Descaling Yanmar 2GM

shemandr · Mar 14, 2024

The de-scaler that is most popular is Barnacle Buster.
It is caustic. I assume it's an acid.
I have never used it. You should go to their website for more information.

Roland5048 · Mar 14, 2024

I once used muriatic acid to descale my old YSB-12. Don't leave it in very long, less than five minutes I would guess, as it will eat metal. Flush it out completely and you should see a bunch of debris come out the exhaust. I've never used Barnacle Buster but am assuming it is an acid, also. The acid reacts with the calcium in the scale and dissolves it quickly. Use eye protection and don't get it on ya'.

Richard19068 · Mar 14, 2024

azambella said:
I want to descale our 2GM. I can see lots of deposits inside the motor when I pull the thermostat.

Anyone don this? What do you use and how do you do it.

I am making a few assumptions like keep any costic liquids away from the pumps and exhaust....

All info is most apreciated.

Thanks

This might help a little.

Descaling Solutions for Boats - Practical Sailor

Since 1974, Practical Sailor’s independent testing has taken the guesswork out of boat and gear buying.

www.practical-sailor.com

Ralph Johnstone · Mar 14, 2024

azambella said:
I want to descale our 2GM. I can see lots of deposits inside the motor when I pull the thermostat.

What you are seeing inside your Yanmar ENGINE BLOCK are likely the metallic products of corrosion which have been corroded from one location and deposited in other locations. These deposits are not the sea water scale referred to in the Practical Sailor article above. Those are most commonly caused by salt water. Sea water scale as opposed to internal engine block scale require different cleaners.

Search for internal engine block coolant cleaners made by well known Antifreeze manufacturers such as :

https://www.amazon.ca/Prestone-AS105-Radiator-Flush-Cleaner/dp/B00B99U088/ref=sr_1_2_mod_primary_new?crid=3G68YVBAEI5XK&dib=eyJ2IjoiMSJ9.cWEQe8oKW3SkeibihG6y2fHHBjs_GH6vMiursOqO8M6-9Kr0KN60uCUx7nuKkd9Q2uttnFVWN_ERUD6hjmrd7epKfB-aWbldVdsnPZ81Nkec5dnBDGrUkeoredUv9zIBYQnRiAFIZZ8IX9L1a5EeT67m_41t5o4Q598IBz104idKr4zitwYsg5jObsupWWAh0Orw6R4IsShkMrSLX0EenLQ7oOrErEuxNXRIUExzI8c_hbtFuRuA4C_m-z1evdqpNTBZFS_dGzUyQEP3TNX0PZPwIx_eTFJbX4KsqXJydE4.c1o-vnl1hRANvqywCCGji6mJc5DQEw1A4nD7fbODJRw&dib_tag=se&keywords=prestone%2Bengine%2Bcoolant%2Bflush&qid=1710477561&sbo=RZvfv%2F%2FHxDF%2BO5021pAnSA%3D%3D&sprefix=prestone%2Bengine%2Bcoolant%2Bflush%2Caps%2C128&sr=8-2&th=1

Once the internals are clean, use only distilled water to make up your 50/50 antifreeze mix.

kloudie1 · Mar 15, 2024

Note that the 2 GM is seawater cooled.. the 2 GMF is coolant cooled.. He may well have seawater deposits

Ralph Johnstone · Mar 15, 2024

kloudie1 said:
Note that the 2 GM is seawater cooled.. the 2 GMF is coolant cooled.

Ouch, ouch, and ouch ! What a difference the lack of an "F" can make.

Blitz · Mar 15, 2024

I used barnacle buster a few years ago on a 3GMD (raw water cooled only) as maintenance and not because I saw anything alarming and the engine wasn't overheating.

Going from memory so this is going to be rough:
- I used a submersible recirculating pump from home Depot that is used to flush tankless hot water heaters.
- I removed the thermostat and installed fittings for hose connectors right prior to the thermostat housing and at the outlet at the top of the exhaust manifold water jacket.
- the solution (2 gallons??) was placed in a bucket was circulated for some time: read directions since I think it was for 45 minutes to an hour in each direction, then flushed with clean water.
- I think Iay have removed the zincs prior to the treatment and put in new afterwards.
the raw water pump was removed and cleaned manually prior to reassembling everything and running engine.

The solution for this gets pretty dirty but didn't get any big chucks or anything like that out. I felt it was just good maintenance for at the time was an over 35 year old engine (this year it is 40 as well).

good luck and let us know how it goes