The Stovebolt Site Forums The Shop Area Engine Shop Manifold cleaning

I removed the intake/exhaust manifolds on my '51 Chevy 3604, original 216 engine last night. Boy was that fun breaking those nuts off, only took a couple of hours. The exhaust manifold has the usual carbon in it. I did a search and couldn't find any information on cleaning it. Should I even bother with it, it'll blackened right up again won't it? And is it safe to media blast(coal slag) the exterior of the manifolds, being sure to seal up the openings of course? Thanks in advance, Jeff.

It's always fun tearing down a 50 year old engine that is stuck like glue, isn't it? I certainly would clean all the carbon out of it. That was deposited over a long time and probably because it was running pretty rich. A properly tuned engine should have a grey exhaust with little carbon deposit so yes, by all means clean it. As for the media blasting, well what can it hurt outside or even inside? It could only help smooth out the cast iron. Not sure about coal slag however as the proper media...sounds harder than the hinges on hells front door.

Dave,
I was thinking it might not hurt to blast the inside, but I was afraid of any pieces that might remain in the intake even after a good blowing with compressed air. I have been using coal slag on all of my parts. Have not tried it on panel pieces such as fenders or door, I don't know if it will warp the metal or not. Thanks for the input. What else could I use to remove the carbon build up deep inside the exhaust manifold? Jeff

Steam cleaning or just hot water works great on carbon deposits. It dissolves in water. You can also mix up a big bucket of red devil lye and let the manifold soak in it for a few weeks. It won't hurt the metal but all the carbon and oil will come out. Wear gloves and don't get any in your eyes.

Thanks for the tip 4ontheFloor. I just media blasted it this afternoon. Now I can clean the inside, blow it out nice and dry and shoot it. Which is what I wanted to do to it when I was trying to get the mother off the exhaust/tail pipe. I hate rust! Thanks again, Jeff.

Coal slag? That stuff is so nasty that I'm surprised anyone would use it. Try aluminum oxide. It cuts better and doesn't crack or pulverize as bad. You can paint the outside with an "Eastwood" hi-temp exhaust paint which comes in several different styles. It will look sharp.

I couldn't find any silica sand here in town at any of the box stores. They just had coal slag, I haven't checked the lumber yards though. Other than it being pretty dusty, it works great on everything I've used it on. When my supply runs out, I will try aluminum oxide or silica sand, if I can find it.

53MONEYPIT.I haven't seen a gray exaust pipe in 30 years. And be4lieve me I look at a lot.

And you never will with unleaded gas.

The factory would have blasted it with steel shot in a tumbling basket, to remove any sand left over from the casting process. I dont think you can do anything close to this that would harm it or leave something behind that would either.