View Full Version : Lower unit problems

12-12-2005, 02:04 PM

12-12-2005, 08:47 PM
If you have any mechanical knowledge at all you can do this job with ease.Just take your time and lay all your parts out. And follow step by step.While you are in there if you havent had already done you might consider replacing the water pump impeller.You will be there already anyways and if the motors got some age on it its well worth the cost of the impeller.

Good Luck

12-12-2005, 09:06 PM
I would get the manuel it is more detailed.

Barnacle Bill
12-12-2005, 10:30 PM
Kits don't come with instructions. A factory manual is your best bet. Clymers ans Seloc are OK but you have to go thru them to see what applies to your motor. Sounds like your seals under the impeller need replacing. What make motor is it? Year, size? BTW, you can get good advice from people that do this stuff for a living here http://www.iboats.com/cgi-bin/ubb/ultimatebb.cgi

12-13-2005, 06:16 AM
Also go check out the forums on www.bassboatcentral.com there is message board for each brand of motor.

12-13-2005, 02:18 PM
You can also go to the marinedoctor.com It's a pretty good source for info. and I believe you can order parts from their too.

Barnacle Bill
12-13-2005, 06:17 PM
would changing the oil and putting the muffs on and running water through it, then checking the oil be a better way to diagnose the actual leak? Or is it just better to get the whole seal kit and replace it?

There are only 2 places water can get in, assuming the lower unit has no cracks. Thru the seals below the water pump and the seals on the prop shaft. Since you were hearing air coming out of the top, that sort of points to the water pump seals. If it is the water pump seals you should be able to tell using the muffs. If it were me, I would replace all of them. If one set has gone bad, there is a good chance the others might go soon. What kind of motor do you have?

I just realized I have been butting in on the Mo. board. I appologize for that. I just seen someone was having motor problems and try to help.

12-13-2005, 06:32 PM
Welcome aboard IBNFSHN, glad to have ya hehe.

12-13-2005, 08:11 PM
LOL IBNFSHN we will let ya off the hook this time. Nah just stop by any time.:p

Barnacle Bill
12-14-2005, 07:05 AM
It's a 94 Mercury 40HP. Don't worry, we are nice in Mo. We'll take advice, help, and humor from any state.

Question: when people say a cracked lower unit, are they talking about a crack that would be visible from looking at the outside of the unit?

Normally you could see it or at least see oil or water oozing out after using the motor. Usually caused by hitting something under the water. BTW, if you go here http://www.mercurypartsexpress.com/PartsExpress/HomePage/homepage.asp
and put in your serial no you can see some exploded views of your motor. Hope that helps.

12-14-2005, 05:23 PM
Ok guys, I posted this in the off topic, but I wanted to get the opinions of some guys I trust. I have issues with my lower unit, specifically water getting into the oil. I'm fairly confident that it's not the gaskets on the screws. Once I had it full, I tightened the top screw and gave it a few more pumps, and I could hear some air escaping from what sounded like the top area of the lower unit. To be sure I got it in the water at Longview Sunday and then drained the fluid. It had a white color to it.

I called Smithville marine to get a price on a new seal kit. They said it would be 45.00 for parts. If I wanted to have them do it, it would be 400.00.

My question is this: I am a fairly mechanical person who can follow directions. So I wonder, if I buy the manual and the parts, should I be confident that this can be done at home? Have any of you done this before.

mduncan62, I posted this on the off topic thread but if it was me I would work on it myself. You may go to:


Doc is good at helping you out, itís a free advice board. He even has a pay to use tech line, details on the board. I would bet that you just have a seal out of the lower unit, but a crack is possible. There are some jobs that he has how to videos on that you can down load from the board. I defiantly would give him a try before I started. I know that there are to test for the lower unit a vacuum test and pressure test to tell exactly where it is leaking.