Lister Petter LPW3 Engine Cleaning / Maint.

[pallantejm]

I've got an engine that could use some cleaning/sprucing up. Previous owner mentioned having some "organic" fish-based substance/coating/paint applied to the exterior of the engine and it began to flake off.



Looking for some advice as to how to tackle this and make it prettier/cooler. I am considering using brass wire brush to remove the flaking paint and any rust.


What would be the best series of coating(s) to apply? Any advice will be helpful as I've never done this before.


Cheers!

[a64pilot]

I think your brass wire brush has merit, or even a steel brush as I think that’s going to be needed.
Clean off as much of the excess rust and paint that you can, do not try to get to clean metal though Ideally you want a thin layer of rust.
Then threat the rusted parts with a rust converter, I find that stops rust from recurring better than getting back to clean metal, unless you can bead blast you can’t really get back to pure clean metal, a bit of rust remains and if not converted it comes back through the paint.

After the rust has been converted, brush paint with thin paint, not thick. Ideal would be spray of course but it gets everywhere that you don’t want paint and looks terrible, Looks like a hack job.

After the paint is well and throughly dried and cured from running the motor for hours, I Spray the whole engine with a rust preventative, I like Corrosion-X, try to not get it on rubber bits though as it might could soften them. I’ve not had that happen, but it’s a good idea to not get any kind of oily stuff on the rubber.

[tkeithlu]

What a magnificent engine! With a history back to Hawker aircraft, no less.

Rust converters are phosphoric acid, so do be careful with that stuff. My preference among them is Corroseal, which makes a varnish-like primer for paint, but I don't know what is going to happen at high temperatures with it. Straight phosphoric (Ospho) might be better, followed by a good wash.

We're seeing only the top of a rather tall engine, and you don't have access down the sides, as I think I see your photograph. What you're doing, then, is likely cosmetic at the top, a worthy goal, but given this engine's petigree, might you consider simply removing all that ugly stuff and leaving her as bare metal, or using high temperature spray-on clear coat?

[keithw88]

Is it true that, if phosphoric acid-based products are used on parts which will afterwards become hot, fumes will be produced which are harmful to humans and various materials?
If so, how hot do the parts need to get to produce fumes, can painting over the treated metal reduce or prevent the production of fumes, and lastly what harm can these fumes cause?

[a64pilot]

Nothing on your engine really gets hot, hot means cooks off paint, like the exhaust manifold on a car.
Rust converter converts iron oxide into I believe iron phosphate.
Here is a Wikipedia article
https://en.m.wikipedia.org/wiki/Rust_converter
Some converters may have a primer in them as they are almost always meant to be painted over, but I’ve never noticed any smell or fumes, and I’ve used the stuff for decades on everything from farm equipment to aircraft.

[pallantejm]

Wow didn't know what I had. Thanks for the advice. Def will clean her up a bit and I agree, less is more. May just go with the high temperature spray on clear coat after thorough clean up. Need to keep her cool during these summer months here in NZ (hopefully won't need to use her too much either) The Listers got ~1400hrs and works like a charm.

[Uncle Bob]

Originally Posted by pallantejm

Wow didn't know what I had. Thanks for the advice. Def will clean her up a bit and I agree, less is more. May just go with the high temperature spray on clear coat after thorough clean up. Need to keep her cool during these summer months here in NZ (hopefully won't need to use her too much either) The Listers got ~1400hrs and works like a charm.

Looks like it has at some time been coated with fish oil, a truly great rust preventative that does requires regular reapplication. I would first soak the engine with a good industrial degreaser and then pressure wash it off, which will probably yield good results and possibly do it again. You will need to wet vac up the residue but it will also clean the bilge sump Following that brush/sand as required and repaint, white is a great colour as any leaks are immediately obvious.
As others have said, a good engine in apparently good condition that just needs a clean and tart up.

[tkeithlu]

The phosphoric acid is long gone before any heat is applied. That's the purpose of the wash.

The only down side that I know of to the use of acid here is that it leaves the metal very bare, as in ready to rust again. However, in a marine engine that does not get very hot (water cooled exhaust manifold), a slightly oily surface, or some spray clear coat, takes care of that. I think this project is going to result in a very pretty virtually antique engine.

One remaining possible idea: The situation reminds me of my maintaining two 50 year old Honda trail bikes. In that case, group wisdom is that you ScotchBrite (sponge mat with carborundum imbedded) the engine, and then paint it with gray metallic high temperature paint. The result looks like aluminum.

ScotchBrite will let you into the crevasses better than a wire wheel. Just don't leave the stuff around the kitchen - it looks like a scrub pad, and will destroy any non-stick pan it touches. Three M has used the name ScotchBrite for some other less abasive pads - makee sure that you are getting the real stuff.

[Compass790]

When we recoed our engine I just steel wire brushed it, sprayed it with zinc cold galv paint then clear coated it. Neither of those were heat resistant coatings. Seems to be lasting except where salt water gets sprayed on it but our engine is raw water cooled so doesn't get to 60oC even. Should have used rust converter as others suggest 1st tho but it was a budget job.