What do I need to replace on an old cooling system?

I have a '99 XJ with 150K on the 4.0. I recently discovered a coolant leak that is pretty constant every time I stop. I am pretty sure it is the water pump that is finally going out. Because of the age of the system, I would like to do as much preventative maintenance as possible.

I had to replace the radiator a couple of years ago, as well as the upper radiator hose and radiator cap.

What should I replace while I am in there? Also, would this be a good time to replace the transmission cooling lines while I am at it, or would it be better to wait and do that another time? Thanks for your input.

Confirm the source of your leak so you aren't wasting money.

BEFORE tearing things apart, I would buy a strong commercial flush (not the 15-minute stuff) and follow the directions. Once the flush is neutralized and cleared from the system, tear things down. While you have things apart backflush the heater core--its tubes are quite small and easily plugged.

If it is the pump, replace it and the thermostat (Stant Premium 195 degree recommended). Quality hoses should last a few years, but if you aren't sure of when a hose was last changed you should go ahead and do them--no since blowing your fresh coolant all over the road.

And I would replace the radiator cap, cheap insurance, and depending on its quality a couple years it may be due.

Are you having a problem with the transmission lines? Leaks? Corrosion?

Are there lines that run from the radiator to the heating core that I should consider replacing while I'm at it, or should I not worry about it.

I am a believer in the saying that "if it's not broke, don't fix it," but this is one thing that I don't want to have to deal with for a long time again, so I'm not worried about blowing a lot of cash to cover all my bases.

My tranny lines seem to be slowly seeping out oil because they have little droplets of fluid building up on them that are just waiting to drip. I think that it's the start of a leak that will probably get progressively worse. I heard that NAPA sells a kit for the tranny lines, but I can't find it on their website.

So far, I have that I need to replace the waterpump, thermostat, radiator cap, old radiator hoses. Anything else to add?

After closer inspection, it appears that my water pump is fine, but that there is a seal that is slowly leaking. Am I correct in this diagnosis, meaning, is there a seal or gasket that goes with the water pump?

If it is just the seal, I still plan on replacing the water pump since it's 10 years old and probably on its last leg. Let me know.

yes there is a gasket for the water pump. just about anything like that on your jeep is going to have a gasket. ie water pump, differentials, oil pan,throttle body, valve cover

Does the gasket come with the new water pump, or does it come separately?

jeeperguy21 said:

Does the gasket come with the new water pump, or does it come separately?

Click to expand...

I did my water pump about a month ago and it came with a gasket.

Perfect. Thanks for your help everyone.