Painting engine - primer?

[copyman]

Just curious what some of the members here have experienced with painting small engines?

I've been using Moeller marine paint with good results holding up to heat, etc. but was wondering about primer. Is it necessary to prime engine before painting? I've painted with and without primer and both look good. Does it matter if primer is Hi-temp or not?

Of course I know prepping the engine in most important for a good paint job so I spend most of the time doing that!

Attached are a few engines I've done. One is prepped and ready to paint

Thanks in advance

 

[creia]

What does Moeller say on the spray can? Do they state to use a primer? Most of these engine paint manufactures (e.g., VHT) also provide their own proprietory primers to be used under their finish coats. Personally, I would never paint an engine (over bare metal) w/o using a heat and oil/gas resistant primer.
Michael

 

[Bird Brain]

Hi-Temp paint can only help. Ive painted many home made BBQ grills with pretty good success without primer but they were made of steel and not aluminum. Aluminums tougher for paint to bite and hold on without proper prep like etching or media blasting the surface. Only advice i can share would be keep it as light a coat as possible only use enough to cover. That keeps it from bubbling up with heat. Good luck.

 

[cfh]

i don't use primer on tecumseh blocks. you want to keep everything as thin as possible, to transfer heat. using a primer adds film thickness. and to what end? are you trying to fill scratches? i think not. so how does primer help? i use rattle can spray Rustoleum Appliance Epoxy without any issues and it works well. now on the steel blower housing maybe you want primer to fill scratches (personally i powder coat these.) but for the block, i can't see how primer would be helpful.

 

[copyman]

Thanks for the replies. Great feedback! The Moeller paint is specific for inboard / outboard engines so sure it's ok for the heat, plus it's gas & oil resistant.

On this topic, what are you guys using for paint remover?

 

[Bird Brain]

Oven cleaner used to work rather well believe it or not. Not sure if the formula has changed in the last 20 years due to the enviromental folks but, it used to be great for that. Might be worth a try.

 

[sparkwizard]

Oven cleaner used to work rather well believe it or not. Not sure if the formula has changed in the last 20 years due to the environmental folks but, it used to be great for that. Might be worth a try.

Oven cleaner with lye is getting hard to find but is what I use. No greasy residue. I do not use primer on small engines. I do use Rustoleum industrial and farm implement paint. It comes in spray cans, but your choices are kinda limited to green, yellow and a couple shades red.
Stands up to heat, gas, chemicals, sunshine and even some hammering.

 

[superflea]

In the old days, we used naval jelly for paint removal. Don't now if it is still around and it can be a bit nasty to work with.

 

[Lizardking]

This is what I've seen used but haven't tried it myself.

 

[VeritableFox]

You can get into a huge debate with engine-heads over using primer or not. My dad likes to use primer on cast iron blocks but not aluminum. Personally, I don't primer engine blocks but items like blower housing and other attachments I do. The main argument for not using primer is for better heat dissipation, which is true for air cooled engines. Not so much for liquid cooled engines as the radiator is doing the vast majority of the work on those.

For stripping paint, others have put out good ones. I typically will do a degreaser soak for 24 hours on really dirty engines and then spend time with a fine pick to really get into the nooks and crannies and air blast while picking away. After that a quick run through the blast cabinet with the holes plugged or covered with painters tape and air blasted again to get any grit off.

It's always a good idea to wipe the surfaces to be painted with metal prep before painting and I do that with all painted parts, including the engine. I just soak a rag and work it in between the fins, give it the directed time to set before toweling off any residue left and a final air blast. Just have to make sure that the rag is dripping wet all the time while wiping since you can't have too much metal prep on a surface. The metal prep works to etch the metal and give a stronger bond for the paint even on already rough surfaces like a cast block.

 

[Harquebus]

i don't use primer on tecumseh blocks. you want to keep everything as thin as possible, to transfer heat. using a primer adds film thickness. and to what end?......

For a semi-custom look, I once cleaned up and beautified the cooling fins on a flathead, left them bare masked them off and just painted the rest of the block. Looked cool and more like a "motorcycle engine" and it wasn't an attempt at an authentic OEM paint job.

On the other hand, the only way I think you are hampering heat dissipation to a great degree is if you're painting the whole block with multiple thick coats of enamel/poly/powder coating or whatever you are using. It looks like many of the restorers here are doing that for the minibikes in their man caves, ones that are not ridden but were built for maximum beauty and glamour.

You are indeed insulating the block, a little bit, with thick coats of paint but how much is open for debate. Tecumseh and Briggs painted their entire L-head blocks for years and years and then Briggs stopped around the late 1980s early 90s and just painted the fuel tank and blower shroud. I think they did it to cut costs and not because it retained heat.

Paint stripping -
The aircraft stripper or other paint strippers work good. You brush it on and it bubbles up the paint in short order. Eazy Off works really good too but it attacks aluminum and darkens it. I don't know what it does if you leave it on aluminum for a really long time and I don't want to know, lol.

Goof-Off made a Pro-Stripper paint remover in an aerosol can that you sprayed on and it foamed up, and because it foamed up it had great staying power because it didn't evaporate before it had a chance to work, but I can't find it any longer. It was aluminum-safe too. Their Graffiti Remover might be the same thing. . .

 

[creia]

Re- Paint Strippers:
For years I used "Kleen Strip's Aircraft Paint Remover" and it was (bar-none) the best stripper out there. Then , a few years ago along came the "environmentally safe" (non-methylene chloride) version, which is the only one you buy now. It does not work anywhere close as good as the original...
Michael

 

[cfh]

i like to use as little paint as possible on the block. but a lot of people, and i mean *a lot*, used 2 part paint with thick film to paint these. it seems like a really bad idea. now if you want to do that to the blower housing, fine. but for the block, i use the Rustoleum Appliance Epoxy, which goes on quite well with just one thin coat (maybe two, if you missed a spot.) and it's gas resistive. Now on the blower housing i do use powder coat. but i certainly don't do that to the block!

 

[sparkwizard]

If we are talking about removing the original finish completely, I take the bare block to my friendly local automotive machine shop and have them put it in whatever they do to clean cylinder heads. I don't ask too many questions. I pay them $20 and they hand me a bare aluminum block.

 

[copyman]

Update, I ended up trying the Rust-oleum aircraft remover and it worked great! Primed everything on this Rupp HS40 except the block see attached. Now on to painting. Will post finished pics at a later date. Thanks for all the feedback.

 

[copyman]

By the way this is the Moeller white paint I use for Tecumseh engines. I've tried several different paints and this seems to be the perfect "off white" like Tecumseh used. Moeller also has a black paint called Phatom Black. Both apply really nice and gas/oil resistant. Best price and always in stock at myinboardmarine.com

 

[Donrokon]

Voice of experience here: several years of experience stripping paint from aircraft.... USE RUBBER GLOVES......