Thermostat won't open - PeachParts Mercedes-Benz Forum

Phil Schuyler · #1 01-06-2012, 11:58 PM

Quote:

Originally Posted by Yak

I misinterpreted which gauge was calibrated - I thought you meant the Fluke probe, not the cluster gauge.

Does the lower hose get warm at any time with a thermostat installed, or only when the t-stat is removed? If the t-stat(s) don't open until above the mid 90's I suggest that the main and bypass valves aren't operating correctly.

If the bypass doesn't start to close above approx 80, then coolant will continue to circulate in the block and bypass the radiator. The bypass is supposed to fully close above 94. The main is supposed to open at 80.

The lower hose never gets warm with a thermostat installed. I can't say that I've ever felt it without a thermostat.

From your last part of your post I don't think I fully understand this cooling system. Are you saying that there are 2 valves in the system? One being the thermostat and the other one being what? Where?

Phil

Phil Schuyler · #2 01-07-2012, 12:12 AM

YAK

The link you PMed me is very informative. I'm looking at it now. Thank you.

One thing I did not mention is that the upper hose gets hot to the touch.

I wonder if the bypass system is plugged. That still would not explain the thermostat not opening.

Phil

Phil Schuyler · #3 01-07-2012, 12:24 AM

The last time I drove the car I drove it hard up hill for about 1/2 mile and the temp immediately went to 100C. I turned the heater on and drove it mellow for the remaining 1/2 mile home and it stayed at 100C. I parked it with the engine running and felt the lower hose. It was cold. The upper hose was hot and the engine side of the thermostat housing was hot.

I can't believe this is right.

Phil