Valve guide damage

[jons999]

I have a head with a damaged valve guide, there is a gouge near the top part of the guide (on the interior surface where the valve rides), the guides are not replaceable. The valve seems to move smoothly in the guide, it doesn't look like it would scratch the valve stem. Is the head still usable? In a perfect world i would like to replace it but how much of a chance does this engine have of living without burning oil if i use it? I would like to have it go for at least 50k miles.

 

[mslent]

A cylinder head machine shop can machine out your bad guide and press in a new one. You will need to have the valves ground at the same time. To keep from using oil you will need to have new valve stem seals installed.

 

[evelrod]

jons999, you didn't say what type of engine or what caused the damage but 'mslent' is correct in that the damaged guide can be replaced and 'seals' can be used. I personally do not subscribe to this method for economic reasons. If the damage is bad enough to require guide replacement in an older cylinder head then, replacement heads, rebuilt heads, exchange heads are all available at very reasonable cost and a much better way to cure your problem. (This assumes your engine is not an 'exotic' one off).
On race prepared heads it is not at all uncommon to grind away ALL the exposed guide in the intake port. Not good for longevity, but great for performance.

Bottom line---Take the damaged head to a reputable machine shop and let them have a look. It is entirely possible that the damage is only superficial.

Rod

 

[patprimmer]

Depending on the damage, it might be possible to ream just the damaged area, and still maintain "good fit" and support for the valve stem. If this is done, it will be even more important to use good stem seals, but as Rod says, it all depends on original design, degree of modification and replacement vs repair cost Regards
pat