Guys, I would appreciate your expert feedback. 2001 Scarab twin 502 EFIs stock. Port motor was running rough and spitting fuel out the exhaust and after inspection revealed a bent valve, subsequent valve job is under way.

My mechanic says the stock exhaust manifolds on these motors tend to cause slight reversion and have ruined many motors with only few hours like mine which have only 135 hours. Headers are advised.

Your input and any connections to low cost or used headers available would be greatly appreciated. Also could this have been caused at the wash rack by having the to much water pressure from the flush hose?

Thanks,

Mike

Your mechanic is most likely correct. Not that the exhaust is prone to reversion, but usually caused by a leaking gasket between the manifold and riser or if your using in salt water they corrode internally. This can also be caused by improper winterizing. Pocket of water freezes and cracks internally.
(not related to excess water pressure from the hose)

Try Revolution Marine exhaust manifolds. They only cost $1100. You don't need $2500 manifolds for stock motors.

Thanks for the tip, I'll check the gasket at a minimum and look into the headers.

I'm no merc tech but my bud says to change those riser gaskets at minimum every other season. Does that make sense, pull the risers , inspect the manifolds , replace the gaskets as part of routine maintenence like servicing your drives?

Makes perfect sense and probably would have avoided a bent valve and subsequent 2K valve job. After inspection I'll post what we found.