Magnum 18 Front Crankshaft Seal

[aaytay]

Yesterday I was mowing the yard and noticed that the 1872 began BILLOWING black smoke. It turns out the front (PTO end) crankshaft seal is toast. It sprayed almost all of it's oil all over inside the muffler-box.

After removing the PTO, I was able to spin this seal in the bore on the engine case. You can see the marks on the face of the seal where I used a couple of small picks to pull the seal out of it's bore. It came out very easily.

As you can see, this seal is encapsulated in rubber. Two questions come to mind:

1) What caused this seal to loosen up in it's bore... Is the bore somehow damaged, (it looked fine) or does the rubber on the outside edge of this seal break down?

2) What can I do to keep this from happening in the future? If it was a standard seal with a steel casing, I'd probably grease up the outside with some JB-Weld or Hi-Temp RVT before installing it.

Any thoughts are greatly appreciated. As you can tell, this is my first go around with one of these.

 

[dcalkins]

i would go back with a c/r seal .they are metal ,and use leather for the seal area ,and you can get them with double lip .David

 

[vthomley]

Art - we are expecting a step by step detailed removal and re-installation procedure.... Many thanks yous in advance!

Another option is after you've perfected this you can do the same on my Mag 18...!

 

[vthomley]

Oh I forgot, I kinda thing I have an answer for ya.

This seal fails do to the down pressure of the belt on the clutch pulley - well that's what a small engine mechanic guy told me.

 

[jchamberlin]

Art: I noticed that you qualified your designation of "Front" seal as being on the PTO end of the engine. As you dig into the manual, you will find that Kohler considers the PTO to be situated at the "rear" of the engine; they consider the flywheel to be at the "front." The cylinders are numbered starting from the flywheel and moving "backward" toward the PTO. It confused me at first, but it is just a matter of orientation.

Edit: I agree with Vince though, if you will do mine, I don't care what you call it.

 

[bjames]

The seal Kohler supplies must be junk. I hear of this problem all the time with KT series and Mag twins. I am going to try a C/R seal. P/N CR 13734.

 

[bjames]

I put a CR13734 seal in my KT17 today. I'm fairly confident this seal will last but only time will tell. It fit very snugly and is a high temp rated seal. Chicago Rawhide is now SKF but still made in the USA. You can get it at NAPA but they probably don't stock it.

http://www.napaonline.com/Catalog/CatalogItemDetail.aspx?R=NOS13734_0349835347

 

[sblunier]

Art,

Sometimes these need to be super glued into their bores. Works well, just dont mess up and take too long!

 

[aaytay]

Update: Well, Steve's post makes THREE people that mentioned some sort of a glue or sealing compound to hold these seals in place, so that's what I did...

First, I got the seal from a forum sponsor, and a can of Permatex Hi-Tack from the local NAPA and installed the seal, waited 24hrs, then reinstalled everything else (PTO, muffler, shields, etc)

After finally having a rain-free day yesterday, I can tell you that the seal seems to be holding just fine after a two-hour mowing session.

The tough part of this job was not tearing it down and installing the seal, it was cleaning up the MAJOR MESS the oil made all over everything. There was oil everywhere under the hood, as well as on the mower deck and the belts like you took a misting bottle and sprayed down the entire tractor from the console on forward!

Anyway, if anyone else has this issue, buy a new seal and a can of Permatex and you'll be good.

THE END

 

[vthomley]

So do I bring my Mag 18 over tonight....? LOL

I too have that MAJOR MESS from the oil leak.

Glad to hear you got it fixed - thanks for the info!

 

[aaytay]

Vince-
Read my last line just above the words "THE END"...

 

[jchamberlin]

Art: Thanks for sharing the story of your seal replacement. I've taken notes for when it's time to put my M18 back together . . ..

.

 

[bjames]

Yea, that's what I thought too but it only lasted about 2 years. Even the service manual says to use a sealant but I don't think a seal should fit that loosely. The SKF seal fits tighter and has a Bore-Tite coating on the outer edge.

 

[vthomley]

Thank you for this write up - my seal replacement was easy with this help.

 

[bproctor]

I recently had this problem on a mag 20. The service manual said to instal at a depth of .314 inches. I did and it was tight but not as tight as a seal usually is. Failure came within 2 hours! The next seal was installed at a depth of about .15 inches. Much tighter! I installed it just deep enough that the nubs on the back of the PTO can't touch the seal. Let it run for an hour at different RPM's, Zero leakage.

I believe oil was leaking at the outer edge of the seal not at the shaft. What are your thoughts on this?

Have any of you moved your seals deeper or shallower from spec. and has it worked?

I rrreeeaaallllyyyy don't want to take this back apart!

 

[bproctor]

6 hours and no leaks! Fingers crossed!