Help! 225 carbed Johnson melting prop hubs / high exaust temps through prop hub

[Tunnelvision1995]

Hey guys my first thread about this issue wasn't detailed enough so here is my second attempt to explain this problem the best that I can to all you OMC guys out there I am here because you guys are true enthusiasts with great advice.i have a 1995 21' liberator tunnel with a late 90's Johnson carbed looper on it.i am having a problem with my prop hubs literally melting from the heat from my exaust that comes through my prop hub in my coned lower unit.I have a bobs snout in the mid section where almost all the exaust is relieved, so a minimal amount exits through the prop hub anymore which is what has me baffled as to why my hubs are melting.i know these moters have been known to have fairly high exaust temps but something just isn't right.the hubs spin after I hold the engine wide open for about 30 seconds straight then boom my prop hub is spun .i have the rubber pressed in hub in my OMC shooter prop, then I have the quick change plastic hub in my Mercury trophy prop.both of which I literally melted .multiple times.the trophy prop has little plastic pieces in the vent holes that melt as well.how could the exaust possably be getting that hot?.my engine runs nice and cool and the water pump is strong.now soon after the hub problem my rear rubber prop shaft seal decided to pop out and spill about 1/2 of my gear oil out.i immediately pulled the boat out of the water and took it home after that.im assuming from the heat in my lower unit from the excessive exaust temps . Have any of you OMC guys seen this happen?? Not a lot of water flows through the prop anymore since it goes right out the snout.my lower now needs to be checke out and new seals installed.

[Gorilla0178]

Im not sure about the exact answer, but I also had a 99 johnson 200 on my boat. No issues with melting hubs though. I do remember that while working on it i was told that water was supposed to flow through the hub too cool it off. If you look closely at the torq tab thats above the prop you will see a small water inlet on the bottom of it, that feeds water directly into the exaust stream, as far as i remember. I had my exaust relieved and was running a solid hub with the plastic insert, no issues. I dont know if this helps but as far as i know water should flow over the hub to cool it.

[SPANNA]

I have same engine and bobs cone and mine is good to the props .how much water pressure do you have is i keep melting top pistons i have 30psi and this could be to much cheers

[Jason Joe]

Hey guys my first thread about this issue wasn't detailed enough so here is my second attempt to explain this problem the best that I can to all you OMC guys out there I am here because you guys are true enthusiasts with great advice.i have a 1995 21' liberator tunnel with a late 90's Johnson carbed looper on it.i am having a problem with my prop hubs literally melting from the heat from my exaust that comes through my prop hub in my coned lower unit.I have a bobs snout in the mid section where almost all the exaust is relieved, so a minimal amount exits through the prop hub anymore which is what has me baffled as to why my hubs are melting.i know these moters have been known to have fairly high exaust temps but something just isn't right.the hubs spin after I hold the engine wide open for about 30 seconds straight then boom my prop hub is spun .i have the rubber pressed in hub in my OMC shooter prop, then I have the quick change plastic hub in my Mercury trophy prop.both of which I literally melted .multiple times.the trophy prop has little plastic pieces in the vent holes that melt as well.how could the exaust possably be getting that hot?.my engine runs nice and cool and the water pump is strong.now soon after the hub problem my rear rubber prop shaft seal decided to pop out and spill about 1/2 of my gear oil out.i immediately pulled the boat out of the water and took it home after that.im assuming from the heat in my lower unit from the excessive exaust temps . Have any of you OMC guys seen this happen?? Not a lot of water flows through the prop anymore since it goes right out the snout.my lower now needs to be checke out and new seals installed.

The hole in the trim tab above and behind the prop. is suppose to divert water into the exhaust cavity to cool the prop. hub- propshaft seals. Your probably running high enough that this is not effective though. One trick you could try would be to cut a notch out of the trim tab right above the prop. where the numbers are cast into the trim tab.

[Tunnelvision1995]

Hey guys thank you so much for the replies, I checked my trim tab and what a ya know there was a small splinter of wood lodged in the tiny water pickup on the trim tab blocking the water flow. Clearly that is why my prop hubs have been overheating,I'm going to take the boat out sometime soon and run it and see how it does.

[seahorse]

Drill 1/8" hole in exhaust extension for better hub cooling








Drill out passageway to 5/16" for better water flow to hub

[billybob]

If your prop. hub melts in 30 sec.,the water going thru trim tab is not going to be enough to cool prop. hub. especially on a tunnel w/jacked up motor. you most likely have a plugged w/debris exh. adaptor. I have seen this multiple times. remove p,head and inspect adaptor for cooling holes that spray water on exh. tuner.

[flabum1017]

If your prop. hub melts in 30 sec.,the water going thru trim tab is not going to be enough to cool prop. hub. especially on a tunnel w/jacked up motor. you most likely have a plugged w/debris exh. adaptor. I have seen this multiple times. remove p,head and inspect adaptor for cooling holes that spray water on exh. tuner.

2 years old, think he solved it