Mechanic told me bent valves, but no damage to pistons?

Question

A few days ago on my drive home my care suddenly lost power and died as I was coming to a stop. I was still able to crank the engine, but it was misfiring and shaking badly, and would stall every time I'd put the car in gear. 
I had it towed to a agrage where the mechanic told me that my timing belt had slipped, which resulted in damage to the valves. The only thing that raised a bit of a question for me was when i came in the next day to see the engine taken apart. He said he had sent the top end it for a rebuild, so I didn't have a chance to see it myself. I inspected all the cylinder and non of the pistons showed any signs of hitting the valves... there were no dents or scratches on the tops of the pistons. This made me wonder.
Is it possible for pistons to hit the valves without suffering any damage, or could it be that the mechaninc just told me that to get a higher repair bill

? · Answer

It all sounds straight to me. You can go to the shop doing the rebuild on your cylinder head if you want to see the bent valve for yourself. Sometimes the valve strikes a divot into the top of the piston, sometimes it barely leaves a mark, but the valve still bends, only slightly enough to stick. The engine still runs, but the sticking valve is causing it to run very poorly.

Timing belts should be replaced every 50,000 miles to avoid costly damage to the engine. First thing I do when I buy a used car.

thebax2006 · Answer

The intake valves will all be bent. The exhaust valves need to be removed and inspected by spinning them in a drill or lathe to see if they wobble due to being bent. A mechanic doesn't make much money off a machine shop job and is just a hassle because the car sits on his lift while the machine shop does it's work.

jon_mac_usa_007 · Answer

As you were at a low RPM this sounds reasonably, if you were at high RPMs  then you would a greater chance of piston damage.  Pistons are a whole lot stronger than the Valves are, so no surprises.

? · Answer

The valve would leave a dent in the piston, there is no way you bend the valves and not leave a mark. You may have missed it though. Do a Google search on your engine to find out if it is a interference engine.

CB · Answer

you should have seen some marks in the carbon on top of the pistons  - this happened to me on a 1981 Civic and I repaired it myself - didn't need to machine shop the head just replace all the valves lap them in and go - just like nothing happened.

? · Answer

Go back to the shop and tell them you would like the bent valves returned to you as you will be making a "Desk Paper Weight" crafts out of them.
See what story they come up with.

Trending News

Mechanic told me bent valves, but no damage to pistons?

6 Answers