Tales from the Auto Shop: Oh Yes You Will Pay

[Catwoman2965]

It could. Some cars come with timing chains that don't run on metal sprockets, so the teeth on the sprockets wear out over time.

My mother had a car where she needed her timing chain replaced, and the replacement sprocket didn't come with metal teeth.

True, and sometimes they just wear out. SHould have been a bit clearer. COnsidering i plan on driving my car until its dead, which could be 200K or more, i may. But i know i won't have to replace at 60K mile intervals or whatever belts are.

[Cia]

The serpentine belt let go in my Jeep, since it didn't want to go alone it took out the water pump too.

[BPFH]

I got lucky when the timing belt in my Elantra decided to quit - I was just starting the engine up, so no collateral damage.

Of course, that car was taken out 9 months later by a gentleman who put the emphasis on the I in DWI (likely both drunk and high according to the cop), so you can't win everything...

[MadMike]

The serpentine belt let go in my Jeep, since it didn't want to go alone it took out the water pump too.

The same thing happened to my first car. It decided to crap out on me while I was sitting in traffic, in a construction zone on the interstate. I didn't realize anything had happened until I tried to give it gas. I had to push it through the cones to get it off the road.

[roxtar]

gotta love interference engines.

I'm curious if a fiber optic camera down the spark plug holes could determine whether or not the valves were bent... a new head/new valves would be cheaper (parts wise) than a new engine... but if the bottom end had problems, you'd be out even more money.

[peach2play]

No, the optical camera can't get in there. You have to take the valves out one by one and inspect them.

[Nunavut Pants]

A borescope can get into the combustion chamber through the spark plug hole, but it can't necessarily tell that the valves are bent just by looking. To be sure, you really do need to remove the valve and inspect it.

You can see witness marks on top of the piston where the valve impacted, but those don't always mean that the valves are bent. Of course, if you see a piece of valve embedded in the piston crown, that's a stronger indication....

[roxtar]

figured as much... seeing as how it only takes a little bend to make the valve not seal. combine a borescope and rotating the valve and you might see a bend.

need to find the picture I saw years ago where somebody had dropped an allen bit down into the cylinder.

edit: found it... torx bit

[crazylegs]

need to find the picture I saw years ago where somebody had dropped an allen bit down into the cylinder.

Now, I'm no mechanic but even I can see that's knackered. How much to replace all that?

[roxtar]

Now, I'm no mechanic but even I can see that's knackered. How much to replace all that?

no clue... you'd need a new head, new piston (maybe rods/bearings/crankshaft), and possibly machine/sleeve the block depending on what kind of damage it did to the walls.
cheaper to just swap in a different engine.

[RealUnimportant]

need to find the picture I saw years ago where somebody had dropped an allen bit down into the cylinder.

edit: found it... torx bit

Damn... Shows how tough those little bits are though!

[Nunavut Pants]

There's a reason that there's a special designation for "tool steel". It's very tough stuff!

[Jay 2K Winger]

Now, I'm no mechanic but even I can see that's knackered.

As the Mythbusters would phrase it: "Well, there's your problem."

[Mental_Mouse]

Yow.

need to find the picture I saw years ago where somebody had dropped an allen bit down into the cylinder.

Oh, my. I especially like where at the left you can see the bit's inscription cast in relief on the cylinder bottom.

[protege]

Now, I'm no mechanic but even I can see that's knackered. How much to replace all that?

Knackered? No, that's truly and royally...fucked

As to cost, the engine would have to come out, get stripped down, and everything inspected for damage. Cost? Probably a grand or more. That doesn't include the obvious new cylinder head, valves, and any machining work. Probably another grand or so for the parts, putting it all back together, and resetting the ignition timing. Unless the car is a classic, you'd be better off buying a good used engine and rebuilding it.

Sometimes you can't do that. I got very lucky when the MG's engine finally went some years ago. All I had to do was fit a new cylinder head (complete with hardened valve seats, so I could run the car on unleaded), have some light machining done, and fit new gaskets. I got very lucky that the engine block wasn't damaged--scrapyards aren't exactly teeming with them, and rebuilt blocks usually run about two grand