Hello! I have a 2005 X-Type 3.0L. About a month ago one of the nozzles on my coolant reservoir tank broke off and I replaced it. Yesterday as I was coming home my temperature gauge shot up rather quickly. When I pulled over and checked it out there was coolant underneath the tank. Also, what I believe is the belt tensioner pulley next to the water pump, the pulley was pretty damaged.

After having it towed home, I pulled the coolant tank off to see if it was damaged. I could not find any cracks or holes. I even plugged the ports and filled it with water and let it sit overnight and no water was lost. Also, all hoses were in good shape. Any suggestions?

 

Did you happen to pressure test the cooling system with all components in situ?

What is the condition of the water pump?

 

I didn't test the cooling system. Honestly, I don't know the condition of the water pump. I bought this car used about a year ago. It has 113,xxx miles on it.

 

It is probably a good idea then to pressure test the system to see if there are more than one leak.

Given the age and number of miles, you should consider changing the coolant and heater hoses then refilling with the correct coolant and mixture appropriate for your location and weather.

 

NB, where can I find out what the correct coolant and mixture is for my car?

 

It is listed in the vehicle Owner's Manual along with the correct strength for your location.

 

The following is quoted from the Workshop Manual:

'The long life engine coolant is formulated to last for five years or 150,000 miles (240,000 km). The coolant is silicate free and orange in colour. The long life engine coolant must not be mixed with conventional engine coolant.'

'Fill the cooling system up to the MAX mark on the coolant expansion tank using a fifty percent mixture of Jaguar Premium Cooling System Fluid or equivalent, meeting Jaguar specification WSS M97B44-D and fifty percent water.'

The coolant specification is a Ford standard, which is compatible with several common brands such as 'DEX-Cool', for example.

 

Just a thought, could the coolant under the tank be left over from when you replaced the tank? The water pumps tend to last about 100K and if the tensioner is bad and the water pump doesn't show any signs of being replaced, you probably want to do that. Not that expensive or difficult.

 

A couple of things to add..Always use Distilled water if you are mixing with the specified coolant concentrate (the book is written for dummies and it doesn't specify distilled water...Another reason the OM is just a little bit of a guide and not gospel)..Prestone DexCool (Orange stuff) will work or you can get the Premixed version of the DexCool and forget about mixing yourself..either one will work in the Jag.

 

The coolant under the tank is from the pressure release built into the plastic tank, it got hot and forced it out. On the high area on the underside of the tank is a slit, enough pressure in the system forces the slit open and the coolant sprays out of it like crazy, been there and witnessed it happen before. The vent is hard to see and one would never think that is what it is.
I would assume whatever issue the tensioner pulley had caused the car to overheat and forced the evacuation. Can you turn the water pump by hand easily? It is a quick and easy, under $40 DIY repair if the pump needs replaced.