I am in the process of replacing the water pump on my '04 XJR, and am not sure where the O ring should be installed. The water pump was supposedly replaced by the previous owner, but I had two different Jag dealers tell me that it was leaking and needed replacement. I ordered an AC Delco 252-800 pump from Amazon (couldn't believe they were cheaper than Rock Auto) and it arrived with a steel gasket and an O ring. Taking the old pump off, there is no O ring to be found anywhere, so I'm not quite sure where I'm supposed to install it. I've checked several parts diagrams, but I can't figure it out. My guess is that it should be placed on/in the block and the pump presses against. Can someone please confirm?

 

Did the AC Delco pump come with instructions?

I can only relate to the 2000 S Type water pump.

I replaced with the steel gasket and I thought the O-Ring goes on in front of the metal gasket.

Also, I used Hylomar on the steel gasket for extra insurance.

I'm sure others will chime in here.

Another thought... the OEM Jaguar water pump used 2 O-Rings I believe - I find it bizarre your pump had no O-Ring. (maybe the cause of your leak) Be sure to check the cavity where the water pump sits on the block to ensure it's not wedged in there, somewhere...

 

The pump had instructions, but it made no mention of the O ring. They appeared to be generic. I did double check, and there was not an O ring anywhere to be found on the block or the pump, which I believe is why there was a slight leak.

There was a groove in the new pump where the O ring appeared to fit perfectly, so instead of placing it on the block and having the pump compress it, I installed the ring into the groove, and assembled it on the block. I didn't use any additional sealer thinking that if it does leak, I'll take it apart and try putting the O ring on the block. If anyone else has done this procedure, please let me know where you installed the O ring.

Thanks.

 

That's the way I did my 2004 4.2 S Type. I used Jaguar parts and no sealant--that's the way the original factory install came.

 

I used an aftermarket water pump. Another forum member highly advised using the Hylomar as additional insurance. Instructions do not specify using sealant on the metal gasket.

This was a personal preference of mine for peace of mind...

It's been 2 years since replacing the pump and no issues. In looking at a few pics of my install - I did install the O Ring in the groove on the pump.