1997 Maxum 5.7L Mercruiser need carburator

[gica]

The old one was the victim of hydro lock and it no longer holds idle after everything below was fixed. SO either rebuild or by something else. What do you guys think I can get?
Mine was a 2bbl 807312/7202 original. I see Rochester models, Holley that need modifications to work, Sierra Int. etc.
What would you recommend? Thanks in advance.

 

[Scott Danforth]

a good rebuild kit and rebuild what you have.

 

[Scott06]

Likely a basic cleaning and rebuild would do it As mentioned above. The Sierra options are new aftermarket copies of the mercarb you have , should be a relatively bolt in replacement If you don’t want to rebuild.

have you done other tune up items like cap rotor plugs and wires as well? May not just be carb related.

im not sure how a hydrolocked engine would hurt the carb unless it was completely full of water out the carb top? What makes u think the hydro lock affected the carb

 

[gica]

I think some rain water got in from the top. It filled the engine compartment to the starter. I have done the tune up. Took out the manifolds and removed the little rust that they showed replaced flappers. This boat hasn't seen much water and only touched salt once. That's the last time it was in water. I flushed successfully no problem right after and then a few months later. It rained and the drain plug was left on somehow so water gathered in the bilge area up to and a bit above the starter bottom and motor got locked. it was like a mirage remember I flushed it successfully twice no problem. Removed plugs water poured out, flushed with oil 3 times right away and did the starter which broke the plastic gear from the locked engine. Really weird how this transpired. This boat was running perfect, the flappers were kind of worn out especially starboard where as I understand it's hotter.
Are these flappers supposed to stay opened all the time and only close from backwash water? New ones stay stretched out but I imagine they eventually stay joined from the heat.

 

[Scott Danforth]

most hydro locks come from improper timing and the motor diesels on shut-off

to properly clean a carb, you need to take it apart, go thru it and clean all the passages on the inside, then assemble and adjust it properly. there are only a few moving parts.

 

[Rick Stephens]

A motor that filled up the cylinders with water from the intake side will have rusted a few things as well. Rings and cylinder walls get rusted pretty fast, and they will cause both wear streaks and pitting will be left behind on the walls. At times if the rust is bad on the rings they will stick in the piston grooves. The other big place for rust is valves. They will rust very quickly and get sticky. Only way to actually know what condition things are in is to do a compression check. If the compression is down, then a leak down test will tell if it is rings or valves.

I would certainly rebuild the carb. Just the fact it got water in it is enough reason for that. Or replace it. Rebuilding a carb is normal maintenance on a carbed boat motor.

Rick

 

[zellerj]

When I replaced my flappers on a 5.7 L 1988 model, I also noticed that the flappers did not fit well and did not open up easily because the plastic cage was squeezed inward, which hindered the flapper freedom to move easily. I took a razor blade and trimmed some of the rubber away from the flappers so when the cage was squeezed, the flappers moved easily. That allowed them to open up even though the plastic cage was squeezed into the y pipe.