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Engine Oil Seals

Discussion in 'The Garage' started by 5twins, Jun 21, 2018.

  1. 5twins

    5twins XS650 Guru Top Contributor

    I've started re-using the original red colored o-rings on the points/advance housings if they still look good (not all flattened out). On my rebuild, I used the black replacements that came in the Athena gasket set. They worked OK until I pulled the housings a few years later. They didn't seal back up. They were deformed, square shaped now instead of round. I'm thinking they are just plain Buna-N rubber and that doesn't have as high a heat rating as a red silicone o-ring would. The head is one of the hottest spots on the motor.
    Paul Sutton likes this.
  2. I still have the old ones, in fact I think I still have a set from the 75. Have you ever tried the O-rings from Partzilla?
  3. tzimmerm

    tzimmerm XS650 Junkie XS650.com Supporter Top Contributor

    Iowa City
    I never got around to mentioning it, and I don’t even remember exactly how long ago it was now, but I had to replace the RH cam seal about 3-4 weeks after I initially replaced them both and installed the Pamco ignition. I wish I would have taken pictures and kept track of which was which, but the original 2 that I replaced both came from the local power sports store. The thing was, one of them had been in stock for years, and had the old yamaha part #. The other they had to order, and had the newer yamaha #. If I remember correctly, they both appeared identical, but obviously the one that ended up on the RH (advance) side didnt hold for long at all. I ordered another from the same place, and it was the newer part #, and it’s been in there leak free ever since. I want to believe the old seal they had been sitting on forever was the leaky one, and that the newer seals are dependable, but since I didnt keep track of which was which, I can never be too sure. I suppose only time will tell how long these will be good.
    Paul Sutton likes this.
  4. I have just installed three cam shaft oil seals and none kept oil from seeping. I cleaned the shaft. I had and old Mike's seal, the thick one. Still leaked. I went to the Yamaha shop near me and got a thirty-year-old one...obviously leaked and then I got the new 5mm OEM genuine Yamaha part and it leaked as well. So, what are my options? Can I try mounting the seal a little further toward the shaft rather than flush with the mounting plate? What about this speedi seal thing? I never had this leak before or if I did, I sealed it and forgot about it. I am not running any cam ignition so there is no advance rod or mechanical advance weights. Whatcha think guys. You've solved every other problem I have run into.
    Oh yeah, '81 H. Hugh's CDI system ( which I love and will report on in detail soon).
    Thanks for your help.
  5. 5twins

    5twins XS650 Guru Top Contributor

    You have to press that seal as deep into the housing as you can without it hanging out the back side. You don't set it flush with the outer face of the housing. If you're already doing that, then I don't know what else to tell you.
  6. xjwmx

    xjwmx It's just the unknown. Top Contributor

    That is one of the trickiest seals. Position it so it makes good contact with the real circumference of the shaft. What finally worked for me was doing that with a Mike's seal and buffing the shaft with a Scotchbrite pad, like the kind used for household cleaning. That will also help you slip the bearings off the ends of the shaft if you ever need to. There are cheaper brand look-alike Scotchbrite clones but they are different. One side I couldn't get a new seal to work on and resorted to reusing the old one, which is still working (never throw anything away). I will take up the suggestion in this thread of filling the space between lips with grease. XSJohn replaced the spring on one with a heavier spring. He took the larger spring off an old different seal that he hadn't thrown away and cut it to length.
    Last edited: Jul 11, 2019
    Paul Sutton likes this.
  7. xjwmx

    xjwmx It's just the unknown. Top Contributor

    Do OEM seals have a retaining ridge shaped to allow them to be pushed in from outside? Some of Mike's are advertised that way.
  8. What I did is push the seal into the housing so that it stuck out the back a couple of mm and then I carefully screwed the plate in which kept the seal furthest in while still in the housing. I haven't tried the bike yet, but I am praying that this works. I did polish with scotch brite.
  9. TwoManyXS1Bs

    TwoManyXS1Bs BBQ Hunter Top Contributor

    Marlin72xs, Paul Sutton and NorazDad like this.
  10. Gator xs2

    Gator xs2 XS650 Addict

    Again. Damn you guys are good.
    TwoManyXS1Bs likes this.
  11. Exactly...that's what I was thinking last night. So, the cool thing about this issue is that testing only take a run and a cool down and then you try something else. I leaked today because it rubbed. Tomorrow, I will try a measured maximum seal seat without contact with the bearing race. And I am going to try the crazy XSJohn spring thing too. I've got seals coming out of my a$$. I can steal a spring or two. But when this issue goes bye bye, it's of to the races with this old girl!
    Grace and Peace!
    TwoManyXS1Bs likes this.
  12. TwoManyXS1Bs

    TwoManyXS1Bs BBQ Hunter Top Contributor

    Let's have a closer look at the camshaft seals, and the concept of seating them deeper to solve oil leaks.

    This pic, from Jim's overhaul thread, post #4.



    Shows that the preferred oil seal seating depth is to have the seal's backside be flush/even with the backside of the cam endcovers.

    The question is: If the oil seal is seated deeper, will its OD contact the bearing cage?

    Here's an oil seal, 40x25x5mm, and a cam bearing.

    The cam bearing's outer race ID is 39.5mm, just slightly smaller than the seal's 40mm OD.

    Placed atop the bearing, and pressed down, the oil seal will NOT contact the bearing cage.

    What DOES make significant contact is the inner lip's backside to the bearing's inner race.

    Measuring the clearance depth of the bearing cage shows 0.5mm (0.020").

    Another view, showing the backside of the oil seal, reveals a slight chamfer of its edge, and a slight chamfer of the bearing's outer race ID.

    Even with these chamfers, I was not able to press the oil seal deeply enuff to contact the bearing cage.

    What this means, based on this test of 'my' parts, is that camshaft oil seals can be safely pressed a bit deeper, if need be, without concern for contact/rubbing on the bearing cage.

    However, the seal's inner lip backside WILL be in rubbing contact with the bearing inner race. It would be prudent to ensure that there's a bit of lube on that contact face during assembly.

    Update 10/6/2019
    Member Wulfbyte encountered seal to bearing cage contact in this post.

    Post #6499.
    Last edited: Oct 6, 2019
    Mailman, Marlin72xs and NorazDad like this.
  13. TwoManyXS1Bs

    TwoManyXS1Bs BBQ Hunter Top Contributor

    Thermal expansion.

    Using 8" as the nominal width of the head, at the cam bearings mounts, and a temperature rise of about 200°F, the aluminum head will expand about 0.008" (0.2mm) more than the steel camshaft.

    This means that whatever lateral side-side movement exists at the cam during install (hopefully none if the bearings are properly fully seated), will be increased by at least 0.008" (0.2mm) when hot. The cam bearings, clamped between the head and camcover, will move outward with the head, allowing an additional 0.008" of camshaft side-side shuttling.

    To accommodate this shuttling, each seal will need to reveal at least 0.2mm of exposed camshaft end. Anything less risks loss of sealing at the seal's outer lip...

    (I need to find a picture of this)
    Wulfbyte, Mailman, Marlin72xs and 2 others like this.
  14. Wow, the depth of knowledge here is amazing.
    Thanks again.
    Wulfbyte likes this.
  15. wildav

    wildav XS650 Enthusiast

    A friend told me about an issue he once had when he replaced a seal and the oil continued to leak from around the shaft. After puzzling over the situation he replaced it with another new seal and the problem was fixed. But he couldn't understand why the first seal leaked since it was new and appeared to be identical to the first one he had installed. After closer examination he found that the raised lines on the inner surface of the seal were reversed from the original seal he was replacing and the rotation of the shaft directed oil flow in the outward direction where the original seal with lines counter to rotation caused oil to be retained by the seal. The first new seal was made with those lines backwards by some production foul up.Same part it appeared but maybe misidentified during manufacture. At any rate those lines inside seem to have a function in making the seal work properly.
    NorazDad likes this.
  16. You aint seen nothing yet!
  17. Excellent 2M! As usual! I just replaced my 7mm thick Mikes seals with the Partzilla 5mm seals about a month ago. The 7's were spitting and spraying my side covers, and probably my black levis, but who knew? So far about 1500 miles and the right side is clean, but the points side has a very slight weep. I set mine flush with the back of the cover. Time will tell. If it gets worse, I push it back a mm.
    Thanks again, 2M.
    Mailman, Paul Sutton and TwoManyXS1Bs like this.
  18. Ozboy

    Ozboy XS650 Addict

    My left cam shaft was always leaking too and i put an SKF Speedi-Sleeve on it and been perfect since.
    I put three new seal on of these two different mm thicknes but still leaked. Buy two as you may damage one installing it
    Not sure if Speedi-Sleeve will work with points tho. I have a TCI.
    I would SpeedieSleeve-Sleeve all bearing surfaces on these old girls now.
    TwoManyXS1Bs likes this.
  19. 650trader

    650trader XS650 Addict

    "ARS" is Yamaha OEM although they sometimes are marked "ARX"
    Oil seals for the Camshaft were replaced by the Original Mikes XS by triple lip ARS
    Honda Seals 25 x 40 x 7 Honda OEM Ref.# 91216-729-921 SDD replacing
    Yamaha OEM #'s 93101-25044/93102-25090
    It's possible that they are now selling Non Japanese oil Seals that cost them less
    as this seems to be the trend to increase profit which is their target.
    If you have oil spraying out anywhere you probably have other issues.

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