US1 Fountain

iTrader: (1)

To start.... last winters drive oil changed showed a discolored oil when drained on 1 drive. Not the clear green of the Merc oil, but a dark black- greenish. The other drive oil looked like brand new.

I change the oil every yr. Might average under 50 hrs/yr. Boat never in water for periods longer than several hrs at most. Both drives were resealed approx 3 yrs ago.

I didn't know if it was a fluke or what since I never seen any oil leaks and the drive bottle never filled up, so just refilled with new oil and ran again last summer, planning on checking after a few hrs. But never got around to it. This fall while draining, same thing. 1 drive like new, other had the discolored oil again. I'm leaning towards a seal not sealing, and thinking of dunking the drive in a pool and pressuring @ 15#, then vaccum testing.

I'm thinking a seal is failing under water pressure since water is getting in, very minute though since the drive oil level doesn't rise, but seals good enough that no oil leaks out.
Does this sound about right? Small seal betwen upper and lower halfs?
Can I just lay the whole drive in the kiddy pool to check, or do need to block/seal off the shifter and input shaft?

Thanks

US1 Fountain

iTrader: (1)

Actually this drive is running a RH prop. Also running drive showers and pretty easy on the throttle. Didn't do any WOT runs this yr more than 15 sec. burst. So don't think heat is an issue. I used a vaccum/ brake bleeder hand pump and pulled it down to around 10" of vac for a quick check. I can see it dropping very slowly, but haven't checked the tester to make sure it wasn't leaking. Going to install a shut off valve in the line and pursue in more detail. Thinking be easier to see water bubbles when pressurized, as long as it's not internally leaking. Thanks

Vinny P

I agree to pressure test. 20 psi is a bit on the high side. I never tried to pump that much air into a drive. I usually stop at 10-12 psi. Not saying it wont hold 20, just dont know. In any case, if the drive oil is that discolered, you will have to at least take it apart and wash it out. While you are there, replace all the seals to be safe. Most likely, the prop shaft seal is leaking in. Be aware, the prop shaft has 2 lip seals that face each other, 1 to keep oil in, the other to keep water out. Take a close look at all the bearings, they dont like to run on oil diluted with water.

DiamondPerformance

iTrader: (2)

We sell a pressure/vacuum tool just for testing outdrives.

DMOORE

I'd be more concerned if the oil was lite milkshake/ moca colored. This would be more indicative of water intrusion. With the oil darker, it's more of a heat issue, which to me, would be reason to have the drive pulled and inspected for bearing/gear problems. I have mine done every year JUST to be sure.


Darrell.

Mr Gadgets

US1,
I have pumped them up to 20#, but normally only 15#. I have dunked them in the tank to find that small leak. If it bleeds down any over a 24hr period, I do it again checking the lower plug gasket, spray some soapy water on it. If that isnt it and it bleeds down real slow, I dunk it. Look for small bubble trail after the inside gets wet and all the surface bubbles work their way out.

Good idea to pull a vaccum also. See if it holds for an extended period.
If it is a seal, also look at the seal surface. The input yoke can be worn where the seal rides. 600 grit wet dry paper will help clean it up. Also the propshaft should not have groves or damage. Normally they seal up ok.. If your drive oil is getting dark, it surely can be a heat issue, but check it for leaks also.. And check the gauges you use. I have chased a few leaks that ended up being a bad hose on my guage..

Hope this helps..
Dick

US1 Fountain

iTrader: (1)

Ok, Thanks for the tips.

I'll look into the heat possibilties if nothing shows up on the press. gauge.

Mr Gadgets

Let me know what you find..

US1 Fountain

iTrader: (1)

Dunked in pool, very small bubbles from the input seal. I tapped the shaft it in a bag tight around the housing to keep it water tight. The pressure didn't drop any like before. The bag pressurized do to the seal leaking. Probably do to the bag acting as a secondary seal. So thinking that wasn't an issue since that area in the bellows is bone dry. No oil or water. Pointing towards an internal problem at that point. The lower just sounded odd when turned freely after the drive was split. The upper bearing looked like it had a sludge film, I assumed a mixture of oil and water. Gotta tear it down now! After I got the prop shaft out, I noticed the l verticle shaft nut was backed way off. I could see where it rubbed on the prop shaft in the undercut clearanced area. No grooves or such, just signs of rubbing. The verticle shafts threads are toasteded along with the nut threads. The nut was new and torqued @120 ft lbs, (seems like a lot for that slim nut) when I rebuilt the lowers 3 yrs ago. So not sure what/why. Also the large roller bearing race appears to be dropped down some. It has a good 1/8" gap from being bottomed out in it's bore. But if it were seated tight, the needle bearings would be riding higher on the verticle shaft. As it is now, the needle bearings are centered on the shafts straight race. The 2nd pic shows how they are riding right now on the shaft. I don't see the location of the that bearing being a major issue though. Wondering if the additional heat loosened up the light press fit on the race allowing it to slide down? Looks like will I will replace all the bearings/races, seals and verticle shaft. The 2 gears have a few dark spots were water drops must have been in the mesh of the 2 gears. However it is on the non contact side of the teeth when the drive is in forward. Contact sides look normal, no spots and are smooth. So not sure what to do about them. If you run a pointed tool over the spots, I can feel a slight change in texture. Will have to think about these as they aren't in contact under forward engagement. They are recessed, pitted, if anything. So only hold oil.
The counter bore in the lower half that accepts the bearing spacer that prevents the shaft from being pushed upwards for the verticle shaft is fine. So does the upper housing mating surface. I don't think the shaft was able to moved up/down any do to the 2 bearings keeping the verticel shaft in location.

Best I can see is that the pinion gear was able to move on the verticle shafts splines until down onto the loose nut/spacer, changing the teeth mesh clearance. It wasn't jammed tight on the prop shaft. So not sure if that was enough to over heat the oil??

updated:
The upper tear down resulted in brown spots on the gear teeth. Again assuming droplets of water. Also only on non contact side of both gears. A little polishing on them and they should be fine since those gears never turn the other direction. Mating teeth surfaces look normal.



I'm open for any thoughts. Have you ever seen a nut come loose before? My other drives oil always looks perfect, so hopefully this is an isolated issue.

US1 Fountain

iTrader: (1)

I suck at takng picture! The above pics show the rusty crud on the cages. BTW, the bearings feel like new when turned. The crud will wipe off. The other pics show that the nuts corners rounded over when it rode on top of the prop shaft. Also the shafts threads are pulled.


My main conscern is the fit of the pinion gear on the verticel shaft. It doesn't fit real tight, but not sloopy loose either. So don't know if the gear splines have worn from being able to move on the shaft. No visable wear marks on either spline.