Timing Belt


#1

While replacing the timing belt the mechanic tells me he bent the pistons and that I need a new motor. It this possible?



This post has been moved to the new Car Talk Discussion Area, by a Car Talk Lackey. The original poster is Brae.


#2

I take that the mechanic is going to fix his mistake at no charge. BTW did he expand on what he was going to do to fix it, like send the head out to a machine shop to have fixed, or put a used head on. Its good to know there are still honest people in this world


#3

Yes, it’s entirely possible. The mechanic who damaged your engine owes you a new one, or free repairs on the damaged engine. Pay only for the timing belt service, nothing more.


#4

I’m a little unsure about the phrase “bent the pistons.” It’s possible to damage the pistons, the valves, and/or the connecting rods during a botched timing belt job. Whether the pistons are “bent” or not doesn’t matter; the mechanic should still fix everything at no charge.


#5

It is possible.
To be sure, let us know what year, make, model and the size of the engine in your car.
That’s the only sure way to give a correct answer.
Make sue the mechanic repairs it at his expense.


#6

I’m not sure how you “bend” pistons, so I would be very leery of letting that mechanic continue working on the car. Sounds like time for a second opinion from a pro.


#7

I DON’T KNOW HOW A PISTON CAN BE BENDED? IT’S ROUND & NORMALLY ABOUT 4 INCHES LONG (DEPENDS ON THE TYPE OF VEHICLE), & CONNECTED TO A CONNECTING ROD THAT’S CONNECTED TO THE CRANKSHAFT. THE PISTON IS INSIDE THE ENGINE BLOCK (PISTON CYLINDER)PACK TIGHTLY WITH PISTON RINGS (COMPRESSION & OIL). THE ROD CAN BEND OR BREAK BUT I HAVEN’T ENCOUNTER BENDED PISTON. TELL US MORE, PLEASE.


#8

If the piston and valve timing is not correct, then it is possible to bend valves, dent or break pistons because the valves and pistons will, with many engines, then collide or interfere. This can be described as an internal engine crash. Your mechanic may have installed the belt improperly and then tried to start the engine. If he will not make it right, you may need to take your case to small claims court.


#9

Since your mechanic screwed up the bill is on him whether he likes it or not.

A broken timing belt seldom means you need a new engine and if your mechanic knew what he was doing this problem would not have occurred and he should know that a broken belt does not mean total destruction.
A good rule of thumb even if a tech KNOWS the belt is on correctly is to ALWAYS rotate that engine through a few times by hand before touching the key. If something is out of whack, rotating it by hand will bring the engine to a stop without damaging anything.
If not, then the starter motor will turn the engine with enough force to cause damage.

Usually some or all of the intake valves will get bent and this is repaired by removing the head(s), replacing the bent valves, and performing a complete valve job at the same time.

Many times the piston tops may get nicked up but this usually will not hurt anything. Simply grind off any sharp edges on the nicks.
In a rare circumstance, it is possible to suffer a cracked piston or bent rod but this seldom happens. In that rare case, a new engine may be needed; 98% of the time is is not.

No matter; your mechanic owes you.


#10

Knowing the car model, make and year would be helpful.