Aluminum Manifolds & corrosion/oxidation?

by 77mali Tue Jan 17, 2012 4:08 pm

I have my car stored outside & it's covered & waterproof. I looked under the hood today and saw what looks like rust possibly forming on my air intake manifold, which is an "as cast" (not polished) Edelbrock aluminum...anyone ever have this happen? They are very small yellowish spots...almost looks like it's getting the measles. Will polishing solve this? I really wanted to keep it "rough" but now I'm concerned.

by Joe73 Tue Jan 17, 2012 5:50 pm

I think its oxidation. I have he same thing on my manifold. I'm thinking that I'll take it off, bead blast it, and then have it powdercoated clear. Then just be careful when tightening the bolts not to chip the powder coat.

by ant7377 Tue Jan 17, 2012 6:06 pm

maybe squirt some light oil (3 IN 1) on it then wash it off in the spring.

by 77mali Tue Jan 17, 2012 6:07 pm

Ain't it a drag? Thx 4 the reply. I have some Por15 I'm gonna try that with an engine enamel topcoat, I think. I'm getting PO'd at my buddy who was going to dig his engine crane out for me...like before Thanksgiving. I gotta get that engine & trans in the workshop...Ugh.

by pila Wed Jan 18, 2012 1:39 am

I've bead blasted a couple, and used a satin clear coat on them. It's good for a few years.
I've had more problems with aluminum manifolds corroding under the water neck/thermostat housing than with the outside.

by 77mali Sat Aug 04, 2012 9:32 pm

Well I finally got around to tackling this problem. Thought I'd try the Dremmel and some wire wheels, working but it's taking a while. Never again will I get an aluminum intake without it either being polished or powder coated. This "as cast" finish leaves all kinds of crevasses for water/moisture/humidity, etc... to sit on the surface and cause problems. Still has a "rough" finish so not too disappointed but it will have to get painted now & clear coated with hi-temp enamels. There wasn't one square inch of it on the top side that wasn't affected. Evil or Very Mad

Aluminum Manifolds & corrosion/oxidation? P1030916

Aluminum Manifolds & corrosion/oxidation? P1030918

Aluminum Manifolds & corrosion/oxidation? P1030917

by ant7377 Sun Aug 05, 2012 8:15 am

Might try cleaning it with rim cleaner for unpolished,uncoated wheels. Just spray it on, aggitate it and wash it off.

by 1973 454 MONTE Sun Aug 05, 2012 10:47 am

What about some straight acid

by 77mali Sun Aug 05, 2012 12:35 pm

The wire wheels are working good...it's just time consuming Rolling Eyes

I'm going to wipe it with acetone after and paint it. The manifold is very sensitive... Gay

by pila Sun Aug 05, 2012 4:13 pm

It's too bad that you don't have a small sand blasting cabinet. Of course there are various types of media, like glass beads, which work good on aluminum.
If you weren't 1000 miles away, I would be happy to blast it clean for you !! Very Happy

When yo do get it cleaned up, using the power wash wand at the local car wash, on the engine (cover the distributor with a plastic bag) works good to keep it clean, when washing the car. Very Happy

I wash all my engines that way, since I'm always having to work on them !

by jerry46765 Sun Aug 05, 2012 4:18 pm

It's just a raw intake manifold with nothing on it.

If you lived close I would bead blast it and then you could paint it. Paint is cheap and easy. Powder coating would be better but it's not a cheap do it yourself process. Polishing is a nightmare unless you never plan to get it wet or dusty.

Here was a pretty sorry set-up before some rattle can art. These valve covers were from a 150k mile vette, and the manifold was 'as-cast.' They looked like crap together so they got a couple of coats of hammer tone silver. They look like they belong together. Now, if the engine fairies would stop by and insert it back in the car...

Aluminum Manifolds & corrosion/oxidation? INJ_406

Aluminum Manifolds & corrosion/oxidation? INJ_406

Thanks -

by dragons_lair59 Sun Aug 05, 2012 4:39 pm

eagle one aluminum wheel etching spray just spray on wait couple min spray it off
http://www.eagleone.com/mag-wheel-cleaner

by 77mali Sun Aug 05, 2012 5:34 pm

Viola, she is done...Back in Black.

Por15...will top coat with the Duplicolor engine enamel & hi temp clear. Por 15 is rated to 350* F. Water neck to be painted too.

Aluminum Manifolds & corrosion/oxidation? P1030921

Aluminum Manifolds & corrosion/oxidation? P1030921

by jerry46765 Sun Aug 05, 2012 5:42 pm

Looks bitchin'... Why do want Por-15 on it?

by 77mali Sun Aug 05, 2012 5:47 pm

BTW, thanks everyone for all the suggestions & offers to help out. I'm pretty confident in the Por15 & Duplicolor products, I've had great luck with each. That vette engine looks nice Jerry...is is in a Vette or something cooler?

Sam, I've used that tire cleaner before...it's REAL aggressive...turned my blackwalls brown on my Mercury Laughing

Probably would have worked on the intake but i was too Chicken Sh*t to try it, did not want to potentially compound my problem. I have some so I'll try a little on the bottom side and see how it does.

by 77mali Sun Aug 05, 2012 5:49 pm

jerry46765 wrote:Looks bitchin'... Why do want Por-15 on it?

Por 15 will never let the rust/oxidation out again. I know it's probably over kill but I use it because it's pretty fool proof unless you skimp on prep.

by jerry46765 Sun Aug 05, 2012 9:59 pm

I'm not sure you would want por-15 on something that gets hot like an engine. Paint will stop that black oxide.

by jerry46765 Sun Aug 05, 2012 10:07 pm

[quote="77mali"]BTW, thanks everyone for all the suggestions & offers to help out. I'm pretty confident in the Por15 & Duplicolor products, I've had great luck with each. That vette engine looks nice Jerry...is is in a Vette or something cooler? quote]

The only thing vette is the valve covers. It's an early 70s 400 with a Holley Ramjet like manifold (don't remember the brand name). It was in my El Camino when I did an upgrade. It ran good with a carb, so it will run better with EFI if it ever makes it back in there. I just need to make it through summer... Why does the plumber always have a leaky faucet?

Thanks -

by DiscoMalibu Sun Aug 05, 2012 11:07 pm

I do a lot of restoration of old cast aluminum parts. Repair, sand, wet sand and then polish and have always clear coated the parts afterward. The only thing is the clear tends to yellow over time but no problems with oxidation.

Why does the plumber always have a leaky faucet?

Boy do I hear that. Working as a tractor trailer mechanic, running a small engine repair shop, there's just never enough time in the day to work on my vehicles! Never buy a mechanics daily driver. Embarassed

by 77mali Mon Aug 06, 2012 8:30 am

jerry46765 wrote:I'm not sure you would want por-15 on something that gets hot like an engine. Paint will stop that black oxide.

http://www.por15.com/Por15Test.asp

Jerry see the very last line on this tech page, I was wrong on temp resistance of Por15 @ 300 degrees F (it's actually 450 F). I don't think the manifold will get that hot (at least I hope it won't).

by pila Mon Aug 06, 2012 10:41 am

Is that a single-plane manifold ?? Kinda looks like it in the pics......if it is, hope you don't plan on driving it in cold weather Very Happy

by 77mali Mon Aug 06, 2012 1:48 pm

I have an electric choke on the carb...it's a Vortec style manifold.

Description of EDELBROCK 2116: Chevrolet 262-400 Small-Block V8, PERFORMER VORTEC (idle-5500 rpm)
Based on the popular and powerful Edelbrock #2101, this dual-plane intake is designed for the street rod, industrial and engine swap market utilizing 262-400 c.i.d. Chevy V8s with 1996 and later Vortec (L31) cast iron or the new Edelbrock E-Tec aluminum heads. Manifold has provisions for external water bypass and may be used on either Vortec blocks or 1995 and earlier blocks. No provision for exhaust heated chokes. Accepts both square-bore and spread-bore carbs and late model waterneck, alternator, HEI and air conditioning brackets. Will not fit under stock Corvette hood.

by Joe73 Mon Aug 06, 2012 2:35 pm

I run a single plane, Weiand 7546, all year round. And I dont run a choke a all. No problems here. Hopefully this winter I'll be running a Victor jr. single plane with a holley 750 again with no choke. Never really had any issues without the choke. I fire it up and hold the throttle at about 1600 for about 10-15 seconds, then she'll idle.

by 77mali Tue Aug 07, 2012 7:45 am

I drove my 77 Cutlass in the winter back in the day...never had any issues unless is was super-duper cold out (like under 5 degrees). Even then it would start & after about 10 seconds the idle would even out. I'm thinking the manifold was one of those single plane cross-over types but I'm not sure.

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