Had a small drip leak coming out of the back seal of the water pump (not the water pump bearing). The water pumps on the x350/358 tend to be rather reliable up to high mileage but ok it happened early, only 51K miles on my 2008 VDP. The water pump for my car was part #AJ88912 from a Jaguar Dealer; rock auto sells the same airtex pump for only $32.00 plus $8.00 shipping but there uses a basic back seal while the jaguar one has an improved metal with rubber infused in it seal.


While I was at it I decided to also change out the water distribution and thermostat housing (the unit that looks like a heart bypass as many have referred to it) because they are known to break internally or develop cracks since it is made out of plastic and become brittle with engine heat and age. This is a matter of when type part. Jaguar part number AJ811793. Jaguar Dealer wanted $175.00 initially but after talking about other online jaguar dealer selling for $125.00 he agreed to match the pricing. Overall good deal as I got the parts and did the whole job the same day. Took 5 hours in total to replace both parts.


Thanks to member a4500435 for showing pictures of the process of changing out the water distribution and thermostat housing.


https://www.jaguarforums.com/forum/x...3-tips-114486/


Here is an excellent post that was on jaghelp.com that provides very good step by step procedures with pictures.


jaghelp.com: How to change the thermostat housing on your Jaguar XJ


Anyways, when I took off the thermostat housing I noticed that the rubber ring around the thermostat pressure end was actually peeling up out of its setting. I had no hot water issues but just goes to show that with age the thermostat can be an issue even before it causes big issues.


Attached are pictures of the thermostat where you can see the rubber ring lifting up, another picture showing the thermostat taken apart and the rubber ring tearing lose. The last picture shows the water distribution unit and the front is where the thermostat housing screws on with three screws.

 

Many thanks for this post. Great pictures

My new to me 07 XJR 90K miles has a seeping header tank (thanks Fraser)

looks as if the thermo housing, thermo, and water pump should be replaced about now also? Anything else while the coolant is drained?

 

The Jaguar dealer confirmed that water pump failure is not to common but that they have replaced many of the water distribution units. It seems that the harder one drives their car the higher chance for failure of the water distribution units, but age will eventually make it give in since it made of plastic.

A leak in the header tank is very common with age. I just relaced mine just a few months ago. The bleeder nipple got a crack in it which is all so common at 8 plus years old.

The other wear item tends to be the circulation pump that pushes radiator fluid to the heater core which is located at the left side of the radiator kinda out of sight as the big radiator hoses hide it as it is below these hoses. The electric brushes inside tend to wear down to nothing. There is a post showing how one can replace the brushes and save about $175.00. When this happens people tend to notice less heat coming out of the interior vents.

 

Many thanks

I will replace the distribution piece and the aux pump brushes (with coolant tank, thermostat, and coolant)

In preparing to inspect this 07 xjr, believe I read that the heater core is prone to plugging up (no heat on LHS?). Is this related to aux pump?

 

The no heat to heater core can be from a few reasons. Low heat temps can point to a non working aux pump. To verify if the aux pump is working simply turn the key to the position just before the car starts and turn on the heater, then go to the engine an listen to the area below the coolant tank, you will hear a humming noise which is the aux motor spinning.

Heat on the passengers side but almost no heat on the drivers side has ended up being a clogged heater core. Search the forum and there are many articles on theirs. Many speculate the someone may have mixed other coolant types with the cars orange coolant when topping up or fixing issues causing a gel like substance to form and clog up the heater core. One member shows pictures is this issue by cutting in half their clogged heater core.