hello,
I have an 87 240dl and it has a coolant leak behind the plate where the two heater hoses run through the firewall. Ive been told this is part of the heater core but I just cannot see how this can be. It looks to just be a metal coupling that runs through the firewall. Im so confused, I cant find a good schematic of the system anywhere. Has anyone else had this kind of leak?
thanks

ok, so i determined that it is not the heater core but the metal pass through on the firewall. I have sucessfully taken this off (lucky me) and after inspection I can find no cracks in it but this is not to say that there is not a microscopic one. Has anyone had a firewall pass through leak before???????

they pop like balloons on audi/vw motors from the late 80s, so count yourself lucky.

It's still going to be a pain to replace.

Again, if you don't have steam/coolant odour you're okay for now. Don't change anything on the cooling system (i.e. thermostat, hoses) that will affect the amount of pressure.

I'd wait for a nice springlike day to do hoses/flush/thermostat. Remember, a hotter thermostat increases pressure and can reveal corrosive punctures in a rad/core, so leave it alone if you have not confirmed their integrity.
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Stef (81 245 B21A SU M46 3.91 330000km, 81 244 BW55 3.31 220000km)

Sorry, dude. It's either the heater core or you have a heater hose splitting. Whatever you do get it fixed pronto.

That is not the heater core, it is just a pass through. If your lucky it's just a loose hose clamp or a bad hose.
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Bruce S. near D.C.

remove the console side panels and look at where it is. Heater core manifests as steam out of the vents if you want heat. Temporary fix is to close off the valve (run full cold), but if you don't have steam you aren't looking at the hc.
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Stef (81 245 B21A SU M46 3.91 330000km, 81 244 BW55 3.31 220000km)

Greetings:
This is by no mans the best or permanent fix to a heater area leak but you might effect a temporary fix by using a large amount of heavy duty stop leak (such as Bars pellet stuff HD version)flow it through the heater for several days at max output. Then drain the coolant as possible to get rid of the excess pellets, which will be circulating around looking for something to clog (especially the radiator). Soak the coolant you drained onto a newspaper or otherwise make sure small animals can't get it since drinking it causes kidney failure and painful death. If your radiator is old and partially clogged this will make it worse, but a radiator swap may be easy and $120. Again, get the excess stop leak out as soon as the core is responding. If it is a hose leak the flexing may prevent good sealing. Many heater core leaks provide a steam effect rising from the defroster tubes, with an anti freeze smell. Again, not the optimal professional solution.

jengland in indy.