da9guy

ok guys heres the deal i bought my very first jeep two weeks ago now the problem is....... the other day i was going out mudding (it rained) and before going i checked all fluids (as usual). i noticed that the coolant was a few inches low so i though... what a great time to add some water wetter. i went out bought the wetter and added it in. the system was just low enough to swallow the whole bottle but needed nothing else. i stared the old beast up and sat outside on the phone while she warmed up. as soon as i started it i instantly noticed a fluid dripping from the rear of the engine so i crawled under there and saw it was 100% for sure green coolant running down and dripping off of the bell housing. so like a normal human i went into panic mode assuming that it was the infamous freeze plugs on back of block issue. but then it just stopped. within 5 minutes no drips no drops nothing. so i went out on my expedition and kept a very close eye out for coolant leaks. it didnt leak all day or the next day or the next. now i go out to my truck this morning and notice a small puddle of coolant on the ground running down the bell housing again. so i fired the jeep up popped the hood and checked the heater core hoses and everything toward the firewall for coolant leaks and found nothing. also the whole time it idled while i was investigating it didnt leak at all not even one drop. i am stumped guys anyone have a similar problem or any ideas for me? any help would be great thanks in advance... guess you might need to know that its the 4.0 I6 with an auto trans....

COSXJFAN

Not trying to be a worry wort, but it could be a head gasket....at least worth a look.

ol"blue

Welcome to CF. You can go to the auto parts store and use/rent their cooling system pressure tester. It has different adapters that fit on in place of the radiator cap, and a hand pump and gauge. You pump it up to the operating pressure of the system, 15 psi for example, and watch for any leaks, and check the gauge for pressure drop. If you have an external leak, it will almost always show itself. Be careful if your radiator is hot before you remove the cap. Wait for it to cool a bit, cover it with a rag, and remove it slowly.

Mech17

I'd bet it is a freeze plug and will only leak while it is hot and pressurized and when you parked it, it was hot and not flowing anymore, so it leaked. I'd do the pressure check previously mentioned.

da9guy

i just did the pressure test while the truck was completely cold and then warmed it all the way up and did it again. the pressure held tight durring both tests and never made it leak. if it were a head gasket wouldnt i be burning some coolant in exhaust also? i just dont understand a leak that leaks today and not tomorrow not really having any significance if its been driven or not. just seams to leak when it feels like it. never heard of a freeze plug that was tempermental they usually leak or they dont right?

Mech17

If it's leaking down the outside of the motor, I REALLY doubt it's the gasket. You did make sure when you did the test to check for leaks after you were done and the engine was hot and NOT running, right? That's the only situation that I can think of that may cause a freeze plug to leak so inconsistently. Does the exhaust smell like antifreeze?

tjwalker

With where it is leaking and dripping to ground, a freeze plug is a very real possibility here....Not at all likely to be a head gasket.

da9guy

gunna have to try to see back there with a mirror or something and physically look at the freeze plug to check for any signs of leakage IE rusty stains running out of the plug and down the engine block. if its not a freeze plug then i am super stumped with this one guys cuz i tightened all the hose fittings on the block radiator and heater core and visually inspected all hoses and cant find a thing. merry christmas and thanks for all the help and extremely quick response time. ill keep you all updated.

5-90

Concur with the core plug leaking - there's a largish one on the back of the head that can let go on you. You'll have to remove the head to do the job (so you'll end up doing a head gasket anyhow - but, as mentioned, head gaskets don't tend to form external coolant leaks. Usually, coolant will leak into the cylinder or into the oil sump.)

Use a "mirror-on-a-stick" to examine the back of the head, hang a lamp back there if you need to. If you don't have a mirror-on-a-stick, get one! The ones with the telescoping sticks are best (I have several of those with 1" round mirrors, and one with a 3" round mirror.)

If/when you replace a core plug, use brass for the replacement. The "CRES" plugs (they say they're Stainless, but then why do they rust?) usually don't last anywhere near as long - particularly if you do something silly, like use tap water for your coolant mix (a very bad idea...)

If you don't see signs of coolant at the rear of the head, I believe there are coolant-sealing core plugs at the back of the block (I'd have to check,) and you should also thoroly clean your engine and run it for 30-60 minutes after it dries, then re-examine (get the heat and system pressure up.)