Yanmar 2GM (KM2-A) transmission fluid question!!

[Northeaster]

I have read, in many posts, that it is recommended to use the same lubricating oil in the Yanmar 2GM transmission, as in the engine. However, when I read my official Yanmar manual (ch11, operating instructions, page 11-6) it states to use Dexron, Texamatic fuid, ATF220, ATF, etc, in the clutch case (several different fluid vendors). To me, this seems quite clear - does the ATF not stand for Automatic Transmission Fluid??

My engine is a 1982 2GM, with a KM2-A transmission! Is there a difference in years, or did later 2GMF, 2GM20, etc come with different transmissions, etc?

Would like some advice as to what to use. Ran the boat last year with whatever was in theer from PO, and topped up with ATF. After taking apart, and reassembing this winter I added Rotella 15W40 - same as engine, but am now second guessing myself.

Help please!

[Delezynski]

Northeaster,


My Yanmar 2GM20F has a “KM2P” transmission on it, not the 2-A.
Stamped into the back of my tranny is:


MODEL KM2P
GEAR RATIO 2.62
OIL SAE 20/30 HD
OIL QTY. 0.3 LTR
NO. (Not put in here for this use)
KANZAKI
OSAKA JAPAN


Any help?? You might look for the same stamp markings on your....



Greg

[Chief Engineer]

You use ENGINE OIL...the manual says 10W30 CC rated

The KBW10D and 10E use ATF

I have had 3 trannies on customers boats "go" because some "mechanics" replaced the oil with ATF

[Northeaster]

Del = thanks for the clarifictaion on your engine / trannie type!

Chief - Thanks for the advice!!! I am not trying to be difficult, I am just wondering if the ones that you have worked on have been K2M-P, etc where the manual says use engine oil.

I have the original manual for mine, and have quoted the pages above, where it says to use ATF. I just would like to know why my original manual syas ATF, when your's and other's say engine oil. Are they different models, or has wisdom changed in the last 20 years, and engine oil is now recommended for mine as well.

[Chief Engineer]

About your transmission.

A number of the Yanmar gears I have seen have all the details/cast/stamped into unit.

For a definitive answer, contact Mack Boring & Parts Company - The Power Behind The Power

[Ex-Calif]

What's in it now?

ATF is easy to distinguish from motor oil. I would also seriously check the case for the model number before I added anything.

[Northeaster]

I will check the trannie to see what is stamped on it! If I can't read / find it, I will call Mack Boring. Thanks for the input!

Yes, I have posted numerous times on Sailnet - I joined that site before this one. I find the two site very helpful!

[GordMay]

Charlie Wing gives a pretty good description of how the KM2-A works on pages 42 & 43 of:

How Boat Things Work: An Illustrated ... - Google Book Search

[Inlet Marine Services]

The tag on the trans shoud say 20 / 30 which means 20 weight or 30 weight. We use 15/40 in the engine and 30 weight in the trans. Some older units had hurth gears used ATF but you KM series use motor oil and very little.

[Northeaster]

Well - checked the tage on the trannie - it odes say 20 / 30, as several members have suggested! I will leave the SAE 30 oil in it!!

I did not want to beat a dead horse - however, as my manual (and I quoted the page in the 1st post) says to use Dexton, ATF ,etc - I just wanted to make sure.

Thanks to everyone who replied!! It is confusing when the maual says one thing, and the stamp / tag says another!!

[Chief Engineer]

Jiminy Xmas go by what the metal sez....not the paper.

[Inlet Marine Services]

I am a Yanmar Dealer, use 20 or 30 weight. The manual is generic and could be for some older models. Do what the tag says.

[Southern Star]

Does anyone know, is there also a stamping on the case of the Yanmar SD20, or does one just rely upon the manual as to the correct lubricant?

Brad

[kibo]

When the km2p failed during a particularly hazardous anchorage while running in from a storm in a boat I was delivering, I put in for repair with a yanmar mech in the next port.
He pulled it down and confirmed that it had recently been overhauled and could not see anything outwardly wrong with it and admitted that he rarely saw them as they are very reliable, so he lapped in the cones and took $500 off the owner.
After calming said owner down on the phone he tells me that the oil he used to fill the box both before and after the first reco was under the sink.
Punch line.
Under the sink I found a friction modified Teflon 15/30.
Yanmar mech installed by volume 300ml 30 single weight.
Owner eventually reeducated at a cost of over $1000.