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So the title seems like an obvious duplicate or easy answer. But my question is actually a bit different.

I am trying to get a nut off the shaft of an engine. This is the "master" nut that secures the blower rotor to the engine shaft. It has a lot of (surface?) rust and it does not move. I have successfully managed to snap the almost 1 inch thick steel adapter for my impact in half trying to get it off. I used all sorts of penetrating oils, nothing helps.

I have been in a similar situation recently, I managed to unscrew it with a blow torch because I read in the manual that the nut in that machine was secured using thread lock and I assumed (knew) that heating it up to almost glowing hot would get rid of it.

This is where this question gets interesting. The nut is surrounded by non-removable plastic and that plastic is never further than 5mm away from the nut. So a blow torch is kind of out of the question. Here is a picture:

image of nut

Everything black is plastic. I cant use a blow torch, it will melt off the plastic... What are my options here?

chicks
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Yanick Salzmann
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    Are you sure it is not a left handed thread? They use righty loosey instead of lefty loosey. – crip659 Aug 27 '22 at 20:01
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    ah yes, I forgot to mention that, I tried both directions – Yanick Salzmann Aug 27 '22 at 20:09
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    Was hoping for easy. Might need to think about cutting if good tools don't turn it. Looks like it is in PITA place for cutting. Can try https://mechanics.stackexchange.com/ and see if they have other ideas. – crip659 Aug 27 '22 at 20:16
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    I would first make triply sure which direction IS the correct one (might want to dive into the maintenance manual). That screw secures a rotating object, so its thread may be oriented in whichever direction makes it go more secure when running. Your attempts may have tightened it further! – MiG Aug 29 '22 at 08:22
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    Is the plastic part cheap and readily available? – Andrew Morton Aug 29 '22 at 09:36
  • Have you actually tried using heat? I can get a pretty fine flame from my propane torch - you might be able to aim it at the nut and focus the heat there without melting the plastic. It too, though, would look into finding a replacement fan shroud and consider this one disposable. – FreeMan Aug 29 '22 at 12:09
  • @FreeMan Unfortunately I only had a pretty large flame anvailable (think weed burner), but ultimately the problem was something else - the fan shroud and the nut are one part :) – Yanick Salzmann Aug 29 '22 at 19:41

4 Answers4

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You have not applied enough force in the correct direction. So, good fitting socket and a knuckle bar 18" is usually more than enough (that's the one I have and it either comes undone or breaks...)

But, if you don't succeed, then you can drill down the nut in the middle of the flat sides - choose two opposing ones. Make sure you drill accurately as you don't want to damage the reads on the shaft. Then split with a chisel.

This takes a bit more time but you removed the option of using heat.

Solar Mike
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  • You gave me two good ideas. 1) put some rope in the cylinder and then using raw force instead of an impact. Cant use it normally because the plastic wont support the opposing force but with some rope in the cylinder it should be fine. 2) If that doesnt work, cut the nut with my dremel :) – Yanick Salzmann Aug 27 '22 at 20:19
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    You can also use a **nut splitter** (tool that saves the bother of drilling and just cracks the nut off via brute force..) – Ecnerwal Aug 27 '22 at 20:21
  • thats the third idea now, I do have a nut splitter (in German they have the more metal name of "nut exploder" :D) – Yanick Salzmann Aug 27 '22 at 20:23
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    @Ecnerwal I considered mentioning that, but did not as all the good ones I have used would not fit inside that plastic cup. However, if that plastic cup was removed then it would be an obvious solution. – Solar Mike Aug 27 '22 at 20:23
  • Also when it comes to drilling if I damage the thread on the shaft I will grind it down and then cut a new outer thread with a smaller size – Yanick Salzmann Aug 27 '22 at 20:25
  • Well, if you do damage the thread - it will likely still be strong enough. Often nuts were "locked" by drilling and pinning through the thread, if the radial access was restricted. – Solar Mike Aug 27 '22 at 20:27
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    It is off. Indirectly your answer was right. I was not applying enough force in the right direction, but its a bit more complicated. Nut and fan shroud are one single piece. Therefore by using the fan shroud as the place I applied the counter force to I was cancelling my own effort out. Eventually I started using a larger and larger lever until I could no longer use the fan shroud like that and had to hold it somewhere else. Then it immediately moved *facepalm*. – Yanick Salzmann Aug 29 '22 at 19:27
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Step one - are you positive this nut needs to be removed at all? If you can get into the motor from the other side, it may be easiest.

Can you source a replacement plastic fan? If so, the current one is disposable.

Another option might be to carefully cut the plastic in a circle, just outside the washer visible in your photo.

Then once you've removed the nut and done your business, secure the fan between two larger-diameter washers/straddle-plates and clamp with the nut. A good surface-toothing with sandpaper and plenty of quality 2-part epoxy should be enough to hold the fan to the washers, and the clamping action of the nut on the shaft to hold them all together at spinup/down.

We can't see what's on the other side of the nut either - it might have a positive interface with a drive key or pin in the shaft.

Criggie
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Kroil (a quality penetrating oil) and a breaker bar of adequate length (I have three different lengths and cheat with an extension pipe from time to time).

J D
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We can now get [buy!] an induction heater coil which can heat any conductive object e.g. that nut via an kinda transformer effect. https://www.youtube.com/watch?v=psk4wGBX8uI It is very localised, and might get you out of trouble. See also https://www.ebay.com.au/p/2273627200

BigPete
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