Question on soda blasting an engine

[canuguzzi]

I've used soda blasters before so if it's the right cleaning method isn't where I'm headed.

Sand blasting an assembled engine is the pits (maybe literally) and can mess with gaskets and so on. I have a engine that was black and is 30 years old. It was at one time, black but some of that has come off. Naturally it has come off where you see it, not in the nooks and crannies where you can't see it and where it looks new. Figures.

I thought I'd soda blast it while assembled, taking care to cover all the ports, openings and such, just enough to clean it up prior to a wash down and then paint the public showing areas.

Vapor sounds good but I'd rather not take apart a non leaking and fantastic running mill if possible. Just trying to make sure paint adheres. Was thinking about using a ceramic paint unless there is something better.

Last time I painted an engine was before Honda sold V4s to the public.

Thoughts?

[Huzo]

Just about to start work on a cosmetic restoration of a mk2 Le Mans. I hope this thread really grows some legs

[huub]

i had a complete guzzi engine glass bead blasted by a local guzzi specialist, without the need to strip it.
so it can be done as long as you manage to close all the ports and openings.
having said that , i was glad he had adapters for the guzzi engine , and i didnt need to make those myself

[Perazzimx14]

I'm not sure soda will cut the paint.

[Cam3512]

I had an old Duc 250 engine soda blasted (man was that single a work of art), but I had pulled it out of the bike.  Leaves a dull matte finish, but man that stuff gets EVERYWHERE.  Cleans off easily, but you'll be finding residue for years.

[Chuck in Indiana]

I painted the Lario engine (Lario rehab) and detailed how I did it in that thread. It still looked new when I retired the engine when it wiped a cam lobe.

[boatdetective]

Tough question. It's one thing to blast an engine down to bare metal and it will not be painted. It's another altogether to get the paint to stay stuck to aluminum. Everything I know about finishing aluminum (and that's just painting boats and sailboat masts) says that it is critical to prep the surface with an acid wash then a "conversion" coat to prevent "filiform corrosion".  Mind you- I work in the marine atmosphere, which may be more harsh. Nevertheless, aluminum really, really wants to develop its own oxide coating on the surface- and it's this oxide coating that can cause paint to lift.  Here's a  quick video showing the process: https://www.youtube.com/watch?v=b7FX85Q838Q

 I know what you're going to say- "how am I supposed to do that with an engine". Well, you're correct. The point of all this is that Guzzi did not dunk their blocks on original construction- and now you have to pay the price. Personally, I'd saturate some towels with the solution and pack them into the nooks and crannies.

Of course, if this all seems like too much work to you- go ahead and rattle can the engine and hope it works. Didn't work the first time. No reason why it will now. But hey, knock yourself out. The point of all this is that finishing aluminum is more than just cleaning the surface with an abrasive before you prime. The conversion coating etches the surface perfectly clean then chemically prevents the metal surface from oxidizing.

[blackcat]

I had the CX engine soda blasted by a guy who does whole cars and he charged me 75 bucks for the engine,transmission and final drive. I assume it took him no time as his equipment is quite substantial.
Blasted, pre-painting:


Then I painted it:




I thought that my prep work was good but some of the paint has failed on the transmission and oil pan, fortunately it is hard to tell. If I had to do it again, i'd pass on painting it but I have no intention of pulling the engine and starting over.

[JoeW]

I customized a neglected jackal a few years ago. The engine and trans were originally painted silver but, the paint was flaking. I bought a cheap soda blast set up from Harbor Freight. It removed most of the paint, it was good enough to repaint. In the picture it looks great but, up close, you can see where the old paint remained.

[Groover]

I had my engine soda blasted when I restored my G5 last year. All went well, no damage at all to anything. I used black rubber plugs from the hardware store (various sizes), then I stuffed saran wrap and aluminum foil over that where I couldn't used plugs - e.g., the drive shaft exit and the rotor shaft area. The foil will protect the saran from shredding.

The soda cleaning took care of most of the oxidation and it cleaned it very well. To take care of the bit of oxidation missed, I sprayed the entire engine with ACF-50 and let it sit for a couple of weeks until I was ready to mount the engine to the frame. A final wipe down made the engine look great.

Of course, ACF-50 is probably the last thing you want to apply to a surface you plan on painting....

Onto the paints... I did a little homework on this and what to use when and why. Eastwood.com has great products, and they can sure hook you up with whatever your project may be. I used some of their products and their stuff is great.

As far as easier accessible and easy to work with equally good products, I'd suggest you take a look at the Duplicor ceramic spray paints. They have a bunch of different types for various applications and I found their stuff to be really nice a great to work with.

http://duplicolor.com/product/engine-enamel-with-ceramic

Good luck.

[Groover]

Another note on the paint removal by soda. My engine was not painted, but I also had several other parts soda blasted at the time. Triple Tree parts, lower fork legs, and the factory finish off the mag wheels. According to the soda blaster tech, the forks and the triple parts were easy to strip. The wheels on the other hand were very hard, but with dedication they got them stripped. I did see their rig, and they were pretty much using trailer type compressor that you'd see used typically along with a jack hammer.

Soda Blasted Wheels:



Soda Blasted Engine:

[canuguzzi]

 Thanks for the comments. Going to give it a try tomorrow. I found a method to paint aluminum some time ago, not engines but structural stuff. After cleaning, a wipe down with denatured alcohol, dry then immediately paint. This time I'll use a ceramic paint but in the past the paint lasted (still looks like new) for over 7 years and some small parts that are over 20 years old and look fresh.

The engine isn't off a Guzzi but rather a four banger that was blck from the factory. The black paint wore off but strangely, the parts painted gold look like new after 30 years.

[Groover]

Denatured alcohol is definitely good, especially is you can push it through a compressed spray gun.

Another option:

http://www.eastwood.com/eastwood-pre-painting-prep.html

Some personal notes from my last paint job (this was collected from tech support calls because I just wanted to do the job right)

1) Prep Spray clean
2) Spray 2 or 3 coat light mist 10-15 minutes apart within an hour. If not within the hour, then wait 7 days for extra coats. Same temps as dupliclor, 60-90 degrees F. temperature, 50% or lower humidity levels.

The humidity level is especially important during the clear coat application otherwise you'll get hazing. The hazing will occur on solid paint as well, but more noticeable in clear obviously. If you want the best color depth, then be sure humidity level is low.

If hazing does occur, it will "eventually" burn with time, but I didn't want to test that theory.

[atavar]

Probably going against common wisdom but in my experience I do not try to remove all paint but scuff the paint surface to promote adhesion.  old paint that does not remove easily is a great pre-coat. 
For engines I have had great success using one of the major brand wrinkle finish paints.  The theory is that the high temp wrinkle finish increases the surface area and promotes cooling.  I find it to be a *very* durable finish.  On some engines I have had great cosmetic effect by sanding the fin edges to expose aluminum creating contrast to the painted color. 

[canuguzzi]

Yup, this engine had the edges of the fins left bare. Its a liquid cooled engine so the fins are thick and a cosmetic statement more than any function.

[atavar]

I have seen the high temp wrinkle coatings in red, blue, green and black which could open up some interesting possibilities for custom looks. 

[canuguzzi]

It got through the clear coat of the grab rail, it ought to work just fine on the black engine paint.





That clear coat was very heavy and tough. The blaster is running 90 psi serviced by a 200 psi 30 gal compressor. I check the work frequently so the compressor doesn't have a difficult time keeping up.

The nice thing about refinishing is that I can remove all the casting marks like the small ridges and clean up the radiused portions to make them look un-massed produced. I'm not a big fan of highly polished aluminum and prefer matte finishes.

The parts not attached to the engine will get an acid bath, DI water rinse then denatured alcohol wipe and either satin clear or paint.

That small portion took about 2 minutes using a medium grit soda.

[Zinfan]

Every time I hear about soda blasting I think of this post http://advrider.com/index.php?threads/lovingly-restoring-the-worst-bike-ive-ever-ridden.618122/page-5#post-14253267 .

[canuck750]

I buy my soda from an industrial supplier of blast media, the soda does not make a huge mess, I use both a Harbour Freight pressure blaster tank and sometimes just a siphon spray right out of a twenty gallon pail of soda. Most of the soda just sweeps up and gets dumped into the garbage, the rest just washes down the lane. I find soda works great at removing paint from steel and aluminum, removes oxidation fro aluminum etc...

Acid washing works much faster and can be done carefully with the motor in the bike, just use a paint brush to apply a diluted solution of NAPA aluminum brightener then after a few minutes blast away with a pressure washer. A follow up with a soda blaster will return any old corrode piece of aluminum to look like fresh casting.

These parts were acid washed (no acid on the inside of the transmission) pressure washed then, once dried, soda blasted.

[Rusnak_322]

What is the point of the acid washing step? I am going to soda blast my assembled motor once I drop it from the frame. I was going to buy the HF soda blaster this past weekend but was under the weather.

I have used a homemade soda blaster with baking soda I stole from the fridge and freezer. It worked great on some old carbs. I have degreased the motor and was just going to blast it. Will the acid step really change the outcome or just make the soda blasting go faster?

[canuck750]

Acid washing will remove the oxidation and staining of the casting very quickly.

Usually it takes three or four wettings of the cast surface with the acid/water solution (mixed 50/50) and applied from a spray bottle. I soak the casting, let the white foam build up for a minute or two and then using a very high pressure washer I blast off the solution and oxidation that has been released. I repeat this step until the casting is very clean. Castings that are so blackened from oxidation may take more soakings.

The soda blasting gets the residue of oxidation off that the high pressure car wash blast will not lift.

Acid can be dangerous so exercise caution and wear a full face respirator that protects your eyes.

If you start with something like this



and soak with acid several times



then after pressure washing touch up with soda and it comes out like this

[Triple Jim]

I assume it took him no time as his equipment is quite substantial.

Don't be too sure.  I've used a big professional sandblasting cabinet and it still took time.  For $75 he may have put a guy on the job for an hour or so.

[kirb]

have you considered vapor blasting?
https://www.youtube.com/watch?v=-jRkKrbR160

A local guzzi restorer uses these guys and loves the results.

[canuck750]

have you considered vapor blasting?
https://www.youtube.com/watch?v=-jRkKrbR160

A local guzzi restorer uses these guys and loves the results.

I would be very interested in Vapour Blasting but being cheap I much prefer the do it yourself route whenever possible