MarineEngine.com - Your online store for all types of marine engines and boat parts.
PHONE ORDERS
Monday - Friday
9:00 AM - 5:00 PM EST
Click for TOLL-FREE Number
Online Checkout
Special $9.95 Flat Rate Shipping
(800) 209-9624 | Home | Contact | Shipping | Returns | Cart View your shopping cart.
Part Number Search
Shop by engine/drive part number.
Original & matching parts for sale.
Manuals & Accessories
Shop by description, item number
or manufacturer's model number.
Boat Repair Forum Boat Repair Forum   Boat Video Gallery Video Gallery
   
Get instant online access to repair manuals for your Mercury / Mariner outboard. Online Manuals
MercuryMariner
Order printed Mercury / Mariner service manuals — shipped to your door! Printed Manuals
MercuryMariner
Use engine diagrams to find & order parts for your Mercury / Mariner engine. Engine Diagrams
MercuryMariner
Find parts quickly with Mercury application guides. Quick Parts Guide
MercurySierraCDI
Results 1 to 9 of 9
  1. #1
    Join Date
    Sep 2010
    Location
    louisiana
    Posts
    76

    Default Changing outer seal in lower unit

    I've got a lil water in the my lower unit oil. Is it a big job to change the outer seal? Are they any 'traps' that I should be looking for?
    Thanks

  2. #2
    Join Date
    Sep 2010
    Location
    near warrenton, Va.
    Posts
    3

    Default Re: Changing outer seal in lower unit

    are you talking about the propshaft seal or the hub o-ring
    they dont usually leak unless disturbed
    most problems come from the shift shaft seal or input shaft seal under the water pump
    would be best to take lower unit off and have pressure and vacum tested to be shure

  3. #3
    Join Date
    Sep 2010
    Location
    louisiana
    Posts
    76

    Default Re: Changing outer seal in lower unit

    A friend told me someone he knew had changed the prop shaft seal, and it stopped the water in lower unit oil problem for him. His is a Yammy.
    So before I took it in, I was inquiring if maybe I could do it on my Mariner and save myself a few bucks.
    One thing I noticed when I changed the oil last week was that the last set of gaskets I got do not fit real tight on the "plugs" that go on the vent and drain. Think this could be part of the problem?? Thanks handyman for your response...BF

  4. #4
    Join Date
    Jun 2010
    Location
    Queensland Australia
    Posts
    193

    Default Re: Changing outer seal in lower unit

    I would suggest that if you are able to change the prop shaft seals you are capable of replacing the others. I'm very new to outboards but since you mention your friend's mate's Yammy, and also that you have a Mariner, I am assuming that yours is a Yamaha built Mariner (like what I have). I am in the process of replacing the water pump gaskets and the seals in the top of the lower leg assembly. Mine has an o-ring and an oil seal for the cover that the lower shift rod protrudes through (very easy to change both), three gaskets in the water pump assembly (not to seal the lower leg unit just the water pump assembly), as well as an o-ring and two driveshaft seals for where the driveshaft exits the lower leg assembly and enters the water pump assembly. The seals (2) in the bearing carrier (prop shaft seal) looks to me to be the hardest to replace but I could be wrong. The Yamaha dealer I got my parts through said it can be tricky getting the prop seals out without damaging the alloy bearing carrier - he might just be looking for work but he struck me as genuine - and if they aren't leaking he wouldn't mess with them. I know they aren't leaking now as the engine has been sitting unused for years and a lot of oil came out when I drained it (not milky either so is promising).

    I wouldn't be concerned about the gaskets (fibre washers I think) not being a tight fit on the "plugs" (bungs, etc). They are designed to seal between the under side of the plug head and the flat machined surface of the lower leg (gear housing) under the gasket, not around the threaded area. If you replaced them making sure that no grit came out of the gear case they should be fine.

    I would look at replacing the oil seal and o-ring for the plastic/nylon cover around the top end of the lower shift rod, and the o-ring on the underside of the water pump assembly for a start (easiest to sort out) and inspect the oil seals around the drive shaft. Maybe tip the lower leg upside down and see if oil comes out through there with the water pump assembly removed.

    I'm no mechanic and I have had very little exposure to outboards, check what others post also. You probably should be a little more specific about what outboard you have too, serial number is best but hp and year would suffice (mine is a Mariner 55hp - 2 cyl 2 stroke, serial starts with 663.
    Last edited by wynjim55; 09-02-2010 at 09:58 PM. Reason: added details of my outboard

  5. #5
    Join Date
    Sep 2010
    Location
    louisiana
    Posts
    76

    Default Re: Changing outer seal in lower unit

    Thanks, jim55 for responding to my request for suggestions. My engine is a '95 150 HP Mariner.
    I have not had any dealing with any work on the gears and seals on the lower unit. I have changed the water pump, but have not and will not attempt any work inside the drive assembly.
    Found some old records and had all the seals changed 5 years ago. I think I may have time this weekend to pull the prop and look see whats staring me in the face.
    I have no knowledge of a Yamaha built Mariner.
    ...BF

  6. #6
    Join Date
    Jun 2010
    Location
    Queensland Australia
    Posts
    193

    Default Re: Changing outer seal in lower unit

    Yamaha built Mariners are old and will be completely different to yours. All the parts I mentioned are at the top of the lower leg assembly on old Yam-iners, I don't know about the newer stuff. I found the information in part number books and workshop manuals allow you to see where problems could originate from, if you can get your hands on these for your engine you will be miles in front of where you are now.

    Hope you find it is something easily and affordably fixed.

  7. #7
    Join Date
    Sep 2010
    Location
    louisiana
    Posts
    76

    Default Re: Changing outer seal in lower unit

    Well, I took the prop off and guess what.....About 5 feet of mono on the shaft...Kinda of think thats got to be part of my problem...The friend and his friend will come and get me and we go to breakfast one day soon and then we will change out that seal...Hope that fixes the invasion of water...
    Something different happened when I put the prop back on. The star type nut keeper didn't line up in the slots like before. Either its a lil tighter or looser. I think I'll try it tomorrow to see what's up with that...Boats, don't ya just love em!!! BF

  8. #8
    Join Date
    Jun 2010
    Location
    Queensland Australia
    Posts
    193

    Default Re: Changing outer seal in lower unit

    Sounds like you've found the culprit, hope that sorts it out for you.

  9. #9
    Join Date
    Sep 2003
    Location
    New Tripoli, PA, USA!
    Posts
    12,436

    Default Re: Changing outer seal in lower unit

    If you and your friend are clever, you might be able to change that seal without pulling the unit apart. Drill a small hole or two in the seal body, screw in a self-tapping sheet metal screw, and gently pry the seal out. Then press in a new one.

    Jeff

Similar Threads

  1. Changing lower unit shaft
    By texangator in forum Yamaha Outboard Forum
    Replies: 0
    Last Post: 08-10-2009, 04:20 PM
  2. 8HP MARINER OUTER PROP SEAL
    By anddoh in forum Mercury Mariner Outboard Archive
    Replies: 7
    Last Post: 04-30-2009, 09:40 PM
  3. Changing lower unit oil on a 275
    By tim the toolman in forum Volvo Penta Gas Archive
    Replies: 14
    Last Post: 04-20-2008, 08:39 PM
  4. Changing Lower unit oil
    By jabaker007 in forum Johnson Evinrude Outboard Archive
    Replies: 3
    Last Post: 05-14-2007, 05:45 PM
  5. Is there a method of changing lower unit oil
    By scumbuster in forum Archive 2003-2009
    Replies: 1
    Last Post: 07-14-2003, 10:05 AM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •