In Reply to: Coolant leak in Throttle body? posted by Randy on October 17, 2001 at 12:11:32:
Anyhow the two protrusions often get crudded up and over this residue of engine coolant will corrode the aluminum. I have seen this occur at the TB as well as the thermostat housing. I have found holes where the corrosion has eaten all the way through the metal. So it could be very possible that you have a leak there...which is why the TB was bypassed. I wouldn't mess around with this thing. Before you know it a head could be cracked or warped. You may pick up a good TB at a junk yard for $20.
My son just bought a '90 525i (M20 engine) that had the two coolant hoses that should go into the throttle body connected to each other, by-passing the TB. Figuring that configuration would not pass CA smog, I hooked them back as they should be. Now the radiator is nearly empty. Why does coolant run through the throttle body and what is the fix for the leak?