how to check for bent valves

[Joker96]

My ps belt broke and it got to the timing belt on my v6. Timing belt broke and when try to star the car it goes blank all I can hear is starter turning so am very postive I bent all valves fml. Any clue on how to know for sure??

[mko]

When the valves are bent the engine looses compression which means there will be no load to the starter. When cranking you'll hear how the starter spins kind of freely. Best way is to have a compression test done - if it shows 0 or close to zero then you know it for sure.

[Joker96]

On each cylinder right?

[Joker96]

I just replaced that damn ps belt I don't understand why it broke!!!

[Galanttuner10]

I would personally do a leak down as it doesn't involve turning the motor over just rotating by hand in the firing order on compression stroke and pumping shop air in. If you hear air in the intake, intake valves are bent, air in exhaust is exhaust valves, air from the oil cap is rings, and air in another cylinder is head gasket. I like it as it tells you more of what's going on than just checking for compression. A leak down tester is slightly more than a compression tester. There always will be some leak down as the rings aren't perfect seals but you will know if you bent valves quickly using that test.

[Joker96]

12 intake valves bent found them on rockauto for 2$ each car fixed.

[keith6110]

Nice! Was the belt a dayco belt by any chance? I did the same exact thing on my original engine in my old galant. Awesome you got it running again. I could have been more informative if I saw your thread earlier.

[Silvertune]

Not really. Heads will need remachining for the new valves or they won't seal worth a damn. When the valves bend they damage the seats.

[Galanttuner10]

Usually bent valves ruin guides as well. Gotta fix guides before seats get cut then surface the heads. So new guides, valve seals, a valve seats cut and heads surfaced. Should run you around 300-400 and make sure the shop does a 1 degree interference angle on the seat to ensure a proper seal. If they lap in valves, take your head and find another machine shop.

[Joker96]

Machine shop charged me 60 $ dont know what the hell they did. Lol

[Galanttuner10]

That's not good at all man. I would inspect the head. Or call and ask what they did

[keith6110]

Machine shop charged me 60 $ dont know what the hell they did. Lol

Probably just changed them out for ya. I understand the proper way is the machine them out to fit the new valves, but my 2.4L also bent valves and it took about 2k miles to restore it to it's previous power. Nothing to worry about, just make sure you are doing filter changes with your oil changes.

[Silvertune]

Yup. Half ass everything! What could go wrong!?

[Galanttuner10]

what are you saying to machine out? we have knock out valve guides not integral. if we had old school cast iron heads we could machine it out for a larger stem guide, knurl it back to normal size, use the winona process to make it normal size or machine it out for a thin wall sleeve or machine it for a thick wall sleeve(best). But we have an aluminum head and knock out iron guides from the factory. the proper way according to mitsu is to heat the head and press the guide out the same way you put it in then hone the hole and put in a .5 mm larger diameter guide. But you can heat the head and drive them out towards where the other way then put the normal sized guide in whether it be a normal replacement or an upgraded bronze guide etc.

for 60 bucks im willing to be nothing was done besides changing the valves and there is a good chance of cracked guides, bad valve stem seals and probably a worn un touched or poorly lapped and you could have a terrible seal and or non at all and could smoke like hell. i would call and find out. wish you lived closer cuz i would be able to do a lot more for you.

[keith6110]

Ahh shit, every v6 I've seen that had a timing belt problem had cracked valve guides. My 2.4L method would not apply here lol! My 2.4L did NOT have cracked valve guides where both my old v6 engines did.

Probably should look at getting some JY heads in the meantime.