Repaint / touch up engines

I can't see any colour name or code in your photo.
Can you (or anyone else of course) be more specific?
I'm assuming you are talking of white engines, which is what I am interested in.
MAN also used blue and grey in the past, but AFAIK only for some commercial engines.

These work pretty well.

https://www.westmarine.com/buy/precision-valve--paint-sprayer--P004_123_001_512?recordNum=1

Yes. White engines. Works very well. Perfect color match for MAN engines or atleast those installed by RDI the MAN distributor on the West Coast.

Many thanks, good to know.
My understanding is that MAN ship the engines to their distributors and/or builders already painted.
So, I don't think the white is different in those installed by RDI (or any other dealer for that matter) vs. those installed elsewhere.

From what I have seen RDI orders engines primer only and has their own paint booth so they can paint once the engine is set up for the intended installation. Here is a pic from a recent visit.

That makes sense. A customer could want a custom color such as gray for navy vessels. Also if they decide one day to change their color it would be no big deal at that point, but if they have 40 painted blocks on the assembly line it could get expensive.

I did an engine room detail for a captain friend, one time. The guy is notoriously OCD, so performing to desired quality was a challenge. After getting the engine room bilges sparkling and shining using the whole Alumaprep line of products to his spec and methods, I moved on to engine paint. The motorsailor had a pair of Yanmars in it that weren't a stock green, but some custom hue. I took the oil filler cap from the engine and went to the local Sherwin-Williams automotive paint jobber, and found that they could easily match it with a computer spectrograph (that was new, then). When I was talking to the guy, I wondered if it could be put in spray cans. Turned out that wasn't a problem if I bought six!
So, off I went with a six pack of rattle cans in an ugly green color and went to work. I learned a lot about masking, especially the difference between just enough and overkill. I found that a piece of cardboard held in one hand at just the right place at hose ends and clamps did almost as good a job as crazy amounts of blue tape and fine-line tape. I just had a can of Xylol with plenty of rags and Q-tips to detail misses and overspray.
Captain OCD was completely satisfied, a thing that a few by-standers didn't think possible
Two years later, he asked me for a repeat engagement, but I was fortunately in a position to decline.
Over the years, I've kept a rattle can of engine paint and a piece of cardboard close to hand during voyages. I often will clean an area with soap and water on the running engines underway during an engine room check, and then shoot paint on it at the next engine room check. A great way to keep on top of the job and not have to take too many fume and vapor precautions.

One thing to consider is that if everything is painted then at some point in the future a mechanic is going to have to strip some of that paint before they do work. So your costs go up at least a little for the extra labour.

If you paint it, do the best job you can and don't get paint on things that shouldn't be painted. Like hoses, copper tubing, etc. When I look at online boat ads and see a freshly spray-painted engine in an older boat I close the ad and move on. It makes me wonder what they are trying to cover up. How well the engine has been maintained is indicative of how well the entire boat has been maintained. Were they just making it look cleaner or were they covering up a rusted out mess?

For minor touch-ups (without hosing-down every hose in sight) don't use masking-tape. Use aluminum foil to mask-off those areas (like hoses, clamps, alternators, electrical plugs, etc.) that don't need paint. Aluminum foil is only about $25 for 500-feet (and easy to pull off). Should you need more than a rattle-can for those touch-ups; get it professionally done