What is the Name of the Tool to Remove this Nut?

[Wotname]

Originally Posted by jimbunyard

'Gentle' heat is not what's needed here. Looks like L/H thread to me, but enough thread is visible to tell for sure in person.

If you have access to a welder (and something tells me you do) a very simple tool to remove this can be made with 2 pieces of 1/2" (or so) steel key stock, a 3" x 3" (or so) piece of 1/2" steel plate and a 1" (or so) nut.

Mark the center of the square plate and weld the nut to it. Mark the center of the other side and weld the two pieces of key stock, from this center mark, parallel to each other, half the distance of the total width between the flats of the 'nut' holding the pulley on.

Secure the assembly holding the pulley and nut very strongly, a big vise or clamped to an immoveable table would be ideal.

Get a 1" (or whatever size nut you've welded to the steel plate) socket and breaker bar or such ready.

And here is the important part...quickly heat the 'nut' holding the pulley on with an ox-acetylene torch as much as possible, just before dull cherry red would be about right, immediately you've got it hot, put your homemade tool on it and break it loose. If it turns a little and locks back up, let the whole assembly cool (or quench it yourself) and do the heating thing again.

Sometimes dousing the threaded area with some kind of penetrant in the cooling part of the cycle will help speed things up...

The idea of quick, strong heating is to get the nut to expand before the shaft does, and turn it off before the expansion of the shaft equals the expansion of the nut. Hence the (general) futility of using propane or Mapp gas in this application; one can't add enough heat quickly enough to take advantage of the differential rates of expansion...

This is why I like CF; I never would have thought of using key stock for making a custom socket
And yes, welding is not a problem!

[Wotname]

Originally Posted by Seeking Solace

Maybe this will help? If nothing else you'll have a PDF of the service manual. It gives detailed instructions.

http://seekingsolace.28thid.us/Yanma...e%20manual.pdf

Thanks but unfortunately this service manual makes no mention of this nut (and also not of a similar nut on the camshaft).

Interestingly the manual in the link does not include pages 41 & 42 which lists general and special tooling required. However I have seen other copies that do include these pages and again, nothing is mentioned about these nuts.

[meatservo]

ATF and Acetone mixed 50/50 is what they used offshore for loosening nut/bolt fused together in a marine enviroment on oil rigs...


meatservo

[boatman61]

From looking at the picture the sides look square enough to take a bog standard open ended spanner and a 10lb lump hammer to assist.. maybe an overnite soak with 4-1 penertrating oil to ease the job.

[weavis]

Originally Posted by boatman61

From looking at the picture the sides look square enough to take a bog standard open ended spanner and a 10lb lump hammer to assist.. maybe an overnite soak with 4-1 penertrating oil to ease the job.

I must be older than I think..
I only remember 3-1 oil...

[sailah]

I'd measure the width across the flats then mill a slot in a piece of round bar. Grab the round bar slug with a pipe wrench.

Or weld a nut to the nut and back off. Replace with hex nut.

If you want to measure it I'll make you the tool nocharge or you could make yourself with a cutoff wheel in a grinder in about 2 min.

[motion30]

My question is why does yanmar or need to use a Fastener like that. It looks like they tried to make it hard poor service the more I see of them the less I like yanmar

[aclmck]

get an old pair of stillisions, (the type you would use on gal pipe) 600mm or larger , tighten onto the nut and twist (if as you say it dosen't look frozen this should undo it) , that is what I use every time I need to change a belt on my rideon mower.

[Wotname]

Originally Posted by motion30

My question is why does yanmar or need to use a Fastener like that. It looks like they tried to make it hard poor service the more I see of them the less I like yanmar

I have to say I was surprised when I first saw it - your question is relevant - why use such a fastener; presumably it was cheaper to make these than to buy a off-the-shelf hex. We are talking about a mid 1970s engine here.

The most important thing I take from this thread is that there is no normal engineering tool out there for this shape of nut.

Thanks to all who have contributed - some good ideas have been posted.

I will get it off and hopefully without further damage.

[Wotname]

Originally Posted by sailah

I'd measure the width across the flats then mill a slot in a piece of round bar. Grab the round bar slug with a pipe wrench.

Or weld a nut to the nut and back off. Replace with hex nut.

If you want to measure it I'll make you the tool nocharge or you could make yourself with a cutoff wheel in a grinder in about 2 min.

More good ideas - thanks.

The round bar would need to around 40mm (1.5") and I don't have that sort of size lying around - I do have a bit of 4" round bar but that ain't going into this job . FWIW, the flats are 24 mm across.

Welding a hex nut on will work but I'm more interested in getting it off without doing further damage - just a pride thing I guess.

Apart from the Gator Grip, it looks like whatever I use will be custom.

[Wotname]

Originally Posted by aclmck

get an old pair of stillisions, (the type you would use on gal pipe) 600mm or larger , tighten onto the nut and twist (if as you say it dosen't look frozen this should undo it) , that is what I use every time I need to change a belt on my rideon mower.

Well I do have a couple of Stillisions; 600mm and 900mm; I will check tomorrow if the jaws will fit inside the pulley depression. Will also see if the 24" Crescent will fit.

EDIT: Just realised the standard Stillison won't allow the fixed jaw down into the pulley depression far enough to grip properly

[MV Wanderlust]

I had something similar, though not from a Yanmar, a couple of months ago. After fiddling with it for more than an hour, I finally borrowed my buddy's battery-powered impact driver. That spun it off with no problem.

[sailah]

Originally Posted by Wotname

More good ideas - thanks.

The round bar would need to around 40mm (1.5") and I don't have that sort of size lying around - I do have a bit of 4" round bar but that ain't going into this job . FWIW, the flats are 24 mm across.

Welding a hex nut on will work but I'm more interested in getting it off without doing further damage - just a pride thing I guess.

Apart from the Gator Grip, it looks like whatever I use will be custom.

Sacrifice an old 1/2" drive impact socket and notch it using cutoff wheel to fit the nut.

[justwaiting]

Old farm tractors used to use square nuts - someone who restores them may have already made a tool you could use. How ever because i am as rough as guts i would grind a couple of triangles to go on the flat sides and try with quality socket and a breaker bar.

[Kita]

That will probably be a special tool from yanmar, you know those guys have been there & done that! I have bought many thousands of dollars in tools & some just for certain jobs, & I have made tools sometimes, but I can say this,having the right tool can make the difference between easy & costing you more than the special tool in damages. ....I once had a half shaft stuck in a transmission, I spent an hour trying all kinds of stuff,mind you I have 50k or so in tools so I am no rookie here I've done this many many times. Well it just so happened that that day my snap on man arrived and walked up and he says hey I got just the tool. I say yeah right how much? He says 90 bucks, I told him if it would work I'd buy it! Well I walked over there with that pry bar bent at just the right angle and popped it out of there in about 10 seconds. I looked at him and said sold! The point is the right tool can save you a lot of frustration. Call Yanmar and buy the special tool make your life easy