Which engine is used in the Yanmar YB20 excavator?

[bmaverick]

I found yet another site with the pump (I think) I need. This site also mentions all dimensions (photo 2 which I also attached to this reply) plus some useful info about typical causes of failure of this pump and a list of engines in which this pump is used, like (amongst many others) 3T72HL and 3T75HA-S. So it looks like my YB20 does not have the standard 3T75H-LTBS engine. Maybe the original engine was replaced by a previous owner, who knows...
The dimensions are almost the same as the ones I quickly measured. It's just that I took the photo from the other side, so the order of the measured dimensions is the other way around.

Water pump, 121000-42100, 121000-42101, Yanmar 2T72

Water Pump, 121000-42100, 121000-42101, Yanmar 2T72, Yanmar 2GMF, Yanmar 2GM20F, Yanmar 2GM20F-YEU, Yanmar 2T72, Yanmar 2T72HLE, Yanmar 2T72HLE-S, Yanmar 2T72HLEG1, Yanmar 2T72HLEG1-S, Yanmar 2T75H Yanmar 3GMF, Yanmar 3GM30F, Yanmar 3GM30F-YEU, Yanmar 3HM, Yanmar 3HM35F, Yanmar 3HMF, Yanmar...

traktor.com.pl

I know the Log Life coolants out there today are more like water and do not have the slippery feeling between your fingers like the older coolants did. One of the failures is bearing wear mentioned at the link.

Prior, I had listed those other coolants. If they are not slippery enough, then add in 16-ozs (0.5L) of Propylene Glycol coolant, also known as pet safe coolant for RV and Marine.

I run with this one, since I have an organic farm.

Amsoil has PG too,

Amsoil PG is also compatible with fully formulated diesel antifreezes and other organic acid technology (OAT) and hybrid organic acid technology (HOAT) formulations.
ASTM D 6210, D 3306
Caterpillar EC-1
Chrysler MS-7170, MS-9769
Cummins CES 14603
Detroit Diesel 93K217
Ford WSS-M97B51-A1, WSS-M97B44-D
Freightliner 48-22880
GM DEX-COOL
John Deere 8650-5
Mack Trucks CN H
TMC RP-330
US Military CID A-A-52624-A

PG (in concentrate) per Amsoil,
Composition by Weight:
Total glycols, > 92 percent;
Corrosion inhibitors and antifoamants,
= 8 percent; Water, < 1 percent

If you really want a long life coolant for a vintage machine, then PG is the way to go.

 

[Jaap]

Update per Jan 21, 2025 in the morning (in The Netherlands).

I noticed a particular piece on the side of the gear housing that is different on a 3T75H-LTBS, 3T75HA, 3T75HA-F, 3T75HA-F, 3T72HA-N.

In the 3T75H-LTBS service manual a simple "triangular" plate is shown, which is exactly what I see in my engine.
All other engines seem to be different in this regard.

You know what is "funny"? I see now that even the part number for the waterpump in the 3T75H-LTBS service manual was correct all along, 121000-42100.

So the confusion started when looking engine numbers at the parts suppliers websites (eg Fab Heavy Parts).

As long as I would have followed EXACTLY the part number mentioned in the 3T75H-LTBS service manual, which is 121000-42100, I would have ordered the correct water pump, even though Fab Heavy Parts (and most other suppliers) mistakingly DO NOT LIST this as a 3T75H-LTBS water pump.

Long story short (until proven wrong ):
My YB20 DOES have the standard 3T75H-LTBS engine, just as it is supposed to have.
The 3T75H-LTBS service manual shows exactly the same "triangular" camshaft/gear housing plate that I can see in my engine.
The 3T75H-LTBS service manual shows exactly the correct part number for my water pump, which is 121000-42100.

I should NOT have looked at the engine numbers mentioned by Fab Heavy Parts, and I should just have ordered the water pump with part number 121000-42100.

 

[ponytug]

@Jaap good detective work! I'm glad that you have it sorted out. I have had a couple of older engines over the years and learned the hard way, like you, that cross reference numbers fall into the "trust, but verify" category.

I hope that this restores your machine to operation soon, as I'm sure that the horses are still producing manure...

All the best,

Peter

 

[careyo63]

Checked the Water Pump Part number and it came up real close. Repl. 121000-42100 and came up with Repl.121023-42100 which several tractors use it. WP-4201 is the Fredricks water pump # for it.

 

[Jaap]

Update per January 30, 2025. Good news.
Yesterday I received the water pump 121000-42100. This time Fab Heavy Parts shipped it using Fedex which took 10 days, whereas the previous (wrong) water pump from Fab Heavy Parts was shipped using UPS which only took 4 days.
Anyway, I received it yesterday and immediately installed it. It fitted perfectly and the engine was up and running in no time. So my tracked Yanmar YB20 "fork lift" with snow plow is back in business.

Fun fact: the box containing this new water pump 121000-42100 was labeled 3T72HL.

So for reasons unclear to me, Fab Heavy Parts (and as far as I know all other suppliers) make the mistake of not listing engine 3T75H-LTBS on the list of engines on which this new water pump 121000-42100 will fit. If you follow their recommendations for 3T75H-LTBS you will get water pump 129327-42100 / 12900142005 / 12800142100 which DID NOT fit on my 3T75H-LTBS engine.

So if I have to order other parts in future, I will pay extra attention and compare the parts for 3T72HL with the parts for 3T75H-LTBS, to make sure I get parts that fit my 3T75H-LTBS engine, regardless of the supplier's engine lists.

Anyway, all's well that ends well. Thanks again to everybody helping me with valuable suggestions.
Best regards from The Netherlands.