Anyone use POR 15 in engine room

[Deano]

Previous owners of our boat have neglected corrosion control in the engine room. My winter task is to get things cleaned up and painted. The engine, mounts and drives are terribly rusted.
Good surface prep is going to be a challenge due to access issues.
I've used POR 15 before on restoration projects but never in a marine environment. It is the only product I'm aware of that really works on heavily rusted metal.
Your thoughts or experiences are appreciated.

 

[Puffin_NT32]

POR 15 should be OK in the engine compartment. Just remember that you want to wire brush off any debris and loose rust, and degrease. You need to prep the metal with the POR 15 "Marine Clean" and "Metal-Ready" products. POR15 has no UV blocker (I know, I used it on windshield wipers and it flaked off) and if outdoors, needs an overcoat, but in an engine compartment, shouldn't be a problem.

I have a frame-off 1990 GMC pickup, and there are other products that you can use on rusted or rust preventive applications. They are "Rust Bullet" and "Chassis Saver". Restorers have a preference for those 2 over POR 15. All these products are essentially one-part epoxy paints, designed to overpaint rusted metal, and have a smooth, self-leveling property.

Keep in mind that these products have a tenacious hold on metal, and painting bolts, engine mounts, fuel lines, etc, will make them difficult to loosen or disconnect. For engine mounts and throttle links, I've used CRC Corrosion Inhibitor.

For my engine, I just stick with small 8 oz cans of Rust-Oleum oil-based paint. A 50/50 mix of white and almond gloss is a perfect match for my Cummins 6BTA.. Prep is key. Degrease, wire brush, and thin the paint a little.

 

[Nomad Willy]

When I had my BW gear rebuilt I insisted on it being coated w POR-15.

That was 10 years ago and there's no rust.
But there is rust on the engine mounts that were new at the same time.

 

[Deano]

Thanks for your responses. I wish I could do a proper surface prep but access is limited at best. I done frame off restores (my '32 Chevy) and that's easy compared to this. Disassemble and send everything to the sand and soda blasting shop. Surface prep not so easy without lots of disassembly on my perfect running engines. That's not happening. Much of my surface prep will have to be chemical vs mechanical. That's why I was thinking of POR 15. Their chemical prep products are great.
NW. 10 years is good enough for me. Thanks.

 

[sbu22]

Excellent advice I got from FF regarding stainless.

"You simply put some oxalic powder in a small SS bowl and add some water and a good squirt of JOY. When its a paste you brush it on the rusty SS. All the Joy does is keep it in place and keep it from drying out too fast.

A scotch brite pad will help scrubbing the rust off. When it "looks" clean , leave the paste on for an hour or so to help it pull iron from the SS surface.."

From Amazon: FlaLab, Oxalic Acid, 99.6%, 2 Lb. Deck, Crystals - $11.99

Found it works great on steel in the ER, as well - as I discovered cleaning up after a wet cell battery cooked off. Followed by Rustoleum oil base.

 

[Deano]

Unfortunately everything I have to deal with in the engine room is carbon steel or cast iron but conversely above decks I have plenty of such issues with ss and will try your advice. Thanks

 

[Jeffrey S]

This is a subject near and dear to my heart and I'm getting pretty involved in maintaining our new-to-us steel boat. Previously, I've used POR-15, Ospho, and Corroseal for initial rust treatment.

After consulting with a variety of surveyors and steel boat yards, our schedule is to treat all rust with Corroseal as a first treatment after brushing/sanding assuming the entire area isn't getting ground down to white steel. In nasty rusty areas, I've been using needle guns to chip away rust followed by orbital sanding. For inside areas, 2 coats of Rustoleum Rusty Metal Primer is then applied, followed by 2 top coats of Rustoleum gloss coat. If the area expects pooling water (which I've been building systems to remove) then the top coat is changed to Bilgekote over the Rusty Metal Primer because it's better with standing water. For outside areas, we use a variety of PPG Ameron 2-part epoxy primers and paints for treatment after Corroseal.

Corroseal combines a rust converter and a temporary primer. It stabilizes the rust and allows it to accept paint pretty well. It's pretty great stuff and has been working exceptionally well for us.

Rustoleum's are one-part paints and are much less noxious for interior work. They probably don't last as long as a good 2-part epoxy but they are easier to apply and are quick. It's nothing to touch up a few places a week with this process and Rustoleum.

For the last 2 weeks, I've been preparing and painting the inside of our second water tank. I did the first tank over the summer. It's a terribly obnoxious job and requires special FDA-approved epoxy paint and a 10 day air exchange followed by water flushing with antibiotics applied. I wish that job on no one. I should be finished with it tomorrow.

 

[Deano]

Interesting. In my younger years I spent a lot of time in the corrosion control sector of things. My situation here is being unable to do a proper surface preparation. I will research your suggestion. Thanks

 

[Deano]

PS. I have a gallon of SW heavy zinc paint. By heavy I mean 12 lbs per gallon. Whatever prep I'm able to attain, I'm going to put a layer of that before the finish coats.

 

[sdowney717]

POR 15 SILVER color has metal fillers, the other colors do not.

I plan to repair my trim tabs with the POR 15 Silver.

 

[sbu22]

Deano. I wasn't clear - the home-brew works on carbon steel as well - with all the caveats regarding removing surface accumulations, surface prep, coating systems, etc.

 

[Jeffrey S]

Deano. I wasn't clear - the home-brew works on carbon steel as well - with all the caveats regarding removing surface accumulations, surface prep, coating systems, etc.

Oxalic acid is great for removing rust stains and even doing some preparation on steel. But it does nothing afterwards to protect the steel from immediately rusting again. Some other type of coating is needed on steel, preferably in the same afternoon - rust will start forming again immediately.

 

[sbu22]

No question, Jeffrey. Not suggesting otherwise. The point is that FF's elixer is a cost effective step.

 

[Deano]

Oxalic acid we have lots of. Our other home is a log cabin and when the logs start to turn black the oxalic acid brightens them back to new looking. We always use it to prep before refinishing with Cetol. A little off the subject but an interesting aside.