I have a 01 XJ8 (VDP) 4 liter non-sc. I changed the coolant 2 days ago. Got about 2 gal out, but can only get 1 gal back in. Reservour is full, low coolant light does not come on. I burped it, drove it, drove it. Temp gage never goes above 1/2 way point. Could I have a bad thermostat?

 

Well if 2 gallons came out 2 gallons should go back in ! I suspect you have an airlock somewhere, nothing unusual in that if the exact procedure is not followed when refilling. I don't know the Jaguar procedure text, but first thing on most coolant refills is to set heater to maximum, and rev engine a bit to make sure the heater circuit gets full of coolant. Thermostats is not normally a problem as they normally have a bleed hole to allow for filling. There may be coolant bleed valves that need opening to ensure coolant goes back in where it should, the V12s had these.

Only V8 experts can confirm or deny my post above; c'mon guys, help him out !

 

As Fraser said, you obviously have air in the system. My solution to this, on lots of cars, has always been to just drive it, keeping an eye on the reservoir and adding as needed. I am sure that a professional technician has a better way to get it filled quickly without come-backs.

Someone will be along shortly, I am sure.

 

First, you should always have the heater on HIGH (heat and fan) when you refill, start engine, warm up, top off, Bleed. Keep the heater on high the whole time you test drive and make sure the engine reaches op temps, gauge at the 1/2 way point. Stop, let it cool, check it now.

 

Agreed. Be sure you have the heat on. You may have drained the heater core, but it won't refill until the water is hot and the heater is on.