Bukh Gearbox Coupling Nut .. LH or RH thread?

[VicMallows]

Can anyone confirm that the staked 30mm nut which holds the coupling flange onto the BuKh gearbox output shaft has a NORMAL DIRECTION thread?

Local Bukh agent says he is 'almost certain' it is normal-thread, though that on a YANMAR is reverse-thread.

I am having enormous trouble shifting the nut (engine in boat....to change rear oil seal) and it would be helpful to know I'm really trying to turn it the correct way.

Many Thanks,

Vic

 

[jerryat]

Hi Vic,

I have done this, though it was several yeras ago. As I recall, the thread is normal i.e. not left-handed, and the nut was not difficult to undo. I have the workshop manual to hand and no mention is made of the thread being anything other than 'normal' which I'm sure it would if this was so. The pictures aren't clear enough to see the actual threads though a cross section drawing definitely shows the threads as normal.

If you wish to be re-assured, why not give Al Pearson or Norman Griffths a call at Bukh Diesel UK. The number I have is 01202 668840at. They're super chaps know the motors inside out, and are always willing to help.

Incidentally, the manual suggests that a puller will be needed to remove the output flange (the thing you're trying to remove to get at the seal) but I found mind slid off with no problem at all. Fitting the seal is a doddle.

All the best

Jerry

 

[VicMallows]

Thanks Jerry.

That's pretty well confirmed the other info I've received. As you say, others have suggested the nut should be easy (and can even be re-staked) but getting the flange off can be difficult. (I have a puller; only question will be available clearance).

I am starting to worry that the nut (and almost by defintion the coupling) have rusted together since they've probably spent some time immersed in bilge water (Sadler 29; water collects in engine bilge on drying mooring due to heavy rain getting in cockpit sole locker if boat tilts forwards).

Thanks again for input. Will post how I eventually get on.

Vic

 

[poriordan]

Hello Vic,

Almost certain here as well it is a left hand thread. I had a Bukh gearbox apart about two years ago and I do not think I had any problem with the nut itself. If it was right handed I would have remembered it as I was trying to clamp the whole unit in a vice to open same. I have a parts manual here in the house somewhere so if you need a copy of a page give me your email address and I'll send same. You can get me at info@abcsmarine.com.

Patrick.