I'm working on a 86 and I constantly work on it. It's not what you think... I love working on it. Recently I changed the master cylinder and all the brakes. I took it for a test drive and thumbs up on the brakes. A half hour later I went to the garage to see whats next and a puddle of water is around the drivers front tire. At first I thought it was brake fluid but it's water. It's getting hot here in Vegas and this is my summer car as it never overheats and the A/C kicks butt. I took it the next day for a short spin... 5miles .... after making sure the radiator was topped off. This time I can see water is coming out of the expansion tank at the cap. New cap still leaking. Took it to my mechanic and he seems to think the lip on the expansion tank is bent and the new cap is not seating properly. I think it's the water pump going out. I have been driving this car 3 or 4 times a week for over a month. NO oil in the water, NO water in the oil. If I don't figure this out I'm going to end up with a blown head gasket. ANY AND ALL THOUGHTS ARE APPRECIATED. I'm leaving town for a month and a half and when I get back I expect there will be some opinions that will start the gears turning. Thanks in advance....Robbin

 

Hi Robbin,

Just so I understand...is this plain water or is it antifreeze?

If it antifreeze then I would look at the line that goes from the expansion tank to the overflow bottle that is located in the drivers side fender well behind the panel on the backside of the tire.

The rubber tube from the expansion tank goes to the rear of the engine bay and into the fender. It connects to a short metal tube that passes between the fender and the fender well behind the tire. Another rubber tube from the overflow tank connects to the other end of the metal tube.

On my '90 I found that the metal tube had been completely blocked and prevented water from passing back and forth from the expansion tank to the overflow tank. For the XJS to cool properly it is important for the overflow to work. Check your tube to make sure it flows as it should.

Of course the leak could just be overflow from the overflow tank (too much water in the cooling system. It might do that once or twice until the system is balanced. After that you wont see it again) or a deteriorated hose or loose clamp.

If it is plain water then it could only be from the AC or from one of the water drains that goes from the cowl to the fender (and onto the ground.)

If you washed the car or had rain and one of your drains is partially clogged it could take a long time to drain. You think the car is dry but when you park it you get a puddle of water due to the slow drain.

Mark

 

I think you hit it. I'm going to tear into it when I return. It is water on the floor, and that's what I topped off with. Had it had anti-freeze mixed it would still be a puddle on my garage floor. So in conclusion the water bubbling out of the expansion tank never made it to the block and the pressure created by anti-freeze trying to make it's way to the expansion tank couldn't get there because of the blockage in the line to the overflow bottle. Your the best. If I had time I'd be under the hood tomorrow! THANKS

 

In my '90 the metal tube was so clogged that I had to use a drill bit to clean it out. The rubber hoses were fine. Now the system works as it should.

I hope that fix works for you. Good luck!

Mark