Topic: Duplicolor vs. VHT vs. POR-15 Engine Painting Tips and Recommendations

[SOHC4 Cafe Racer Fan]

I'm about to paint my engine cases.  They were wire wheel polished but have been since sitting for about 2 1/2 years.  I am pulling the motor so I thought I'd paint them to give them some protection from oxidation, fuel, elements, etc.

Does anyone have any strong recommendations as to the best paint to use and the best process.  The cases will still be attached to the cylinders and head.  I am just replacing the valve cover gasket and side gaskets.  With that in mind, I will not be baking the engine after.  Is there a preferred prep process to maximize success (paint adhesion and durabilty) under these circumstances -- masking and painting??

HELP!

[mono]

I've worked with por 15 a lot this summer all helping a buddy of mine restore an old Camaro. Por 15 is a very strong paint , but it definitely gets the best adhesion when you actually paint over a rough and mildly rusty surface.  When we used it to paint over smooth clean metal, it had the tendency to peel off in sheets if it got a snag in it. But the areas that were painted over crap or rock hard and did not come off.  I'm not sure if that would be the best option for clean aluminum unless you really sandblasted first.

I don't know the heat tolerances of Port 15 , so you may want to research that first if you decide to use it on your engine, but my guess is that it probably isn't a good idea.

I touched up my engine with very high temperature rust Oleum, but there are better engine paint out there.  You'll definitely want to use a high temperature paint though... 1 that will handle above 500 degrees.

** edit - removed my comments about Duplicolor since the guys below informed me that they make a high-temp duplicolor, which apparently works well  !   

[Jerry E.]

I just painted my cases with Duplicolor, which is a "ceramic" paint. I have used this paint on other things, and it gets very hard, seems to last well. Duplicolor recommends using their primer before painting w/final color. I cleaned my cases(the soda blaster/dishwasher clean method), then used wax and grease remover, before priming/painting. The primer seems to have helped-the paint seems to have adhered very well.

[NewOldSchool]

Just repainted my engine with Duplicolor Engine Enamel 500 degree. I followed the instructions to a T laying down 3 coats of primer with about 10 minutes of cure time between each coat. I followed up a week later with silver. It looks brand new and hasn't chipped, scratched, or come off with minor oil spills or anything.

[SOHC4 Cafe Racer Fan]

Mono,
FYI the Duplicolor is their ceramic enamel specifically for engines and is high temperature rated.

[FunJimmy]

Timely. I plan on painting my engine with por-15 engine enamel this winter too.
If you read the application instructions, you will see that "prep & ready" is recommended for smooth metal and aluminum. Then the enamel.

I've also used Duplicolor ceramic engine paint and have nothing but good things to say about it.
Especially being a rattle can paint.

[toytuff]

Subscribed.

Will be doing this myself in the future.

tt

[madScientist]

I've used Duplicolor on my car engines but those are cast iron. On my bike I'll be using VHT simply because a lot of people here have recommended it.

I'm not sure it totally matters on what engine paint you do use as long as you focus almost all of your energy on the prep work. Scrub the parts to be painted with a mild detergent, rinse, do it again. Then wipe it down with an acetone soaked rag...do it again. Do all of this with gloves on. When you're done do not touch any of the to be painted parts with your bare hands. The oils in your skin will have a negative effect on the desired result.

I would also recommend using "self-etching' primer as aluminum is pretty resistant to coatings. The self etching primer allows for maximum adhesion.

[SOHC4 Cafe Racer Fan]

Any recommendations for primer? I bought a can of Duplicolor primer but it does not appear tones elf-etching.

[madScientist]

I'm using the VHT Self Etching engine primer. I read somewhere that there is a rattle can self etch primer (not VHT) for boats but I would be leery about it since it isn't rated for high temp and might bubble out on you.


This is the stuff I bought.

http://www.tcpglobal.com/spraypaintdepot/vht-self-etch-primer.aspx

[mono]

Mono,
FYI the Duplicolor is their ceramic enamel specifically for engines and is high temperature rated.

I see that you guys are talking about that, and it makes me happy!  Why don't i see it at the auto-parts store?  Where are you guys finding it?

didn't mean to be mutually exclusive, but i didn't know it existed!  good news.

Regarding VHT paints -- i like them a lot too.  used a bunch of the VHT caliper paint on a number of parts during my rebuild and the stuff dries rock hard.  also seems to have a little thickness to it to conceal very minor prep defects.

[mark52]

I too am in the process of painting my engine, was planning on using the Duplicolor, spray can, in the color many have recommended. Would like to hear more comments on the use, need, or what ever of using a primer first. First hand experience would be great.  Thanks

[madScientist]

TCP was the only place I could find the VHT Self Etching primer. I couldn't find it local at any of my usual haunts (O'reillys, Carquest, Napa, Autozone, Advance, a mom and pop place down the road).

This is my first time with the VHT engine paint but I LOVE their header and caliper paint. I did the headers on the 66 mustang with their silver. After banging them around in the engine bay there are no chips anywhere. They've also thumped the floor a couple times. The brake caliper paint held up really well too...even after dripping brake fluid on it...

The duplicolor engine paints worked great on my cast engines. I stripped them down, washed them twice, acetone wiped them twice, sprayed 2 coats primer and 2 coats color.

My concern with using the duplicolor primer on my case is that it doesn't etch and would be susceptible to chipping. I really dont want to have to do this job again. BTW...just picked my cases up from the blaster today...so i might be able to get it painted this weekend and will let you know how it works out.

[SOHC4 Cafe Racer Fan]

Thanks MadScientist,

I will wait to hear your report!

[madScientist]

So I realized I wasn't going to have time to do the whole set of cases so for this example I have my oil pain and clutch cover.

Duplicolor Test:
First, the oil pan I did last week in the duplicolor engine paint. Sorry I dont have pictures...this thread came about after I did it. I planned on doing this comparison anyway for my own edification. Here's what I did:
-- stripped it to bare aluminum using air craft stripper
-- "scrubbed" it with steel wool
-- soaked it over night in Krudder Kutter
-- washed it again in a clean solution of Krudder Kutter.
-- Wiped it down with acetone (wearing nitrile gloves that had also been wiped down with acetone)
-- did it again
-- sprayed duplicolor engine primer... 2 light coats about 10min apart
-- the next day sprayed two light coats of color about 10 min apart

After a week of sitting I tried to scratch it with my fingernail. It scratched very easily (see the picture). I also threw a couple of small rocks at it. It didn't chip really bad but you can see in the middle of one of the fins there is a chip. Pretty sophisticated tests going on here...

VHT Test
I used the clutch cover for the VHT. The different part aside this was also sandblasted versus chemical stripped. That may make this test a bit unfair since the sandblasting would have already done the steel wool's job...probably better. Anyway the steps are as follows:
-- sandblasted (as much as i LOVE chemical stripping, sandblasting was exponentially faster...and probably safer)
-- soaked over night in Krudder Kutter
-- wiped it down with acetone
-- did it again
-- sprayed 2 light coats of the primer (see picture)...NOTE: The VHT primer had a different texture and felt thicker to me. It could have been my imagination. It just felt more substantial.
-- after a couple hours I sprayed the color.

The picture shows the final product. I'm going to let it sit over night and do the same tests i did with the Duplicolor paint. The picture below is the part sitting for over an hour.

The conditions (temperature and humidity) were the same for both parts. I did not do any wet sanding of the primer on either coat. The feel of the VHT paint is pretty smooth which confuses me a little since I would think the etching would have carried over into the feel of the paint. The only explanation I have is that the paint settled down into the primer. With the duplicolor I feel more of the cast aluminum versus the coating. 

I'll report back tomorrow night (or Tuesday morning) on the result of the rock and fingernail test. I'll probably do a gasoline test tomorrow however I dont have much confidence in the Duplicolor from what I've seen here. If you want me to attempt any other tests let me know. Barring the results tomorrow the oil pan might be getting stripped in the near future...

[madScientist]

Here are the pic's of the clutch cover. I kept getting 413 Entity too large errors and didn't want to shrink them down any further...

[SOHC4 Cafe Racer Fan]

Madscientist,
I love the scientific method!!
Can't wait to see the VHT results.

[Retro Rocket]

Baking the parts after spraying would improve the hardness of both products....

[madScientist]

Retro --

I would love to bake them however the missus gave me a pretty stern lecture the last time I had engine parts in her oven. It was not a good conversation. Ended up with me sleeping on the couch a few days...

I'm doing my analysis based on the initial setup since they can only get better with the proper heating right? If one scratches and the other does not before the heat treatment wouldn't it mean that the one that didn't scratch would be inherently better after it has had it's heat treatment?

With all things being equal I have had very good results with Duplicolor on my car engines. I think the Duplicolor would have proved close to if not equally good had I picked up their self etching primer. However when I did my searching all I found was references to VHT so thats what I went with.

So in summary I'm sure both Duplicolor and VHT are great IF you use self etching primer and put a HEAVY focus on prep. Aluminum HATES a majority of coatings. I think that not using the Self Etching primer was Duplicolors down fall in this test.

I wish my bike wasn't in 100 pieces right now to do a proper run out...geez my posts are long winded...

SIDE TANGENT: If you want a REALLY good engine enamel...i finished up painting a 347 a few months ago for my mustang using the Eastwood engine enamel. When it's all said and done it was about a mil thicker than the Duplicolor and the color was closer to advertised. Along with that, after a couple heat cycles, it resisted; gasoline, brake fluid, carb cleaner, anti-freeze, and a very hard hammer whack...

[rb550four]

When I paint engine parts, I use a hairdryer on it before, between each coat and leave it on for a 1/2 hour or so always on hot. The paint doesn't run much that way.
 The kitchen stove is always a no-no. But the outdoor gas grill won't stink up the house. Mine has a side burner that comes in handy for boiling up some carbs. And even so,it seems that women don't like carb soup. Just so ya know.

[mono]

+1 on that.  A little heat seems to really make paint lay down a lot better.   

Sent from my SPH-L710 using Tapatalk 2

[SOHC4 Cafe Racer Fan]

I would die where I stand if I baked my engine parts in the oven!!

[madScientist]

Yeah she caught me right as I closed the oven door. The conversation went something like this:

GF: "Oh are you making dinner tonight?"
ME: "Sure if you intend to eat my intake manifold..."
GF:  Incoherent yelling and screaming
ME: "C'mon i just painted it and want to cure it!"
GF: more incoherent yelling and screaming
ME: "Fine i'll figure something else out..."

[mark52]

MadScientist, your last comment to GF propably should have been your first, HaHa. Thanks for all of the info. I'm sure it will come in handy when I paint my engine.  Does any one have any tips for paint th engine if it has not been broken down into the different parts?

[SOHC4 Cafe Racer Fan]

Yeah she caught me right as I closed the oven door. The conversation went something like this:

GF: "Oh are you making dinner tonight?"
ME: "Sure if you intend to eat my intake manifold..."
GF:  Incoherent yelling and screaming
ME: "C'mon i just painted it and want to cure it!"
GF: more incoherent yelling and screaming
ME: "Fine i'll figure something else out..."

Madscientist,

You are one brave man!! 

Thanks all for the information.  The painting date is approaching for me, too.