Our 97 XJ6L began running cool and replacement of the thermostat seemed the lowest cost repair with which to start. I purchased an O-ring separately based on information at the parts store. However, when the old thermostat was removed there was no evidence of an O-ring and I do not see how the new O-ring will allow a tight connection with the new thermostat. There is a flat gasket which I believe can be reused successfully.

Is an O-ring actually needed for the thermostat? If so, perhaps I was supplied an incorrect one.

Thanks for help on this.

Jim

 

There is no o-ring. Just that gasket you mentioned between the housing and cover.
Part number is NBB2217AC

 

I appreciate this information. The low mileage on your XJ6L is impressive. Ours is approximately 125,000.

Thanks,
Jim

 

The 'O'ring is for the AJ6 engine.
If you install the 'O'ring in the AJ16 housing you WILL break the mount ears off the cover.

bob gauff

 

Given that we sometimes do not communicate the final outcome of our issues, I wanted to do so in this case. I allowed some driving time to ensure that the fix was okay. The new themostat appears to have solved the failure of the car to achieve proper operating temperature. I did reuse the flat gasket with sealant applied to both sides (if new gasket readily available would have gone that route). As advised, I did not attempt to use the O-ring sold to me by the local parts distributor.
The operating temperature is now slightly below "N" and no signs of leaks.

Thanks to everyone who contributed advice.

Jim

 

There has been a lot of discussion on the forum regarding the correct antifreeze to use in these engines. My 1997 Vehicle Care manual indicated the proper antifreeze was one with specification ESD M97B49-A. My internet research showed this was a Ford specification that was superseded by Ford specification WSS M97B44-D. Zerex DEX-Cool meets this specification. This concurs with a response that a member received from Zerex and was what I used after flushing with distilled water. Hopefully this was an appropriate decision.

Again thanks to everyone.

Jim

 

I hate to get into another antifreeze discussion, but I thought the cars of this vintage used Xerex GO5.

 

If you read "dex cool" on ANY anti freeze / coolant product, it's designated for GM vehicles.

Jag, "cough", Ford would not recommend "dex cool" for the x300 era

 

My research indicated that the specification ESD M97B49 A (Ford) in the 1997 XJ6 Vehicle Care manual was superseded by WSE M97B44 D (Also Ford).

Valvoline indicates that DEX-Cool meets or exceeds WSE M97B44 D.

The attached document includes relevant text excerpted from both Ford and Valvoline (Zerex) documents.

I claim no expertise on this antifreeze topic and somewhat regret raising the issue, but it would be welcome to find some consensus on the matter.

Thanks,
Jim

 

I will never use anything with Dex Cool in the name. That crap turns to gel and plugs up heater cores and generally a mess. Worked in a GM service center and as a mechanuc in private owned shops. Seen lots of GM vehicles in for new heater cores, some new pickups with very little miles. Lots of warranty repairs just for that problem. Lol, almost as much as the Dodge truck automatic transmissions. Id buy expensive OEM Jag coolant before using Dexcool.

 

don't use "dex-cool" ever in anything. The gauge in the X300 vintage is an "idiot gauge" as is the "oil press" gauge and not a real depiction of actual operating temp or oil pressure, IIRC. When mine exhibited signs of running "cool" it was actually the sender to the gauge, not the thermostat or cooling system.