drive shaft seal

[Sangster21]

Hello, I am putting my MC1 upper and lower back together after a new water pump, shift shaft and bushing. I am going to replace the lip seal in the upper where the drive shaft from the lower enters the upper case. I don't know which way the seal is to be installed. Does the spring face the towards the upper or the lower? I guess the question also could be is this an oil seal to keep gear oil in the upper or is it a seal to keep water out of the upper?
Alan

 

[achris]

Re: drive shaft seal

It's to keep water out of the splines, so the spring faces the lower... And do not put an 'O' ring in the groove on the top of the drive-shaft.....

 

[Sangster21]

Re: drive shaft seal

This is what I thought, thanks for the info! I am going to make up a seal driver today and chuck the O ring. I guess the seal is a little trickier to install in this direction as you have less of the seal housing to push on. Thanks again.
Alan

 

[ktbarrentine]

Re: drive shaft seal

Uh-oh! now I am confused.... "spring faces the lower"? Gotta look at a diagram of this now. (for referene, pls look at post # 6 in this thread to see the orientation I am referring to for this seal).

http://forums.iboats.com/mercruiser...ser-165-outdrive-gear-lube-exaust-590532.html

 

[Sangster21]

Re: drive shaft seal

In most cases when you install a lip seal, the seal is installed with the spring facing in. For example if you are replacing a crankshaft seal. The oil is inside the case and the spring is there to maintain pressure between the seal and the shaft. In this case, we are trying to prevent water from making it past the seal from the outside, so the spring faces "out" so to speak. I believe it is the same for the 2 identical seals in the lower bearing carrier (behind the prop), one seal faces the oil inside the case, and the outer seal faces "out" to prevent water from getting in. Hope this helps.
Alan

 

[achris]

Re: drive shaft seal

In most cases when you install a lip seal, the seal is installed with the spring facing in. For example if you are replacing a crankshaft seal. The oil is inside the case and the spring is there to maintain pressure between the seal and the shaft. In this case, we are trying to prevent water from making it past the seal from the outside, so the spring faces "out" so to speak. I believe it is the same for the 2 identical seals in the lower bearing carrier (behind the prop), one seal faces the oil inside the case, and the outer seal faces "out" to prevent water from getting in. Hope this helps.
Alan

And the 2 seals in the water pump base....

 

[ktbarrentine]

Re: drive shaft seal

Uh-oh! now I am confused.... "spring faces the lower"? Gotta look at a diagram of this now. (for referene, pls look at post # 6 in this thread to see the orientation I am referring to for this seal).

http://forums.iboats.com/mercruiser...ser-165-outdrive-gear-lube-exaust-590532.html

So am I to take it then, that the photo of this seal in post #6 of the above thread shows that this seal is installed upside down? (Which, by the way, is how mine is installed and how I got it from the PO.)

BTW...My merc manual, page 3A-29 states "Apply loctite 27131 or Type "A" to outside diameter of drive shaft housing lower seal and install oil seal with lips facing up (toward top of housing)".

 

[achris]

Re: drive shaft seal

...BTW...My merc manual, page 3A-29 states "Apply loctite 27131 or Type "A" to outside diameter of drive shaft housing lower seal and install oil seal with lips facing up (toward top of housing)".

Quite right... Can't explain that one. And as seals work well in one direction and not so well in the other, this is contrary to what you would expect.

Chris......

 

[mercs4mark]

Re: drive shaft seal

I have always wondered about that seal....every one that I have seen has been installed the way it looks in the other thread with the spring toward the inside of the housing. But as Chris says the seal only works in one direction and to keep water out of the splines would be installed as Chris states. I always thought the slinger would tear the seal up if it where installed that way tho.

 

[dubs283]

Re: drive shaft seal

My merc manual, page 3A-29 states...install oil seal with lips facing up (toward top of housing)".

that is correct, and your seal is installed correctly as well

the way the seal is made really only allows you to install it this way - the OD is stronger on the end you use the installer on otherwise you can risk destroying the seal

this is why there is the rubber slinger on the top of the water pump housing - not just to keep debris out of the housing but to also prevent water wicking up the driveshaft and entering the seal area

also - there is an o-ring that everybody here seems to say to disregard, it is there to aid in keeping grease in the splined area and help keep water out if water makes it past the seal, if you assemble the halves correctly the o-ring works perfectly (another reason why the seal is installed lips up - the o-ring slides through the lips, not possible if the lips/spring is facing down)

 

[mercs4mark]

Re: drive shaft seal

That makes sense so this seal is acting as a grease seal and with that said would it be advantages to pump that area with grease after the seal is installed to repel any water that makes its way up

 

[ktbarrentine]

Re: drive shaft seal

that is correct, and your seal is installed correctly as well

the way the seal is made really only allows you to install it this way - the OD is stronger on the end you use the installer on otherwise you can risk destroying the seal

this is why there is the rubber slinger on the top of the water pump housing - not just to keep debris out of the housing but to also prevent water wicking up the driveshaft and entering the seal area

also - there is an o-ring that everybody here seems to say to disregard, it is there to aid in keeping grease in the splined area and help keep water out if water makes it past the seal, if you assemble the halves correctly the o-ring works perfectly (another reason why the seal is installed lips up - the o-ring slides through the lips, not possible if the lips/spring is facing down)

Thanks! I feel much better now in my understanding of what I have, and what I have seen. Also, on my last impeller change, I did install the O-ring on the shaft (before reading later that I didnt need to or shouldnt install it) and carefully slid it up and past the lips of the lower seal and it is working as originally designed. That might also explain why when I did my last impeller change-out, the old O-ring somehow stayed up in the spline area in the upper and I had to fish it out (didnt want to make it past the seal lips on the way out).
Hopefully we havent fully hijacked the OP's thread, but this is good information he needs, since this is his vintage drive, as well.
KB