Yanmar 1GM10 internal clean 

Good Video! Great presentation. Just a comment re: Winterizing Boat engines for Rich C. I run anti-freeze through my raw water cooled engine until it's coming out blue or purple depending on temp range and manufacturer. Collect the AF that's been through the engine and pump it through the heads. Drain water tanks etc. I've had -35C with wind chill -50C in AK and N Finland. Engine always started and ran fine. 2GM20. My 2GM20 has 4361 hours from new and starts on the button every time. Nothing but regular maintenance and 3 elbows (The cheap knockoffs) plus a bunch of bleed screws which tend to get weepy. I bypassed the lift pump (wobble pump or butterfly depending on where you are) and installed low capacity electric pumps wired to the ignition. Key on pumps starts/key off pump quits (actually 2 in a mini wire dioded splitter for quick changeover) so bleeding is a non-event. I did this 4 years ago and swap the electric pumps over on my 100 hour checklist. both still put out 4.5 psi on a $7.00 radio shack gauge ...BTW - The engine quits if the mechanical lift pump dies on both GM engines. The 1GM suffers from lift pump failures more than the 2GM but not if well filtered fuel with no diesel bug etc. On my previous boat I had a 1GM I bought second hand - with hours unknown for 200USD. Got 2800 hrs or so out of it, but always polished fuel (10microns) between main tank and 22 liter day tank and used Prist in cold wx. Changed oil every 100 hours religiously. Yanmar make good engines and the ones that die early have been murdered, it wasn't suicide ;-) One other thing to watch...The gearboxes that come with the 1 or 2 GM are produced by Kanzaki (Subsidiary of Yanmar I think) and have a goofy yellow handled dipstick on the left side of gearbox. There is no high/low fill line. Just one line right at the bottom and that's the high level limit. The end of the stick is the low level fill line. It takes a standard beer can amount .03 to 0.33 litres after draining (you never get it all). It just feels wrong with that goofy dipstick, but that's the way it works. Rest the dipstick on the fill hole rim to check but don't screw it in. I've used the beer can measure about 40 times and is the easiest way to be sure. You won't see the level as the dipstick is too shiny; so either rough it up with wet and dry or as I do, drain it out and use a beer can full to replenish it. You might have to drain and wipe out the beer can first. ;-) Finally! Some manuals say use the same oil as the engine. some don't - but Yanmar France told me to use straight 30 weight oil in the gearbox. Do not trash the gearbox. The price of a new one will make your eyes water.... Final tip...The engineer in Yanmar France caught me out. I was bragging that my engines starts before I can get my finger off the button. He said an engine that takes 5 seconds to start is better because mine is up and running before any oil has circulated. I'd never heard of that before but it sorta makes sense. Now I don't use the batteries crossover for engine start. Just remembered: I take the water pump impeller out so it has a chance to relax and go back to normal shape. No point replacing it next year if it's all good. Cheers...

Great video and very useful thanks. I have similar issues with my 1GM10 and the warning light is on. Hopefully this will work.

Thanks very good video,I have a 1GM.all the best..

Nice video, v.informative, was working on mine today.

The engine block drain you mention is not from the thermostat but from the block itself situated below the exhaust elbow and behind the fuel lift pump. It has a plastic knurled knob and often blocks so worth unscrewing and back flushing if it doesn’t drain easily. Important to drain the block when cold weather winterising the engine. I’ve used the vinegar trick regularly to clean my engines but didn’t realise the importance of neutralising it afterwards so thanks for that

great video. Nothing like an engineer talking about engines. Any idea where I can get a pdf file for that "old" 1GM manual with the detailed drawings of the cooling systems? I have the newer version only.

Very useful. Many thanks!

I did something similar, but removed the thermostat and pinched off the bypass and just ran fresh water thru the jacket

No one wants to overcomplicate any installation. That said, for the life of me, I can not wrap my mind around circulating seawater through an engine. I have seen many low-hour marinized engines corroded to a point where it would be pointless to attempt any rebuild or put the engine back into service after an inspection. There was simply nothing left to work with. The engine blocks and heads were corroded beyond salvation. These boats were put into the water for the warm season and at a slip in a marina. The engines were flushed with fresh water when the boat was hauled out for the winter. About ten years +or- of this did them in. I saw this over and over many times. My two cents worth, inter-cooling is the way to go if an operator plans to rebuild and not junk used engines. Yes, I do understand you have limited space on a small craft.

What brand of bleach did you use for the final cleaning, chlorine bleach or?

I do this with 1 litre of brick acid in a builders bucket with freshwater (hydrochloric acid) every years otherwise it clogs up really badly. Missed 1 year and paid for it with an engine overheat warning as it was so clogged up. Run it up 1/2hr at a time for 3 or 4 times. The stuff in the bucket is pretty grimy by the end. Then I run it through with freshwater and then saltwater as normal.

Interesting Vid. Did you get better water flow / consider using a stronger acid? Dangar Marine did a similar test with an outboard

Nice video! I'm based in Largs, and about to do the same with my 2GM. Quick question for you if you don't mind - where's the water coming from at 11:42? I wouldn't have expected to see this, since you're taking those hose from the thermostat out of the elbow, and sending it to the bucket? Thanks

Hi, I saw your video and thank you for your help. I'm about to do it so It will help me a lot. It's har for me to understand all your explanation and I lost some points (I have an survival english). My questions are: The yellow pipe is for the combustion gases right? Why this pipe has a key? Could you tell me any example of household bleach brand? (I will try to find it in Barcelona). Did you do 2 times 50 minutes each? Thank you!

Thanks very much for this excellent clear explanation and very nice demo. I'm about to do it on m'y 1gm10. I juste have a question (just to make sure I do it right) : is it actually Bleach that the chemist recommand as a base solution ? No fear of toxic fumes due to the chemical reaction with the vinagar ? Many thanks for your answer, Denys

Thank you for that. I'm a new sailor and have been on Lake Chelan here in Washington state. I haven't been in a tide or current that will be in Puget sound. My question is how well do these 1gm10 perform in a current? Is there sufficient thrust to motor into a current? Is there an equation to calculate the thrust needed or a rule of thumb?

Hi mate, thanks for the video. I have the same engine and after watching this video I went to my boat and did the same set up as this but it wasn’t drawing any water from my bucket… did you use a 12v pump to pump the vinaigrette solution though or is your water pump on the engine doing all the work? I have a weak water flow from the stern of the boat so I thought I would try this. When the engine is running via sea water it is pumping water but not as much as I think it should. But no draw at all from the bucket method.. Any advice would be great. Thanks Phil, gosport uk

Thank you for your tutorial on the Yanmar 1GM10 , I have a fault on my cooling system .After changing the impeller and thermostat it runs perfect .But every so often if I raise the throttle to fast it appears to get an air lock. The water in the pipe above the thermostat housing appears hotter less water is pushed out astern causing the alarm there is an anti sython valve above that pipe which then goes to the exhaust elbow . I see that on your boat you do not have this set up ,your pipe goes straight to the elbow .Do the thinK this may be a route of my problem and pehapes I by pass this value and connect the pipe straight to the elbow junction (this sython value must be is there for a reason ) to avoid this occasional problem ? If is starts in the first place to run cool the engine can go there after at the right temperature but it may just warn up from go to hot or if I speed up the throttle to quickly . It happens approx one time in five. Any advice will be highly appreciated Thank you

I just got this model 4 month back last week I got hot and the sensor cut in and I switched of I switch on to moor on a swing for there was no way back in due to tide no issue but after 10 mins sensor sounded but I was moored for the night after sailing the next day coming in I lost wind I run the engine three quarters and appeared fine for 15 to 20 mins no issue now in my berth I will be running maintance to sort this . How did that glove filter set up ? I understood the hose water feed to the out pipe which pushes fumes and the close system to flush the engine . Also I saw a hairline crack on my engine in what looks like the cover in the front of the engine with out close inspection I think it is on the housing its under the yellow oil cap would this affect the engine there is no leak of oil and it is not in the block it appears, can I replace this as I think it just looks like a cover it`s if cracked may have come from vibration ? Any other thing I can check , which are not the routine like the strainer or sea cock impeller . I will not be attempting the procedure yet but will be on board this Thursday to identify all the things in your video and organise that hose to insure safety and next visit flush . Thank you for you help . Just parted with a 10 HP Sabb 1964 different world and time, raw water straight through crude and forgiving . This 1gm 10 appears good but less forgiving and I am learning it and grateful for you expertise I am not a mechanic but have a good basic knowledge probably enough to own a boat !!! Any help apricated Jeremy

I have the same engine. My current project is attempting to add a tachometer. Have you done this? If so, any tips?

Hi!! was missing new videos from your channel!! I don't have any experience with this concrete engine... but it seems to me, due to the knocking noise and vibration, that a crankshaft bearing needs some service. keep an eye on the oil pressure!! Maybe this engine has this knocking behavior as standard....I don't know, hope yes!!. Cheers!!!

Please explain again what the yellow hose line was used for?

I have terribly hard domestic water supply. I find it makes two kinds of sclae: whitish stuff which fizzes if I put acid on it and easily disappears, and yellowish stuff which is much harder and doesn't seem to be affected by proprietary descalants. I am a physicist, not a chemist. I did take chemistry A level but have entirely forgotten it. I'm wondering if the thing you put in second - the base solution - is what I need to tackle the yellowish stuff?

have you ever rebuilt this engine. i am really tempted to do my 1gm. also have you much experience with wiring? ta muchly

where can I buy a hand crank for my Yanmar 9 hp GM10 diesel engine

Hi would you mind telling me how you drain the fresh water from it over the winter. I can’t find a drainage point in my manual. Many thanks

Count on me if you need anti vibration mounts.

I belive raw water cooling not ideal. I would prefer coolant with a heat exchanger arrangement.

Salt or brackish water cooling in a motor is murder. In your shoes, I'd replace it with a car radiator, distilled water, and 60 % prestone antifreeze. In my shoes, l'll be looking to outfit a sailboat with a tiny 168F air cooled diesel, that can create more electric than propulsion, run forever, save a lot of weight, and keep one water circuit out of the boat. The dry heated air is quite welcome.

What a waste of time!