Starter motor pinion jammed with rust in 14 days.

[FionaJC]

Ive had excellent advice on this group so I pose another for you.
I have a Perkins 4107 with a LRS189 / MG42 inertia starter, this starter was soaked in vinegar and then paraffin each for a week and it was clean. No grease oil or graphite was added. I put it in two weeks ago and yesterday all it did was whizz. I removed it to find the pinion jammed again with rust. See the first two pictures. Pictured new in the next two pics. The bilge is relatively dry and the ring gear appears normal and rust free.
Now the whole story. This is the third time this has happened and I have tried graphite powder grease each time before, in a few weeks the same problem.
The boat was flooded in 2022 with sea water up to the depth of the just below the injector pump, last picture, killing the alternator and rusting the old original starter (more of that later) I pumped out all the water in the bilge and sump (not much) and filled it with diesel twice before putting in oil, starting the engine and changing the oil filter and oil three times after that. Then engine starts and runs fine. I have put about 5 hours on it since as I haven't been able to use the boat for two years .
I have freed up the old original starter but I cant put it in as its missing a pinion return spring.
My questions:

1. Why does this happen?
2. How do I cure it, should I lacquer or grease or oil the moving parts?
3. Is it just a cheap knock off starter not for the marine environment?

[Statistical]

I would not grease the starter. Likely you have rust inside the engine where the starter motor interfaces (flywheel?). It is sticking to the grease and creating a rust mudpie which eventually chokes the starter. You probably need to open the housing where the starter is mounted and clean out the rust inside there.

Note even outside of the flooded engine issue I wouldn't grease the starter motor it tends to just attract dirt and metal shavings and end up wearing out the gears faster. Starters have such low duty cycles that they are just built to deal with the friction of metal on metal contact.

[CrispyCringle]

Ive never heard of lubing a starter before. But Ive never soaked one in vinegar either. I think the vinegar promoted the corrosion. If you can free up the pinion shaft so it will function, Id just clean it up with a wire brush, knocking as much rust off as possible. Then spray with an inhibitor like Boeshield. As long as the moving parts are clean, it should be fine. Although the inside may look the same, and I dont think that would age well.

[Turtle Blues]

Your rear housing and support differs from the manual I have.
What is the lower hose on the left side of your photo? It appears to come from the housing extension where the spring assembly resides. The amount of corrosion built up in 2 weeks would indicate something is sitting in that area. Did you remove the housing when the engine out?

[Renegde_Sailor]

For it to get that rusty that fast there still has to be water in the housing along with salt.

The factory starter on my Yanmar 4JH3E lasted from 2003-2022, then it corroded and stuck, I pulled it out and cleaned it and got it working again and set it aside for a spare.

There has to be a source of water coming in there.

[Renegde_Sailor]

Also I did look it up, if you soaked it in vinegar, vinegar is corrosive and probably jumpstarted this process.

WD40 would be the correct stuff to use here.

[Nicholson58]

Not bad advice here.

I would not hesitate to lube the parts. In addition to the above, I have used nickel seize. If you buy all new parts you will detect a light coating of lubricant. I also try to lubricate the ring gear.

Vinegar is indeed corrosive. I have rehabilitated rusty parts using any of the “rust converters”. Personally I would replace the starter, at least the pinion assembly.

In the photo the spring looks to be in tough shape. It may be weak.

[FionaJC]

To all that have answered so far - Thanks I really appreciate and have taken in the comments. Here are some extra comments

I only greased it the first time, then used graphite powder. All jammed after about a month.

I looked at the ring gear and it doesn't have any rust on.
The bell housing is dry.

Interesting view on the vinegar, that's why I then soaked it in kerosene (paraffin) for a week.

The lower hose on the LH side is cooling for the TMP gearbox, the mounts were replaced from an original 4107 that was fitted but seized over four years non use.

I have ordered a new starter motor.

I have ordered Boeshield T9 after looking at loads of videos about WD40 vs Boeshield vs FT....... you get the idea.

I have used kurust on the pinion gear and I will use Boeshield T9 on this starter and the new starter. I will use this starter and pull it every two weeks. I will also use it when on local runs where I can sail out of trouble and for long runs change the starter to see what happens. All I will need to do is sort the overheating and the jammed Simpson Lawrence Sprint 600 windlass. Oh and the new mast and boom would take my old mizzen, ho hum on we go. Once again thanks every one for the valued opinions and advice. Ill keep this updated.

[boatpoker]

Graphite plus water will galvanically corrode steel ... bad choice of grease.

[CrispyCringle]

Getting a new starter is a good plan. As an FYI, I would not mix graphite with any other lube. In general it is designed to be a dry lube used on clean metal. The advantage being it doesn’t cling to dirt like petroleum products. And I’d advise against ever using vinegar around your mechanical components, as you found out. That’s an odd one. I’ve never heard of that before. There’s just to many other good cleaner/degreaser products to mess with something like that.

[Island Time O25]

According to my buddy the boat builder - when in doubt use the lower gear lube. Can't go wrong with it in any marine environment.

[deblen]

I have used NeverSeez (Thin coating) on rust prone metal & threads for 50yrs.
Fluid Film (Lanocote) lanolin based lube is excellent for marine use.The lanolin is waterproof.
Cheers/Len

[Tsuru]

I think you are on the right track with Boeshield T9. Light coating and see how it goes.

[more]

use rust remover Phosphoric acid with additive. also try apley in flywheel.
and simply lube with oil in spray, lot.