What's the thread size of the block drain plug? I'd like to make a fitting to go in that hole for flushing the engine. Hose water would flow into the block and out at the pressure cap opening on the overflow tank. With the thermostat out you could flush the whole system.

I have a radiator hose heater now but would like to have a block heater. Once I get the trap catalyst off of the engine (for testing) I'll be able to access the plug. With the trap cat in place, it's almost impossible to see, much less remove, the plug in the block.

Jeremy

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"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970