Leak in Prop Liner

[mikiek]

Zelos 36, stock stuff tube, stock liner, OSE cables - This is strange. I was just preaching to Vinny to put his boat in a tub to see if any leaks could be detected. I've had a leak problem for a while so I did the same this evening. No motor running, just floating. It took about a minute but after that there was a steady drip (about every 2-3 seconds) coming from the liner in the stuff tube.

1. I just lubed the shaft before doing this.

2. The stuff tube is bent slightly upwards. The end is higher than water level. How the heck is water managing to rise above itself?

3. The drip is so consistent it's almost like there was pressure pushing it thru.

I'm stumped.

[vinnyp]

Unless the liner is wiped out, I would have thought the grease would keep the water out. When I tank tested the boat yesterday, the tubes stayed dry. Did you test the boat with lipos in it? That would make the weight right. As I said, I didn't do that. I will have to test it again after I get it back together. I am wondering if the end of the tubes are actually below the water line. A quick test would be to remove the flexes and place the boat in the water.

[REDLINE1]

Zelos 36, stock stuff tube, stock liner, OSE cables - This is strange. I was just preaching to Vinny to put his boat in a tub to see if any leaks could be detected. I've had a leak problem for a while so I did the same this evening. No motor running, just floating. It took about a minute but after that there was a steady drip (about every 2-3 seconds) coming from the liner in the stuff tube.

1. I just lubed the shaft before doing this.

2. The stuff tube is bent slightly upwards. The end is higher than water level. How the heck is water managing to rise above itself?

3. The drip is so consistent it's almost like there was pressure pushing it thru.

I'm stumped.

Did you remove your struts and remount them with silicon sealer?

[CraigP]

All of these current struts/stuffing tubes are "open flow" design, meaning there is no definitive seal in the driveline. When running, grease is designed to migrate towards the strut by the threading action of the flex cable. It then is lost through the static of floating bushings of the strut. So sitting in the tub, the water can go the other way. Mikiek, for the water to drip out the tube inside the boat means the water level has to be close the the end of the tube.

I recently modified the back of my strut to accept a rod U-cup seal. The seal stops the grease loss while running, and keeps water out of the stuffing tube. Others have used sealed bearings in their struts, but they would need to have the outer races Locktite Blue'd in there to pass a static water leak test.

Some guys use a piece of silicone tubing on the stuffing tube up by the motor coupling. That works great, but my data logger shows that it adds a lot of resistance to turn the shaft, and my current goes up with a slight loss of speed. The U-cup had no power loss. I imagine a sealed bearing would be slightly better...

[mikiek]

I have never taken the struts off. Vinny might be on to something - maybe the tube is worn? I did have a cable break in the tube once, maybe that did some gouging on the Teflon. Unfortunately I don't have a spare so I'll have to order.

From inside the hull I can see that the brass tube goes to the transom wall and I would suspect thru the transom and into the strut for some distance. Does anyone know how far the liner runs? Does it extend out of the brass tube inside the strut?

What gets me is the constant drip - almost the same as when you don't turn a faucet off all the way. A random drip here and there I would write off as normal but this is weird.

[REDLINE1]

I have never taken the struts off. Vinny might be on to something - maybe the tube is worn? I did have a cable break in the tube once, maybe that did some gouging on the Teflon. Unfortunately I don't have a spare so I'll have to order.

From inside the hull I can see that the brass tube goes to the transom wall and I would suspect thru the transom and into the strut for some distance. Does anyone know how far the liner runs? Does it extend out of the brass tube inside the strut?

What gets me is the constant drip - almost the same as when you don't turn a faucet off all the way. A random drip here and there I would write off as normal but this is weird.

I'm running wire drives. There .078 dia .So I get no seal between wire and Teflon liner from the grease and I have no water leaking in . The strut mount surface on the hull is not 100% flat plus it mounts flush with the bottom of the sponson . There's not much room in that area a seal to be made. I would take the struts off and remount with silicon. when you re installing them keep your cables installed to hold the alignment while your tightening the strut mount bolts

[vinnyp]

Mike,
Here is a picture of mine, when I tore it down for the transom plates I made up. The teflon liner doesn't come out last the back of the tube.

[mikiek]

Thanks Vinny - that's a big help. Man how did you manage those screws? Especially the nuts on the inside? And good for you for taking pix while it was broken down. I need to start doing that.

[mikiek]

You know now it is all coming back to me. The joint where the strut mounts to the transom has been spewing grease since day 1. I guess I probably should make an attempt at sealing that up.

[fweasel]

I sealed mine with silicone without completely removing the nuts from the screws on the inside. Just loosened them up enough to create a gap. I used clear bathroom silicone and it stopped all of my leaks from the back end of things.

[mikiek]

I remember doing that only on the starboard strut. Right now it's the port tube that's leaking. I'm trying a gasket I made from some sheet rubber. Cut a small square then set the transom end of the strut on it and trimmed around the footprint. Cut holes for screws and shaft. Floated the boat in the tub again - no water. At least after 5 minutes. Ya'll have no idea how long that has been plaguing me. Every race, 3-4 oz of water sloshing around. It never shorted anything, but you know it wasn't doing any good either.

Thanks everyone!

[vinnyp]

Man how did you manage those screws? Especially the nuts on the inside? .

I stood the boat up on its transom. Leaned the bow up against the wall, then used a long needle nose pliers to set the nuts onto the screws, while turning the screws with a 2.5 mm allen wrench. Cursed a few times when I dropped the nuts in the hull, but I got it done. I posted this picture before, but here it is again.

[REDLINE1]

Ya your gonna invent a few new swear words trying to get the strut bolts in and out.. Its like building a ship in a bottle LOL. I use a hemostat clamp to get the nuts off then a small socket with a universal joint with an extension to re install

[vinnyp]

Cant say that I have access to a hemostat. Long needle nose is all I have. Yes, after I got the nuts started, I tightened them up with a 1/4" drive swivel socket.
BTW..... I have been a mechanic for too many years to admit to. I don't think there are any new swear words for me to invent. I have about used them all up!

[REDLINE1]

Lol u must have invented a lot of swears then lm still able to come up with a few new ones
You can get the hemostat at menards or ace hardware. Nice cause you can lock them on the nut.

[vinnyp]

Thanks.. that looks like a handy little thing to have around.

[mikiek]

It's called expanding your one word vocabulary.

[mikiek]

On a more serious note, all this mess was happening on the left stuff tube. The right tube has been just fine. However, I got to thinking I have now extended the left strut 1/16" further out than the right one. I suppose that might cause some weird behavior especially when running the struts positive or negative. So I'll be putting a gasket in behind the right strut this evening.

Hoping to get the z-boat out tomorrow and 'wet test' her.

[vinnyp]

Getting back to leaks from flex shafts... I just noticed these new little items on OSE. They may have been around for a while, but I have not seen them before. May look like a nice idea, if you can fit them in between the end of the tube and the motor. They are 1.2" long. I am thinking about the possibility of them causing drag??

[CraigP]

Vinny, what are you referring to? No pic or part number? Are you talking about Areomarine's STS?

[vinnyp]

oops... I didn't attach the link. Here it is

https://offshoreelectrics.com/prodde...d=aero-sts-125

[CraigP]

Yes, I run one... Works very good for me, others have complaints. The trick is how you set it up. There is a collar on the front. In between that and the bearing block is an O-ring. Need to lock you shaft down in the motor collet. Then hold the front collar has tight as you can against the bearing block an tighten down. It acts as a shaft saver and helps on the water leak. It's not a 100% seal... Here's a pic...

[fweasel]

To me, that's a good idea on paper. In actual application, too complicated, more stuff to go wrong. I use a little bit of heat shrink or cooling hose over then end of the stuffing tube to keep the grease mess down to a minimum. The one boat I had problems with water coming up the tube (Zelos) was really caused by a leak between the hull and strut. Stopping the water at the top of the tube was not the right fix in that scenario, sealing the strut was.

[CraigP]

It has a barb fitting on it. I took that out and put a screw in it's place. I use the stuffing box support block as my oiling point.

I put in a shaft seal at the end of the strut. That stops 100% of the water and stops my stuffing box from losing grease. I've ran now approaching 10 times and still haven't pulled the shaft or re-greased. I posted pics of that somewhere, but seems no one was interested in that solution. Oil and water don't mix! Keep the water out, the oil will stay good for a very long time!

[CraigP]

Fweasel, I had silicone tubing on that, but was pulling much more power than with this device. There's a lot of drag using the silicone tubing. Vinny, as you can see, the diversity of thought is one of the things I love about this sport! In the end, you need to visualize the solution that works best for you. It don't matter what the rest of us do... only what you do with th your model...

On the zelos, I have to say it would seem the U-cup rod seal is a no-brainer. I'm surprised nobody is making a strut with that in it. I also don't leave grease in the water.

[CraigP]

Vinny, a good thread on this topic is called Strut Bushings under Boat Building Talk. You can see all kinds of perspectives and good pics!

[vinnyp]

Craig,
What kind of shaft seal at the end of the strut are you referring to? I am not familiar with it. That STS seal seems too big to fit in my Zelos 36. Since I burned up a pair of ESC's a few weeks ago, I have become obsessed with keeping the boat dry.

[CraigP]

I had to make it... I milled a pocket for the seal to sit in, then made a plate to hold it. Pics on Strut Bushing post under Boat Building talk. If you can do that, I'll give you the part number/vendor of where I got the U-cup Rod seal. Use the search box, type in Strut Bushings, you'll see it listed there...

[CraigP]

Most people know that when running, the flex shaft tries to move the grease to the strut, due to the screw action. So no water can get in. But when the boat sits in the water, then water can get back into the stuffing tube. Once the grease has water mixed in, it will need to be replaced. So however you do it, it makes life so much easier not having to take that damn, greasy flex shaft out every 2-3 runs and re-grease! I'm sure there are plenty of objections on the site to this approach. But it makes me happy, the boat is running fast, and my hands stay clean!

[vinnyp]

Craig,
I found and read that thread you referred me to. Interesting read to say the least. I looked at my Zelos. No way I can fit that STS seal between the tube and the motor. Simply not enough room there. I like your idea of sealing the outer end of the strut. I like the lip seal idea. However, the Zelos strut is rather small. I don't think there would be much room for me to bore a hole to allow a lip seal to fit. I will have to look closer at it the next time I pull the flexes. I do notice some play in between the end of the flex and the strut. If I grab the end of the strut, I can wiggle it up, down and side to side a bit. That may not make for a good seal with a lip seal. Ideally, I would think the best scenario would be to have roller or Torrington bearings in the strut to hold the flex stable. Then a lip seal would be the ticket.
A bigger issue , at least with my boat is the leaky hatch. Other than tape, I still have not found a way to seal it.