Thread: Cooling System Sanity Check

Originally Posted by cummo

Before I delved into the spaghetti of wiring to find and check the temp gauge earth, I pulled the new thermostat out and did I a side-by-side comparison with the old one in a saucepan brought them up to boiling. Should have done it for the hell of it before I installed it. I did it a few times to make sure; old thermostat cracked open to let air bubbles through at 76-78 and opened visibly at 82 degrees; the new one cracked open at 88-89.

Not sure if the later opening thermostat is causing the continual higher operating temperature on the gauge; other than the new correct sender and coolant nothing else has changed. Additionally my understanding of thermostats is that they should work correct from day one; AFAIK there isn't a "bedding-in" period or the like following which they "loosen up".

Heading back to the Isuzu dealer tomorrow to discuss and possibly order in a replacement. Heading from Newcastle to KLR at Windsor on Thursday; may end up putting the old thermostat in for the trip.

Cheers, Dave

Then they are both not working properly.
as per my post a while back the thermostat should start opening at its nominated temperature (82c in this case) and according to my mechanic should be fully open no more than 3-5 degrees above that.

Personally (because I am supremely paranoid about overheating things) for a long trip I'd put the old one it, and have it run cool and burn a bit more fuel than the new one which is going to make your engine run hot.

Originally Posted by Gardi01

Thanks, mine is definitely running too cold. Not good.

The other thing you could check is the earthing. But I'm fairly sure if there was a bad earth it would read high.