So I have a minor, but annoying issue. My XJ has a small coolant leak that seemingly comes from the lower rad hose, but when I replaced it, there was no change. When it's running there is no leak whatsoever, but once I shut it off it drips from the general area of the lower rad hose. There is no smell of burning coolant and there is no exhaust smoke so Im hoping to rule out head gasket issues. Does anyone have an idea?

 

Being near the lower rad hose would suggest either the leak is above... coolant overflow hose, radiator hose, or even the rad itself is possibly cracked.

 

Go to your local parts store and get the cooling system pressure test tool via the loaner tool program and put some pressure on the system. It should be pretty evident where the leak is coming from and keep you from going nuts trying to find it.

 

Its likely coming from the water pump weep hole. Which is right by where the lower radiator hose enters the water pump. This weep hole lets you know that coolant is starting to make its way passed the water pump seal and bearings and gives early warning that the water pump is beginning to fail. Look for wetness on the bottom rear of the water pump, the weep hole can be hard to see.

Here is a prior post that explains a little better:

https://www.cherokeeforum.com/f2/lea...lancer-243745/

 

Water pump was my next guess but I wanted to check with some people first. Ill take a look at that next.

 

If that's what it is, you should see a tiny wet trail down the underneath side of the lower hose all the way to the bottom where it drips off. The only way to see this is laying on your back underneath it or up on a lift. Sometimes this leak will seal itself under pressure and only leak after it cools down. My WJ 4.0 water pump has a weep "chamber" that holds about a teaspoon of coolant that is allowed to evaporate and not show a leak until it gets large enough to overfill this chamber, then it drips into the back of the pulley and is thrown off on startup. I never knew this until we were bleeding the brakes up on the lift. The guy topside started the engine and coolant splashed all over the front of the engine, then quit! WTF? Looking at the AC Delco catalog showed this chamber. I was flabbergasted that some engineer thought of this!

 

That sounds very similar to my leak, there is a trail of coolant that runs down the hose and drips off at one of the turns in the hose.

 

But now my question is, I'm looking at water pumps and there is two different hub heights. One is 2 3/8 and the other is 3 1/4. Which one would my XJ use? Or how could I find out?

 

Unless you have some special situation like right-hand-driver, this is the water pump you would use:

 

This is a simple thing, but when you changed your rad hose, did you look at the hose fittings on your pump and radiator for damage? A small crack could cause the leaking too, although it's not too likely.

 

I replaced the radiator last summer when 21 Iowa summers finally caught up with it, and the plastic sides of the radiator blew out and puked all over the highway, leaving me stranded on my way to my last final test for sophomore year haha. Sorry got a little side tracked, but the radiator is fine and doesn't have any cracks. The leak comes from the engine side of the hose anyways. Im going to replace my water pump because its a cheap part that wouldn't hurt to be replaced, even if its not my current issue. This will likely be my last winter of daily driving my XJ because its starting to get tired, and honestly its not worth pouring money into for how rusty it is. Next summer I plan to find a decent Second Gen Cummins, and keep my XJ as a backup.

 

Thanks, this is the cheapest one I've seen as well. I've got access to a lift coming up in a couple weeks so I can change my oil easily, check for any issues in the suspension, and do my 3,000 mile torque check. So I'll keep my eye on the temp gauge and top off the coolant every morning until I can get in there and replace it while its on a lift.

 

Make sure your new water pump has a metal impeller. When you get it off, you'll see that the impeller runs about 1/16" from the first cylinder barrel and any looseness in the shaft can make it strike the barrel and shatter if it's plastic. Getting broken pieces of plastic out of the water jacket is near impossible.

 

Or you can have the madness that I experienced 1000 miles from home in my old 00 TJ where the plastic impeller just broke inside the pump and wasn't moving coolant, but there was no bearing noise and no weeping. After several days and a couple grand of repairs (frame rust and transmission parts breaking during the tow) I still found myself replacing the water pump on the side of the highway in the middle of a hot summer day south of the mason-dixon.

 

Thanks very much for your help. Replaced the water pump and serpentine belt (It was shot as well) and not a single drip from it since then.