engine and drivetrain Exhaust Manifold Rust Pitting

['76mintgrün'02]

I acquired a used tii exhaust manifold from a fellow FAQer.  I knew it had "surface rust" when I bought it, but it had some deeper pitting too; especially on the flange of port number three.  

 

 

I wound up using the 6"x48" belt sander to take the pits out and took measurements of the thickness of the flanges ahead of time, to try and keep the new surface parallel to the original.

 

 

Once off the sander, I checked for flat and noticed that the slight buckle in the belt caused a little rounding at each port, so I finished flattening with a large file.  Cast iron files almost like plaster... very easily.

 

 

The 49 state '76 car that I have has the typical 'boat anchor' manifold, with the extra emissions plumbing.  I have not had it off to see if they took the air injection tubes out, but I am guessing they did that when the rest of the emissions stuff was disabled.  I have read that the late manifolds may flow better than the tii manifolds, once the tubes are removed, as they increased the ID to accommodate them.  Another difference is in the dimple which is put on the tii manifold to give access to the mounting nuts.  These do not protrude into the port on the '76 unit, which allows for better flow.  

 

I have to admit, much of the appeal of the tii unit, for me, is the look; so I thought I would do what I could to make it pretty.  (here it is next to a spare anchor)

 

 

The casting mold parting lines detract from an otherwise smooth form, so I chose to grind them off.  I appreciate the smoother surface, but it was too smooth, compared to the rust pitted 'original' surface; so I dutifully added pits to the freshly ground surface, using a slag hammer and a small stone on a dremel tool.  (this was the most fun part of the process)

 

 

 

 

 

 

 

After a sand blasting and a soak in the electrolysis rust removal bucket, the 'finishing touch' was to give several coats of charcoal colored stove paint.  I would not have considered this color, but had a can on hand.  I think it will look nice and I will give the downpipe a coat when it comes out to receive the AFR bung.

 

 

Used parts are fine by me, but sometimes they take a little fiddling to be ready to install.  I doubt I will notice an improvement in performance, but the 'new' one will be much nicer to look at (what little shows of it under the heat shield).

 

The important part -- flat flanges with pits removed.

The fun part -- casting flanges removed, with pits added.

 

In the end, I know that most of this really does not matter... but it makes me happy, so I thought I would share.

 

 

[PaulTWinterton]

Nice work.

[jgerock]

Good stuff - I was just cleaning up my tii manifold today in preparation for a coating of Eastwood HT paint.

[thinksound_mike]

I bought some apple cider vinegar today to soak mine. I'm going to try to soak it to see how it cleans up before painting it. Yours came out great!

[JackF]

When I had the Turbo's motor re-built I had the manifold ceramic coated. It was a "new" turbo manifold. It took no time and the ceramic was shot. Back to the copter and he said his process could not stand up to turbo temps. I found a company called KECO Coatings out of Indianapolis. They do the Indy cars. Years later it still looks good.

Nice work on your manifold.

['76mintgrün'02]

thank you for the positive responses.

 

I have not tried vinegar on rust, but I just did a little searching and it sounds like an interesting approach.

 

Have you ever tried electrolysis?

The manifold inspired me to set up a bigger 'bucket'

 

All you need is--

Battery charger (not 'automatic'), bucket, water, baking soda, manifold, garden shovel... or something made of steel or cast iron.

 

Fill the bucket with water and a cup or two of baking soda.  

Put the shovel blade in the bucket with the positive lead off the charger clipped to it.

Put the manifold in the bucket with the negative lead clipped to it (don't let it touch the shovel).

Let it bubble for a day or two and then rinse it off with water and wire brush.

 

Here is the 'bucket' I am using.  I made this 'holder' to be able to dip eleven things at once.  It works well for the tang on files, smaller drill bits, smaller taps (shown).  I wonder how many pounds of rusty metal I have put through this bucket... it looks nastier than it is, in this photo.  Evaporation leaves a crusty residue, but it just washes back in.  The rust and stuff settles in the bottom of the bucket and I have been using the same solution for a long time.  I just top it off with more water, as need be.

 

 

 

One discovery I made with this system, is that over time the ammeter on the charger keeps getting lower, as in it is unable to deliver full power.  I tried switching the positive and negative leads and was amazed at what happened.  The ammeter pegged 'full throttle' and the griddle I am using instantly started dumping rust back into the solution.  It is like the griddle is a sponge/filter, trying to absorb electrically charged rust.  It got 'plugged up' and stopped working.  Reversing the leads cleaned it right out and then it was effective again.  

 

 

Another interesting thing I noticed was that the rust that came off the griddle stuck to the iron piece I hung in there, but the copper (which had come off the copper wire used to hang things) was attracted to the copper wire.  For some reason the metals were attracted to their 'like' metal.  I hung a piece of copper sheet metal in, while the leads were reversed and it turned blue.  

 

 

 

After the blue copper dried out, I scraped it off and saved it, to sprinkle on the next batch of pottery I glaze.  It will be an amusing association to see that on my mug as I drink my coffee.  It may be a while, but I will post pics of the results... because I know you care. 

 

On a more serious (on-topic?) note, it is good to know of a coating that lasts.  This was just shot with stove paint, to make it look better and maybe last a little longer.  I suspect it will burn off before too long.

 

I am debating using the sheet metal heat shield that came with the tii manifold, or the gasket with the heat shield built into it.  I have both options on hand.  It seems like the gasket style would provide a little better protection for the plug wires, especially out on number one.

 

 

 

 

 

 

 

[Chamonix72]

Since you are somewhat local, if you want a ceramic coating, try Performance Coatings in Auburn. I think they offer protection up to 2000 degrees, but double check their website or call them. I have their coatings on the headers of both BMWs.

['76mintgrün'02]

Thank you.  Funny parallel... ceramic coatings/glazes.

[thinksound_mike]

Mine is soaking right now. I'm going to leave it over night and then flip it over and do the other side. (The top is sticking out of the vinegar). JDeitch sent me a video about using it to clean gas tanks; so I figured I'd give it a shot on this thing. Most likely going to give it a once over with a wire wheel when I'm done and then spray it with several coats of high temp engine paint.

[thinksound_mike]

Here's my set-up. I filled an aluminum pan with Apple Cider Vinegar and put the manifold in to soak. In these photos it hasn't been in long. I turned it over this morning and plan to leave it in the until tomorrow or Wednesday. I brushed the top part after flipping it today and a good portion of rust and gunk just came right off.

 

After soaking like this, I plan on washing it with soap and water and then hitting it with either a wire wheel or a scotch brite pad. Curious to see how well it will clean up.

 

[Dev02]

Mintgrun and thinksound, both great ideas! Thank you. Mint, do you need to use special water or is tap fine?

[John_in_VA]

Apple cider vinegar has a table strength of 5%(50 grains) acidity.

Heinz has a cleaning vinegar with a special cleaning strength of 6% acidity.

Super or double strength vinegar contains 10% acetic acid.  

Nature's Wisdom has a 20% vinegar if you want to get serious!  It's used as an herbicide.

['76mintgrün'02]

Thank you for sharing the photos Mike.  

I like the 'edibility' of your solution.

Baking soda and vinegar are 'good for us'.

 

Can you let your vinegar solution settle out, pour it back in the jug and use it again and again?

 

I like using a wire brush, by hand.  If it takes more than that, it needs more time in the tank. 

Electric wheels are fast, but they burnish the surface and they are not an option on things like taps, drills or files because they make them dull.  Wire wheels are good for some things though.  

 

There is a product called Rust Off, which is a 5% Oxalic acid solution, which basically dissolves rust.  I like to use it where rust has stained paint.  I rubbed some on my stock steelies and it brightened them up quite a bit.  

 

 

 

 

At $15 per quart, it made me wonder whether I could mix my own, out of the crystals they sell in the paint department of the hardware stores.  In fact I have some, as well as the neutralizer. (O.A.N. crystals ).  I don't see why that neutralizer would not work for Acetic acid as well (Vinegar).  A baking soda solution will neutralize them too, I'd imagine.

 

 

 

Regarding tap water, it should be fine.  I am on a well, so no chlorine.  Chlorine is good for cleaning, right?  

 

The 'instructions' I have read online suggest using Arm and Hammer laundry detergent (soda ash), I believe.  It has sodium carbonate, as opposed to sodium bicarbonate, which is baking soda.

(Both made by Arm&Hammer, I figured same difference    ) 

 

Apparently you can bake baking soda to make sodium carbonate. 

 

Make Sodium Carbonate--

Sodium bicarbonate is CHNaO3 while sodium carbonate is Na2CO3. Simply heat baking soda or sodium bicarbonate in a 200°F oven for about an hour. Carbon dioxide and water will be given off. Dry sodium carbonate will remain.

 

I have been lazy and simply topping off the bucket of baking soda water, as it evaporates.  

 

I'll bet I would see a huge improvement with a clean solution of the proper powder.

 

The soda is the electrolyte, which improves the conductivity of the water.

The cleaning of the Anode (Griddle in my bucket) showed that the rust which is removed takes with it the dirt and oil.  

I believe this oil has to do with the inability to conduct electricity as things get dirty. 

 

It also reminds me that the cleanliness of the operation has to do with what I hang in it.

Mostly it is dry rust.  I have done crusty old cast iron pans (you can skim off the foam to  help keep the solution clean).

Most of what comes off settles to the bottom.  

 

It is so gratifying to hang a rusty piece of metal in there, flip the switch and watch the hydrogen bubbles rise to the surface.  

[thinksound_mike]

Those wheels cleaned up great! I have a set of basket weaves from a 320is on my car that I'd like to clean up. I was thinking of just painting them, but your last post has me thinking that it might not be necessary.

 

As for re-using the vinegar, um... it's looking more like poop-soup than vinegar. This is a photo from this morning. I think I'll dump it tomorrow. 

 

 

 

What's your take on using grill paint? I read in the archives here that some have used it and the results were good. I want to paint it when I'm done but I don't want to have to bake it. I'd like to paint my down pipe to match the manifold and that isn't going to fit in an oven at my house. Rustoleum has a brush on paint that's good for 1200 degrees. That should be sufficient right? 

['76mintgrün'02]

I masked off the mating surfaces and shot mine with paint I already had.  I think the temp rating is 1200-1300 degrees.  I figure it will be better than nothing, but probably will not stay looking nice forever.  The Eastwood product Jim mentions above is probably better paint.  If you really want it to last, ceramic coating is the way to go.

 

 

 

I wouldn't use that vinegar for salad dressing, that's for sure!  

 

Rust off is pretty cool for washing things like old tool boxes, or cleaning lightly rusted metal.  I think you need something stronger for really crusty stuff.  Fighting corrosion (oxidation) with acids is fine as long as you can stop the process.  

 

Ospho is another product I reach for.  As the name suggests, it contains Phosphoric acid. Oxalic acid dissolves rust, whereas Phosphoric acid converts rust into a paintable surface.  (as I understand it)

 

Por-15 makes a metal etching product for use prior to applying their paint.  They suggest rinsing after applying it.  

 

I sand blasted my front suspension bits and then treated the bare metal with Ospho.  It turns the metal a darker gray.  I tried rinsing some pieces and they immediately turned to rust, so I reapplied and let it dry before painting.  Once again, I used rattle can paint, not higher quality stuff.  If I had it all to do over, I would use better paint.  It is the same amount of work and just a little more expensive.

 

 

 

 

It looks like your vinegar has made some progress, based on the muddiness, but I would be setting up a battery charger bucket, if it was mine.  I just cannot say enough good things about that set up.  I am somebody who gets a kick out of old tools and such, so I use it a LOT.  People basically throw/give stuff away when it gets rusty, yet that rust is often just a fluffy coating that bubbles away with the help of a little electricity.  

 

Electrolysis is not just for hair removal!