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would a broken timming coze a bent valve


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Well 90% no. there is always a chance of a bent valve when a timing belt snaps. I dont remeber how the valve adjustment is done on this, but a split shim can cause a timing belt to break.

 

you may be looking at this the wrong way, as it may be why did the valve bend, then cause the timing belt to break. As fast as these things open and close, they are "eased" onto the seat, and there is always contact with the cam. If the valve stuck open, it would slam against the cam. Thsi sudden loading could cause a well worn belt to snap. Inspect the cam for damage too

 

Chicken (belt) - egg (valve)

 

i vote for the egg.

 

nipper

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PS. is this a stock engine, or have the heads been milled?

 

ANother possability, not that any of us ever do this ....

 

DId you over rev the engine, miss a shift, or have a bad valve spring? All can cause bent valves under the right circumstances in a non interference engine.

 

 

nipper

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wowsers nip! that's much higher than %90 in my experience and i've never seen it on the couple XT6 boards or on here either. good to make sure nothing catastrophic happened, but an old belt probably just broke. even on the couple engines that have seized that i've seen (blocks and cams), i haven't seen a broken belt before...not saying it isn't possible though.

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wowsers nip! that's much higher than %90 in my experience and i've never seen it on the couple XT6 boards or on here either. good to make sure nothing catastrophic happened, but an old belt probably just broke. even on the couple engines that have seized that i've seen (blocks and cams), i haven't seen a broken belt before...not saying it isn't possible though.

 

Maybe it didnt come out right, i meant a 10% chance. I mean in general on engeins, not just subaru engines. In doing a quick search (refreshing my memory) i found quite a few on the toyota board that were non-interferance but had the same scenario. They ranged from debree to who knows to oil pump failure to weak valve spring.

 

What did the top of the piston look like?

 

nipper

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Well 90% no. there is always a chance of a bent valve when a timing belt snaps. I dont remeber how the valve adjustment is done on this, but a split shim can cause a timing belt to break.

 

On the EA series engines the amount of mecanical damage required to cause a valve strike would be far more concerning than a bent valve. Only time I've seen it happen was once when a valve stem broke clean off the head and the valve was sucked into the cylinder. Cracked the piston into three peices and scored the cylinder up badly.

 

A broken timing belt alone could not cause a bent valve unless there were some pretty severe circumstances going on. Also if mechanical damage caused the belt to break.... well that would mean the belt was already about to go because a decent belt will either skip over the cam teeth, or strip the teeth right off the belt. It generally won't break unless the internal steel belts are ready to fail anyway.

 

99.99% of the time with EA82 series engines a broken belt is just that - not something more sinister.

 

GD

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On the EA series engines the amount of mecanical damage required to cause a valve strike would be far more concerning than a bent valve. Only time I've seen it happen was once when a valve stem broke clean off the head and the valve was sucked into the cylinder. Cracked the piston into three peices and scored the cylinder up badly.

 

A broken timing belt alone could not cause a bent valve unless there were some pretty severe circumstances going on.

 

99.99% of the time with EA82 series engines a broken belt is just that - not something more sinister.

 

GD

 

Oh i agree, but hes saying he has a bent valve too, so something is up.

 

nipper

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Oh i agree, but hes saying he has a bent valve too, so something is up.

 

nipper

 

HHhmmmm - I guess you could read that into his post. I figured he found he has a broken belt and someone might have mentioned that he probably has bent valves and is asking here on the board for us to confirm or deny this claim.

 

At least that's how I read his post. That he is asking if that's possible or not. Heck - maybe he replaced the belt and now it runs like poo so he's asking if it's possible a valve was bent. It's hard to say since the post is just a bunch of question marks :confused:

 

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He's got 19 posts.... I think he's just ignorant of this engine design, and probably has experience with other makes of cars that exhibit this phenomenon, or has heard of it occuring. It's a pretty commonly held belief by the general public that a broken timing belt will damage valves. I would say that it's only actually true in about 50% of cases if you take into account the 20% of the time that interferance designs DON'T bend a valve, and the percentage of engines that are non-interferance - there's actually quite a few - especially older ones where timing belt maintenance has been neglected or forgotton. It was common when belt intervals were short and belt designs primitive to build the extra precaution of non-interferance into the engine design.

 

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He's got 19 posts.... I think he's just ignorant of this engine design, and probably has experience with other makes of cars that exhibit this phenomenon, or has heard of it occuring. It's a pretty commonly held belief by the general public that a broken timing belt will damage valves. I would say that it's only actually true in about 50% of cases if you take into account the 20% of the time that interferance designs DON'T bend a valve, and the percentage of engines that are non-interferance - there's actually quite a few - especially older ones where timing belt maintenance has been neglected or forgotton. It was common when belt intervals were short and belt designs primitive to build the extra precaution of non-interferance into the engine design.

 

GD

 

well also its rare these days for a belt to snap. Usually they just jump a tooth as we see that a lot here (when the timing is off).

 

I'm just wondering if some "drivers error" was involved.

 

nipper

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It generally won't break unless the internal steel belts are ready to fail anyway.

 

(no disrespect intended) - Where are you getting timing belts with steel in them? I've never seen one, OEM or aftermarket.

 

The cords look like some kind of fibre / fibreglass "string"..

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(no disrespect intended) - Where are you getting timing belts with steel in them? I've never seen one, OEM or aftermarket.

 

The cords look like some kind of fibre / fibreglass "string"..

 

Hhhhmmm - yes that could be. Last one I saw broken looked like it had rusted. But I didn't look real close either. I assumed that's one of the reasons they tell you not to bend them beyond a certain degree. Either way - steel or fibre - eventually they get stressed to the point of breaking.

 

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but hes saying he has a bent valve too
oh there's the confusion - i didn't read that, i think he's just asking because many people don't know...interference or not. does that make sense????????? if not, let me explain it this way:

?????????????????????????????????????????????????????????????????????????????????????????????

sorry i need to go to bed, that was probably only funny to me.

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Oh i agree, but hes saying he has a bent valve too, so something is up.

 

nipper

 

 

Actually, he said

 

?????????????????????????????????????????????????? ????????????????????????help

 

:lol:

 

Advice to the OP - a little clarity when requesting help will go a long way here.

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a friend of mine works as a mechanic he did the work for 165. plus 30 for part. tensioner pully went on my car so it ate the timming belt but wont start and shakes a little when starting i think he just doen't know how to time a subi he use my chilten book so i need help i'm driving my wifes car and she is driving me crazy cuz she cant go know where and ford focus suck:Flame:

her car

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a friend of mine works as a mechanic he did the work for 165. plus 30 for part. tensioner pully went on my car so it ate the timming belt but wont start and shakes a little when starting i think he just doen't know how to time a subi he use my chilten book so i need help i'm driving my wifes car and she is driving me crazy cuz she cant go know where and ford focus suck:Flame:

her car

 

I'm tellin ya, just sell me the thing :lol:

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