Yet another change your crank seals post

[Sprailfire340]

I finally got around to replacing the crank seals in my 78 LF 440 tonight. I purchased it last spring from a friend who had just taken it for 25+ mile ride and it ran great. I was SHOCKED at what I found.

[Sprailfire340]

Once I got it on the bench it took me about 2 hours to tear down and put back together. Seals cost about 3 bucks each. Pretty cheap compared to burning it down. I like the looks of the new seal much better. GOOD LUCK

[I500]

Mitch

Is that my old sled?

[Sprailfire340]

It sure is.

[I500]

Bought that sled 3 years ago from unknown party , Put a new CDI on it. Fired right up and ran great and drove about 800 miles on it. Never missed a beat...................That is one tough sled.

[Sprailfire340]

That's what you keep saying and why I was so surprised to find what I did. The old seal literally fell off the crank. No prying necessary. Hopefully a good seal doesn't screw it up its mojo. It's going back in the sled very, very soon.

[JD_Sledder68]

I have a 78 LF 340, how hard was it to change the seals in yours? Is is similar to seal changes in the fire series engines? Never had one of these engines apart yet.

[harleysportster]

It's easier than the Fire-Series. There is no need to tear down the bottom end. The service manual gives instructions and dimensions of using a square block of wood to drive in the new seals. Use a seal removal tool to pop them out.
-Remove the primary clutch for PTO side
-Remove the fan tower and flywheel on the MAG side
It's easier to work on the engine on the bench but it can be done in the sled.

[JoeRainville]

Mitch,

Thanks for posting this for all of us to see. Any vintage sled with original crank seals needs to have them replaced in my opinion. I've torn down 8 year old snocross sled motors to find the seals shot, much as less 30 to 40 year old Deere's. I am guessing a typical seal is good for maybe 10 to 15 years.

-Rainville

[HoosierDeereMan]

I just replaced the seals in my 78 340 Liquifire. I did the mag side first as I new it would be a bear. I did it in the sled. I pulled the exhaust, water pump cover, and recoil. On the 78 the radiator is kind of in the way. I was scared to death I was going to poke a hole in it while replacing the seal. The flywheel cover that the recoil bolts to doesn't leave much room to access the seal with a seal puller. It's tight quarters. Of course you have to work around the stator and trigger hanging there loose while you do it. I managed to pull the rubber grommet that protects the wiring through the engine case halves while wrestling to getting the old seal out. The new seal was a challenge to get started. The seal was round but the case halves seemed oval. I liked to never got it started straight. Once the seal was installed I had the task of getting all the wiring neatly tucked back inside the rubber grommet and stuffed back into the case halves. That is no easy task! When you install the trigger and stator you have to very easily work the excess wiring back through the grommet with knocking it out again. I had to pull the CDI off to gain better access to pull the wiring back through.
The mag side was a piece of cake. My clutch came right off. I had a harder time getting the seal protector to come loose. All together it took me about 5 hours to replace the seals. Neither of mine looked bad. I used Winderosa replacement seals. They are a double lip seal were the orginals were a single lip seal.

Troy

[cledussnow77]

Are the seal pullers the same for all the sleds or is there a difference between the fire series and the older sleds . And where could I find one for cheap . Thanks Ed

[Sprailfire340]

You can use a mid-size screwdriver. Push it through the seal (will take a nudge from a hammer to get through the metal liner of the seal) and then a twist and the seal should pop out. Just be careful not to drive the tool too far through the seal and into the bearing behind it. There is less than 1/2" or so of room back there. Something like this should work too although I have never used one.
http://www.amazon.com/Crank-Shaft-Crank ... 08-6142731

Personally I'd op for pulling the motor. Troy said it took him 5 hrs to do it in the sled vs me a short 2 hrs on the bench and this was the first 1st gen LF I've done. I think you'll save time in the long run even with pulling the motor first and be able to do a better job. Just my thoughts, but as said before it can be done in the sled.

[JD_Sledder68]

Cool. Thanks for the info guys. I will pull the engine, replace the seals, and put a newly wound stator in while I am in there.

[400brian]

I have a 78 LF 340, how hard was it to change the seals in yours? Is is similar to seal changes in the fire series engines? Never had one of these engines apart yet.

The other thing is the fuel pump. The 78 LF has the pump bolted on under the intake manifold. Pretty much impossible to remove without removing engine. I'd rebuild the pump while you have the engine out.

[ChickenRat]

Brian is right on the money there. Change the fuel pump if you have the motor out as it is a pain in the arse to get to otherwise.

Robb