Pressure test of RV shaft and crank seals

[etemplet]

OK.... as long as it flows you should has a good shot at success. If that crap leaks out.... you got a big problem. LOL Good Luck man.

"Better to have dared mighty things, won glorious triumphs even though checkered by failure than to rank among those poor souls that live in the cold gray twilight that knows neither victory nor defeat." TS Roosevelt

Git Sum !!

 

[GGuillot]

I hope that was a joke.
Filling a seal with sealant will not stop it from leaking, it will still leak right past the seal lip and the crank.

Why would it be a joke? I was referring where the seal meets the cases, not the crankshaft itself. Many people put a little sealant in the case groove where the crankshaft inner seal seats. I did it last time on my 787 build using Threebond 1184. Many on the other FB forum I'm on, again, including experienced people and builders like Fullbore, put a little 518 in the groove to give it better seal.

Is there a good reason not to try that? or do this practice when assembling the bottom end?

 

[Chester]

Once you get it apart and go to put it back together, just put sealant, whatever you use on the case halves, in the grooves of the inner crank seals to stop it from leaking.

Nope.

Chester

 

[GGuillot]

Nope.

Chester

Nope what? are you saying he shouldn't put a little sealant in where the crankshaft seal seats in the case groove? or nope you don't think it'll work?

 

[mikidymac]

What we are saying is that the seals are leaking in the inner lip of the seal where it contacts the crankshaft, not on the seal shell and case. The seals leak because they get old, and loose tension against the crankshaft so sealant will not help.

For the sealant on the cases at the seals it isn't necessary but in theory will not hurt anything. It could however deform the seal as the seals are made to compress a little on the rubber shell to seal against the crankcase and adding sealant can put even more pressure on them possible distorting them.

The general practice for seals is they should go in dry.

 

[AKnarrowback]

I retired from CHEVRON.... I can't read what type it is but it looks like Ethelyne Propylene (EP2) Is that grease??? I wouldn't do that but I want to try the 75W 90 on my cousins ski It will protect the gears better than the other oil. May lose a horsepower or 2. LOL

The stuff still flows out like a really thick fluid, not a pump style grease. It should flow into any reasonable sized opening to lube bearings and gears.

I know that even if it works it is not a solution that will work for everyone. We're talking an engine component that has failed and we are just trying to put a band aid on it to get more life out of it. Seal wear is not consistant from one machine to the next so results will vary.

I know that on our mixed gas high voltage circuit breakers we have our ratios of gases change over time. The experts who design them say it is literally a small leak in a seal that lets one larger molecule type gas stay trapped while the others escape. If it works for air molecules I'll give thicker oil a shot. The machine was free, it's not my primary ride and it appears many people are facing the same problem.

What doesn't kill me only makes me stronger.

Or

Learn from other peoples mistakes.

We'll see how this one turns out.

 

[funsummerahead]

I have a source that can get me BRP crank, with no shipping (yes!), for 350. So I'm going that route as soon as my "super incredible deals" sell on ebay.

In thinking about it though I always wondered, if you found the proper grease, if packing that chamber full and capping the lines would solve the problem. Not the best solution but having to replace the whole crank for a five dollar seal is the one design flaw I have never liked in Rotax RV motors.

I remember one member saying he has done this on his 787 and it is still going.

If you don't want to put a crank in it right away try something crazy just to see what it does.
I would go with thick gear oil in the rotary valve separating the lines from the oil tank in a loop from intake to outtake leaving 3 inches of air in it to allow for expansion and use a straight thick gear oil like a straight 150. The thicker the better and they are gears so maybe it will work until you get the new crank - which you will need sooner or later. Good luck.

 

[etemplet]

The stuff still flows out like a really thick fluid, not a pump style grease. It should flow into any reasonable sized opening to lube bearings and gears.

I know that even if it works it is not a solution that will work for everyone. We're talking an engine component that has failed and we are just trying to put a band aid on it to get more life out of it. Seal wear is not consistant from one machine to the next so results will vary.

I know that on our mixed gas high voltage circuit breakers we have our ratios of gases change over time. The experts who design them say it is literally a small leak in a seal that lets one larger molecule type gas stay trapped while the others escape. If it works for air molecules I'll give thicker oil a shot. The machine was free, it's not my primary ride and it appears many people are facing the same problem.

What doesn't kill me only makes me stronger.

Or

Learn from other peoples mistakes.

We'll see how this one turns out.

You're gonna have some success I'm sure.... how much will be determined. LOL

If you always do what you've always done, you'll always get what you always got.

Doing the same thing over and over expecting different results is the definition if crazy.

 

[AKnarrowback]

The sno-go shop I used to work at had a customer, wayyyyy back, bring in his little kicker he ran on his boat, maybe a five horse at most. He said it seized when he was way out in the sticks and the river was starting to get ice. This patient Native Gentleman took the head and cylinder off out on the river bank, realized the rings were broken and went about fixing it.

Remember this was maybe 50's era tech. Not high rpm's, very low power.

When they took the motor apart at the shop they saw this guy had whittled a set of rings out of a dried piece of Birch log. They were pretty well used up, but they got him the 60 miles back to his village before the freeze hit. The story made it into Popular Mechanics at one point. The most resourceful and patient people I have met are from the isolated villages in AK.

Sometimes you just have to improvise with what you have.

 

[etemplet]

DUDE !!!!!!!!!!!!!!!!!!!! Wonderful story.

Survivors Bay-BEE !!! That's what we are !!

 

[AKnarrowback]

FIRST TEST RESULTS....

Last week, after I put the thicker oil in the RV shaft chamber, I took the gtx out for a 5 minute ride to burn out the regular injection oil that had built up in the case. I wanted a "cleared out" engine to do the test of the thicker oil.

After letting it sit for a week, more than enough time for enough oil to leak past the inner seal, I pulled the MAG plug and gave the starter a hit. I had the paper towel over the plug hole expecting the geyser of injection oil I always get. Nothing came out...... The cylinder only pushed out air and a hint of regular gas. Promising......

I rolled the trailer outside for the run test. Thinking that if the thicker oil had leaked out, but did not get drawn into the combustion chamber on the first test, a run test might give more insight. The motor started right up with a crisp tone, not a muffled tone and a fight like a flooded motor would. No smoke came out after a 30 second run with some throttle. More promising....

Next was the on the water test. Last week, when I cleared the old oil out, I smoked out the entire boat launch and grassy park area next to it. Imagine the better part of a football field sized area covered with a thick fog of burned oil smoke. Lots of dirty looks from people trying to enjoy the day.... Today, with the new oil, nothing beyond the normal puff of regular injection oil you get during a cold star, no "fog bank" at all. Very promising. (At this point I'm liking what I'm seeing).

I ran it wide open for 40 minutes, got it back in the garage and did a look over. The factory line going to the fitting under the exhaust was the fill line, I capped it and tied it off with the rest of the lines running along the inside of the hull. Before the ride I drilled a 1/16 hole, next to the plug in the line, to vent any pressure. After the ride there was a small amount of the oil that had vented out. This oil was sticky but, as I had hoped it would do, a bit more "liquid" from the heat than when I dropped it in cold.

So for a first test of an experiment things went VERY well. The goal of not having an oil flooded engine and the fight to start it was achieved.

I'm not convinced the problem is solved until the summer is over and I have another 75-100 hours on it without a failure. I still have a new crank standing by, which is the only true solution, but seeing how well this "band aid" test goes is going to be interesting.

I'll keep you guys in the loop if things change.