you are a pretty good candidate for water/exhaust reversion, based on your cam....although Kidnova hasnt had a problem and many others alike. if you were getting water in there it is said that it will make the exhaust valve "brittle", i guess because of the cold water hitting the hot valve. i need to check mine out this winter when it comes apart. i had/have a small reversion issue on my motor (different cam than yours though)

one other thing i would say is that if you dropped a valve there could be a chance that it damaged the head and let water into the oil at that point. that happened recently to a friends car.

sorry to hear of your problems!! keep us posted as to what the head looks like!

 

If you droped a valve it did damage the head.
Yes reversion will cause the exhaust valve to fail eventually due to cold water hitting a hot valve.
You will probably need to replace the head ( or repair if it is aluminum ) replace the valves, replace the piston and probably throw in a new rod.
Worst case you may need to sleeve the block if the piston canted sideways and cracked the cylinder.
I have done all of these.

 

you are a pretty good candidate for water/exhaust reversion, based on your cam

Thanks BOATN70. I doubt if its the cam though since I had these built to marine specs. The builder put a Lunati cam in it (can't tell you the numbers) to avoid reversion along with Manley rods, JE pistons, Inconel valves roller lifters, roller rockers, etc. But I wanted the original EFI and they used the original exhaust so my guess is water got dumped in it from the exhaust.

 

Engines built to "marine specs." do not always include "Inconel" or the equivalent quality exhaust valves. I have seen this so many times. (even on my own, damn-it) Standard ex. valves always fail at just about that RPM after some hard runs. DO NOT LET YOUR BUILDER INSTALL ANYTHING LESS THAN INCONEL OR EQUIVALENT EXHAUST VALVES FOR ANYTHING YOU INTEND TO MAKE MORE HP OR RUN MORE RPM THAN THE STOCK PROGRAM!! The street race guys will tell you it's not necessary, but they are not on the throttle at max loads for near as long as us boat guys. We need to build them BETTER! And although the builder and valve maker will try to blame your exhaust and "reversion" for the failure, the real problem was the wrong choice of ex. valve material for the job. --- Jer

 

If you were getting reversion then you should have been seeing milk shake like oil building up in your valve cover and the oil filler caps first. I bet a head gasket let loose.

 

Thanks Guys,

Like I said, I've just parked the boat for now and haven't removed the head yet. We thought it might be a head gasket too at first but once we took the plugs out number 7 plug was damaged indicating a valve. i have valves drop in in these before when they were first built but that was because they didn't map the ECMs right. It ran well for about 60 hours since then this happened. The weird thing is when the valves dropped before when I started the engine (briefly) you definitely heard the ugly rattling. This time there's nothing so I wonder if the stem went out the exhaust.

 

I assumed your valves were inconel valves. Are they ?

 

I assumed your valves were inconel valves. Are they ?

yup.

 

I had reversion problems with the Merc 496 and I now run Dry-Tech reversion control inserts and have eliminated the problem. www.p-res.net

 

Wow, this is a bad memory thread from '06. I fixed the reversion problem too...bought 2 brand new engines last spring. :winker: :laugher: :confused1

 

I had reversion problems with the Merc 496 and I now run Dry-Tech reversion control inserts and have eliminated the problem. www.p-res.net

How much $

 

Sorry to hear that Go fast, sounds like you did not have the fix.

Forcnme - I paid $1600