120HP Force being smothered on exhaust fumes at idle

[jerryjerry05]

I've learned a few tricks over time.

 

[palerider9999]

Here’s a pic of the old mid leg seal. Installed too high and looks like it was crushed. No doubt it was NOT sealing and exhaust fumes were rising up through the mid leg and into cowl area. The one pic shows a hole where the exhaust was exiting and it would naturally rise to the mid leg seal.

 

[jerryjerry05]

Something else that just came to me: on some drives there's a block that goes across the top of the gear housing it's about 2-3" wide x 1/2"tall x 1/4" thick it's silicone'd in place and blocks excess exhaust from going back up to the cowl.

 

[palerider9999]

Finally figured out the issue. On the front side of the mid led there is a 3/4 x 3/4” vertical channel that the shifting linkage runs down from the engine all the way to the top of the lower unit. If the mid leg seal is shrunk even a small amount the exhaust gases rise up through lowers shifting rod hole and follow the shifting rod linkage right up into the cowling. I made a new mid leg seal out of 1" rubber mat material. It worked perfect to make a seal.

Another thing I did while I had the back cover plate off the mid leg was I pumped grease into the area just ABOVE the mid leg seal in the front. I put at least 1/2 a tube of it in the front center so it blocks the shifting rod channel from allowing fumes to rise up through that channel.
The goal is to get enough heavy grease that is fills that void around the linkage and stops the fumes from rising. You can’t use expandable foam because it will glue onto the shifting linkage and freeze it in place. The grease is heavy enough it “loads” up the channel and still allows the linkage to function. I think in some situations pumping the cavity full of grease might some the problem without replacing the mid leg seal.

Worked like a champ on mine and problem has been solved.

 

[puffitu]

Finally figured out the issue. On the front side of the mid led there is a 3/4 x 3/4” vertical channel that the shifting linkage runs down from the engine all the way to the top of the lower unit. If the mid leg seal is shrunk even a small amount the exhaust gases rise up through lowers shifting rod hole and follow the shifting rod linkage right up into the cowling. I made a new mid leg seal out of 1" rubber mat material. It worked perfect to make a seal.

Another thing I did while I had the back cover plate off the mid leg was I pumped grease into the area just ABOVE the mid leg seal in the front. I put at least 1/2 a tube of it in the front center so it blocks the shifting rod channel from allowing fumes to rise up through that channel.
The goal is to get enough heavy grease that is fills that void around the linkage and stops the fumes from rising. You can’t use expandable foam because it will glue onto the shifting linkage and freeze it in place. The grease is heavy enough it “loads” up the channel and still allows the linkage to function. I think in some situations pumping the cavity full of grease might some the problem without replacing the mid leg seal.

Worked like a champ on mine and problem has been solved.

Awesome info!