i just to my 96 xj on a trip to the beach after an oil change and some new front brakes. i live in nc about 200 miles from the coast, so yeah it's kind of hot. anyway she did fine, even with over 200 grand on the engine. now, the following week, i drive 3 miles to the bank and when i come out i'm leaking coolant all over the parking lot. keep in mind i didn't have to add any fluids (besides oil) before the beach trip. so i'm trying to see where the leak is, and it stops before i can locate it. then i drive back home and park in the street, turn the engine off, and walk to the front of the jeep and wait. it takes a couple 1-2 minutes, but then it comes. the leak seems to be coming from where the big hose from the radiator attaches to the bottom side of the water pump. what i'm trying to figure out is, why doesn't is constantly leak, instead of waiting a couple minutes with the engine off? it's like once i turn it off, pressure builds up or something, and pushes the fluid out. what could cause this? thermostat? water pump? it just doesn't make sense to me.

thanks for any advice
wes

 

check your hose clamps to make sure they are tight, then check the hose for cracks. clean the area up good, run it down the street and back and shut it off. Crawl under and enjoy the show. inspect the pump if you haven't found your problem yet. There is a weep hole in the bottom I think that often leaks, never worked on mine to know first hand though.

Places to look after that would be a bad rad cap not allowing pressure to escape, or an issue from one of the lines by the tstat and gravity allowing the coolant to drip from the lowest point, which is your lower rad hose.

 

That is exactly what happens. It isn't unusual to have more pressure right after shutdown than you do running. The fans stop running and the pump stops pumping... the coolant sits still and can no longer remove heat efficiently from still-hot engine parts, so the coolant in those areas just gets hotter and expands, increasing the system pressure.

You could put a cooling system pressure tester on there, pump it up to the cap rating and look for the leak cold.

 

thanks guys, i think the first thing i'll do is swing out and by a new rad cap just to see if it is an easy fix. i forgot to mention, however, that the day this started happening, the jeep didn't want to start. actually it would start fine, but wouldn't idle and would shut off unless i gave it gas. i tried several times then went under the hood and wiggles some wires and banged on some stuff (more or less for my own satisfaction and because i didn't know where to look) and then she started, ran rough for a minute and finally came back to life. i wouldn't think these two issues are related but i'm by no means an expert.

 

My money's on a water pump seal leaking trying to warn you of an impending pump failure.

 

I would bet on the water pump failing.

 

I'm guessing water pump too, I've honestly never had a radiator cap go bad. Once the engine is cooled off, slide your hand under/behind the water pump pulley and you should be able to feel the weep hole in the water pump. If it's wet, then it's the water pump going out. Can happen all of a sudden.

Go ahead and replace at least the lower hose while you are at it. Upper hose too if it's been a while.

Where in NC are you?

 

Radiator caps frequently go bad, but they don't cause water pumps to leak.

 

Nope. But replacing them does.

 

I was thinking that as I typed my first response.

Getting ready to road test the wife's XJ. I had already done the rear disc brake conversion and today I put new braided brake lines on it.

 

X2, 3, 4... whatever number we're on for water pump. I was experiencing virtually identical symptoms. After a few minutes I would notice a small puddle with coolant dripping from the lower hose. I figured a tiny puddle was no big deal and for weeks, it wasn't. Until I came out last Thursday to find this...



I'm broke so I went the cheap route and replaced the upper and lower hoses then refilled with 5 quarts of distilled water and 5 quarts of coolant. Had I known what lay ahead of me, I would have tested with 10 quarts of distilled water first, dealing with coolant is a PITA and the water costs less than $0.25 per quart while anti-freeze is between $4 and $5 a quart. Needless to say, the hoses didn't fix my problem so I drained the coolant into a bucket and replaced the thermostat and thermo housing/gasket, filled with just water this time and it was still leaking. Finally, I replaced the pump (TruFlow from NAPA, $38), filled with water and voila, no more leak. I drained the water and filtered the new coolant mixture I had drained and saved after replacing the hoses (used one of those micro-filter coffee baskets). Filled her back up and she hasn't dripped since, even after sitting in L.A. traffic for over an hour with an ambient in the mid-80s.

 

sorry for the delay. so i finally could see that the water pump was leaking somewhere behind the pulley. i went ahead and changed the water pump, thermostat, and while in there, noticed my radiator was rotting away so i replaced that too, along with the serpentine belt. that night i took the jeep out to a field, got drunk, and did donuts until the water temp was in the red zone. then i let it cool off and went for round two and three. she managed to hold it together and not blow, so i guess my work was good, but there is no telling what i may have ruined otherwise. thanks for the help people oh and someone asked, i'm in greensboro, nc.