Water Pump rebuild - con't

[Warren Milberg]

Anyone know if the nut holding the pulley onto the raw water cooling pump for a Yanmar 2GM20f is reverse threaded? I've tried every trick I know, from using a strap wrench to stabilize the pulley, to using a torch on the nut, and I just can't get it to budge. At this point, if it is reverse threaded I'm not sure I could move it in any direction. Anyone have any tricks that worked in getting this nut off the pulley?

 

[RichH]

Use a magnifying glass and carefully look at the end of the nut/shaft for traces of the thread direction used ... typically these exposed surfaces are chamfered but you may see some clue as the thread direction. For stuck sheaves, etc., remove the pump, 'chuck it' in a vise and use an impact wrench .... once you verify which is the correct thread direction.

Otherwise call, Bayshore Marine Services in Annapolis (410 263-8370) and simply ask which way - CW or CCW - the normal thread pattern direction for the pump shaft to sheave attachment. The parts counter guys there are 'that good'.

 

[cbsailor]

Should be a right hand thread if it's like mine. Here are some pics of the disassembly of mine.

 

[Chris Patterson]

Yeah, the impact wrench is going to be your friend here. Just like an alternator pulley nut, most times it's your only recourse.

 

[Ken13559]

Nope. The only reverse thread is the nut behind the pulley that tighten the shaft to the larger bearing.

 

[capta]

Spraying it with PB Blaster several times a day can really help dismantle equipment without breaking things. I've seen a very old (on a commercial fishing boat) rusty steel windlass come apart quite easily after a couple of days of repeated spraying. We use it everywhere, like the engine mounts, couplings and any rust that might be on the engines. Not as good as Fisheline (a Kiwi product I've found nowhere else), but better than anything other than repainting properly.