? about tstat and rad flush
 

A couple simple questions. I plan to flush the coolant system on my 91' 190e 2.6 this weekend. After draining the crappy coolant and flushing the system with water, I close up the system, fill with water, add my bottle of Zerex Super Flush and run the car for 6 hours. During the 6 hours with chemical flush in the system do I leave the tstat out or reinstall it?

Also where is the engine block drain plug on a 190e? The picture I have of this is so poor, I can't really tell where it is?

Thanks,
D Stang

There's no need to remove and reinstall the thermostat for the flush. The block drain plug is on the RH side about mid-way between front and rear, under the exhaust manifolds. It's a hex nut with a nipple. You should be able to reach it with a socket or crescent wrench.

Once it's loose attach a piece of about 3/8" thin wall flexible tubing to the nipple, route it to a drain pan, and turn it about one to two turns out. It's very easy to drain the coolant on 103s without spilling a drop. The radiator drain is behind the pop-out panel on the RH side of the front valence and also has a nipple for a drain hose.

A coolant change on the 103 is easier and less messy than on most cars.

Duke

Found this info on another MB diesel list. This was news to me and it is certainly a 'good to know' bit of info it it's accurate.

"To block the thermostat open (use an OLD thermostat as it may NEVER work correctly again) you can heat it until it opens and block it open or dismantle it. Running without a thermostat will allow the coolant to flow through the by-pass and NOT flow through the radiator and make a joke of the entire excercise. The thermostat must CLOSE the by-pass passage and open the passage through the radiator. The heater must be ON full throughout the process (put it into defrost - that's full heat). "