Engine Flushing

[Neil McDonald]

I have just finished an extensive internet search on what liquid to use to flush out and/or soak the fresh water cooling side on my Yanmar 3GMF engine. I want to clean it out to improve cooling efficiency. There sure are a lot of different opions out there! The most agressive approach seemd to be using full strength muriatic acid, although many thought that this would quickly damage the engine - particularily if left overnight to soak. Others used a 50% solution of muriatic acid. Some said use a regular autoshop rad flushing liquid, but make sure that it is suitable for use with aluminum. On the other end of the scale, several people liked the idea of soaking with a 50:50 vinegar/water mix and noted that this selection made final disposal of the flushing solution much easier because it had minimal environmental impact - which made me wonder if it would also be much less effective at cleaning out the inside of my engine and water heater!!Do any of you have any thoughts on this topic? Neil

 

[Jacques LeBlanc]

Giveing it a flush

If you flush with acid don't leave it in over night I WOULD ONLY LEAVE IT IN FOR NO MORE THAN 10 TO 15 Min.because if there is freeze plugs witch are no thicker than a DVD or CD or a radiator on this motor the acid could eat right through it not to mention a heater core if it is built any where near the way a auto heater core and radiator is built.Than flush real good to make sure all of the acid is out. If the boat is on dry dock and can be ran than you could use regular automotive flush, the automotive flush needs the heat from the engine for it to work properly. And the reason why I say dry doc is because you must put the flush in ,run the motor for 20 to 30 min. than drain the fluid,fill again with water run 20 to 30 min. then attach a water hose with the adapters you get in the separate flush adapter kit. And flush till the water coming out is clear.And i'm sure you don't want to drain that stuff in the slip.

 

[NYSail]

vinager

I have heard vinagar works good...also muric acid deluted. I have to attend to the cooling system this spring and worry about harming the rubber bushings inside the heat exchanger with acid. I plan on removing the tubes within the heat exchanger and inspecting. It has been said that it comes apart quite easily.Greg3HM35F

 

[Steve Dion]

check out Marsolve

I do not know if the product is still available, but check out Marsolve. It is a product that is specifically made for this process. It is also suppose to be environmentally safe.

 

[RAD]

Try this Link

NM

 

[walmsleyc]

I have used Automotive Flush

This past fall I performed multiple flushes on my 3GM30F. I used an automotive flush liquid (safe for diesel/aluminum engines) off the shelf. The operation was a big success in that a large amount of brown sludge was extracted from the system. I was not having an overheating problem, but simply figured I should do it because the POs may not have done it recently (or ever).I repeated the flush a few times, and then rinsed with fresh water a few times before refilling with 50/50. The process is somewhat of a pain as it required the use of a foot-powered air pump (from an air mattress) to force the coolant from the water heater circuit. I think this was where most of the sludge was hiding. I plan on doing it again next year to ensure that the sludge is fully removed.Chris

 

[walmsleyc]

Another link

BTW ... here a link that might be of help. I replaced the "blowing" on the heater hose with the foot pump to avoid passing out from having to blow so hard.

 

[Nice N Easy]

Flushing

Not sure how it would work in your system, but in the raw water side, I have used straight muriatic with good success. I am going to do mine which is raw water cooled very soon, and plan on using straight muriatic for this. Do not leave it in the system. Run it through, let it sit a couple of minutes and flush. You will be amazed at how much gunk comes out. Whatever you decide to use in your engine, put a box of baking soda in there, and make sure it is thouroughly circulated, and then drain it out before putting anti freeze in. Anything that will take the crud out of the engine is acidic. You need to neutralize the acid or over a period of time it will eat things up. Anything that will clean it is going to be acidic, so I would consider the baking soda a must. On the raw water side this shouldn't be necessary, as you have a constant flow of water through there.

 

[Bill Roosa]

Fresh water flush

Well if you have been using antifreeze and replacing it regularly there should be no need for a flush. Anti has anti corrosion and water pump lubricants that wear out over time. That is why you change it out at intervals. The glycol never wears out just like water never wears out. Soooo if you keep a regiment there should be NO corrosion on the fresh water side. I've driven autos for over 200000 miles (200000 mi / 50 MPH = 4000 hours on the engine) and when we tore her down at 300000 there was no sign of corrosion in either the block (cast iron) or the radiator.Much more likely there are salt/mineral deposits on the raw water side and in the mixing elbow that are MUCH more serious impediment to heat flow

 

[Neil McDonald]

Removing Tubes

Greg says that he has been told that pulling the tube assembly out of the heat exchanger (HE) is not a problem since "it comes apart quite easily". Seeing the hidden side of the tubes woud make me feel much happier because it is quite obvious that the efficiency of heat transfer in this location is much more critical than elsewhere in the engine. Is it really this easy to remove the tubes from the HE?Neil

 

[Steve Dion]

New coolant should be extended life Havoline

Neil:Once you get your engine flushed, you should be using Havoline Extended Life coolant or something equivalent. This is what is recommended by Yanmar for their fresh water cooled engines.

 

[RichH]

Use an organic descaler .....

Muriatic, acetic, etc. etc. will dissolve the base metal when they penetrate through after dissolving the carbonate layer. Such inorganic acids will also destroy the ferrous oxide (black rust) coating which is a preventative or protective layer against ferric oxide (red rust - 'bad' rust). IF you do use one of the above inorganic acids to 'pickle' the engine you MUST soon after run the engine at max. operating temperature for an hour or MORE to restore the ferrous oxide coating inside the cooling circuits .... doesnt matter if raw water or fresh water circuits.If you use distilled/de-mineralized water in the Fresh water side .... you WONT have any carbonate fouling. Organic commercial boiler descalers will attack only the carbonates (not the base metal). www.marsolve.com or rydlyme.com or rydlyme.netPickling is usually only done to the raw water side as the carbonate fouling can be bodaceous'. If the raw cooling water exceeds ~145degrees you WILL begin carbonate precipitation. On engines that historically form raw water side fouling, installation of a thermostat that fully opens at 135 degrees can greatly retard the fouling (but you suffer from less combustion efficiency). Use a commercial boiler descaler ... RUST (in the cooling circuits) is THE destroyer of marine engines. Forget the muriatic/hydrochloric, acetic/vinegar, oxalic, sour vomit, etc. .... you want stuff that removes ONLY the carbonate not the base metal.