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

T-Cut · 20th January 2012, 13:50

In spite of lengthy discussions and interjections, the true functionality of the diesel thermostat remains to be established. It seems almost certain that it is different from what we know about 'ordinary' wax stats. It has two valves for a start. Well, it has a standard flow sealing valve/disc and a second, co-operating disc, moving on the same axis. The function of this second valve has yet to be identified. Since the stat is placed in the coolant flow to the pump, the usual understanding isn't valid.

The ultimate reason for this thread is to identify why so many diesel stats appear to malfunction. They seem to open early or begin opening at too low a temperature. This causes the already cool-running engine to run too cool, even tepid in many instances. That there is a change in the stat's workings seems to be undoubted, since replacing it with a new one restores the running temperature it originally had.

Please note, this thread is not to discuss the in-line modifications. This thread does need your thinking head on.

TC

20th January 2012, 13:50	#1
T-Cut This is my second home Rover75 and Mreg Corsa. Join Date: Nov 2006 Location: Sumweer onat mote o'dust (Sagin) Posts: 21,753 Thanks: 341 Thanked 3,660 Times in 2,924 Posts	The Function and Malfunction of the Diesel Thermostat In spite of lengthy discussions and interjections, the true functionality of the diesel thermostat remains to be established. It seems almost certain that it is different from what we know about 'ordinary' wax stats. It has two valves for a start. Well, it has a standard flow sealing valve/disc and a second, co-operating disc, moving on the same axis. The function of this second valve has yet to be identified. Since the stat is placed in the coolant flow to the pump, the usual understanding isn't valid. The ultimate reason for this thread is to identify why so many diesel stats appear to malfunction. They seem to open early or begin opening at too low a temperature. This causes the already cool-running engine to run too cool, even tepid in many instances. That there is a change in the stat's workings seems to be undoubted, since replacing it with a new one restores the running temperature it originally had. Please note, this thread is not to discuss the in-line modifications. This thread does need your thinking head on. TC