The 75 and ZT Owners Club Forums - View Single Post - The Function and Malfunction of the Diesel Thermostat

Mike Noc · 20th January 2012, 22:47

TC from the feel of it I don't think that normal pump pressure will move the disc. So it is more for overtravel when the disc valve has shut but the thermostat needs to open further.

If the system overheats then steam could well force it open if it could escape that way.

Regarding the ball valve I'd say definitely used to bleed air from the system when filling, as the pump isn't self priming, and there is a vertical length of pipe below the thermostat that could airlock if the air can't escape. Once the pipe is filled with coolant pressure from the pump will keep the ball valve closed with the engine running.

Mike

20th January 2012, 22:47	#12
Mike Noc This is my second home Rover 75 CDT Manual Connoisseur SE, Rover 75 CDT Automatic Connoisseur SE & a Freelander Td4. Join Date: Jul 2009 Location: Hampshire Posts: 11,570 Thanks: 3,470 Thanked 3,119 Times in 2,247 Posts	TC from the feel of it I don't think that normal pump pressure will move the disc. So it is more for overtravel when the disc valve has shut but the thermostat needs to open further. If the system overheats then steam could well force it open if it could escape that way. Regarding the ball valve I'd say definitely used to bleed air from the system when filling, as the pump isn't self priming, and there is a vertical length of pipe below the thermostat that could airlock if the air can't escape. Once the pipe is filled with coolant pressure from the pump will keep the ball valve closed with the engine running. Mike Last edited by Mike Noc; 20th January 2012 at 22:51..