I have been noticing a small drop in coolant levels over the last few weeks. Nothing that caused overheating or anything. So, I finally started looking for the leak and found that the upper radiator hose, where it connects to the thermostat housing, was leaking. I took the hose off and examined it. There are no holes or tears in it. I looked at the thermostat housing, as best as I could without taking it off the car, and I didn't see any cracks. So, I reconnected the hose and pressurized the system and it leaked as if there was no hose in place. The hose is fairly new, but it is not an OE jaguar part. I have ordered a new hose ( OE this time) and I'm looking into buying another thermostat housing. When the new hose arrives, I plan to completely remove the housing for a closer look. Has anyone ever experienced this? Does anyone use any kind of sealant when replacing hoses? How likely is there to be a crack in the housing? Any Suggestions?

 

NO SEALANT, these plastic thermostat housings are designed to fail internally, they seal with o'rings
Water pump, belt, tensioner, idler pully bearing, auxiliary water pump with any suspect hoses, while your there.

 

I'm sorry my signature line does not have my car. I have an "04 XJR, with the aluminum thermostat housing