These valve units are known to play up. Sometimes corrosion strikes due to moisture being pumped up from the air compressor. The compressor has a silica desiccant canister. The contents can become sopping wet with compressed air moisture with age and high mileage. On a garage compressor, you would drain the air receiver down prior to say spray painting. On the car compressor that isn`t possible...hence the canister. Sadly there is no official maintenance procedure so this poor old compressor gets ignored until is wears out or exhibits other faults. Over that period the desiccant floods with water and some of it gets pumped up to the air tank in the boot and the adjacent valve block which can corrode and cause issues.
Probably best advice would be to talk to a Jaguar independent and describe your symptoms. Why not drop an email to our club tech advisor, [email protected]
I get this firmness in the suspension in my 2003 V6 after visiting a rather rough piece of tarmac (cats?). The nearside front and rear ride height is also 15mm higher than the drivers side. So, I'll be very keen to understand what's happening and welcome a solution suggestion. Richard