Tom454

I have cleaned up my leaking OEM intake etc. and I'm ready to re-install it all. It's been a while since I clear coated an aluminum intake. I normally use Dupli-Color DE1636 Hi Temp Engine Enamel but this yellows pretty quickly. What are ya'll using for this nowadays?







Before





After

Joe C

FWIW - i'm a big fan of PPG chem-film (DX-501). it's an almost invisible chemical film or coating, that soaks into the aluminum, and will pretty much will stop aluminum oxide dead in it's tracks. I've been using chem-film on my corvettes for at least 20 years. DX-501 is available at any PPG automotive paint supplier.

BTW, nice job cleaning the intake! how did you do it, and what did you use?

THE 383 admiral

Much better appearance. Are you using Dex-Cool OR Glycol anti freeze. Any other additives. your Water stat seat is eroding. just like I have witnessed on many cars. Any white residue powder? from the reaction.

Tom454

De-greased using gas & several parts cleaning brushes- stiff, soft

Repeat 2 or 3 times:
Soaked in Gunk Hydraseal II cleaner
Sprayed with hose
Scrubbed with hot water and Black Magic (Westleys) tire cleaner
(toothbrush, wire brush, screwdriver etc)

Sandblasted, wire-wheeled

The EGR passages were impossible to clean completely, and they were totally plugged.

I have an account at a local body shop supply house ... they have ppg... I'll check it out.

Tom454

I was going to use Prestone. (?)

I don't know the history of this car.

mtwoolford

Ah, how many times have I heard or read "But I replaced the EGR valve and it still won't pass smog"?

Dt86

You can try spraying some oven cleaner in the egr passage to break the gunk up. I personally wouldn't bother with painting the intake since it's covered up 90% anyway. Nice job cleaning it up!

Tom454

Found the following on PPG's web site:

"DX Metal Treatments are not recommended or advisable on sandblasted metal."

They do not provide a reason.

All of my stuff is sandblasted except for the runners.

Back to square one I guess.

Joe C

well, all I can say is I've (glass) bead blasted ALL my parts before the DX treatment. as I said, been using the stuff for around 20 years. never an issue!

here's a couple pics of me NOT following directions -

side note - the valve covers are not aluminum, but magnesium. they are painted, not chem-film'd. exhaust manifold heat shields - VTH header paint, color, flat aluminum, and fuel rails - just solvent cleaned - natural, factory, OE finish.



my "under-construction" 85 -

xrav22

I like the natural look also, I'm getting ready to do mine. Hey Joe C where did you get the valve cover tubing and injector covers for the 85?

Joe C

original equipment. I'd like to replace the VC grommet and the 90 degree rubber elbow, but haven't found a source for suitable replacements. may have to retrofit later L98 hardware - ???

Tom454

Okay.... I'll go talk to the supply house people. Maybe PPG said that about blasted but not wire-wheeled parts. Wire-wheel (buffing) may make a difference.

Nice job by the way... that's the look I'm shootin' for.

Tom454

Yeh... me too. Plus, I'm replacing the valve covers and my experience with removing heat exposed valve cover grommets is that they tend to crumble when you try to remove them.

v8vette84

POWDERCOAT!! IT will last forever! I had my LT1 intake powdercoated.

Tom454

How did they manage to coat only the outside surfaces and avoid the gasket surfaces?

Dt86

You mask them off with heat tape like you would mask any paint project.

v8vette84

Tom454

I went to my local Body Shop Supply and took a look at the PPG DX 533/503. Each quart is enough to do several manifolds, but it also costs $25/quart. This would mean $50 to coat this intake. Not in the budget unfortunately. And they had no answer as to why PPG dictates not to use it on sandblasted items.

tunedport85inject

it's a good chance to port that manifold,do you plan to port out some aluminum from those intake ports

Joe C

first of all, what do you mean "enough to do several manifolds?" these are not one time use products. a quart of concentrate mixed 1:1, and stored in a 1/2 gallon jug will last you a long time. after you condition parts, pour it back into the storage container. dx533 is a cleaner - I have almost a gallon, but don't use it too often. pretty much just use the DX501. granted $25/quart is a bit pricey, but it will last you a long time. if you buy a couple quarts (one each DX533/501), you pretty much have to consider it an investment. I've had my current stock for about 3 years now, and done the majority of two L98's including accessories. you might be able to get by with only one quart of DX503 concentrate.

i have done some on-line research on the DX sand blasting thing. on one site, i read that silica sand contains contaminants that could become embedded in the base material, and could have an effect on the conversion coating. since DX is a aluminum painting prep, these contaminant's could impact the final finish. i use glass for my blasting medium, and it may or may not contain the same contaminants, and i do not paint or topcoat my engine components. this may be why i have not had issues using this product. i had some parts on my 85 that were originally done back in 1996, and they damn near looked as good today as they did 20 years ago.

BTW, you want DX501, not DX503. 501 is clear, 503 is orange/gold color.

http://us.ppgrefinish.com/getmedia/9...tment_2-13.pdf