to bring the coolant to boiling temps? The solder connection is a good idea, but wouldn't that leak constantly and not just under heat?

You probably damaged the bung when you 'rounded' it out. Either that or you weakend the solder joint between the bung and the tank. The metal rads I've been looking at the past year or so have gotten really thin gauge wise. I came across an old 69 willys wagon rad I had in the shed, it was the original that I replaced back in 90 or so, thing has tanks that are twice the thickness of an XJ rad I have in the shed I just have not changed yet. The two bungs are also much thicker than the newer ones.
As for the temps going up when you first shut it off, yes, generally the coolant will go up about 50-60 degrees within the first 5 min of shutting it off, thats what the coolant expansion tank is supposed to be for, when it gets hotter the coolant expands even more and as it cools down it contracts and sucks coolant back in from the overflow.

hey man here is a question for you. I am having overheating problems in my 1990 laredo, i had the same problem in my old 1989 limitded. But its only when i go up long hills. I am running 33's with the stock gearing (3:55) did you have a overheating problem before you put in the 3 core and if so did the new radiator fix the problem?

Before I put in the 3 core I was overheating on really hot days. I doubt you even get hot days, but yeah, beside this leak I've loved the CSF.

alaska3452000@yaho said:

hey man here is a question for you. I am having overheating problems in my 1990 laredo, i had the same problem in my old 1989 limitded. But its only when i go up long hills. I am running 33's with the stock gearing (3:55) did you have a overheating problem before you put in the 3 core and if so did the new radiator fix the problem?

Click to expand...

Have you ever had your rad rodded out to clean out the crud & open up the tubes usually helps cool everything down?To help cool your rad down add some Red Line Water Wetter worked for me,a friend dropped the temp 30 degrees in his truck using it.