Pressure testing a L/U

[keithm1961]

Replaced all the seald and orings in a 1976 Johnson 85. Went to lake test and found water in the oil. I drained the unit and pressure checked the unit at 10 lbsfound leak at the shift rod. The shift rod has no seal but does have an oring under the cover. There is a lot of play in the shift rod. I pulled the lower unit off of a 75 model and pressure checked it 10 lbs held for over 30 minutes. I noticed if I shook the shift rod back and forth it would leak air also. Why is there not a seal on this shaft do they not have problems with water entering thru there. All the seals and orings in the parts diagram are there. I've looked at a few of these and discovered they all have a little slopiness in the shaft. Any ideas where else this water could be coming from.

Thanks
Keith

 

[ezeke]

Re: Pressure testing a L/U

The o-ring is the seal and should be replaced if it leaks. They don't last long if there is a lot of shifting. Be sure to use the OEM o-rings if you can because some of the aftermarket o-rings are not fat enough. If you feel that a new o-ring is too loose, you may need to drive the bushing a little tighter.

All of the seal kits for your motor include the o-ring.

I find that the seal lasts longer if you grease the shaft and keep the area as free of sand and dust as possible.

 

[bob johnson]

Re: Pressure testing a L/U

Replaced all the seald and orings in a 1976 Johnson 85. Went to lake test and found water in the oil. I drained the unit and pressure checked the unit at 10 lbsfound leak at the shift rod. The shift rod has no seal but does have an oring under the cover. There is a lot of play in the shift rod. I pulled the lower unit off of a 75 model and pressure checked it 10 lbs held for over 30 minutes. I noticed if I shook the shift rod back and forth it would leak air also. Why is there not a seal on this shaft do they not have problems with water entering thru there. All the seals and orings in the parts diagram are there. I've looked at a few of these and discovered they all have a little slopiness in the shaft. Any ideas where else this water could be coming from.

Thanks
Keith

I pressure tested my lower unit at the mechanics shop with his homemade hand pump...it holds pressure till you touch the drive shaft...boom, then the air leaks out...he said that will always happens...I wanted to buy a new drive shaft seal,...he said dont bother...air will leak out of a new one if you move the drive shaft..

didnt make too much sense..and i am not 100%sure if its the way to go...Ill check the lower unit in a month or so and see if it still has no water...

try that with yours

bob

 

[ezeke]

Re: Pressure testing a L/U

I use the same V4 1970's gearcases for many many years and never had a problem with the shift rod seal leaking on any of my motors. When the seals are new the case will hold 15 PSI for 45 minutes or more.

Yes, you can get them to leak a little if you push the shift rod off center.

It is one of the easiest maintenance jobs on the gearcase to change that o-ring. All you need is a couple of small dowels and a little oil.

Take the barrel swivel off the top of the shiftrod, unscrew the cover and seal assembly and lift the assembly up and off.

Use a small awl to pull part of the old o-ring to center and then push the o-ring out out with one of the dowels.

Fold a new oiled o-ring in half and stick it in the hole, then use the two dowels to push it into position from both sides.

 

[keithm1961]

Re: Pressure testing a L/U

thanks, I'll give it a shot

Keith