Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 02-08-2015, 17:02   #1
Registered User

Join Date: Jul 2009
Location: 2017 - cruising west coast of Italy
Boat: Amazon 49 cutter, custom steel boat built in Surrey, Canada
Posts: 430
Images: 1
KBW21 Gearbox oil

I have a Yanmar (Kanzaki-Hurth) KBW21 gearbox that I had rebuilt in the Azores. Short story - the rear locknut backed out allowing all the oil to drain into the bilge. Not knowing if any damage was done to the gearbox internals, I had the disks and separator plates replaced while they were replacing the seals.

The mechanic put SAE30 oil in the gearbox. The manual states to use ATF. I tried to ask the mechanic why he put in SAE30, but the language barrier kept me from getting an answer. I do not readily ignore manufacturer's recommendations and I do not know any reason not to use ATF.

So two questions - 1) should I use ATF, and 2) if I pump out the SAE30, there will be some leftover oil in the gearbox. What will happen if I put ATF in the gearbox with a small amount of remaining SAE30?

Thanks in advance!

Steve
__________________
steve77 is offline   Reply With Quote
Old 02-08-2015, 18:22   #2
Certifiable Refitter/Senior Wannbe
 
Wotname's Avatar

Cruisers Forum Supporter

Join Date: Jan 2008
Location: South of 43 S, Australia
Boat: Van DeStat Super Dogger 31'
Posts: 7,331
Re: KBW21 Gearbox oil

Quote:
Originally Posted by steve77 View Post
I have a Yanmar (Kanzaki-Hurth) KBW21 gearbox that I had rebuilt in the Azores. Short story - the rear locknut backed out allowing all the oil to drain into the bilge. Not knowing if any damage was done to the gearbox internals, I had the disks and separator plates replaced while they were replacing the seals.

The mechanic put SAE30 oil in the gearbox. The manual states to use ATF. I tried to ask the mechanic why he put in SAE30, but the language barrier kept me from getting an answer. I do not readily ignore manufacturer's recommendations and I do not know any reason not to use ATF.

So two questions - 1) should I use ATF, and 2) if I pump out the SAE30, there will be some leftover oil in the gearbox. What will happen if I put ATF in the gearbox with a small amount of remaining SAE30?

Thanks in advance!

Steve
1), yes do use ATF.
2), I would overfill the gearbox with ATF, rotate it by hand if you can (decompress engine if possible), drain it out, refill to correct level with fresh ATF, operate for say ten minutes, drain again and finally refill with fresh ATF.

Disclaimer, I am no oil expert but really ATF is still a mineral oil and will mix with other oils. Doing the above will dilute the remnants of the SAE30 to next to nothing IMO.

I suspect the mechanic used SAE30 simply because some other Kanzaki boxes use SAE30 and that is what he was familiar with.
__________________
All men dream: but not equally. Those who dream by night in the dusty recesses of their minds wake in the day to find it was vanity: but the dreamers of the day are dangereous men, for they may act their dreams with open eyes, to make it possible. T.E. Lawrence
Wotname is online now   Reply With Quote
Old 02-08-2015, 21:43   #3
Senior Cruiser
 
Jim Cate's Avatar

Cruisers Forum Supporter

Join Date: May 2008
Location: cruising SW Pacific
Boat: Jon Sayer 1-off 46 ft fract rig sloop strip plank in W Red Cedar
Posts: 11,450
Re: KBW21 Gearbox oil

If it is a hurth tranny under that K- nameplate, it does want ATF, and Dextron III grade to boot. This seems to be important if the gurus on the Hurth forums are to be believed. They also stipulate that one change the tranny oil every time you change the engine oil.

These trannies have a reputation for short life times, and giving them all the help you can seems a good idea.

Jim
__________________
Jim and Ann s/v Insatiable II , lying Port Cygnet, Tasmania once again
Jim Cate is online now   Reply With Quote
Reply

Tags
gear, gearbox, oil

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Gearbox Oil Cooler for Perkins M92 SariTimur Engines and Propulsion Systems 14 10-07-2010 09:39
Alternative oil for Perkins Engines and gearbox anglooff Engines and Propulsion Systems 14 06-03-2009 18:03
First gearbox oil change, Problem? noelex 77 Engines and Propulsion Systems 14 13-12-2008 17:20



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 13:38.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.