S2000 Under The Hood S2000 Technical and Mechanical discussions.

confused about bent valve and broken valve guide

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Old 03-29-2010, 07:13 PM
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Default confused about bent valve and broken valve guide

So my car is at the dealer, misfire codes and leakdown test shows 25% loss in cylinder #3.

They haven't taken the head off, but i'm not sure if its a broken valve guide or bent valve. The car has been driving fine, mpg normal though idle is just barely "rough".

1. are broken valve guides under warranty? over revs are not so i'm hesitant to pay to them to take off the head, dealer told me they just can't charge to take of the head, i would have to pay for full estimate of repair. I take it that broken valve guide can cause a bent valve?

2. anyway i can tell if its the guide or bent valve w/o taking off the head? I have been driving it like this as the cel came on over a year ago and just recently again. I think i must've put on 10k miles.

I would like honda care warranty to pay for it, but they are being stubborn and tell me that i need to pay for it to be diagnosed and must not be because of over rev. Service guy told me that results are too consistent to be a broke valve guide......though broken valve guides are not unheard of. I'm just unable to gamble at paying $3k for them to tell me my warranty is void.

WTF!!!!!!! Any thoughts are appreciated.
Old 03-29-2010, 08:27 PM
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Valve guides are not a thing that "breaks" by themselves. They can wear out with high mileage, but this will not cause leakage past the valves. On the other hand a bent valve can damage the guide as a bent valve stem is pushed up the straight hole in the guide. This normally results in flaring or splitting of the end of the guide.

If they did a leakdown they should be able to determine if the leakage was past the rings, inlet or exhaust valve, and if they remove the appropriate manifold, which of the two valves is leaking.

If they are claiming a broken valve guide is the root cause of the misfire I'd be a suspicious of their technical capabilities.

I would try to find an independent automotive engineer to provide an assessment . You will probably find the dealer will stop the BS and fix it under warranty. If they think you are collecting information for legal proceeding they will get their smarter people on the case.

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