Best paint for engine blocks and tranny cases?

[Blownolds]

Title sez it all, what's the best paint for engine blocks? Something that resists heat, oil, gasoline, rust-through. Something that still looks as glossy as you applied it (however glossy that was), 10 years later.

Does Por-15 have a product for this? Or maybe an industrial machine enamel?

I'm not having good success with VHT rattle-can...

[chopolds]

I posted this on 'another' forum (so sue me!) has all the basics of doing a nice job.

Prep is anything that will clean off the gunk...spray degreasers, power wash, mineral spirits, or thinners and a parts cleaner brush, whatever. Rust needs to be eliminated completely, with chemicals, or glass beading. Be sure to remove all traces of the cleaning beads before continuing, they WILL ruin an engine if they get inside! Even a hot-tanked engine needs to be cleaned thoroughly before paintwork, as the caustics can hide inside the cast iron pores, only to surface after painting the engine!
Painting engine parts is not very different from doing regular painting, but there are some special 'precautions' and materials you need to know about. First of all, the actual cast iron parts do not need primer. But they come out better if you do prime them The sheetmetal pieces, as well as aluminum/diecast need it. I prefer epoxy, but have used etch, and even POR-15 (good if you have a clean, but slightly rusty assembled engine, that you cannot blast) as primers successfully. ABOVE ALL, do not use any lacquer based products! Either primers, or paints. They do not hold up well in the heat.
Be sure your parts are perfectly clean, no oil, grease, or moisture, or rust. I prefer to primer, and paint the same day, saves sanding the primer the next day. Sanding will inevitably bring up bare spots, needing re-priming, and leaves behind a lot of 'fuzz' when cleaning the sanding residue. Unless you are using the primer to fill imperfections, as in a smoothed out, show car job. Then, epoxy is your best bet, after smoothing out the castings with sanders, and cartridge rolls.
Paint can be anything from spray can engine paint, to Centari w/hardener, single stage Urethane, base/clear urethane, or Polyurethane (Imron). These all produce very nice finishes, tho cans are the hardest to control, and are probably the lesser quality . You can buy a cheap-o touch-up gun to do the job, you don't need a good gun.
For most engines, I paint the block and heads bolted together, but everything else separate (oil pan, timing cover, intake manifold, etc.) This gives a nice detailed look, especially if you use new, plated bolts and washers to assemble it. Stainless hardware is a nice custom touch, and can be polished to look like chrome, without the chipping, and rusting that wrenching them causes. If doing a strict restoration, tho, you can't do this! Many engines were painted assembled, even with exhaust manifolds in place. So too much detail is not wanted there.

My choice for the nicest finish, and best durability would be either Imron (polyurethane), or a Single Stage Urethane. Base/clear if it's a metallic. Color selection is endless.

[modernbeat]

What about smooth aluminum castings, like modern transmissions?

[chopolds]

Modern, the only problem with aluminum is the prep, and choice of primer. Clean it good, sand it thoroughly, and the epoxy or the etch primer will work fine. There are also aluminum prep solutions you can scrub it with, if you think you need to. Dupont makes a 2 step Alumi-Prep system that is supposed to be the ultimate in getting alum. ready for paint. Used it once, and it DID last forever, but haven't had problems with painting aluminum without it, either.
Paint almost doesn't matter at that point. I have heard that painting aluminum automatics isn't a good idea (blocks heat transfer), but haven't ever had a problem with mine, or the cars I've built. Of course if you want to be cautious, just limit the amount of the primer and paint to "just covering it', to minimize heat insulation.

[Ayers Garage]

I use POR15 engine paint.

This is a big block I'm finishing up for my work truck.

[JimC]

The method I use for prepping the aforesaid items is filling a bucket with water, mixing in a squirt or two of dishwashing liquid soap, and taking a sponge, several different size course bristle brushes, and scrub away. then with a sponge and clean water, just keep on scrubbing, rinsing the sponge, then scrubbing until no more suds apeear.

Blow dry, let set in the sun until you get the paint mixed(I use PPG Concept(usually black) then spray a couple of light coats, Next, follow with a wetter coat, then a couple of wetter coats. Take your time with the wet coats, not too wet that the paint runs.
You will get a glossy block and tranny case that will last and clean up easily.
Regular body paint will stand up to the heat that the engine produces.


Jim

[shifts]

JimC, you mean to say that you painted over our absolutely beautiful "cast blast" paint job? Dave

[Greazer]

POR-15 makes an entire paint/prep "kit" that is specific for engine applications (I was considering buying this):

http://www.por15.com/product.asp?productid=319

[Just Gary]

Can't emphasize cleanliness enough. I wipe the engine, scattershield & tranny down with brake cleaner, followed by a tac rag to remove dust.