Painting surface rust on marine diesel

[belizesailor]

Originally Posted by EqPierre

Going to try this on my 30 year old but never used engine that has suffered rain damage. Hope I can find it here and that Ospho 605 comes with adequate instructions. Thanks guys!

30 y.o., but never used...how did that happen?

[mickt243]

it doesnt look like anyone has mentioned it yet..... but for any of those treatments to work properly, and to get the primer/paint to actually stick to the metal surface, the first step is to totally degrease it. no oily residues at all.


that wont be fun or simple in situ.

[chrisr]

there is stuff called LANOX which is lanolin based liquid to spray on rusted surfaces instead of paint

doesn't look pretty like repainting, but a whole lot easier ie don't need to de-scale / prime, and does a super good job pf protecting engine from further rust

i use it extensively and works really well

cheers,

[slug]

The paints that were developed to paint steel bridges, storage tanks , pipelines ... are formulated to adhere to “ brown “ steel
Brown steel is non sandblasted surface

, heavy rust must be chipped , hammered , brushed away

A common industrial “ surface tolerant “ paint would be DeVoe Bar Rust

https://international.brand.akzonobe...R_20170925.pdf

[Afrakes]

Quick and dirty solutions. Like putting lipstick on a pig.

[slug]

Originally Posted by Afrakes

Quick and dirty solutions. Like putting lipstick on a pig.

Yes.

But in applicators were sandblasting is not possible lipstick is better than nothing

Also. Engines don’t rust when properly maintained

Lipstick will work

[Squanderbucks]

I’m afraid what you are calling “surface rust” would more likely be classified as severe rust. I doubt that more than a few of the components and bolts will not come apart without wringing off or breaking. Better now at port when they can be fixed and parts obtained more easily.

You might consider this a job to be done in stages.
1. Gross descaling with various chisels, small hammers, heavy wire brushes.
2. Soaking every bolt with something like PB Blaster for a couple of days
3. Moderate rapping each bolt with a hammer
4. Taking apart all rusted parts
5. Cleaning all removed parts with further chipping and heavy wire brushing
6. Wire brushing anything you can on the engine by hand
7. Then do your Ospho or other chemical treatments
8. Reassemble with good quality lubricants and sealers where appropriate.
9. Repaint.

[Afrakes]

Take a good look at the bottom of your oil pan. Out of sight, out of mind. Short term solution spray everything visible and ignore the rest. The engine in my boat sat unattended on the hard for 5 years before the previous owner purchased it. The cabin ended up with 6 inches of standing water in it. The engine was started with no consideration for what might have happened corrosion wise with the piston rings and cylinder walls. The engine ran fine but was very rusted and severely pitted almost everywhere. After two years of ownership I pulled the engine for a rebuild. The extent of the rust damage was amazing. IMHO After so many years in a salt water environment there is only one way to do the job properly once that amount of rust damage is visible. Pull the engine and do it right. The next owner will appreciate it and give you more money. Sorry for the photo orientation.

[Disailor]

I've had very good results on non-hot surfaces with 3 coats of linseed/turpentine (50/50) then enamel.

[EqPierre]

Originally Posted by belizesailor

30 y.o., but never used...how did that happen?

Boat hull build in NZ, partially finished timber. Project sold in 2000 and shipped to Europe by freighter, then abandoned. Bought it 6 months ago and started the rebuild. Alternator not even wired, came with original plastic cap on connector. Look at FB Pierre Van de Casteele or Eqmar.net

[Michael Cobbe]

There is no paint to stop rust and having tried them rust converters don't work. As I've said before the only way to get rid of rusts and stop it coming back is to sand blast it and paint it with zinc rich epoxy. There are small sandblasters to use inside a boat an example is: https://www.machinemart.co.uk/p/clar...SABEgIrM_D_BwE I cannot see a power cable so I asume it is battery powered but check that before buying it.

[belizesailor]

Originally Posted by EqPierre

Boat hull build in NZ, partially finished timber. Project sold in 2000 and shipped to Europe by freighter, then abandoned. Bought it 6 months ago and started the rebuild. Alternator not even wired, came with original plastic cap on connector. Look at FB Pierre Van de Casteele or Eqmar.net

Wow, you hear of owners never finishing builds, but this one will span several. Hopefully the third time is a charm! Good luck.

[Wotname]

Originally Posted by Michael Cobbe

..........There are small sandblasters to use inside a boat an example is: https://www.machinemart.co.uk/p/clar...SABEgIrM_D_BwE I cannot see a power cable so I asume it is battery powered but check that before buying it.

Ahh... no. It's air driven so one would need an air compressor that can deliver 100psi (~7 bar) and 10 cfm (~280 lpm).

[daveNZ]

POR have a very good ‘marine clean’ product that just seems to get metal visibly cleaner and non-greasy, probably best after basic degreasing with simple green or better. (I’m sure that was the name but I can’t find it online now, there is a cleaner degreaser though)

I’ve brush painted a rusty steel 2 M shaft (between engine and thrust bearing) with POR primer. It self levels so well it looks glossy like it was sprayed and I haven’t done any top coats.

[SuW]

Originally Posted by Scrimshaw4

I have used POR 15 very successfully on my Westerbeke Diesel.
POR15.com
After applying, followup with a good heat resistant primer and engine enamel.
JMHO

Agree with POR 15. Get a tiny can, a little goes a long way.