Hi Seabreeze community,

I have an old Yanmar YSE8 in my sailboat. I bought the boat about a year ago and I did some work on the engine initially as the engine was not running. The boat was sitting for a few years and the engine needed some work. I am new to this still and just learning about diesel engines and fixing the engine last year was my first go ever at diesel engines (changed hoses, belts, crank chain, starter motor and brushes).

The last four months I didn't have much time and didn't look at the engine much and when I opened it up last week I found a lot of water damage, crystallization, rust and corrosion. No water in the bilge though, so it must just be drops from the water system.

The engine runs just fine and turns on first try but there is some diesel leaking (right side of the engine looking from the front) and water dripping left. My main issue is the water damage.

Any advice on how to tackle the rust, corrosion, treatment and maintainance, eg paint afterwards, as well as changing the water system would be appreciated. I had a look Online for spare parts but YSE8 parts are hard to find and I am not sure about the aftermarket parts I have seen Online.

Thank you in advance.
Yamaha24ft

Any thoughts on just metal brush and Corrosion Inhibitor?

Yamy, that's a very nice example of an older style engine. I wouldn't be concerned about the rust and corrosion, but if you must I suggest a spray with phosphoric acid or oxalic acid solution, then when dry perhaps some light oil, kero,diesel,lanox etc

Dear friend,

Jump to Bunnings and buy a spray of wood stain removal and a can of heat proof spray and 2L of vinegar.
carefully remove all clamps and spray that wooden stain removal ( Oxalic acid) all around the engine and go home. Day after repeat. Wash all off and rust will go away. Light send and than spray the colour. Repeat day after. Check that bolt where leakage is and tighten it. Put new rubber hoses and SS316 clamps. Close your seacock and disconnect the rubber. Put that rubber in the vinegar bottle and start the engine. As soon as all vinegar is gone shut the engine. Leave it for a week. Connect the hose back to seacock and you should be good for a while. Repeat with vinegar once a month so all salt deposits can soften and get out of the engine. Periodically tighten the bolts but do not force too much. The simplest and the best engine ever made.

Paint won't last unless you go the whole hog and remove the engine for a complete clean. Find out where the water is coming from and fix it. Brush off the worst bits then spray Lanox everywhere. It won't make it look beautiful, but it will slow the corrosion right down. There are quite a few Facebook groups dedicated to various Yanmar models, try looking into that to help build your knowledge.

Cheers, Graeme

Thank you everyone for your replies. Much appreciated :)

I guess the Oxalic Acid is a bit more aggressive for rust removal, will Lanox (never used it before) also get some rust and corrosion off or is it more for protection and should I use it afterwards as @woko suggested? (@wongaga, thanks for the tip but unfortunately I don't have Facebook, otherwise I'd try and have a look).

Also @Serb1980, is it ok to use vinegar to flush the engine? Doesn't the acid in the vinegar attack the rubber and metal bits? (apologies, I am new to this so it might be a stupid question).

Wongaga's right.
This is a case of if you are going to do it , do it right.
I would say a YSE needs to be removed and repainted every 10 years or so.
Did mine 6 years ago , cared for it and have so say it is looking a little tired now.
They are not originally marine engines, but they are getting on for 40 to 45 years old and still run well.
If you want to spread little bits of rust all over the place, where they can do their evil deeds a wire brush in the engine bay is the way to go.

Two hours to remove it.
Take everything heavy off first.
Plug all the holes and pressure wash.
Get into it with a wire brush on a drill and other anti-rust treatment.
Primer and paint.

It might sound like a lot of work , but as a winter project it is not so bad and you will love the shinny new paint job.
Engine will even run better, or maybe not.
The heavy rust that you see on the head is a leak from the thermostat or the zinc. anode (You are keeping and eye on the zinc, aren't you?)
At this stage to stop further rusting I would just go through the process that Wongaga has suggested.
That might be smelly on startup, but hey its an old Yanmar.
You don't need to buy gaskets ( for thermostat and anode), because you can easily and cheaply make them yourself,
Youtube will show you how.
Now you have something to look forward to in the downtime next summer. Lucky!

Lastly, try not to leave it for too long without running it. That can be the death of a marine engine.


gary

Thank you @garymalmgren. This sounds like a job for the winter :) Would have to do some planning and maybe get it out of the water.

In the meantime I will try and slow the corrosion and rust down and try LANOX and maybe some Oxalic Acid for the really rusty bits.

But following up on your comment @garymalmgren, is using a metal brush to get rust and corrosion off the engine in the engine bay a bad idea? I guess you are spreading the bits? Any recommendations for minimising potential rust and corrosion dust? Vaccum?

Might all be silly questions but I am learning, so thank you all for being kind and supportive :)

Also, thank you for the thermostat tip. I had not consider this. I found this link, which might be useful sabre27.wordpress.com/2011/11/07/the-anode-and-the-thermostat-a-tale-of-yanmar-yse-spare-parts-and-a-mystery/

Oxalic acid or vinegar will not be aggressive enough. I use "Metal Gleam" for this particular job. It's mostly phosphoric acid and is similar to any of the rust removing products on the market sold for silly money. I use this product on internal flushing on raw water cooled engines and heat exchanged engines as well as all the stainless steel deck gear and fibreglass surfaces on the boat. If your looking at tidying up this unit in situ I would wire brush it the best you can. Mix the acid mixture at 5 parts water to one of acid and slop it all over the engine with a sponge. The acid wont hurt your hands but you can wear gloves. Watch out for your eyes. Keep it wet for 5 minutes or so, longer if you can and agitating with a scouring cloth helps. Just let the acid fall in the bilge it will clean that too. I then pour a warm mixture of truck wash and water over the engine and pump the lot over the side. Let it dry and if you don't paint, run the engine to get nice and warm and spray the lot with lanolin. Now and again after running the engine just top up the lanolin while the metal is still warm.

Just for a bit of comparison Yamaha , this is my YSE, 6 years after repainting.

Oh!

Thank you @garymalmgren that actually really helps. Gives me a good idea about what work to put in and the 'to be expected' aging of the engine. Really appreciate you uploading the pictures. This is such a good forum :)

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garymalmgren said..
Just for a bit of comparison Yamaha , this is my YSE, 6 years after repainting.

I would suggest spraying it occasionally with lanolin just after you shut down.

I do Ramona.
That is why it is in such pristine condition.

I can't get this out of my head.
Yamy, in your engine photo the air intake is a vertical tube.
The normal set up is a 90 degree bend on the top of that tube. This offers some protection against something being dropped into the inlet.
You can see the set up in the photo of my (pristine) engine.
Please, measure the tube , go down to Bunnys and get a plastic elbow.
If it is a little too small, put a few cuts in it with a hacksaw, heat it up and force it on. Plastic is fine for that job.
As it is now, it is a disaster waiting to happen.

gary

This was mine after rebuilt. It was a hell ti put it back. I used a car jack and somehow made it. I am strongly suggesting to disconnect your sea intake and connect it to a 2 lit of vinegar and as soon as all vinegar is gone to shut the engine. It will soften all deposits inside but will not destroy your engine. Do it ones every month and you should be fine. If you can disconnect the engine, clean it off the rust paint, remove the mixing elbow and remove all carbon off. Change the oil, clean the diesel filter out all new clamps and you are good for next 5 years. Enjoy..

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Serb1980 said..
This was mine after rebuilt. It was a hell ti put it back. I used a car jack and somehow made it. I am strongly suggesting to disconnect your sea intake and connect it to a 2 lit of vinegar and as soon as all vinegar is gone to shut the engine. It will soften all deposits inside but will not destroy your engine. Do it ones every month and you should be fine. If you can disconnect the engine, clean it off the rust paint, remove the mixing elbow and remove all carbon off. Change the oil, clean the diesel filter out all new clamps and you are good for next 5 years. Enjoy..

When you need to spend some time experimenting again collect a few seashells. Set up a few glass jars with different vinegar mixtures, CLR cleaner and phosphoric acid. Place a shell in each and note how long it takes to disappear. The CLR is slow but not as slow as the vinegar. Add some bits of cast iron, brass etc but not aluminium to the mix and see what happens. Leave the metals there for a week or so before rinsing in fresh water.
Phosphoric acid is the main constituent in "Barnacle Buster", the expensive engine cooling system cleaner for a reason.

@garymalmgren thank you. Will do. I'm slowly learning :)