Will valves bend or break if timming breaks at an idle?

(2011-11-17 15:20:25)

1. Chris Says: 2000 nissan frontier timming belt broke 30 seconds after starting the truck could the valves be bent or broke at idle

2. Carroll Disher Says: It's a crap shoot basically, sometimes you can luck out and sometimes not. It depends on the position of the pistons/valves when it let go. Best bet is to replace the timing belt, remove all the spark plugs and do a compression test. Any damaged cylinders or cylinders with bent valves will show no compression.

3. BFH Says: Absolutely. You must have the six cylinder, because the four is a chain, and the 2000 Nissan Frontier V-6 3.3L has an interference engine. Some, not all, of your valves are undoubtedly bent, and if they are, and you replace the belt without replacing them, they can end up breaking and punching through your pistons later.

A leakdown test will confirm bent valves, at which point the heads should be removed, and all the valves checked and serviced by a machine shop.

4. TommyMc Says: Well, it's definitely an *interference* type engine, so the chances are good that you did damage. A valve and the piston occupy the same space at least once in the ignition cycle. With your 3.3 V6, the odds are pretty good that at least one of the pistons and valves were near a point where they could collide. I guess you can cross your fingers.

Replacement interval is 105k on that engine, so next time.....

5. Rick Says: It depends on the type of engine. Some engines are what's called an interference engine, meaning if the valves are open when the piston reaches the top of the stroke, they will collide. Call the dealer and ask if your car has an interference or non-interference engine. They will tell you the answer right away.
Mechanic since the Earth started cooling.

6. keith p Says: They could have but the only way to find out is strip the top half of the engine down and have a look .