A1997 XK8 Vert: After a couple of years of smelling a slow leak from my coolant tank I finally got at it. I pulled the old tank out without too much trouble. This is the original one that I actually patched/epoxied a crack in the bottom of about 4+ years ago. So far, so good. Next is not so good.


At the time I repaired the tank I also bought a used tank that looked identical to my original. When I started to install the used/replacement tank I was surprised to see that one of the top two nipples that run from the tank to the "tower" and the top left of the radiator is closed off.


The nipple that should be open to the top of the radiator (assuming its purpose is to return expanded/heated water to the radiator) does not have a hole through it. Not clogged, there is no passage for anything.


First question is "why" is it blocked? Second, can I just drill a hole through the nipple and get the same effect the original had?

 

Not sure why but one of the nipples is blocked on the tank, no need to drill out just use the one that is available. Make sure it mounts properly as some tanks have a different mounting offset that you will not notice until you try to mount it.
Yes, it is strange to me also.

 

I went through the same thing when replacing the expansion tank on my 97.

Attached is a TSB explaining what you need to do when using the revised expansion tank (with the plugged nipple) on a 97 model year. See the diagram on page 3 which shows very clearly what to do with your 2 bleed hoses.

 

Brad,
Thanks for the update and sharing the diagram. Great to know!

 

Welllllllllllll.....


First, thanks for the TSB. That clarifies some mysteries about this replacement.


Not being sure I would get a reply, I drilled out the second nipple of the replacement tank. Nice and clean. THEN, I found the replies and started looking at both the illustrations and my car. Still puzzled, I found some pics I had taken of the engine several years ago (though I don't really know it they were taken before of after I removed and repaired the "original" tank.


I say "original" because when I looked at the location of the two lines they are already crossed over....but with both nipples open. Hmmmmmmmm. I can only guess that when I R&R's the tank before, or when I did my cam chain tensioners, I must have used some source that told me to cross them.


SO, I guess my only move now is to either plug the nipple I just drilled out,,,,,OR leave both open like they have been for several years (with no overheating or problems). It is odd that Jaguar originally had two tubes for liquid to return to the tank from two different places. But if they (we) are SURE there is no problem with only ONE tube and nipple working, I guess I can go with that.


Is there any engineering or other reason not to keep using the two nipples/hoses?

 

I "re-plugged" the second nipple and hooked the whole assembly back up after spraying the sensor fitting and connection with some sealant to hopefully stop any leaking. That clamp on the big lower drain tube is such a bitch to get on straight.


I had a new gallon of Prestone "All makes, all models, all colors" coolant sitting by, so I filled the tank and jiggered with the top cap until it finally tightened down, then ran the car to full warm, turned on the heater to "HI" to make sure all the coolant circulated....and waited.


There was some leaking at the sensor where it went into the tank for a bit, but it stopped after a few minutes and did not return when I shut the car off and waited for pressure to build. So far, so good.


Added a little more coolant after everything cooled down, and then stuffed some white paper towels under and around all the lower fittings and the two upper hose ends. As of today, 24+ hours later, there are is no evidence of leaking. So far, so good.


If it's not raining tomorrow I'll get her out and get a good run of 30-50 miles or so to make sure there's no overheating with the single tube fluid-to-tank setup, and no leaks. I can always smell the coolant long before I actually see any wet places.


For now, it looks all good. Thanks again for the help!!!!!!