What diesel engine is this on my new-to-me 1978 Catalina 30

Nov 6, 2006
10,102
Hunter 34 Mandeville Louisiana
Welcome to the forum!
Not 100% on this one but I think it’s a Yanmar YSB 8 or YSB 12.
The hand crank chain might say it is a YSE-8?
This chart is taken from Toad Marine's web site:

Y Series
These horizontal models lay down in a low profile. The series was updated three times with the YSE being the earliest model, followed by the YSB and then the YSM. Either a 2:1 or 3:1 transmission. The models were sea-water cooled, singe cylinder, heavy duty. This series includes the following engines:
EngineHPYears In ProductionComments
YSB12121976 - 1977B=Between
YSB881976 - 1977B=Between
YSE12121974 - 1976E=Early
YSE881974 - 1976E=Early
YSM12121977 - 1980M=Modern
YSM881977 - 1980M=Modern
 
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jssailem

SBO Weather and Forecasting Forum Jim & John
Oct 22, 2014
23,265
CAL 35 Cruiser #21 moored EVERETT WA
Catalina data base on the data sites like SailboatData.Com say the auxiliary used was “variable.”

Wiki shares this bit of info (sourced from Frank Butler)
“The design was initially fitted with a Japanese Yanmar diesel engine or a Universal 5411 or Universal Atomic 4gasoline engine, but by the mid-1980s these had been replaced by the three-cylinder Universal M-25diesel.[1]”
Your best bet is to inspect your engine and identify the serial # and any labels inscribed on the engine.
 
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May 4, 2023
2
Catalina 30 Providence
Thanks for the help!
Comparing pictures and diagrams of various Yanmar engines, mine appears to be a YSM8 or YSM12.
Luckily almost all of the commonly replaced parts are the same:
104271-77350 Alternator Belt
124060-59380 Bleeder Plug
23418-060000 Bleeder Plug Washer
104500-55710 Fuel Filter
24341-000440 Fuel Filter O-Ring
104211-42070 Impeller
104271-35130 Oil Filter
704507-92100 Tool Kit
104511-78780 Water Pump Belt
104211-42090 Water Pump Gasket
104211-42100 Water Pump Seal
27210-200300 Zinc
123210-09310 Zinc O Ring
23414-250031 Zinc Washer