Coolant leak

[Firstjeepbuild]

Found a coolant leak in the front of my 99 TJ 4.0. I see the coolant on the front of the engine. I have not seen the coolant in the overflow tank or the radiator getting low. I cant find a leak in the water pump and can’t see where the leak is coming from. Anti freeze is dripping off the radiator and the driver side below the overflow tank. Any ideas on how to find the leak

 

[macleanflood]

Clean it up real good with a hose...dry it out...start it up and start watching for leaks.

Pictures help!

-Mac

 

[Gollywomper]

See if your local parts store rents tools. Rent a cooling system pressure tester.
Locate leak.
Repair leak.
Have a beer.

 

[Camdenst]

Napa sold me a small bottle of UV dye that you add to the system to help find a leak. I had no idea it existed, but worked very well.

 

[JMT]

See if your local parts store rents tools. Rent a cooling system pressure tester.
Locate leak.
Repair leak.
Have a beer.

I rented a tool two days ago. I literally tried O’Reilly, Napa and got nothing. Advanced Auto had one. When I got it home none of the adapters fit (there were 20 adapters and 3 universal). None of the universals worked either. Either too small, hit the fins, or too big. I had to wrap some thread tape around the one that hit the fins to get it to work. Required two people. One to pump and the other to hold it on so we could get up to 18psi. Pain in the neck.

The dye is probably a better route.

Further, none of the adapters for checking the radiator cap fit either. IDK if this is the new norm for radiator cap sizes, but the ones that would fit our radiators and caps were all way too small. The vast majority of the caps were those that screw on the reservoir tank. I think that’s the most common way it’s done now.

This is the kit I rented.

https://shop.advanceautoparts.com/p...-nRiMCI54sNfIwXbUXAaAuyhEALw_wcB&gclsrc=aw.ds

 

[Gollywomper]

Wow. That sucks. In 25 years I have used maybe 3-4 different Adapters. The Jeep adapter is a very common cap size.

 

[JMT]

Wow. That sucks. In 25 years I have used maybe 3-4 different Adapters. The Jeep adapter is a very common cap size.

Yeah, I called @Wildman and the first thing he said was “jeep radiator cap is the most common size.” That ain’t true anymore or else the people who put the kit together are complete morons.

 

[Wildman]

Yeah, I called @Wildman and the first thing he said was “jeep radiator cap is the most common size.” That ain’t true anymore or else the people who put the kit together are complete morons.

I've had this pressure tester kit for 35+ years and it's fit every American made car I've ever tried to use it on including the radiator in my daughters TJ when her top tank split open.

So, either that kit is missing an adapter or someone is a moron.

 

[Firstjeepbuild]

The Jeep motor is very clean I don’t have and oil or dirt on it. I will try the die Gollywomper suggested.

 

[Jerry Bransford]

If the leak is on the front of the engine and runs down from behind the big engine pulley it's very likely coming from the weep hole on the water pump. When that happens it's a clear sign of impending doom for the water pump.

If you end up replacing the water pump avoid store brands even if it comes with a lifetime warranty. I'd try very hard to find the OEM Mopar water pump or at least a good quality brand like Gates.

 

[JMT]

The Jeep motor is very clean I don’t have and oil or dirt on it. I will try the die Gollywomper suggested.

The only bad thing about the dye is it doesn’t test the radiator cap. If you can find a pressure test kit that has the Jeep cap adaptor then it would also have the cap tester. That’s the advantage of the pressure tester. But if yours is just a leak, then the dye should work fine. Just need to clean everything up and have some good eyes to watch for such a slow leak.

 

[Firstjeepbuild]

I took a good look at it today. Part of the problem is the coolant appears to be running down the fan shroud there is also coolant on the overflow bottle. I have looked at the radiator and the cap and can not see any coolant. The coolant trail appears to run down to the bottom of the shroud and it seems to be being blown toward the engine. I will get a pressure tester from my buddy if that does not work I will get some die. I will also look closer at the water pump as I did put a store brand with a forever warranty maybe that was not a good idea. I learn something every day. Thanks again for the info

 

[Shandara]

Take a good look around the top between the plastic tank and the metal core. There is an o-ring between them, both my tanks weeped from there I ended up pulling the rad out and re-crimping the metal retainers with vise grips, that stopped the leaking. That was 4 years ago. I have a new Mopar rad in my shop for when it finally gives up the ghost one of the last two in western Canada as of a month ago.

 

[Firstjeepbuild]

I will thanks. I am also borrowing a pressure tester from my buddy so hopefully I will find it soon

 

[Firstjeepbuild]

I put a pressure tester on it and it definitely has leak I have not found completely identified where yet but it is looking like it the thermostat gasket might be the culprit. I will update when it’s 100 percent. The pressure tester is an awesome tool.

 

[Firstjeepbuild]

The thermostat housing cover gasket was leaking. The leak was between the housing and the water pump I would have never found it without the pump. Easy fix but tough one to find.

 

[mipa]

When that happens it's a clear sign of impending doom for the water pump.

is it a "don't drive the jeep at all any more until pump is replaced" kind of impending doom?

mine started leaking recently.. mid dec after coolant flush (was probably dirt clogging the weep hole), then stopped until yesterday.. but feels leaking much more now , and seems only when engine is cold (overnight when parked).. looses about half what's supposed to be in the reservoir over night.. which I then refill.

it takes me about 2+ weeks to get the mopar from the US to Thailand.. and my jeep is my only way of transportation..

after reading your comment I'm now a bit worried that my pump will completely fail soon and I'm stranded on the roadside - or worse frying anything else.

I've only 40.000 miles on mine btw.. but still 2002.. I would have expected the pump to die of runtime not age.. but could have been running with water instead of proper coolant by prev owner.. when I flushed the system it seemed only rusty water.. which was also a reason for the complete flush.

 

[KennethS]

I've lived with coolant system leaks on multiple vehicles all through my school years. It's not really a drama situation unless you make it one.

Check coolant level in the morning before driving, top off as needed.
Carry 2-3 gallon jugs of water in vehicle at all times.
Check coolant when returning to vehicle after driving and top off as needed.
Finally replace leaky component after saving money / ordering parts / finding time to install parts.

 

[mipa]

since ordering parts to Thailand is always a big deal, I was looking into other recommended parts when you change the water pump.. and thanks to that thread https://wranglertjforum.com/threads/jeep-wrangler-tj-cooling-system-overhaul-faq.3397/ I've learned about a fan clutch and was wondering what it's supposed to do, since the fan is always spinning.. right? .. wrong.. seems my fan is running all the time from the second I start my engine, tearing down the water pump. When I try to move it cold, it's really hard to turn. I've learned from another forum that a sized fan clutch will eat your water pump.