Help with a MERCURY 110, 9.8hp

[mightymite]

Hello All, I came home this Summer with a Mercury 9.8 . I pulled it from my truck and set it on a stand. About 10 minutes later there was about a teaspoon of nice clear 80/90 lower unit fluid under the skeg. So it looks like I may have a seal problem in the lower unit. I know some of these Mercs needed special tools etc. and I was wondering if this was one. The serial number on this motor is 3734061. I was also wondering the year and what the oil/fuel mix is.

All help appreciated, John, Member 954-295-9813

[outbdnut2]

Your 9.8 Merc is a 1973 model and the gas/oil mix is 50 to 1. The first thing to do is remove the prop and see if there is fish line caught in the prop-shaft seal. Sometimes you get lucky and fix the leak by removing the fish line. I haven’t put a sealkit in your model so someone else here can tell you what tools you need.
Dave

[mercuryspecialist]

John,

The two most common leak points are the driveshaft and shift shaft bushing oil seals, except when fishing line is present as wisely advised. The driveshaft oil seal is in the plastic water pump housing (there is an o-ring for the water pump housing to gear housing), and this does not require special tools (do however check for grooving of the driveshaft seal area). Likewise, the aluminum shift shaft bushing does not either (also has an o-ring on outside diameter), but do use extreme caution when sliding the bushing off the shift shaft to not allow the shift shaft to rise very much, or it will come out of the shift cam below, and the gear housing would require disassembly to refit. To replace the propeller shaft oil seal can be tackled by removing and replacing if the shaft is not grooved or damaged (hard chrome plated steel surface is fairly durable), but to remove and replace the bearing carrier to then replace the oil seal would require a tool, or to make one, to unthread and retorque the gear housing cover.

Regards,
Joe

[seakaye12]

If you need or decide you want to remove the bearing carrier you can use one of John McIntosh’s tools….

http://www.johnsmcintoshvintagemercuryo … u1985.html

People sometimes make their own; it hurts to spend $$$ on a tool if you’re just working on one motor.

[mightymite]

There was a decent amount of fishing line wrapped around the shaft under the prop. I just have a feeling there is another leak though. I topped up the L/U fluid using my pump bottle. I then put the screws back in and about a quarter of a teaspoon dripped out of the foot. Through the exhaust, I think. Then I put it in a test tank and ran it propless. The motor ran nice and pumped good. I put the motor back on a stand and put a cup under the fin. After two days a water and oil mixture again about a quarter of a teaspoon dripped in the cup. I’m thinking I should drain the L/U and take a look at the fluid. If it’s milky, I know I have a leak.

[mightymite]

Yep, I just drained it and the fluid is all milky. Just a thought has anybody ever tried Lubriplate 105 or corn head grease in a L/U that leaks ?

[jw-in-dixie]

I use JD corn head grease in my Merc K motors with great success. Not sure it is recommended or will work in a shift motor.

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