Quote:
Originally Posted by leathermang
The problem is the lack of FLOW in the flushing process.... due to the small exit venues usually available... hence my recommendation to take out the freeze plugs and use a directed nozzle on a flexible hose to get down to the bottom of the coolant cavity...and a vacuum inserted will help with muck too heavy to bring to the freeze plug holes .
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I agree. This engine has a serious flow problem.
In my experience keeping a stock W115 at operating temperature is impossible. Every one I've had will hit operating temperature (175) and sink down to about 160. If I open the heater valves it will momentarily drop to 125. I tried numerous new and used thermostats with the same results. Once the thermostat opens during warm up it immediately closes again as a surge of cooled water passes through. However it doesn't close as tightly and 160 degrees is where it ends up. This is all verified with a Fluke non contact thermometer. The gauge is dead on.
This drove me nuts on two cars and three engines until I finally did what the factory did with the W123 and converted to a three stage thermostat and housing. Now I hit 175 and hold it - just like my W123. In my current W115 the only way I can go over thermostatic is 75 mph fully loaded uphill in hot weather. Under those conditions I might hit approximately 195 for a short while but it comes back down immediately. In addition to all this I have a deliberately under driven water pump and a 5 speed which further slows the pump. Now I have good heat and less smoke.
I only mention all this because a hot running W115 is completely outside my experience. I suspect you have a serious blockage in the engine or radiator. A cool running engine in this chassis is the norm. I wish I had a magic solution for you but I think opening everything you can and manually removing sludge is your only course of action. If you have access to an IR thermometer you could check your gauge calibration and sweep the engine for hot spots. That could tell you where the problem is. If you're worried about heater core damage from further flushing just bypass it. Either way I would keep after it. The blocked parts of your engine are well above the average temperature of the coolant.