I don't know if I have any problems. Just going off the advice of dieselgiant over there. Is his suggestion that the Mercedes cooling system is "barely adequate when running properly" accurate? I don't want to find out that it's true in the middle of a 100F day in Texas.

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1984 300D 193.5k miles
ASTM-certified B100 bio when able

Just replace the thermostat no holes needed. Just be sure your fan clutch is in good shape, use the "correct" coolant and you should be fine.

Be sure to drain the old coolant out of the block (on pass. side engine). Be careful with the drain on the bottom of the radiator. It is plastic and breaks easily.

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AJ

1985 300D (SOLD)

I don't bother with the drain. I just take the hose clamp off the small reservoir hose and yank it to drain the radiator.

If you want to build a cheap reverse flush kit get some 1/4 galvanized pipe nipples a coupler a 90 degree elbow and about six feet of garden hose. You remove the block drain and screw in a 3 inch pipe nipple. Then screw on the elbow. Then screw on a longer nipple (4 to 6 inches). Take a piece of garden hose and clamp it to the last nipple. Then you can attach this hose to your normal garden hose turn on the water and watch the crap come out the lower radiator hose (which you pull off) I also put a valve on the end of the vertical pipe nipple with an additional 2 inch nipple to attach to the hose. This way I could flush, reattach the radiator hose and then fill the system then close the valve and run the engine for a while. Once the water is fairly clean, I leave the radiator hoses on and flush the whole system with the water coming out of the filler cap. I run the car this way for about 1/2 hour with the mono valve unplugged to get the water through the heater core. If you are changing the T-stat anyway, remove it but leave the gasket and put the cover back on. This way you can flush with the T-stat out as the cold water will prevent the thermostat from opening is it is in place...

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"I have no convictions ... I blow with the wind, and the prevailing wind happens to be from Vichy"

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Russell has a point about the cooling system. However, we'd need to define "running properly". If we're talking about a new radiator and a clean block, the system is perfectly adequate. If we're talking about a 20 year old radiator that has never been cleaned and a 20 year old block that has never been flushed, then it's a completely different situation.

In any case, the thermostat won't flow any more coolant with holes drilled in the flange. Your only benefit is cooler operation under part load conditions.........it makes you feel a whole lot better........but the engine couldn't care less.

If your radiator is not in excellent condition, you will find out that you've got a problem when it hits 100F. in Texas, and the holes in the thermostat will only delay the inevitable.

Point taken. I guess I will flush, R&R thermostat (OEM, of course) and then fill with the Zerex. If I start to have problems this summer, well, that's why I keep a $900 Honda close to my garage. ;-)

Thanks for the replies.

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1984 300D 193.5k miles
ASTM-certified B100 bio when able