Jump to content

Unofficial Home of Old Simplicity & Allis-Chalmers Garden Tractors

MikeES

M20 Blown Oil Seal - UPDATE!

Recommended Posts

MikeES

See update below.

On another thread about how much snow everyone is getting,   I commented on how I lost an engine while just finishing up 12" of snow, with another 12" coming the next day.  I was blowing with the  7120 (7119 with a M20), when it started smoking, shut it down and oil all over the place.  Looking at the evidence I was hoping for a blown front seal under the flywheel.  (Transferred the cab and snowthrower to a spare tractor 920 gas).

Finally got to the  7120 today and I lucked out, my diagnosis was right, had less than a pint left in the engine.  Popped a new seal in (did coat the outside with a little Permatex Ultra Black to keep it in place) and started the clean up.  Oil is everywhere, just like spilled milk, I lost a little over a quart, but I swear I have already clean up a couple of gallons of oil.

Here's a picture.

IMG_2047[1].JPG

Edited by MikeES
  • Like 1

Share this post


Link to post
Share on other sites
Brettw

I would recommend checking the breather assembly.  I am pretty sure the M20's had the new style breather, but maybe just check to make sure it's working properly.  The few times I had a seal blow out of a KT series, it was the breather causing the back pressure that forced the seal out.  Might not be the case with your M20, but something usually is behind the reason the seal popping out.

  • Like 1

Share this post


Link to post
Share on other sites
phillobbezoo

I have a tractor with a m20 waiting for the same fix. Mine was cause to backfiring at shut down, I was informed to late that it should be shut down around 1/2 throttle. 

Share this post


Link to post
Share on other sites
Brettw

Depending upon the age of the engine, some of the Magnums have the solenoid at the carb.  If you have a electrical wire going to the carburetor it has the shut off solenoid and should be shut down at WOT.   The solenoid stops the fuel, and the engine spinning at WOT purges all fuel vapors from the cylinder and exhaust system; to help eliminate the backfire issue.  The non solenoid should be shut down after a few seconds at idle.  I know it's hard to get used to the solenoid setup and shutting down at full throttle, but that'd how they function. (I've had a few good rifle reports myself!)

Share this post


Link to post
Share on other sites
MikeES

This engine originally had the “umbrella” valve breather, but I changed it out to the new reed style.  I also upgraded this engine to an old KT adjustable jet carb, no solenoid.  Never any backfire, and very little blow by, I did check the breather, and everything looks good there.

It was probably just bad luck. Bad luck comes in threes and this was number 3 for the week. 🙁

Share this post


Link to post
Share on other sites
MikeES

Update on M20 oil seal.  I checked the breather and everything else but it showed no evidence of excess blowby.  I put the engine back into the tractor, and gave it a hard work out blowing 8" of heavy snow.  2 days later I was blowing 5" of medium density snow and it BLEW THE AGAIN!.

I took the engine out and the new seal looked just like the picture above.   I put the seal back in, this using Permtex aviation form-a-gasket.  But before putting the engine completely back together this time I ran it on the bench using the "rubber glove test", which I think came from Al Eden.   This is a test where you remove the oil filler cap and put a rubber glove over the fill and run the engine.  If the glove quickly fills with air (blows up) you have excessive blow by, if it slowly fills with air you have some blow by, if it does not fill up or gets sucked into the filler you have no blow by.

Well my test the glove got sucked into the filler pipe.

So what the heck is blowing out the seal?  Anybody have any other ideas?

Share this post


Link to post
Share on other sites
PhanDad

WAGs for consideration:

1) Oscillating shaft (bad bearing?) grabbing one side of seal and slowly working it out.  

2) Mis-aligned bore such that seal isn't centered and tight side pushes seal out.

3) Too much end play and when shaft goes back and forth pushes seal out.  

Ran this way from factory because seal was "glued in" with some sealant.

Hopefully someone will provide an answer or at least a SWAG,

 

  • Like 1

Share this post


Link to post
Share on other sites
victorsnc

When the second seal failed, did it push out of the block recess EXACTLY like the first one?  Same distance out?  Same quadrant of the circular bore of the recess?

Share this post


Link to post
Share on other sites
MikeES

Seal pushed out the same as pictured above except at 12 o’clock instead of 2 o’clock.

I looked at the shaft, clean and true, the flywheel turns true.  The seal does not push into the block easy, you can even get it started with your fingers, need a tool.   With permatex it was much harder to seat (1/32” below the block face) the seal than with the silicone.  Hopefully it will hold it, plus I gave it 3 days set up.

Share this post


Link to post
Share on other sites
RAC

Been down this road with the K341 in my cadet. Solution was to finally go to NAPA and cross it out to a seal with a metal outer circumference instead of the rubber coating. Problem Solved!

  • Like 1
  • Thanks 1

Share this post


Link to post
Share on other sites
MikeES
On ‎3‎/‎22‎/‎2019 at 9:24 AM, RAC said:

Been down this road with the K341 in my cadet. Solution was to finally go to NAPA and cross it out to a seal with a metal outer circumference instead of the rubber coating. Problem Solved!

I'll keep that in mind IF I have to do this again.  They say "3rd time's a charm".

The seal that popped out was rubber coated and I am pretty sure it was not orginal (I know this engine has been overhauled before) the one I put in was also rubber coated.

Edited by MikeES

Share this post


Link to post
Share on other sites
MikeES
On ‎3‎/‎23‎/‎2019 at 1:44 PM, GregB said:

If the case was split, maybe they put to much goop between the case half's changing the id the bearing press's into ?

 

 

That is also a possibility, but the engine has had many years of use since that overhaul, my guess is over 12 years ago.   I couldn't guess the hours with the PO, but I have used it for 3 years mowing and snow throwing. 

Share this post


Link to post
Share on other sites
RAC

See a lot of people ask that question... Backfire really has no impact on crankcase pressure. Almost always happens when one or the other valve is open allowing pressure to escape the cylinder (either out muffler or carb). If you think about it for a moment, more cylinder pressure is built every time the engine fires while running. Besides, the backfire is isolated from the crankcase by the piston and rings so there's no real additional pressure on the crankcase seals during a momentary backfire. Less probably. Backfire damage to muffler or carb... maybe. Case seals or gaskets, nah.

Share this post


Link to post
Share on other sites
RAC
27 minutes ago, tadams said:

Back fires are also hard on flywheel keys 

Mmaaaybe...... Which came first, the chicken or the egg? In my experience it's usually the bad key that causes the backfire not the other way around. A backfire technically takes place either in the intake or exhaust passage. Neither of which can exert a counter acting force on the crank to shear the key. Now... If the key is already shorn such that the timing is WAY advanced then you can have preignition that would try to stop crank rotation and move things further. Sorry bored today!

 

  • Haha 1

Share this post


Link to post
Share on other sites
colincox1

Hi, Mike,  I am sorry, I am not adding to your solution. However wondering did you overcome the continued blowing out of the seal, and please (as I have the same issue, but , only blew once but have yet to get to fixing it) can you let me know the seal you used and where you got it from, approximate price.  Good luck for the future,  Best regards Colin 

Ps mine blew while snow pushing with a blade, chains .  Got me thinking similar conditions  could they contribute to the cause of the problem , Or coincidence? 

Share this post


Link to post
Share on other sites
MikeES

Colin, so far so good with the seal.  This time I installed the seal with permatex aviation form-a-gasket.  This is a dark brown very sticky glue like substance.  The seal I used was from an overhaul gasket kit, so it did not have any individual packaging for brand name. 

I would recommend using a "glue" with the seal, I also liked RAC's suggestion of a metal case seal (both seal were the rubber coated style.

 

  • Thanks 1

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Who's Online (See full list)

    • John Dyer
    • steve-wis
    • PhanDad
    • Chris727
    • fishnwiz
    • DaveTenney
  • Today's Birthdays

    1. JoggerFogger
      JoggerFogger
      (49 years old)
  • Recent Status Updates

    • Paul M.Murphy

      Paul M.Murphy

      Hello glad I got on this site. I hope to upload a couple of photos of my Simplicity Broadmoor 
      Model 707 Tractor. I have replaced all the belts on it and installed a new ignition switch.
      Have a mower deck which was in poor shape , repaced a couple of bushings and welded the
      deck where there was some holes. The tractor and mower deck came from a friend and the 
      mower deck metal was getting pretty thin. Some new metal was put in it and we also undercoated the underside of the deck. This was done by my friend Greg Toulman.
      I have not put the mower deck on the tractor yet, waiting for Greg to come home and give me a hand. Can you please tell me if there is a manual for the mower deck and where I could get one.
      I would also like to get some moon wheel discs as well.
      I will try and down load some photos of the tractor when my wife shows me how to. 
      I really love driving this tractor and also how well it is made compare today's tractors, especially the flexible rear end and the rollers.
      Tell the next time 
      Paul
       
      · 8 replies
    • jbrooks

      jbrooks  »  Talntedmrgreen

      Josh
       
      folowing  this from a link at the downloads.  I just rescued an AC 920 with the lambodini diesel. I can' t download  yet .  Where did you find the PDF copy you posted. . I would like to figure out how to adjust the injection pump. 
      I assume it's a bosche, correct
      · 0 replies
  • Adverts

×