240D coolant leak frustrations - Page 4 - PeachParts Mercedes-Benz Forum

BodhiBenz1987 · #1 12-07-2011, 05:52 PM

Still going around in circles trying to get the 78 240D to stop leaking coolant from pretty much everywhere (I haven't even started it since June). I replaced the thermostat housing gasket, twice. The first time it continued to leak a lot when I put a pressure tester on the system, so I took it all back apart, got a new gasket, and tried evening up the housing surface using JB Weld and hand sanding it flat. Put it all back together, still leaked. Tightened bolts, and it stopped leaking at the housing, but started pouring out the heater valve on the firewall. So, the latest is I replaced the valve (those little wires were fun!

) and that's all good, but guess what ... the tstat housing leaks again, a lot, again when I put pressure on the system. I pump it to 7-10 psi and the coolant starts dripping out that junction, although the pressure on the gauge drops very slower than before. And here's another odd thing: I can hear a slow drip inside the engine block or head. So two questions:
-What can I do to the thermostat housing to make sure I don't do this job wrong for the third time? Should I just get a new (used) housing? Or maybe try sanding it using a block instead of my hand? Also wondering if I should try without the water pump sealant. I can't seem to get the sealant on very evenly (because I don't want to have it squeeze into the coolant passage) and I'm wondering if it's making matters worse.
-What would be dripping inside my engine? Because my thoughts went straight to coolant pushing past the head gasket and dripping into the cylinder. Unless it's dripping backwards from the hose that goes to the heater core. It sounds like water hitting metal, not water hitting water. One drip about every 20 seconds.