I recently purchased a 1985 BMW 635CSi from a crook in Tampa, FL. He took my money and left me with a car that broke down 1/10th of the way home. The first of several issues I must address is the water pump.

Can someone tell me what I'll be up against in replacing it? Do I face removing the timing belt, or any other umpleasant tasks in the process?

Any help from this forum will be greatly appreciated.

Who is the crook in Tampa?

A water pump on those M30's is pretty simple. The only "non-standard" tool you need is a 32mm (or 1-1/4") open-end wrench to loosen the LEFT HAND THREAD of the fan clutch. I don't recall what an '85 may be, but on my '88 535i, you don't have to touch the timing belt.

On my daughter's now-extant 528e, the water pump change required loosening the timing belt tensioner that is anchored under one of the water pump bolts, so we changed that belt while we where in there as it was cheap and easy to do. The 3453cc mills use a timing chain, so I think you're OK.

You might have to pull the radiator to get the water pump out, though the 635's may have more room up there between the radiator and the water pump than the 5ers. My main caution is to be VERY careful and gentle in removing the small tube that runs from the radiator to the coolant overflow tank. If it offers ANY resistance, cut it off with a razor blade and replace it with new. The plastic fittings on the radiator are delicate, and more so with heat cycles and age.

The 635 had a timing chain and not a belt, so no worries there.

Normally, on the 635, the water pump is not difficult. However, due to the age of the car, some of the bolts can be very difficult or become brittle. Just something to keep in mind.