Coolant Leak

Hi all,

My girlfriend's 96 with 4.0 has a bizarre coolant leak. It seems to leak coolant only after the engine is turned off, and it pisses coolant slowly for a minute or two and then stops.

The leak seems to be coming from the lower radiator hose / water pump area but I haven't delved too deep into yet.

The cooling system is not overfilled and the engine is operating right around 190-200 degrees.

Any ideas?

Thanks,
Andy

first, look deeper. cant see your jeep from were im sitting.

seriously, it could be the bottom hose that leads to the water pump. or it could be the weep hole on the bottom side of the water pump. if its the weep hole leaking, water pump bearing are shot.

but would it still be running at the proper temp with the bearing being shot?

The water pump could just be starting to go bad. Gotta remember, when the hot engine is first shut off, the local engine temp and overall system pressure actually RISE for a few minutes, as the coolant is no longer circulating.

This might be just enough to make the pump seal weep.

Time for a n H2O pump, and a thermostat and serpentine belt, while at it.

Lets not jump the gun here. It may be just a pin hole in the radiator hose. Start checking and replace the easiest/ cheapest parts first. If it happens to be a hose, you're not going to need a water pump. beg, borrow or steal a pressure tester for the cooling system. Pump that baby up to about 16 pounds, whatever your cap is rated for, and look for the leaks. Do this while the engine is cool and not running, of course. It should be pissing out under pressure. Just don't pump the pressure higher than you system is rated for. Not sure what could happen, but I can only imagine.

HTH, Dan

Dan might be right here. At the very least, a thorough inspection of the cooling system with a drop light is in order.

However, in my experience, hoses don't just get pinholes in cooling systems that are maintained well. A good mechanic will spot a bad hose LONG before they are at pinhole stage.

On the other hand, there is NO way to spot a bad water pump until it is leaking or making racket............

I replaced a lower rad hose on a 2.8L v6 and could not get it to seal just using the clamp and a screw driver. Finally pulled it off, coated the inside 2" of the hose with indian head gasket cememt, put it back on, tightend the clamp with a 1/4 drive and socket. That fixed it. What you need to check is the bottom of the water pump, if you feel around the nose of it you will fell a small hole there, bit bigger than a pen point, there is a packing material in there around the shaft that keep the coolant in, this packing is probably going bad, it is also called a seal. Once they start to go you are on borrowed time. Only fix is a new water pump.
And while you are at it, do the thermostat, hoses, belt/belts and pressure cap. It is also a good time to flush the system, add a cleaner and back flush the system before you pull the old pump. When you do the pump you will have most of the front of the engine off anyway so you might as well. If you decide to replace the hoses that go to the heater don't try to pull them off, use an exacto or razor knife to slice them, break one of the heater core outlets and will gain a very intimate knowledge of how to remove the dashboard to replace the core.