Cleaning old paint & marine growth

[BCRyan]

Cleaning paint & marine growth from brass

Another new thread from me, sorry... lots going on with our haul-out happening.

Our boat has Hynautic (hydraulic) cylinders on the trim tabs; two each side for a total of four. At least one of the starboard side cylinders has been leaking (slight sheen of oil after actuating) so I have all four off and am in the process of rebuilding them. They are quite old and now obsolete but I was still able to get new seal/o-ring kits from Seatech Marine.

I've pulled them apart to the point where all the seals and o-rings are accessible. I'm now wondering what the best way is to remove all the years of built-up bottom paint and marine growth. It's not necessary to get them back to looking brand new (pic of a new one from the web below for reference), but it would be nice to get much or all of the old crusted gunk off before reassembly.

Mechanical means would be okay for say, the outside of the cylinder itself, but nearly impossible for the cast hinge mechanism with all its nooks and crannies. I'd like to soak them in some type of acid but I'm afraid that would attack the brass.

Any good ideas?

 

[BCRyan]

I'm concluding that there's no magic way to get the outsides of these cylinders clean, so I've started to simply clean them mechanically. It's a lot of work and they're not perfect, but certainly better and acceptable to me.

Along with new o-rings and seals, I'm hoping that these will give me several more years of service. FWIW, I've found out that Hynautic apparently made very few of these trim tab systems and obsoleted them a long time ago. However, there don't seem to be many choices for potential replacements that can generate the 4,400 lbs of force per trim tab that these old hydraulic cylinders are rated to do.

 

[C lectric]

Maybe late but find a friend or a shop with a bead blast cabinet. Lots of machine shops will have these.
These things with the correct grit will remove the buildup.

Years ago I found locally a painter who had a sand blast set up. He cleaned my windlass housing. I had a few days wait since he did not want to fire the system up just for me. He either accumulated small jobs like mine or did them as part of a much larger job.

I would though figure out how to close the bearing holes on both the cylinders and the mounts as those should not be blasted.
Tap in wooden plugs.

 

[RT Firefly]

Greetings,
Mr. BC. I've had remarkably good success with soaking rusted (iron/steel) parts in plain old vinegar (3%). Takes LONG soak but the vinegar is dirt cheap. For quicker results and more stubborn corrosion I use "cleaning vinegar" (10%).



NO idea as to the effects on brass/bronze. Perhaps a TF chemist could comment of the "dissolve-ability" of your pieces wrt acetic acid.

 

[BCRyan]

Maybe late but find a friend or a shop with a bead blast cabinet. Lots of machine shops will have these.
These things with the correct grit will remove the buildup.

Greetings,
Mr. BC. I've had remarkably good success with soaking rusted (iron/steel) parts in plain old vinegar (3%). Takes LONG soak but the vinegar is dirt cheap. For quicker results and more stubborn corrosion I use "cleaning vinegar" (10%).

Thank you, both great suggestions. Since I'm on a bit of a timeline here, I went ahead and just cleaned them up the best I could using a combination of hand and power tools. They are far from perfect but at least most of the crud is gone, and they're just going to get a fresh layer of bottom paint, anyway. Fully rebuilt internally, I'm hoping they will do the job. I'll get them installed later this week.

 

[RT Firefly]

Greetings,
Mr. BC. Looks just fine to me.