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1982 25HP Yamaha Mariner prop shaft seal help

B

Brandon Lang

New member
Hello all,
I am seeking help and info on possibly replacing the prop shaft seals on my Mariner. Got some gear oil coming from behind the prop due to (I think) some fishing line getting in there. After taking the prop off I dug it all outta there and then ran the motor with earmufs on and didn't see any leakage but left everything off overnight just in case. Nothing came outta the front seal but some oil seeped out from behind. I figure that I have to either think it's the inner seal or the O-Ring. The Cover Nut comes off easy enough without causing any damage because of little or no corrosion (very low hours). Where do I go from here? Is it something simple or am I going to cause bigger problems if I try and fix myself?
 
Is there any water in the gear oil --------And you may not realize that some oil / leakage from the exhaust is normal on a 2 stroke.---Yes it is !
 
It isn't milky at all...but, it's never leaked before until I got fishing line all wrapped and melted behind the prop and it's definately gear oil judging by the smell. It just started the last 2 trips out.
 
*UPDATE*

Okay. I just got home from work and so went out to the garage to mess with it. The oil that leaked this time is black and has a bit of a fuel smell to it. The other oil before I cleaned up the fishing line mess was definately gear oil. Perhaps what came out now was leakage from the exhaust as you suggest. I already stunk up my garage a couple times with this and my wife has forbidden me from working on it in the attached garage lol. I'll have to wait till tomorrow after work to drain the gear case oil and see what comes out
 
I think yer correct. I kinda want to change the seals anyway. After I get the seals and IF I CAN FIND THE O-Ring, I'll drain the gear oul and then I assume I just use a puller to get that carrier out? Am I missing a step? Anything I need to know before hand?
 
Get yourself a Seloc's manual for Mariners.

I haven't worked on one of these Yami/Mariners in a number of years now (have probably all died of old age in my piece of Canada) but do remember them being a "booger" to work on, at least the gearcase.

They have shims on the gears that you don't want to mess with unless you have to. There is an "oil seal" in the rear of the bearing carrier where the propshaft exits (looking at the prop) which can be easily replaced. The carrier o-ring is actually on the face of the carrier (not around the carrier itself like it is on Merc's) - so that o-ring sandwiches between the face of the carrier and the thrust washer which is pressing against the reverse gears "shim" - giving me the willies just thinking about it.

That's why I say, get a manual "before" you start picking at this.

Also, most of the parts in there are "no longer available" - so really don't mess with something unless you must. One "ooops" and you have a 120 pound paperweight.

If you are certain that it was fishing line that caused the issue it is "likely" that it just got to the oil seals where the propshaft exits the carrier. To get at that o-ring they would have got past the carrier completely.

Minimally evasive surgery is probably your best course with this particular motor....
 
I appreciate all of the help. I am absolutely going to order that manuel payday...found it on ebay. I'm also gonna tread very carefully. I think I did in fact get the gear oil leak cleaned up by getting the line out and what I saw yesterday was just exhaust sludge from running it at low RPM's. It hasn't leaked a drop since then. Plan at the moment is to put it all back together and then drain and put all new gear oil in it. Then I'll monitor it over the next few trips and make sure that it isn'the leaking. Then...if it is...I'll study the book and also consider leaveing changing the seals to the professionals
:)
 
Well I put everything back together and made sure to use some anti seize on the carrier nut threads. I then drained the gear oil and there was definately no water in there...just old oil that needed changed. I refilled it and am very confident that getting that line out cleared up my leak and the other was just exhaust sludge. I'll keep a close eye on it over the next few trips. Thank y'all so much for all of your help and advice :)
 
If need be you can change the propshaft seals (back to back seals) without taking it apart. Pull the prop and screw sheet metal screws into the seals and pry them out. Putting the new ones can be a little tricky find a pipe the correct size to press the new seals back in. A real light coat of loctite on the seat is all thats necessary apply it with a Q-tip careful not to get any on the shaft. A little oil on the propshaft will lube it for the initial spin up.
 
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