Rotary valve gear lubrication question...

[dougamclean]

Hi guys, me again..so a bit has transpired with the "new to me" 95 Seadoo XP I bought.

The 657x under the hood turned out to be trashed, water in the lower part of the motor washed the bearings and it's junk..I found a good, clean, low hour 657 bottom end complete on Ebay.

Now, I've been thinking about this oil delete the previous owner did also.

The guys did a piss poor job of looping the oil line to keep the sump filled and it pissed all the fluid out into the hull and destroyed the gear...a real cock up for sure!!

Anyway, it's all in the wash anyway with the new bottom end coming!

So my plan and my question:

1st the oil tank is removed and I want something better than just a hose loop filled with lube in the bottom of the hull. LAME!

I've ordered a new 250ml oil reservoir tank and will be fixing it inside the hull someplace..then running new hoses to either side of the motor to keep the sump on my new lower WET!! A newly designed loop system I can check and monitor regularly..clever right??

Now the question..what oil to put in the sump?

I question if 2stroke oil is optimal lube for a brass helical gear or is it just adequate and a matter of convenience since there is a tank full of the stuff onboard that can be tapped into? Like Seadoo has done all these years?

Maybe the reason many of these old machine burn out their seals and start dumping into the crankcase is because of the fact it's not the best oil for this task....?? And there is a hundred threads about stripped rotary gears>?

I'm thinking more in line with some API GL-4 gear lube and in fact the interweb suggest if might be a better choice for a helical gear drive for various reasons. A half billion outboard lower units couldn't be wrong!

Surely someone else has thought this same thing..?? Thoughts...??

 

[mikidymac]

Easy answer to your questions. The gear and seals were designed to use API-TC oil so just use API-TC oil. I have never seen one fail in 35 years of working on these that didn't have mechanical damage cause it, like a bolt down the intake.

Also make sure you pressure test your new used engine to 8 psi to be sure those used crank seals are good and the engine is air tight.

 

[burtshaver2021]

Be sure to vent this new oil tank, the fitting beneath the exhaust is just a vent hose that should go to the top of the oil tank.
I’m going to make a guess and say that a lot of the damaged brass gears are from people changing the rotary valve gear without splitting the cases

 

[dougamclean]

Be sure to vent this new oil tank, the fitting beneath the exhaust is just a vent hose that should go to the top of the oil tank.
I’m going to make a guess and say that a lot of the damaged brass gears are from people changing the rotary valve gear without splitting the cases

No in this specific case I'll say the damage was lack of oil..as I mentioned, the PO created a sketchy hose loop during his pump delete. Then didn't properly secure it with clamps..

The oil pissed out while the engine was running and was sitting in the hull..

When I split the case to investigate the obvious bearing noise I was hearing, I found the sump area full of gold sprinkles.

 

[burtshaver2021]

No in this specific case I'll say the damage was lack of oil..as I mentioned, the PO created a sketchy hose loop during his pump delete. Then didn't properly secure it with clamps..

The oil pissed out while the engine was running and was sitting in the hull..

When I split the case to investigate the obvious bearing noise I was hearing, I found the sump area full of gold sprinkles.

That will do it, I guess that’s one of the few benefits to pre mixing. The gold sparkles won’t be spread through the oil injection system as well

 

[dougamclean]

Easy answer to your questions. The gear and seals were designed to use API-TC oil so just use API-TC oil. I have never seen one fail in 35 years of working on these that didn't have mechanical damage cause it, like a bolt down the intake.

Also make sure you pressure test your new used engine to 8 psi to be sure those used crank seals are good and the engine is air tight.

Sure will test everything before reassembly..

I understand what you're saying about the API-TC. But at the same time, it's really just a 2stroke oil with good burn characteristics..not so much designed for as a gear lubricant. It's like an after-thought of it's formulation.

I'm looking for something with similar viscosity and API qualities to allow flow and to lubricate the gearing while protecting the seals..something that is specialized for that task.

Realizing API GL-4 is a heavy gear lube, I can't say I was entirely serious about that..

But perhaps something along the line of Ford Mercon V ATF as it's viscosity if nearly identical, it's seal protection additives are exceptional and it's specifically designed for gear lubrication!

I realized I'm asking a long term Seadoo to think outside the box..but does it not seem that this might be a good alternate?

 

[dougamclean]

Be sure to vent this new oil tank, the fitting beneath the exhaust is just a vent hose that should go to the top of the oil tank.
I’m going to make a guess and say that a lot of the damaged brass gears are from people changing the rotary valve gear without splitting the cases

Yeah, the tank I chose has a supply and return..just to ensure that any air in the sump can get back to the tank and ensure the gear is fully bathed at all times.

 

[mikidymac]

That will do it, I guess that’s one of the few benefits to pre mixing. The gold sparkles won’t be spread through the oil injection system as well

The oil doesn't circulate so the debris for the rotary gear can't get to the oil injection part. Also there is and inline oil filter for the injection pump.

 

[mikidymac]

Sure will test everything before reassembly..

I understand what you're saying about the API-TC. But at the same time, it's really just a 2stroke oil with good burn characteristics..not so much designed for as a gear lubricant. It's like an after-thought of it's formulation.

I'm looking for something with similar viscosity and API qualities to allow flow and to lubricate the gearing while protecting the seals..something that is specialized for that task.

Realizing API GL-4 is a heavy gear lube, I can't say I was entirely serious about that..

But perhaps something along the line of Ford Mercon V ATF as it's viscosity if nearly identical, it's seal protection additives are exceptional and it's specifically designed for gear lubrication!

I realized I'm asking a long term Seadoo to think outside the box..but does it not seem that this might be a good alternate?

Well the injection oil lubricates the crank bearings, rod bearings and pistons even diluted with gasoline so it should be perfectly fine for the brass gear and shaft bearings and full strength. Seriously, you are overthinking this. Think of the thousands that are still running with this oil and no wear even 30 years later.

There is no proof that gear oil is good or bad, ATF is really not the best for this applicationa nd could have seal issues. API-TC is proven to work 100% so why reinvent the wheel? Do you really think the people that designed the engine were just using theis spec oil for the fun of it? No, they knew it would work and didn't want any warranty claims.

 

[dougamclean]

I hear you..just drawing on 25 years in the automotive industry for example.

We all know there are aftermarket creative design ideas out there that are better than OEM in any industry.

As this machine already has a pump delete I figured I'd explore other ideas while I'm in the process of rebuilding it..maybe make a good system a bit better.

 

[burtshaver2021]

The oil doesn't circulate so the debris for the rotary gear can't get to the oil injection part. Also there is and inline oil filter for the injection pump.

I knew that the oil doesn’t circulate but I was sure I had seen people post in the past that the fine brass shavings had made it into the oil tank? Maybe I’m mistaken

 

[BrianMoore]

Being a retired engineer who designed parts for a living, it gives me chills when I listen to anyone assuming the folks who make OEM stuff are in the dark about their product and only spend their time going to meetings to figure out how to save a few pennies. Sure there are the meetings where minutes are kept and hours are lost. But the guys spending 40 hours plus a week with decades of experience have thought about these issues. And yes I was one of those guys and yes I did make a few mistakes. I take responsibility for those even though parts were reviewed by multiple other engineers who had their own specialties and they missed something too.

Brass is decorative and cheese is stronger. Bronze makes a good gear since it is strong and slippery. AL-Ni-Br is much better. Cu-Be is the last step up the ladder. It has machining issues being carcinogenic and the surface hardness is close to hard steel. If you pick the wrong materials, no sort of different lube will save the design. And does the design really need fixing?

 

[AquaEye]

Starting to come up to the surface on the oil pump deep dive & this rotary gear lubrication/sealing is the next bridge I'm going to cross.
Done a lot homework on this particular aspect going as far as consulting with ultralight/Rotax enthusiast forum with a few phone calls. 2,000 feet in the air compels one to stick to the smallest details in engine reliability/performance.
In their words, religious preventive maintenance & the proper lubrication regiment, no half measure. No one & done. Stay on top of it & land by your command, not gravity's.
That word regiment.
A plurality of "enthusiast" go closed loop with proper two stroke oil with proper venting. Since there is no circulation, a gentile forced purge of the cavity then replaced with fresh. The used oil is analyzed for particulate's/metals.
All synthetic oils looses its lubricity over time. The rotary gear oil flush is a very pragmatic approach to ensure longevity.
Their words, not mine.
So it boils down to whose word your going to take, the Red Barron 2,000 feet in the air or Jimmy Buffet @ lake level?
I'll cross this bridge when the time comes...