COMPRESSION ?

[RAT540]

CAN YOU HAVE GOOD COMPRESSION AND THE CRANK SEALS STILL BE BAD?
THANKS DAVE

[Cabindweller]

Yes You can have good compression and still have bad crank seals.

[SpitfireKing]

That must be on a Spanish Deere

CD is 100%, compression can still be high because the rings hold that, not the case or crank seals.

[snowkat79]

That is exactly what happened to my 80 TF. Only it did idle for short periods of time, and it did not seem to run at its best either. I did put about 45 miles on it before the PTO side let go to the tune of 35 psi. If I had put in the crank seals.....I would still be riding! Doh!

[Cabindweller]

I aquired an 83 Sprintfire last year. It looked to be in very good condition machanicly, and shows low milage. I tested the compression and it tested 145 on both sides I cleaned the fuel system and carb. I gave it a shot of premix and it fired right up and ran. But it would bog real bad. after I shut it down I couldn't get it to run again unless I left it sit for a few hours. The next day I discovered the clutch side seal was almost compleatly gone (worst I have ever seen). A small leak in one of the seals will often not reveal itself untill you burn up a piston. (been there done that) I major leak in one of the seals will give you more of a heads up. Hard starting, boggyness, The crankcase loads up with fuel. Never trust old seals. It is easy to check for a leak on the clutch side. Spray carb cleaner or WD40 behind the clutch on the shaft, if the idle drops or picks up you have a leaky seal. The best thing you can do with any of these older machines is change the seals right from the start. It is fairly easy to do. And will save you allot of money and agravation in the long run.

[fast823]

Since replacing crank seals is very important is there tips or trick for replacing crank seals on each kind of motor someone has done?

[harleysportster]

Follow the service manual for each model snowmobile.

[fast823]

With all the good write ups done just thought there may be one or someone would have some tips since service manuals are 30 plus years old and people usually find best practices.

[harleysportster]

Kioritz engines do not need the case split to replace the seals but most others do. Some of the Kawi engines have O rings around the bearings that should be replaced once the case is opened up. The 1980 and up Liquifire engines have the oil pump drive that needs to be removed in order to replace the seal behind that.

[RAT540]

THANKS GUYS, ARE THE SEALS EASY TO PURCHASE?

[harleysportster]

THANKS GUYS, ARE THE SEALS EASY TO PURCHASE?

Yes, Matt probably has them in New Breed Parts

[JDT]

New crank seals will be the best $10 you ever spent.

[driftbuster]

the seal will have 3 numbers on it, those are its dimensions.
The last number is the width, my Cyclone called for a xx-xx-10.
The bearing store never had a 10, or a 9, or an 8 wide. So
I bought a 7 and pushed it in the hole and tapped it in (LOTS OF OIL on seal/shaft)
Getting the old seal out isn't too bad. I drill a small hole, try a self tapper.
They usually pull out but makes the hole bigger, patience and cleanliness
work well doing this. A job worth while tho. My new Cyclone performed
well yesterday on it's first 50 mile tour/vintage meet yesterday.
Not afraid to hold that sled to the bar anymore!!

[Matt]

Another tip: make sure you have the right tools. Clutch puller and flywheel puller. The crankcase needs to be re-sealed with an anaerobic sealant that is safe for use with gas/oil.

I stock all the seals used in JDs. Just need to know what sled we are talking about and I'll point you to them.