2002 Volvo S40 Timing belt snapped

Hi troyowens. Welcome to the forum. Many engines are what is called an "interference" engine meaning an open valve and the piston occupy the same space but at different times. This used to be more of a foreign car thing but now every manufacturer has engines like this. (I would never buy one, but I would never own anything very new anyhow). When the timing belt breaks, some of the valves will remain open when the camshaft(s) stop rotating, but since it takes a while for the crankshaft to coast to a stop, the moving pistons hit those open valves and bend them.

It is very rare for the pistons to be damaged, but the bent valves will have to be replaced. Rebuilding the entire engine seems extreme unless they found some other kind of damage, but typically your engine will need a valve job along with the new belt. Ten years ago when I worked at a Chrysler dealership, a typical valve job ran around $1500.00 for a four cylinder engine but we didn't do them very often. Some of their engines are famous for the protection that is built in to prevent valve damage. If the timing belt jumps one tooth, two different sensors get out-of-sync and turn on the Check Engine light. At two teeth off, the Engine Computer shuts the engine down. At three teeth off, the valves hit the pistons. Unfortunately, the sensors cause more trouble than the timing belt. Plus, if the belt snaps before it just jumps a tooth or two, the same valve damage would occur.

If you look in your owner's manual, you might find a reference to how often the belt should be replaced. Honda used to recommend, in the 1980s, that it be replaced at 75,000 miles. Lot of good that did when they commonly broke at 60,000 miles. My old beat up Grand Caravan has 378,000 miles on the original belt but I just ignore it because it's not an interference engine. Someday I'll be sitting in a puddle of tears on the side of the road.

What you might consider is calling a local engine rebuilder and asking if your engine is indeed an interference engine. If they are positive it is not, you should only need a new timing belt. Many engines use the water pump as one of the idler pulleys and replacement at the same time is recommended. Still, you will be looking at hundreds of dollars, not thousands. If it is an interference engine, ask if more than a standard valve job might be required.

Caradiodoc

This engine is an interference engine and I agree with caradiodoc about rebuillding the whole engine being to extreme unless they actually find damage to the pistons or maybe a bent connecting rod? They will not know for sure until they remove the head. But at minimum you will need a valve job. The timing belt on this vehicle should have being replaced at 105k milles.