BMW 325iac

1988 BMW 325iac Engine Won't Start When repairing Always

1988 BMW 325i Convertible Engine would not turn over after timing belt replaced. Timing belt broken while driving. Mechanic replaced belt and water pump. Mechanic says valves are possibly stuck in head or bent and also that the head is potentially cracked. Could this be true? Is this an Interference engine (otherwise no damage should occur to the valves, right?)?

Your mechanic apparently does not know, or wants more money out of you. Take the car else where to a better mechanic. If a timing belt breaks, the engine must be "timed". The 'why' is that after the belt broke, the engine components continued to move around, out of proper sequence. Setting up the proper aspect of ALL components is the FIRST thing a COMPETENT mechanic would have done. I seriosly doubt the block is cracked. This mechanic is hoping that you do not know and he can bleed more green out of you. It is sad, but very true. The valves, one or more, could have struck a piston, thus bending one, or more. A check of engine specifications will tell if there is or is not sufficient clearance. As a reference, in the 2.3 liter Chrysler Reliant engine, there is not enough clearance. In the 2.5 liter, there is clearance. I know, your situation happened to me.
To be sure if the head is cracked, have it 'magnifluxed'. This is a special process that checks for cracks to small to be seen. Personally, I doubt it. A broken timing belt would not do that- normally.
Go to a competent mechanic and have the engine checked. It might simply need to be timed. If so, while you may pay for a new belt, you won't get socked for repairs to problems that do not exist. If any of the valves are bent, well, you should pay more atention to what goes on under the hood of your car. If such a belt is good for 50,000 miles, get it replaced at 45,000 miles. A new belt is a lot less than what you may face with bent valves, IF they are, indeed, bent.