Broken Timing Belt

verdigo · #1 06-23-2011, 06:48 AM

Not a Volvo, but I just got a diesel Beetle into the shop with a broken belt. Just wondering if i should waist the customer's money tearing it down or start looking for an engine.
Dennis

Jason · #2 06-23-2011, 09:29 AM

Depends how fast they were going when it broke, how many rpms they were turning and how long they took to shut it off. I have seen just a ruined head on a tdi from a broken belt, but at a higher rpm or on the highway and they keep going, it will bend rods.

Jason

v8volvo · #3 07-02-2011, 06:34 PM

You can probably put it back together. More than likely all it will need is a head rebuild, probably has some bent valves and broken lifters but 99 times out of 100 the bottom end is just fine and you can stick a head on it without any trouble.

Best thing to do is to pull it apart and measure piston protrusion out of the block. If all the pistons have the same protrusion (assuming they do all protrude), and the pistons look OK, then the bottom end is fine. If you find one or two that don't protrude as far, then you're looking at a bent rod, but even then it's pretty easy to yank the pan, pop that piston out, and stick a new rod/piston/rings in that hole.

I just got finished rebuilding an '01 Jetta TDI that dropped an exhaust valve and did massive damage... trashed the head, rod, piston and injector in that hole, but the bore was fine. Got a weight- and length-matched rod and piston assembly in that hole, quick hone and new rings in all 4, rebuilt head, one new injector tip, and a full timing belt service and it's back on the road running like a champ. That was after a dropped valve and much more damage than a broken belt usually causes. In your case it will probably be even easier to get it back together. I'd pull the head off and see where things stand and go from there -- I bet you will find that it's a fixer.