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Long story short, after a brief near-redline excursion (a long tunnel and open windows may have been involved), and about 10 minutes of gradually loudening TAK-TAK-TAK-TAK that couldn't be drowned out by turning the radio up, a stall out and a 200 mile tow home, I'm fairly certain I've blown a valve stem.

I've read that snapping a stem typically causes an inteferance engine to eat up a cylinder and a lot of other very bad things. Which I would assume would cause the engine to seize or work very poorly. However, after getting the car home I was able to rev the engine to 3-4k and drive it a few hundred feet during which, besides the impossibly loud TAK TAK TAK proportional with the rpm's, it behaved "normally" (meaning it revved quickly, idled normally, and drove with reasonable power, but I obviously didn't push it).

Checking under the valve cover didn't reveal more benign damage like a snapped rocker or any obvious bent valve stems so the damage was presumably lower down. However this doesn't mesh with my understanding of snapped stem = dead engine.

I haven't taken off the head yet to check under, primarily due to lack of desire to spend hours on a worthless cause that could be sold to a scrap yard.

My question then is, given that valve damage is most probable, and given that the engine is behaving somewhat reasonably for the sounds its making, how likely is it that I can replace some valves and be able to drive it? Has it just not decided to seize up yet?

Engine is an DOHC H23A from a '96 honda prelude.

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I wouldn't expect it to sieze necessarily. Obviously you'll need to replace the broken valve, and it's spring. Chances are you'll have wrecked the piston as well, as it'll have been trying to squash bits of valve... There's also the possibility of a bent conrod, but I'd have thought that less likely, and scored or damaged cylinder bore.

At the very least you're looking at replacing and re-lapping the valve (at which point it's worth re-lapping the rest), replacing the piston and honing the bores. If the bore itself is badly scored you might have to get it bored out, at which point you have to do the others as well...

It is certainly repairable, it just depends on how much damage was done and how much time, effort and money you're willing to spend on it... It doesn't take long to whip the head off and have a look, then decide whether you consider it worth continuing...

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