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Discussion Starter · #1 ·
Going through my seld, and checking everything. I'm about to redo the top end new everything. But, I was wondering, I had 90 psi before, I am anticipating 130 + after. Will that put more pressure on the crank seals, and I also thought maybe I was already lossing psi's through the seals before, so does anyone have a good way of checking then before I put her back together? Thx again..I'll tell ya, I love this site, I learn more and more every day.. I've always loved sledding, but never really worked on em that much, but now I look forward to it and confident, because I know where to get answers. As I learn I will pass it on myself. Plus I just bought a 96-98 polaris manual on line, right from the polaris headquarters. Havent go it yet, But when I do, I will post it... Anyway. thanks again
 

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snowmobilexcr said:
Going through my seld, and checking everything. I'm about to redo the top end new everything. But, I was wondering, I had 90 psi before, I am anticipating 130 + after. Will that put more pressure on the crank seals, and I also thought maybe I was already lossing psi's through the seals before, so does anyone have a good way of checking then before I put her back together? Thx again..I'll tell ya, I love this site, I learn more and more every day.. I've always loved sledding, but never really worked on em that much, but now I look forward to it and confident, because I know where to get answers. As I learn I will pass it on myself. Plus I just bought a 96-98 polaris manual on line, right from the polaris headquarters. Havent go it yet, But when I do, I will post it... Anyway. thanks again
The way I was taught to check the crank seal was start the sled. Spray some wd40 on the seal. If its good it will stay at the same idle. If its bad the sled will either idle up or down, I don't remember which one.
 

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Discussion Starter · #3 ·
So, I can see whats gonna happen. I'll get the top end done, everything all perfect like I want it, I'll start it up then spray some wd40 by the crank seals and listen to it idle up, and thats when I whip the can at the engine, then grab the shot gun and shot it... Thats how my luck goes. Is there any other way to check it? Before I waste 80.00 worth of gasketts.
 

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the cranks seals wont have any affect on your cylinder compression, the rings and your topend seals are the only thing that affect that, with 90 pounds, i would guess you rings are just getting wore out, and muscel is right on checking them if you think they are bad,an air leak would lean out your fuel and possibly lead to a meltdown

i was also taught you could use either, and that would cause a rev up

unless you suspect them being bad, i wouldnt worry about them to much, i dont thing its a major problem unless you have a ton of miles on your sled

and not sure on this but, i believe you can access the crank seals from the bottom side if you pull the motor
 

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For what it's worth since you're already doing a top end job, pull the entire motor apart and do a full inspection on the crank itself. There is no sense in putting money into a top end if you are guessing on the health of the bottom end. It'll only take you an extra hour or two and you'll then have piece of mind knowing exactly what you've got. As mentioned above you really can't visually check the seals, doing the "spray test" while the engine is running is the only real way to validate them.
 

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I would shoot carb cleaner or straight up ether at them and if it idles up then they are bad. If not they are still good. IMO ether is the best way as it is burns hotter so it will make it wind up if any gets in. Carb cleaner wont always get you results.
 

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I you think they are leaking dont waste a good top end!I made a set of plates with gaskets to cover the intake&exhaust ports and pressurize the case with a low pressure pump I watch the pressure as well as spray a soap solution around the seals and case seam.
 

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^^^ that is a great idea if you already have it apary
 

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Motor should come out and case journals should be mic'd for tolerance spec. Crank bearings, again the same. Have them inspected. Crank seals are around$ 10, so get 'em and rebuild your motor and be happy you did it the right way. Ask questions, take pictures. A lot of experience on this site that can lend a hand if you request. Madcow, Polaris1man, Ultrawillie, Greaemonkey, WhiteXC, and Dtmmil are a few I'm m sure will assist
 

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CanadianXCR said:
For what it's worth since you're already doing a top end job, pull the entire motor apart and do a full inspection on the crank itself. There is no sense in putting money into a top end if you are guessing on the health of the bottom end. It'll only take you an extra hour or two and you'll then have piece of mind knowing exactly what you've got. As mentioned above you really can't visually check the seals, doing the "spray test" while the engine is running is the only real way to validate them.
Agreed.

A buddy has his sled over and I talked him into replacing the crank seals, motor has over 4000 miles. When I split the case, I discovered the crank was separating. To pull the crank, we pulled the cylinders and discovered a cracked piston. Now it's a full rebuild. The motor ran perfect before tearing it down, it was a ticking time bomb.
At least he won't be down half a season with a blown motor.
You've gone this far, replace them and inspect crank bearings too. You'll be glad you did.
 

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anyone start a sled and spray wd-40 into the carbs? donsnt change anything. wd-40 used to use propane as a propelant now they used co2 or something. spray either into a sled carbs and see what happens, i had a sled in here that was barely running, sprayed anything and everything i had into the carbs and the only thing that changed was the toxic levels of the exhast.


if i was doing a top end on a sled of that age i would do the crank seals, and have the crank/rods inspected. usually dont cost much to have a crank guy look at the rods and crank.
 
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