4 yrs new and rust

[bcguy]

Purchased a 50 hp Isuzu new 4 yrs ago. Pics show rust now appearing. Just wondering if auto brake cleaner and a wash would work or your recommend. Some of this appears to be on aluminum ... the rest on paintable parts. .. Thanks.. After cleaning what coatings (paint or other) should be applied to slow down rusting in this wet PNW coast.

[mike d.]

You must have a very wet bilge, and or there is a lot of sweating going on. It must have to do with your boat being made of steel! That being said, I would use Z.R.C. cold galvanizing spray paint primer, for the steel parts. I have used it for a number of yrs. for different boats. You just have to clean the surface well and make sure there is no oil residue. As far as the aluminum is concerned, I'm not sure. I would use a plastic brush, to clean with warm soapy water then film it with CRC or something like that. I know aluminum, gets an oxide layer on it, but you are getting pitting corrosion. What is that pink powder, under the shaft couplings? It also seems to be on the aluminum after end of the (I assume) tranny housing? You definitely have a wet bilge!!!!!!!!

[Cheechako]

You've not had a leaking hose or etc spray in the bilge? Seems like a lot of rust without that. Not sure what I would do, probably manually clean the rusty areas or maybe with a mild acid recommended for steel. Maybe a type of Naval Jelly. rise or clean well after. Then use a Rustoleum or other protective paint. The engine coupling is quite rusty too, should have been painted when new. That one I understand.

[Boatyarddog]

Originally Posted by bcguy

Purchased a 50 hp Isuzu new 4 yrs ago. Pics show rust now appearing. Just wondering if auto brake cleaner and a wash would work or your recommend. Some of this appears to be on aluminum ... the rest on paintable parts. .. Thanks.. After cleaning what coatings (paint or other) should be applied to slow down rusting in this wet PNW coast.Attachment 99080

Attachment 99081

Attachment 99082

From the looks of your prop shaft, coupler and packing gland area, is it possible you've got to much drip on the packing gland adjustment. Or it's in need of new packing.
That rusty area on the shaft is a hint to slinging water.
All that's needed is a running engine and too much drip, and it gets slung all over.
It's all over the pictured areas.


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[Boatyarddog]

Originally Posted by Boatyarddog

From the looks of your prop shaft, coupler and packing gland area, is it possible you've got to much drip on the packing gland adjustment. Or it's in need of new packing.
That rusty area on the shaft is a hint to slinging water.
All that's needed is a running engine and too much drip, and it gets slung all over.
It's all over the pictured areas.


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Another thought is, do you have a battery near this area in an unsealed box or even mounted openly.
Gassing from lead/acid flooded cells will freely travel through the air as a mist, and that mist is Sulfuric Acid.
If so clean everything with a baking powder solution in water and repaint if that's a possiability.


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[DeepFrz]

Some people put a shroud over the stuffing box and shaft so that the drip doesn't get sprayed all over the engine room.

[leftbrainstuff]

First question. Where is all that water coming from? If there are leaks then fix them. If it is condensation then either ventilate the engine room / bilge or run a blower when you are running your engine.

For the steel components you have 3 options. You can ignore the problem, you can use a rust preventative or you can clean and paint / coat / plate. There are some good spray paints that can be applied to mechanically abraded steel surfaces. Plating is best done before installation. Brush on zinc plate may also be effective.

For the alloy you only need to keep it clean and dry and the naturally occuring oxide will work fine.

There are a range of mild acidic treatment that can help but if you dont treat the components after rinsing and drying the problem will be exacerbated.

I'd start with a biodegradable citrus based degreaser and a stiff bristle plastic brush. If you use a wire brush use a stainless not a steel brush. The wires will lodge everywhere and rust like mad.

It will be lots of work to get that engine room looking good but well worth it. I dont tolerate any rust, dirt or moisture in either our engine room or bilge.

The comments re battery outgassing are also worth taking note off. Sulphuric acid mist can create what you have.

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[Terra Nova]

Looks like salt water has been allowed to spray everywhere.

[Jacko]

bcguy Oh Boy you have a big job ahead, with over a decade of steel boat maintenance I would first look at the integrity of the hull under the motor this will only be done from what I can see is by lifting the motor and doing a full on treatment to the hull ( wire brush, grinding -- best to grit blast ) then proven treatment and 2pack paint. Then attack the motor, forget the plastic brushes they wont do the job you will have to be very aggressive to clean and then once again use proven coating don't worry about the alloy that will be thick and you can wire brush it to get a good clean finish ( do take note of other advise and make sure you do a good clean up to remove all of the wire from the brushes) do not use a power wire brush on a drill this will polish the iron oxide and make it very hard to remove " chipping rust"
If you have some Trawler Boats near by make friends with a well kept boat ( steel ) and talk to the guys they will be a wealth of knowledge and lots of them love to help out. They will be able to put you onto a paint supplier that knows his job and can show you the steps you will have to take.

If you don't do the work now and just patch up with a cheap fix over the rust you will be back in there next year OR SINK PS fix the salt water spray !!!!!

PM me if you need more ideas Jacko

[ozskipper]

The oxidization on the aluminium is different to rust. Unlike rust, which assists in the growth of more rust, Oxidization on aluminium inhibits more of itself .
Step one. Get better ventilation!

[RaymondR]

If you are in Australia you can get a product called Corro Dip from Liquid Engineering in Perth which will eat the rust off the steel pretty quickly. Do not put it on alloy though. I clean the bilge out and mix up a few litres and pump it about using a small submersible pump and plastic hose. If you occasionally wire brush the wet spots it works faster and you can pretty quickly clean back to bare metal.

None of the paints work very well unless you sand blast and I only tried that once on the inside of the boat.

The old style stuffing boxes are pretty useless on a steel boat and I have changed over to the PSS system and so far not a drop of leakage has occurred but it's only been six months or so and I have not done much motoring.

You have to be fanatical and paranoid about water in the boat with steel and whilst it is difficult to keep out it can be done.

[bsurvey]

stuffing box is spraying water on to the back of the engine as the shaft spins is my guess

[captlloyd]

Yes, clean the rust and another good possibility I have used with success is rust encapsulators which convert the rust you can't remove (other than sandblasting) into a paintable surface. Sherwin-Williams has it, it is a white milky substance that turns black when it dries. A topcoat of another type of paint is required, usually epoxy or urethane. Easy to use but all oil and loose rust must be removed. There is also another type of rust converter that requires the same preparation called ''POR''. It is used a lot by car people in restoration projects. Paint it on and it almost puts a marble like finish on your job. Very tough. As stated by the other guys, get that engine room dried-out.

[adamsteel]

Unfortunately all this work could have been prevented by painting the new engine before installation, there is no evidence of paint anywhere. Buy a litre of Kerosene and a cheap hand pump and lightly cover all surfaces including the alloy surfaces, hang the hand pump somewhere close and every few weeks lightly dust the engine and in ten years time think about replacing the Isuzu and remember to paint every thing before installation

[captlloyd]

Originally Posted by adamsteel

Unfortunately all this work could have been prevented by painting the new engine before installation, there is no evidence of paint anywhere. Buy a litre of Kerosene and a cheap hand pump and lightly cover all surfaces including the alloy surfaces, hang the hand pump somewhere close and every few weeks lightly dust the engine and in ten years time think about replacing the Isuzu and remember to paint every thing before installation

Actually this is a very valid option. After a couple of applications you will be able to wipe a lot of the corrosion away. Even better use a small wire brush and the rust will disappear eventually. However I would consider this an either/or option as the this idea does not correspond with painting methods at all. It will save a lot of work. Dry that engine room up.