1985 300d - PeachParts Mercedes-Benz Forum

laird · #1 05-27-2004, 08:13 AM

Hi, I posted the other day regarding my 85 300d and a "warm running" engine. Some folks say it is normal and not to worry. I know the car is not going to overheat as it never gets above the 100C mark. Over the past two years the car's running temp has been creeping up to this level. I had the fan clutch, radiator, and waterpump changed three years back and it ran just a needle's length above the 80 C mark. After sitting this past winter (with weekly starts) the temperature is climbing to the 100 C mark during hill climbs, and runs a few notches below the 100 C mark while on the highway. When heat is turned on it drops to normal, then will eventually climb back up. I had the thermostat replaced with a french brand that my mechanic had to drill a vent hole in, and I also replaced the expansion tank cap with a new MB one. All to no avail. I bought a benz thermostat, might this help? The cooling system loses it's pressure overnight which is a hopeful sign. I had the system flushed a month ago which did nothing to aid the problem. The heater circulation pump has a slow leak, and after the flush the water pump was leaving small amounts of coolant on the barn floor after sitting over night, but this seems to have stopped. If anyone has anymore suggestions as to what might be causing this, I would greatly appreciate it. The only reason this troubles me is because the car did not do this last year. Thank you

SoyDriver Matt · #2 05-27-2004, 08:33 AM

Try checking the tranny fluid, it made mine run cooler with new fluid in my SD. Just got an '85 300D a week ago too, so now I'm in the club also...

jbhebert · #3 05-27-2004, 08:52 AM

I certainly wouldn't trust any thermostat that required drilling to work. Replace it with a quality, OEM unit and it will likely help, or maybe solve, you problems.