The engine block's coolant drain petcock port seems to be plugged within. Today, I replaced the radiator on my '92 245DL and followed up with the intention of draining and flushing the block and replacement radiator.

This car is new to me and I lack any past history. The old radiator had a leak and I had a spare from a '91 I previously owned. Since car was already up on ramps from changing out the engine mounts, I proceeded with the radiator changeout. While removing the old radiator, I was convinced a coolant system flush was necessary. Of course, new radiator was void of any fluids, battery was already disconnected, and I opened wide the cabin heater control. All hoses were connected and I opened the pet cock valve and had a hose attached directed to a bucket. I slowly added water from a garden hose via the expansion tank. I expected to see water exit the petcock. Nope! Water backed up from the expansion tank!

I then removed the petcock valve and still no joy. I swept the petcock port with a small screw driver and still no water. Next, I disconnected the thermostat housing and water poured out with no hint of resistance.

I could continue on with the flushing of block and radiator and refill with coolant, but I would be troubled with the non-functional coolant drain through the petcock valve.

Any suggestions to clear the drain? I had thought of applying back-pressure through the petcock valve, but I would have to juryrig a device to attach and apply that back-pressure.

Mike
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'83 245 GLT, '92 245DL, '90 760 GLT