1991 70hp crankseals

[glenner]

hy out there, rebuilding a 91 70 hp force...when i was lineing up the crank and i broke a seal...theres 2...they look like piston rings. im wondering how to put the new ones back on without breaking them...will they spread that far?...
also the bottom crank bearing appears to have a seal pressed into it...is that the only seal for the bottom end?
any help would be greatly appreciated, my manual sucks...to general..thx glenner

 

[Frank Acampora]

Re: 1991 70hp crankseals

To replace crank seals, you first remove the center bearings. Then slip the seals over the narrow bearing surface. They will spread that far without breaking. Position them on the seal groove, replace the bearings, and seat the crankshaft in the block.

Here is where you need to be careful: If you force the crank down with a seal out of position, you will break it. SO: As you seat the bearings on their pins (from bottom to top) be certain the crank seals are properly set in the grooves. Also, be certain the open end of each seal is down, in the block. That way, when you replace the cover, the seals will be a little safer from breaking

 

[glenner]

Re: 1991 70hp crankseals

thanks frank...noticed the bearings are split...guess you've been there...not to many people around here are familiar with force...
also, I only noticed the one seal in the bottom crank bearing...is there a seal that goes on the bottom plate as well? (I know there's a gasket for the plate) ..seems to me there should be...also what's your opinion on using a small amount of high temp permatex atv sealant on the outside of the inner crank bearings ?
thanks again frank
glenner

 

[Frank Acampora]

Re: 1991 70hp crankseals

You know, Force made so many changes in a couple of years that it is sometimes difficult to make a call.

IF your engine has spaghetti seals in a groove around the perimeter of the crankcase halves, it is accepted practice to put a small dollop of sealer at the point where the tubing touches the bearing shell. If there is no spaghetti tubing, you will use a bead of anaerobic sealer around the entire perimeter. In either case, a bead of sealer is run inward from the perimeter to the bearing and around all the bolt holes, just to ensure no leakage. (In reality, those crankcase halves are so well machined that the sealer is probably not necessary--but hey, it couldn't hurt.)

If your engine has a bottom plate, there is usually a seal or O-ring to prevent water and exhaust intrusion into the splines of the crank and drive shaft. Most earlier Force engines had a bushing and rubber bellows to "seal" the drive shaft. I don't believe it was very effective.

Remember: Force was a relatively inexpensive engine. While OMC engines used two seals (for example on the propshaft) Force used a double lip single seal--cheaper.