SternPowr outdrive strange leak

Nidza · 20 May 2016, 14:19

Hi guys,

Maybe you can help me identify the source of leak on my outdrive.

My outdrive has actually zero working hours, although it is bought as new in 1984. Life circumstances has stopped my fathers boat rebuilding project. I would skip the reasons here. I did not want to sell everything for practically nothing and I have kept everything and waited for the good moment in life to finish that project myself. And that has actually happened. Of course, pause period of around 25 years had some side effects, but I was very patient and did restoration/renovation process "according to the book".

I have removed the outdrive and replaced all seals and O-rings and whatever was suspicious (even one of the gears), everything was original, since my father had bought a spare sealing kit together with the outdrive (lucky me, according to today prices). What I did not have in original pack are the gaskets for the round oil level control cover with 4 bolts and the gaskets between upper and lower assembly of the drive (two of them actually since I have extender in between upper and lower part). So I have used silicone goo for that instead which is especially made for that purpose (from Permatex). Of course, I had to change the seals on all hydraulic rams (trim and steering), but that was easy task when I found the man for the job (and not at all expensive compared to new ones). Of course, new hoses, too, but you can build that anywhere these days. In the end, I tested everything, hydraulics works excellent, both trim and steering. There were no leaks, I rotated the propeller with engine on dry, and there were not any leaks. Then, the boat was in the water for about one month and I made just about three riding hours (each ride was just up to 1/4 of throttle, because I am testing it yet). Not any problems, not oily spots in the water. Then I have pulled the boat out of water for test and I found that oil in the drive is milky because of some water inside. And still I could not detect leak on any obvious location. Then it happened that it was one hot day outside and a bit of oil has shown up on the drive (probably due to heat expansion), but the location is not at all obvious to me. It is in the "cup" where yoke rode is attached to the drive. Of course, I assumed that it is coming from somewhere above, like input shaft seal or O-ring, or from rubber boot, but no oil stripes and lines, everything dry, just drive oil inside that "cup". To be more clear, I am attaching the drawing, where the collecting spot is marked with red arrow. Beside that, I am attaching a bit more photos, of disassembled upper and lower part of drive to see the inside part. that part of leg below the "cup" is not even connected to the chamber of drive, where the oil is!? That is why I am confused.

I would really appreciate if you could give me any advice if you have an idea what could it be, or where else to watch? Or maybe, someone had similar case? Have I made a mistake using silicon instead of gasket? Could the drive body be porous? Currently, I have no clue!?

Currently, I am building an air valve fitting instead of oil pouring plug, so I can put some pressure to the leg and see where will exactly the leak show up.

Thank you in advance.

Nidza · 20 May 2016, 14:50

I have forgotten to say, it is SternPowr model 103, with reduction gear 1.6 swinging propeller 19(diameter)x17(pitch). It is attached to older type diesel Cummins V-504-M (which I have also rebuilt due to long pause period, but it is also 0 hours basically), V8, 504cui, 195HP/3000RPM mechanical diesel. It is attached through Borg Warner 72 gearbox.

Pikey Dave · 20 May 2016, 15:00

I'm guessing ( and it is only a guess) that due to the age & non-use, there is a seal or gasket that has hardened or cracked with age. Even the "new" seals that your dad bought will be old & tired & not as supple as they should be. I'd be tempted to do a complete strip & rebuild with all new seals.

Sh1t happens

Nidza · 21 May 2016, 08:09

I would not rush to that conclusion easy and would wait for pressure test first. You are right about "rubber" seals, but those are bought new according to samples from the box. Metal parts should be ok? But it is still strange that there is a leak that can be seen, but not near any shaft seal or on expected spots. It seems to me more and more that maybe using the gasket silicone instead of real gasket could be the problem and that should show up on pressure test. The same silicone was used to reseal some compass leak, but after a couple of months in the sun it has lesked again. Still confused and impatient of getting that fitting for pressure test. Thank you for your opinion.

Nidza · 21 May 2016, 19:13

Just to update what has happened. Today, I have finally got the valve fitting and pressure tested the outdrive. It is the last thing of all things that I have expected and the worst

. All seals and gaskets are fine. The leak actually goes through the metal upper casing in the zone of that "cup" (inside cup actually). I am not sure if it is porous, which I really doubt, or it is a small crack, hard to see. Bigger chance for crack, since as previously described, just below the cup is blind space, without oil. Tomorrow, I will disassemble it and see what exactly is the case and if it is possible to fix with welding or with some epoxy or whatever is possible according to the case that I will find out.
Any comments are very valuable now. Has anyone had some crack or hole on the casing and what have you done if yes? Would you recommend fixing it at all, or rather changing upper drive enclosure (hopefully, not the whole upper assembly)?
Maybe, no one will answer on this, but maybe it will at least help someone else in the future to diagnose one of potential problems.
Sorry if my English is not very well, since it is not my native language and beside it is mechanical technical language and I am an electrical engineer.
Sh1t does happen! Muprhy has really got me this time!

Nidza · 22 May 2016, 11:42

Believe it or not, it was bad casting during the manufacture process on the inside part of surface, this could have been changed for free by the manufacturer and during the guarantee. Bad luck. But!, good news is , that it can be repaired and it seems that it is much better case than crack would have been for repairing. Maybe I will put some photos of bad casting during the repair. Anyway, now I am slowly rolling towards the solution.

Nidza · 26 May 2016, 07:51

Here is the work progress until now. Unfortunately, no photos yet. I have degreased it using degreasing chemicals, then torch and then the sanding process (not paper sanding, but "sand gun", but I do not know the name of that process in English). Then it showed up the whole bad area of about 2 inches x 2 inches. Then, I have used Loctite EA 3479 (2 component epoxy with aluminum powder) to seal it. Now, the upper assembly enclosure is going to be laminated from the outside, instead of painting it by hand tools. I hope for the best in the end.

Nidza · 31 May 2016, 12:30

Everything finished as described. It seems that I made it, no obvious leaks. It is under air pressure from this morning for some time and I will wait until tomorrow to see if there is still no leak anywhere. If there is no leak, anti-fouling (Trilux 33) and I can return to water. I have photos after "sanding" process in my friends phone and I will attach them as soon as I download them from him.

Nidza · 03 June 2016, 08:28

Here are the photos, as I have promised. The first one is showing the zone where the problem was. The others are a close-ups. The "small" black spots are the shown "porosity" due to bad casting and they are black since the oil was in them. The porosity are the spots, not the black stain. Stain is near the end of that earlier mentioned "cup" and there was a bit of goo and oil, but that is not porosity. The whole material surface looks very rough, but that is normal, since the manufacturer have probably used the molds made of sand. Of course, not all the spots go all the way through, only the biggest ones, but I had to epoxy whole that area and now it looks similar to "fiberglass" tank (but epoxy, not fiberglass). Unfortunately, I did not take a photo after being finished.
Anyway, it does not leak anymore, it was under pressure for about two days. So it can be solved this way. If anyone in the future meets this problem, solution is in this thread now.
Going into water tomorrow

Nidza · 03 June 2016, 08:29

the rest of photos

jwalker · 03 June 2016, 09:54

Well done, Let's hope it stands up to the test of time.

Although you're out of warranty, I'd be tempted to let sternpower know of the fault, the porosity is plainly a manufacturing defect. Likely gas bubbles formed within the metal as it was poured into the mould.

Nidza · 03 June 2016, 10:47

Jwalker, that is exactly what I meant (bubbles in metal as it was poured) when I said bad casting during manufacturing process, just did not know to express myself better at that time.
And yes, I am tempted to let SternPowr know of the fault, although I am pessimistic of "gaining" anything after so many years.

Nidza · 29 September 2016, 14:00

Just to update that after 130 hours of boat operation this season, all is well and working properly, there are no leaks, nor water in oil. I would consider this fixing method confirmed if someone encounters similar problem (hopefully not). I hope it will last in following years, I will use it (as much as possible hopefully) and we shall see.

jwalker · 29 September 2016, 16:13

Quote:

Originally Posted by Nidza

Just to update that after 130 hours of boat operation this season, all is well and working properly, there are no leaks, nor water in oil. I would consider this fixing method confirmed if someone encounters similar problem (hopefully not). I hope it will last in following years, I will use it (as much as possible hopefully) and we shall see.

Well done and it's good to have you report back rather than leaving the thread open ended.