'81 LF Project Revived

[JDboy99]

Been a few years, but I seem to have a renewed interest in getting my old girl running again.

Question is...how long are crank seals good for? They were installed 7or8 years ago and the sled never ran on them. The head gaskets ended up being problematic and I lost interest...would you tear it apart again and replace them or run it?

Thanks for all the great info...as usual!!

KV

[ihengineer76]

Personal opinion, but I believe seals are cheaper than new pistons and jugs. If you have any doubt on their condition, then why risk it?

[trailfire runner]

Change the seals. alot of other guys on here will say the same.

[JD600]

Been a few years, but I seem to have a renewed interest in getting my old girl running again.

Question is...how long are crank seals good for? They were installed 7or8 years ago and the sled never ran on them. The head gaskets ended up being problematic and I lost interest...would you tear it apart again and replace them or run it?

Thanks for all the great info...as usual!!

KV

Actually, In my opinion, i'd say they are still good. Modern rubber compounds are a lot more forgiving than those of 35-40 years ago. The other thing to remember is that what makes these seals brittle over time is the heating and cooling cycles of the engine temps. Since this engine has never been ran, and i assume since it has been a project, it has been somewhat well stored since the seal replacement, i wouldn't worry about changing them. Its a lot more work to change the seals properly in this motor than any other Deere sled engine. This is, however, only my opinion. I'm sure others will have something to say.

DE

[PolCat]

I would run them. How old are they when you buy them from the parts store?
I've got old JLO's that are still running original seals.

[AirborneX4Special]

It's almost a knee jerk reaction around here for eveyone to recommend new seals on a Kawasaki engine because they were notorious for failure. If the engine has never run and the installation was done correctly, I'd be inclined to leave them. The heating/cooling cycles coupled with normal oil exposure followed by an extended idle period is what dooms most any bearing seal, especially vulnerable Kawasaki ones. It's almost as if the seals, once exposed to oil, need a repeated oiling to retain functionality.

[ljm]

I going to weigh in here with a question.

Is the motor in the sled?

If the motor is in the sled I would run them but watch the plugs close. If it seems to be running reaaly good shut it down and check the plugs

Is there oil in the gearcase?
If so the pto side seals should be fine

[kenwaters]

If your head gaskets leaked, then you will benefit from taking the jugs off, removing the studs from the jugs, and lapping the jugs and the heads for a better seal. When you have the jugs off, drizzle some two stroke oil down the lube ports for all of the bearings. This extra oil will lubricate the seals and the center labyrinth seal. Use a good gasket cinch when re-assembling the top end, and hopefully your leak will dissapppear.

[PolCat]

Is there oil in the gearcase?
If so the pto side seals should be fine

What am I missing here? I have been working on snowmobile engines for 30 years.
The only oil in a 2 stroke SNOWMOBILE engine is the oil in the gas/oil mix. Where is the gearcase oil?
The chain case is the only place that I can think of that would have gear oil in it, which is not connected to the motor.
Maybe I will learn something today

[JD600]

The kawasaki powered Liquifires have an oil bath gear case on the PTO end of the engine that drives the oil and water pumps. This case is filled to the proper level with ordinary motor oil.

DE

[PolCat]

See that I did learn something new today:)

[Matt]

Lack of oil on those seals would be my only concern. If the case was fogged, then I wouldn't worry, but if everything was dry, it's possible for them to dry out.

[JDboy99]

Sorry guys, been away for a few days...Thanks for all the great info!!

Well, here is the whole story...sorry for those who remember it from a few years ago...it will likely bore you to death...

I bought the sled, rode it twice, and it broke a belt and ran away on me...major redline.

I tore it down, replaced all the seals, one piston/cylinder, and put it back together.

I couldn't seem to get the head gaskets to seal and consequently couldn't get it to run right.

It would fire up, but wouldn't make enuf power to move the sled...realized it was flooding itself with coolant.

Tore apart the top end again, found the heads were warped, planed them and that's where the project sat...unassembled.

So I suppose i can't really say it hasn't run on these seals, but to say they have any miles on them would be inaccurate.

So now I am basically questioning the whole thing...seals, center bearing, head gaskets, everything.

As it sits, the motor is out of the sled, the heads loose, ready for install and I have a complete gasket/seal kit sitting on the work bench...winderosa kit.

If I replace the crank seals, I assume the cases need to be split, right? Also, how long do the center seals last? Should this project stay where it is, on the shelf??

At the end of the day, I am a fan of anything with a Deere on it, I have a pretty decent condition chassis with a good track and I am sick of it doing nothing! I need to either fix it or dump it, but I don't want to sink a pile of money into it...just want it to run!

Again, sorry to bore you guys, just need some direction.

KV

[JDboy99]

BTW, what kind of engine oil are you running in the side gear case? 5w30, 10w30, Synthetic?

Thanks again,

KV

[JDboy99]

Sorry, one last thought...

I have read here numerous times that the NOS gasket kits are the best... Those would be all minimum 28 years old, still new in the box, no?

Then my seals in the motor that are approx 8 years old should be ok, no?

...or did JD continue building parts after 1984??

Regardless, I can't imaging any NOS LF parts are less than 20 years old...

Thanks,

KV