Plenum Paint Bubbles

[902066]

I have a couple of paint bubbles on the top of my Plenum. I have had my Throttle Body coolant by-passed for a couple of years now. Going to have the plenum off next week for injector change, thought I might fix the bubbles while it's off. Whats the best way to fix them? I'm assuming sand and fill with what? and then repaint. thanks

[billybaloneey]

Visit the Lingenfelter web site...they sell a spray paint designed for the plenum and it is about as close to factory original as you'll find anywhere.

[tomtom72]

When I cleaned up my bubbles the first thing I noticed under the paint was a white powdery deposit. I scraped off the paint then found the white stuff. I hit it with WD40 and a tooth brush. I cleaned up the mess and looked and there was still some white stuff in the pores of the metal. I then went to the brass brush and WD40. Then to 100 grit wet paper + WD40. Every time I dried the metal I still could see white stuff in the pores.

It's a pia to get all the white stuff. I probably should have used Navel Jelly? I eventually used baking soda and a stainless steel bristle brush. It took a while to get rid of all the white stuff in the metal pores.

[902066]

Thanks Tom Tom , thats what I wanted to find out. Whats under the bubbles and how to get rid of it for good?

[tomtom72]

Your welcome!


Since your coolant loop to the T/B is by-passed you should never have this issue again. I am convinced that the white stuff is the result of electrolysis. I used to see this all the time on aluminum in boats. Stray electrical currents and and water don't go well together. Same white stuff and same PIA to neutralize it.

FWIW, I did mine about five yrs ago and I have not had a return of the pox. I used the LPE paint. Good stuff. Key is to get rid of all the white stuff before painting.


Tom

[phrogs]

yeah that white stuff is the corrosion.

[secondchance]

Problem w/ any spray paint is matching color with the rest of the plenum.
I scraped off bubble w/ razor blade, primed the area and then leveled relative to adjacent surface w/ orange scratch filling putty. Then mixed up a batch of paint w/ Duplicolor VHT engine paint - primer, silver, black and a little gold. Primer and black was used to match the amount of metal flake. Once matched, I primed the area again, block sanded using a small eraser as a block w/ 600 grit. Paint was air brushed on w/ a Badger sprayer.
Although I got the color close, this made the rest of the plenum and cam covers look sloppy. So I ended up air brushing the entire top, used paper towel to knock off paint dust (air brushing was drying some particle before hiting the surface) and then hit the area w/ a light coat of VHT clear.
It came out pretty good - real happy with the result.
Just don't over do clear because it will turn yellow after a while.
Also, make sure you clean the surface real good with Simple Green. A lot of masking but the rest was pretty easy. It just takes a lot of patience and a steady hand when painting the recessed letters.
It has been 10 months and holding up with no issue - baked on!

[rhipsher]

If I'm not mistaken the I/H housings and the plenum were made from sand castings which is why our plenums have that rough surface look. Sometimes they get porosity or air pockets during the casting proccess and sand gets packed into them and bingo. There's your white powder. Sand casting aluminum is alot cheaper than an investment casting made from a true mold. And I'm sure that some of those plenums were rejected for porosity.