Why do plugs blow out?

[MNdrifter]

I was installing my TruLock 2s last night and it got me thinking about blow outs. The plugs are in front of the impellers. The impeller should be sucking the plugs down into the tubes, not blowing them out. Anyone have an explanation for where the pressure comes from?

 

[BoaterGuy]

I read that it has to do with temporary cavitation and the pump rapidly depressurizing, then pressurizing again.

 

[Bruce]

Because the lower half swells and they become difficult to install. Then they get partially installed and blow out.

They are behind the impellers so the impeller is pushing water against them.

 

[txav8r]

The reason that blowouts occur is because of physics. True, the plugs are on the low pressure side of the pump in relation to pressure created by intake water and discharge water. But water entering the intake at speed is under VERY HIGH PRESSURE all by itself. And that is pushing on every square inch of the intake side of the pump, including the bottom of the clean out plugs. If you had a plug release at idle, it wouldn't blow out with the same force, but it would then be pushed out of the clean out tube when you tried to accelerate and you wouldn't get any high pressure out the back of the pump to move the boat very fast.

Even a brand new clean out plug can become unlocked and blow out. Putting some form of locks on them is absolutely necessary. If you go to jetboatpilots or Cobrajetsteerings websites, you can find links these guys have done showing the internal workings of the plugs, and how easy it is for a vibration to actually cause the internal lock to let go, which will result in the "locking dogs or tabs" to retract. And Bruce is right, a dirty or swollen plug can and will make it more difficult to get it "seated" correctly, and that can make it very hard to get a good "lock" when your installing them. So keeping them clean and dry, and outside of the tube when not in use is important too.

 

[whaler7626]

So if I'm keeping my boat on a lift at the lake, when the boat is not in use (only 2 or 3 days a week) where would you recommend putting them? Should I leave them locked in place, unlocked outside the hatch, or unlocked in the plug hole itself? Thanks!!

 

[BoaterGuy]

I just pop mine out, turn them sideways and leave them in the hole.

 

[whaler7626]

@RobA thanks!

 

[0627Devildog]

I just pop mine out, turn them sideways and leave them in the hole.

I just did the same thing. . . . . Just gotta make sure to learn from everyone else's mistake that didn't re-set them and keep em on my pre-flight checklist.

 

[0627Devildog]

Here is what I view as a solid video, detailing the pitfalls of the "Stock Plug" and why EZ-Locks (or something) is needed.

 

[0627Devildog]

On a side note, Im also hearing the gaskets lubed will help ensure a proper seat. The question I have is what type of lube should be used and how often?

 

[Jim Robeson]

I was actually thinking about using some form of lub as well. We use vacuum grease here on all of glass ware...glass plugs, desiccators...anyway, it lasts a very long time. May have to try that the next time I'm there.

 

[Bruce]

I have avoided lube and plan to rebuild the plugs at a cost of around $40 each whenever they get hard to use. There is a theory that petroleum products cause the lower half to swell.

 

[Jim Robeson]

@Bruce ... thats good advice, thanks!

 

[0627Devildog]

I have avoided lube and plan to rebuild the plugs at a cost of around $40 each whenever they get hard to use. There is a theory that petroleum products cause the lower half to swell.

Hmmmmm. . . . What about non-petrolium lubricant? Anyone out there lubing plugs? What's the experience been?

 

[Bruce]

Hmmmmm. . . . What about non-petrolium lubricant? Anyone out there lubing plugs? What's the experience been?

When I bought our SX230 one of the plugs required a 2x4 as a hammer to insert and a strap and using the 2x4 as a lever to remove. The replacement lower halves were back ordered so I kept a couple of pieces of 2x4 and a strap in the clean out plug locker. We tried a lot of cleaning the aluminum with things as abrasive as brillo pads and using a silicone spray on the plug. We still had to use the 2x4 in both directions. So I was not impressed with the effect of the lube.

After I changed the lower halves of the plug, my six year old could install and remove the clean out plugs.

Here is link to my thread on rebuilding the clean out plugs Rebuilding Yamaha Jet Boat Clean Out Plugs.

Devildog, with your new boat just remove them, lay them sideways and close the lid when you are not using the boat. They should function perfectly for years to come.

 

[jetboater4life]

A while back someone posted pictures of clean out plugs that had chew marks all over them. His boat was slipped and it was the consensus of the board that muscrats were getting up there and chewing on things. If you don't see any muscrats then you shouldn't have anything to worry about and even if you do have them I think it is extremely unlikely that they would try to get up in there. This was just a case of bad luck.

 

[Boat Crazy]

Hmmmmm. . . . What about non-petrolium lubricant? Anyone out there lubing plugs? What's the experience been?

Swimming pool o ring lube works good. It is non - petroleum. Just lube the rubber seal.

 

[MikeyL]

"Why do plugs blow out ?"

I was installing my TruLock 2s last night and it got me thinking about blow outs. The plugs are in front of the impellers. The impeller should be sucking the plugs down into the tubes, not blowing them out. Anyone have an explanation for where the pressure comes from?

ANSWER: Because they can ! <LOL !>
Laugh ........ It's a slow day fishin', folks !

 

[Britboater]

I just use white grease on mine.

But I haven't fitted my EZ lock because I thought the plug fitted really well and seemed to lock in well, but now reading how vibration can work them loose I'm now thinking of fitting it.

 

[Wayloncle]

The guy I bought my boat from said he put vasoline on the plugs when it was going to be a month or so before taking it out on the water again, I don't know his reasoning for that, but my gaskets are dry and seem to install and come out easily so I haven't used anything on them. I put them in right before it goes in the water and take them out as I clean the boat afterwards and spray them down with fresh water. Oh yeah, I leave them sideways on top of the hole as well...