After a 2 hour drive from Long Island where I picked up my "New-to-me" '89 740 Turbo, I found a quarter-sized puddle of coolant on the passenger floor mat.


One this board, someone suggested it is a leaking heater core.

I am wondering if some sort of "radiator sealer", like Barr's Leak, can be applied as a temporary fix, at least.

Because I already have the intake manifold off, there is easy access to the heater control valve and hoses to the firewall. (Will be replacing these later)

Do you think there might be some way I could reverse-flush the heater core, then introduce the leak stopper medicine just into the heater core, not the engine, by pumping it through these heater hoses only?

Any ideas about how to pump it?

Which way does the coolant flow such that I can figure out which is the inlet/outlet tube on the firewall?

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1989 740Ti 1986 240DL 1984 244GL