Severe Rust on Yanmar Engine

[ckoretsky]

I would like to know if cleaning the rust off the engine is an urgent matter. Or can it wait until the engine is fixed? And any ideas on how to get it off. The boat is in a harbor so no access to water hose

[sabray]

I wouldn't worry about rust but can you break the bolts free. Particular are the 3 that look like their on the heat exchanger. I like to wire brush the pealing stuff and paint it. I also like to be able to fix things. that means the bolts can turn. I take my pedestal apart every so often and lube the bolts with lancote. Because when I got the boat the bolts wouldn't budge and had to be drilled out. I could not have fixed the stearing gear in any reasonable time given the condition. Some things you will not want to leave to corrode and rust up. I dont think I helped you with that.

[Laidback]

Originally Posted by ckoretsky

I would like to know if cleaning the rust off the engine is an urgent matter. Or can it wait until the engine is fixed? And any ideas on how to get it off. The boat is in a harbor so no access to water hose

Of course rust be an URGENT matter. At the same time, what is equally important is to find out what is causing the rust - the engine has the appearance of being sprayed with SALT water. That problem has to be fixed.
The question:- "Or can it wait until the engine is fixed?"
Does this mean that the engine is not running ?
The photo shows the aircleaner filter housing seriously rusted - indicating that it was drenched over a period with salt water - Does this engine have a Turbo ? if so that may have been damaged.
To clean that amount of rust - use Hydrochloric Acid SEE Hydrochloric acid - Wikipedia, the free encyclopedia.
Then with an appropriate metal primer (eg Zinc Chromate, iron oxide) Paint the clean metal - then apply a 2 part epoxy paint.
Guess that to do a proper job this engine should come out of the boat onto dry land with proper facilities.

[Laidback]

Here are a couple of 'before and after' pictures of an engine mounting that was severely rusted- then cleaned with hydrochloric acid:-

[ckoretsky]

Thanks for your input, I hadn't even thought about the bolts.


I was just reading about muriatic for rust, I already use it to clean most of the boat. I used to worry about getting it on my skin or my clothes, that was before I started taking specific gravity readings....

Port side engine doesn't run. Here's a picture of the starboard side for comparison. That salt water is nasty stuff, I used to wash down the decks with it, not anymore. I'll stick with Hydrochloric acid.

Sodium Chloride ruined my tools, all my zippers, and even my feet!

[Laidback]

Washing you decks with Hydrochloric Acid NOT recommended.

In the context of this topic - the only use of Hydrochloric Acid is to remove rust from ferris metals.
Wear rubber gloves and eye protection.

[delmarrey]

The problem with rust is it's like a sponge. If there is any moisture in the air the rust will attract it causing more rust. All things return to the earth one way or another.

Like laidback said one needs to do damage control on any water that is getting into the engine room especially any acid. If you plan on pulling the motors in the future, a temporary fix would be to brush/spray on some corrosion inhibitor to keep the rust from growing any worse. Then when your ready to pull the motors you can do a proper job during a disassembly.

Corrosion Prevention Compounds Testing - Salt Spray

But if you don't plan on pulling the motors, a wire brush, chemical and some paint as mentioned above will be your best option. I'd rather pull apart/work on an oily motor then a rusty one.

[MitchM]

i can think of a number of bolts that i routinely need to adjust like the alternator belt tensioning bolts, engine mount height adjustment, alt belt cover, valve cover retaining bolts, heat exchanger bolts, thermostat retaining bolts, fuel filter bleed bolts...... if those are rusted , you'll have trouble doing routine maintenance. and a mechanic will be charging you $100 an hour to get the rusty bolts off. i'd at least clean off the bolts you need to be able to remove for engine survival... after you clean the rust off make sure the heads of the bolts aren't rounded off, or you'll have some extra problems getting them loosened....