Lower unit oil fill/vent plug seals

[Glastron Boater]

I noticed the factory lower unit fill and vent plugs have a plastic/Teflon gasket seal on the plug.

Well my fill plug is looking a bit cracked and I'm wondering if it's OK to replace it with a regular O-ring or something else.

If the plastic is best, where can I get one?

Thanks in advance.

 

[Yegboats]

12-19183 3 is the mercury part number for the seal. Any merc dealer will have these. If the drain screws are in rough shape 79953q04 it will come with a yellow 26-830749 seal. either will work.

 

[roscoe]

Gearcase drain and fill screw gaskets, are single use. Need to be replaced when changing the lube.



You can buy 2 for a dollar plus shipping on line.
Or go to a Mercury dealer, and they will usually sell you a dozen for a couple bucks.

 

[jerryjerry05]

The drain / fill plastic washers should be thrown away.
Replace with the Mercury fiber washers.
Your mating surface won't work with an O-ring. It will just smoosh out or break.

​The actual drain plug (on most Forces) has an allen headed set screw.
​I use carb cleaner on it and on the threads then as much thread tape as you can get on it.

​Sometimes the set screw weeps and allows water in.
If the oil isn't cleaned up it seems to leak more???

 

[Glastron Boater]

First fluid change before taking the boat out, lower unit had a bunch of water.

Put new fluid in it, took the boat out for a short test trip.

Checked the fluid the next day, fluid was nice and clean. Took boat out another short trip.

Checked again, still clean clear fluid.

I'm still using the plastic gaskets the boat had originally.

I need to find a local boat parts store.

Thank you for parts numbers, I will probably order a good amount to stock up.

 

[jerryjerry05]

When filling: I fill till it comes out the vent, then fill in the vent till it comes out the fill side.
It takes more oil but I haven't had any trouble in almost 30years.

 

[Glastron Boater]

Good tip JerryJerry05. I don't mind using more oil. I don't want any problems with it. I filled it until it came out of the vent, closed the vent, then gave it an extra little bit until it came out of the fill and quickly plugged it. May be the same results/amount in the end.


how often should the fluid be changed? Every year? Currently I'm just looking at condition and make sure no water is mixed with the oil before I take it out.

 

[jerryjerry05]

Since my lowers always seemed to weep a bit I changed a LOT.
3-4 times a year but I used it a LOT

 

[Glastron Boater]

I want to go out every Saturday. So far, been out 3 times... 3 weeks ago, Saturday and Sunday. Skipped the next week. And Saturday last week we were out.

skipped this weekend. Too busy.

And usually we are out at least 5-6 hours. High and low speed in freshwater lakes.

 

[jerryjerry05]

I checked mine after 2-3 trips and changed it anyway.