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jamesgangnc jamesgangnc is offline
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First recorded activity by BoatBanter: Jul 2006
Posts: 389
Default Water in 4.3 Mercruiser cylinders

It's a crap shoot on the engine damage. If the cylinder(s) with the
water stop the engine from cranking right away then usually you don't
have much damage. The starter is not usually strong enough to
bend/break things. The worst case is where the engine got water in
cylinders that are still a couple cycles from compression and the other
cylinders fire right up. In that case you have the engine supplying
the "push" and that's enough to bend rods when the cylinder(s) with
water reach the compression stroke.

The flaps are at the tops of the Y pipe on most later model mercs.
Ther are pretty easy to replace. The new ones are a complete assembly
that just snaps in place. You just have to pull the elbow and hose.

wrote:
I have no water in the oil if that provides any helpful information.

Thanks again,
Trey

MikeT wrote:
wrote in message
ups.com...
After slowing down rapidly water rushed into my engine because (i
think) the exhaust flappers are failing to close or are missing. This
is a 97 Dynasty.

Removed the plugs and got the water out. Starter seems to have been
damaged since the engine was locked but I did get it to start again to
try to evaporate the remaianing water droplets in the cylinders.

After I replace the starter and exhaust flappers will I be good or is
there a lot more damage to my engine?

Thanks for any responses.

Trey

If you had hydrolock, the starter just moaned, you may have bent the push
rods, and blown the head gasket.

Get the water out asap, start it up, then let cool down and check
compression to see what, if anything happened to the head gasket.

You should check the push-rods.

I have a merc 5.7 with the same problem and almost every rod is bent, and I
had to replace the head gaskets. I still run it but very carefully, as I
have to pull the engine to get to the flappers.