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sfhellwig

Tecumseh oil seal replacement procedure

sfhellwig
13 years ago

I'm back. After you guys helped me repair the mower last season (needed a new coil and readjust bail switch) it gave me a few more good mows before another failure. I noticed it smelling more and more like a derby car which I thought it was just burning off old oil that I couldn't clean off. Until I looked down to see the entire cylinder bathed in oil. After looking at the cutaway from my previous repairs I believe it would be the "oil seal" as the book calls it on the top of the engine. I'm sure all of my wrestling with the flywheel didn't help it any. Question is: can it be pried out and tapped in or do I have to split the case?

I have done a front main seal on a car before, appears very much the same. But my neighbor insists that you usually go ahead and crack open the motor and do a rebuild kit. I see no point in doing that if I can avoid it. I would of course purchase the flywheel knockoff tool (couldn't ever get it off last year), a few shaft keys just in case and the seal. All of which would be pretty cheap.

Motor is a Tecumseh on a Craftsman 6.5 horse, 22" deck push mower. Tecumseh motor number 143.986500 if that helps. If anyone has links to a manual or walk through I could work with that also.

Comments (10)

  • tomplum
    13 years ago

    Well, you will need to be able to pull the flywheel. After you watch your neighbor's car head from home, you can screw a sheet screw into the seal and pull it out that way if you want. Be advised that the breather is the more likely culprit on a Tecumseh. The best way to pull the flywheel is w/ the 3 screw puller for it. OR Strap the safety bail so the brake is released first. Remove the starter cup and hardware, then screw on the knocker or thread the nut flush with the shaft. A bar put between a sturdy spot in the flywheel and a shroud bolt boss w/ the bolt threaded in plus a solid rap on top the nut/ shaft will pop them loose w/o damage if done cautiously.

  • baymee
    13 years ago

    The breather can be hard to remove. It's about a 2" hole, the rubber is hardened from age, and if you're not careful, you can get poked by a screwdriver trying to remove the thing. The breather, attached to the breather cover gets reused, if I remember correctly. So, be careful how you take it out.

  • sfhellwig
    Original Author
    13 years ago

    Yeah, I don't remember which one of the helpful fellows tried to help me knock the flywheel off. Even posted a video so I'm familiar with the process but I did not have the knockoff tool or a brass hammer so I backed off and managed to get by without removing it. So I should dismantle and inspect to see if the oil seal appears damaged or if the breather seal is leaking? Baymee, you say the breather gets reused so it would be a seal around it? The exploded view doesn't state a seal there. Just loose and leaking? Could be either one and I need to see with my own eyes what's going on under there I guess.

  • baymee
    13 years ago

    I've only ever seen one leaker over the years. It was hard to pry out and then I discovered a plastic breather underneath. I damaged that with the screwdriver, so I'm warning you about being rough with it. Just pry around the edge carefully and try to preserve the plastic part underneath.

    It's been a couple of years, so I don't remember exactly how the breather assy. was built. I just got that same mower back in the shop yesterday and the oil leak, once severe, is gone. Maybe your model doesn't have that seal, but almost all smaller engines do.

  • baymee
    13 years ago

    Here's the breather that might be leaking. Note how the breather is embedded into the seal. Be careful not to damage the breather if this is your leaky seal.

    {{gwi:127532}}

  • sfhellwig
    Original Author
    12 years ago

    Well I finally returned to the mower. And what do you know, I got the flywheel knocked off. Somewhere between the right screwdriver that wouldn't slip and a few harder hits than I expected, it came free in one piece. So I've attached a photo. Of course I cleaned it up so I couldn't tell which appeared to be the source.

    [IMG]http://i15.photobucket.com/albums/a386/sfhellwig/lawnmower-topofcylinder.jpg[/IMG]

    The seal does appear to not go 100% to the shaft but there is also virtually no play. I know they can be sneaky but this seal appears pretty solid. Also pried out the breather (thanks for the heads up on caution) and it was very loose. To the point that the assembly could rotate freely in the cylinder casing. I guess the white part with the flap in the bottom is the breather, and the black part is the seal? So if I could find the seal this could real easily be the culprit. I mean, if it's that loose I can see why a lot of oil would come out while running. It's basically an oil flinger with a loose cap on it. Any suggestions on sealing it without a new seal? Would super Black RTV work or be too much of a stretch. I have seen the difference between old and new piece on a valve cover plug on my truck. Night and day, I just don't want to wait for several days on the part.

  • tomplum
    12 years ago

    You really should replace the top seal, breather kit and dipstick seals. The seal not sealing the shaft is a clue. These top mount breathers can turn into little oil pumps if you are venting. If there are signs of oil leaking at the sump, its probably tossable sorry to say.

  • sfhellwig
    Original Author
    12 years ago

    So you are saying should replace all of them? Maybe if I could find a place that sold all three, otherwise I got burned up on shipping last year everytime I had to order something new. I did the dipstick seal last year, doesn't seem that it has lasted well but it is there. I was thinking of replacing the breather seal but everything I find is not the exact exit tube that I have. Many are not the pop in like baymee shows and the ones that are, have the very long tube on it. Well since I don't feel like waiting on a part to find out it was wrong, I went ahead and put it back together with a little black RTV around the breather. If that was the leak, it won't be any more. If it's the oil seal, well at least it's cheap. Didn't have a chance to try starting it last night, hopefully it will start so I can find out if I fixed my leak or not.

  • sfhellwig
    Original Author
    12 years ago

    It's about time to start a new thread because it obviously isn't coming from the top of the motor. After sealing the breather up with RTV I re-assembled and even managed to get it started. Pushed it back and forth a couple times and was real happy. Then I could smell it. Then I could see the smoke starting to come from the muffler area. Put it away to tear back down when I had a chance. The entire top of the motor looks about the same but I can see a particularly oily area under the coil. So here is the pic

    [IMG]http://i15.photobucket.com/albums/a386/sfhellwig/oilymess.jpg[/IMG]

    I pulled the muffler and it didn't seem an oily mess itself. Thinking maybe a valve I thought I could try a compression test. The oil that is pooled up is in an isolated place, I don't see how it got there. The spark plug looks pretty ugly for being put in last year. I'm afraid for the isolated area that I may have a crack in the cylinder. Sounds like a chance at least. Maybe a compression test will show this such as when pressure testing a cooling system. If it needs rebuilt I think I may be up for that but a cracked cylinder means she's done for. Any suggestions? I'll see if I can borrow the pressure tester from the store and see what happens but it will likely take a few more days for those results.

  • tomplum
    12 years ago

    How do you know that the breather is working? Isn't there a rubber disc valve in the bottom? I suppose that you could get up close and personal w/ the tube that is coming off the breather blow/ suck and see if air passes out and not in. On these all your bases need to be covered and if you are building pressure, oil will find its way out. My best suggestion at this point is to degrease this thing complete, run it again and see what you can see.