problem with mud motor prop nut

R

rob_g

Active member
hey guys, tried posting this on the mud buddy site, but that place is dead and noone could bother to help me out. So, im having a problem backing the forward prop nut off the bearing cap of my mud motor. I only need to back it off a hair so it spins freely and i can put the new prop back on. Ir happened when i thought i was turning the prop off, i was actually turning this nut. I was wondering if any of you guys have any ideas for getting this thing to turn? i started the engine when it was tight to the cap not thinking thats why it looks like it does

View attachment prop nut.JPG
 
Last edited:
I only need to back it off a hair so it spins freely and i can put the new prop back on.
Click to expand...

First off the forward nut needs to have a good amount of clearance to the bearing cap. My forward nut is about a half inch away from the cap.

Next thing is what exactly is the problem? Is the nut torqued up tight to the cap and you can't break it loose? or is the shaft rotating as you attempt to turn the nut?


If the nut is torqued up tight to the cap, you may have to resort to using a "nut splitter"
View attachment nut splitter.jpg


If the shaft is turning, try "double nutting" the threads on the lower end of the shaft to give you a place to use a wrench to hold the shaft with out damaging the threads. "Double nutting" is simply using two nuts tightened against each other to lock them temporarily to the shaft.

Hope this helps.

 
dave,

the nut torqued tight against the cap. But i think i should be able to turn it off....when you 'double nut' which nut do you have to put the wrench on to? when i tried this before the shaft would just spin in between the two nuts. Am i doing something wrong? I read somewhere else that the forward nut should be about an 1/8 away from the cap so it keeps vegetation out from between the cap and nut.......

thanks though....if not, do those 'nut splitters' actually work?
 
It will mar your bearing housing, but you can use a pipe wrench on it, and your open end wrench on the nut...both with breaker bars, and line them up like a giant pair of scissors, and usually turn it free. Some makes require less clearance between that hut and the bearing housing than others, and less is preferable (so long as no rubbing), as weeds will get anywhere there is a gap.
 
Rob,


Breaking that prop nut away from the bearing cap looks to be a tough sell. I imagine it is torqued up pretty dang tight from the engine torque. It may also be galled up against the surface causing a lock washer effect. Never-the-less, I'd try the double nut trick first.
See the below illustration;

View attachment doublenut.jpg

Nut "A" will need to tightened against nut "B" with more force than the prop nut to bearing cap. I would suggest using grade 8 nuts as they will be harder and stand up to more torque than grade 5 (grade 5 being common hardware store grade)

Once "double nutted" put one wrench on nut "B" and the second wrench on the prop nut. At that point you should be able to turn the prop nut away from the bearing cap and towards nut "B".
 
It will mar your bearing housing, but you can use a pipe wrench on it, and your open end wrench on the nut...both with breaker bars, and line them up like a giant pair of scissors, and usually turn it free.
Click to expand...


By using a pipe wrench on the bearing housing, you run the risk of permanently egg shaping the bearing housing. I would use the nut splitter and sacrifice the offending nut rather than run the risk of damaging the housing. IMHO :>)

 
I guess it's technically possible, but I've probably used wrenches on a LOT of them and have never had an issue....of course, I had extra housings and bearings laying around, too. LOL ....I also had a wrench that fit the housing plate, later on....which was to keep from marring the housing, but I never really worried about warping or bending it, due to it's thickness/toughness.
 
Last edited:
welp, thanks guys, hopefully this works...i really don't want to order again from mud buddy because everytime it takes a week to get the parts. I really wish i realized what was going on but i was sooooo intent on getting that prop off it drove me insane. it was all i could think about haha.
 
Couldnt you stick something ie; wrench or extention in the u joint up by the motor, to keep the shaft from spining. Then just take the nut off.
 
i thought about it, but i think theres to much of a chance of wrecking the u-joint or doing something to the output shaft of the motor...i just got back from home depot with the nuts so im gonna try that i guess first.
 
Rob ,

I would suggest cutting the nuyt off or breaking it with the tool Dave showed , then have a machine shop make another for you , the nut looks locked on good in your picture . good luck !!!!



Dave M
 
Couldnt you stick something ie; wrench or extention in the u joint up by the motor, to keep the shaft from spining. Then just take the nut off.
Click to expand...


I have done that before. Nothing broke but I might have been lucky. My thinking was that the U joint takes a lot more torque than I can deliver by hand.
 
i thought about it, but i think theres to much of a chance of wrecking the u-joint or doing something to the output shaft of the motor,,,,

Rob,

Good thinking! Yes the u-joint is designed to handle more torque than someone can exert using a wrench on the shaft. Trouble is, the u-joint does not have wrench flats. When you jam something between the ears or otherwise try to hold the u-joint, the stress involved is NOT delivered in the normal manner that the u-joint was designed for. Yes, you do stand a good chance of damaging the u-joint this way. I have no doubt that many folks have got by doing it, but it is still not a good proccedure.

Good luck
 
FWIW Looking at the picture, I'd say you might have a bearing issue, to begin with...if the nut has moved forward/locked in like that.....worth checking into, anyway....does the shaft slide back and forth or have more than 1/4 turn of play, etc.? And maybe I mis-understood you to begin with> You are having trouble with the bearing housing turning while trying to turn the nut, or the shaft turning while trying to turn the nut, or both? If it's either the first or last scenario, you are going to have to hold that bearing housing, period.....fixing the shaft immobile, alone, won't work....but you may have to do both? Just pondering on it.
 
Just by looking at the picture it seems like another approach would be to buy a tappet, aka pump, aka "thin" wrench the size of the square protusion on the bearing cap and then use it and a wrench that fits the prop nut to back it off. I can't tell how much shoulder you've got there but it looks like it might work. McMaster Carr has them and usually ship the same day you order. Having said that though Dave's jam nut approach seems like it would work but I have stripped threads using that method when things were really stubborn.

Eric
 
Fellas,

The one thing that should be pointed out is that the bearing housing and the bearing cap are independent of the threads on the shaft. The shaft is also free to turn inside of these items. Holding the cap and/or bearing housing will not prevent the shaft from spinning when the prop nut is turned.

If one were to hold the housing and/or cap and then apply a wrench to the prop nut, the prop nut and shaft would turn as a unit because there are bearings for it to turn on. The shaft itself will need to be held in order to turn the nut on the threads.
 
Dave

Gotcha. I was trying to help but this is an item I've never fooled with and was off in my assessment of how it might be rectified.

Eric
 
the shaft still spins properly, its just the forward prop nut is to close to bearing cap. I bought this motor in real rough shape after it was used in all saltwater. so everything that could corrode was corroded and everything that could rust is rusted haha...Sank a bunch of money into it getting it ready and this is the last thing before im good to go hopefully.

thanks again for all the replies
 
Rob,

I don't have an exploded view of the bearing housing and related parts handy but a couple things come to mind.

(A) Eric is right that it is possible to strip the threads on the shaft if too much force is used. There is a limit to just how much torque the threads will hold before yeilding. If you still can't back the prop nut off using this proceedure, you may have to think about the nut splitter and or doing some surgical grinding of the nut. Carefully grinding away opposite sides down to the top of the threads, at which point you should be able to split the nut away.

(B) I am surprised that the threads run up that close to the bearing cap to allow this to happen in the first place. The threads on my shaft end about a half inch away from the cap. Thus there is no way the nut can ever spin beyond that point. You might want to contact the folks at MudBuddy to see if you have problems with the bearing spacing or such. It is quite possible that your unit may be missing a spacer or be improperly assembled, even tho it still "runs".
 
You must log in or register to reply here.
Back
Top