Cast Iron Intake Cleaning

[Tom K.]

Hello everyone,

As usual, looking for advice from those who have been there and done that.
I was able to find a correct manifold for my 1973 LS4 automatic car. I had the carburetor restpored professionally and it is so nice, I cant just put it back together the way it was. Anyway, I have the correct intake home, stripped it down and cleaned it with a brush and simple green. I was going to sandblast it, but I thought grit would get everywhere and later might end up in the engine, plus its not the best for the machined faces. My next thought was way back when we would use a caustic thermal bath (hot-tank) and it did a good job of removing even the carbon in EGR ports. I dont think that process is done anymore because of the environmental problems it posed. This manifold was purchased off Ebay, so I know nothing about its past life. I was hoping to thoroughly clean it so when its put on the engine I dont add more whatever into the engine.

How do you folks normally clean something like this?

Should I remove the riveted on heat shield from underneath so whatever crud is under it gets cleaned away as well?

As always, thanks for your time and i appreciate the help / advice


Tom

[Patrick H.]

Re: Cast Iron Intake Cleaning

I usually bring them to the local engine machine shop.
Whether they blast it or tank it or I believe now bake it, it comes out like new.
Obviously, remove the accessories that you can remove before you bring it there. They can remove that water inlet if you can't, and can both remove and reinstall the lower shield.

[Arland D.]

Re: Cast Iron Intake Cleaning

FWIW here is a picture of what was hiding under the shield of an aluminum intake manifold. You can see a large ball of greasy glass beads on the lower left from a previous 'restoration' just waiting to drop into the engine so that's why all intakes should have the shield removed when being restored.

[Tom K.]

Re: Cast Iron Intake Cleaning

Thanks Patrick and Arland!
I was wondering how much crud could be under there - now i know. I will find an automotive machine shop in the area and take that route.

Tom

[Kenneth B.]

Re: Cast Iron Intake Cleaning

Would NOT sand blast it. Would get it hot tanked & then paint with hi temp paint. EASY.

[Joe L.]

Re: Cast Iron Intake Cleaning

All------

Keep in mind that while a hot tank works great for a cast iron manifold as is the subject of this thread, it CANNOT be used for aluminum manifolds or other aluminum parts. Why? Aluminum is an amphoteric metal that is dissolved by both acids and bases (like a hot tank solution).

[Kenneth B.]

Re: Cast Iron Intake Cleaning

All------

Keep in mind that while a hot tank works great for a cast iron manifold as is the subject of this thread, it CANNOT be used for aluminum manifolds or other aluminum parts. Why? Aluminum is an amphoteric metal that is dissolved by both acids and bases (like a hot tank solution).

Yes I should have said that C I only.

[Edward J.]

Re: Cast Iron Intake Cleaning

Are not the solutions they use today a citrus base solution. The old acid type has been outlawed? I remember when I had my 63 340 horse motor the dipped the aluminum manifold and valve covers and they look much better.

[Arland D.]

Re: Cast Iron Intake Cleaning

No one has mentioned the cleaning method for aluminum intakes and valve covers involving vibrating in a vat of ceramic media shaped like the filter of a cigarette with an angled tip. This picture is the result for a 63 340hp intake and valve covers and may work just as well on a cast iron intake.

[Tom M.]

Re: Cast Iron Intake Cleaning

Depends upon your location. In the northeast, it seems that shops willing to take on small cleaning jobs like that are getting hard to find. A low buck alternative may be using paint stripper followed by powerwashing. I recently did that with a 75 year old jeep transmission and it cleaned up nicely and ready for paint. Any spot rust may need a little hand work follower by another powerwashing.

[Joe L.]

Re: Cast Iron Intake Cleaning

Are not the solutions they use today a citrus base solution. The old acid type has been outlawed? I remember when I had my 63 340 horse motor the dipped the aluminum manifold and valve covers and they look much better.

Edward------

I believe the hot tank solutions of old were strongly BASIC and not acidic. I don't know if that's what's still used for those few shops still doing hot tanking. The citrus based solutions are citric acid. Citric acid is a weak organic acid.