Cleaned the carb and something strange is still happening!

archangel2003October 25, 2013

Well, I just got this small 1.75 kw generator from 1979 from my neighbour.
It had decades old gas in it and it gummed up the whole fuel system.

The varnish seemed to prevent it all from rusting out as bad as it looked before cleaning.

Other than that everything inside and out looks great for a unit that old.

The stench was unreal and solvent, carb cleaner, or break cleaner would not pull the stench off that thing!

I saw something on line (YEAH, I KNOW) about white vinegar taking the "Old Gas into Varnish and sludge" smell out as well as cleaning the aluminum.

Well, I dump 1/2 gallon of vinegar into an old plastic milk jug with the top cut open, drop all the carb parts in to it and head off to bed.

8 hours later it was bubbling, not like boiling water, but actively bubbling and fizzy.
I pour it out and run water over it, scrubbing with dish soap and warm water.

There was this gray powdery residue caked on it and it is a pain to get off so I scrub it first with comet cleanser, then used baking soda to scrub it with a tooth brush.

Some places I need to use a razor blade and wire brush to get it off.
It also smudges off on my hands as I clean and scrub it, so have to re-scrub to get my hands clean.

Well, here is the issue.
It was shiny aluminum on all the spots I worked on earlier today but tonight when I go back to keep working on it, that gray powdery coating is coming back and it is once again that dull gray color all over.

Is the full strength vinegar still reacting with the aluminum even after washing it with water, soap, comet, and then baking soda?
If so, how do I stop it before it melts away?

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Carbs are made of zinc. They oxidize as a natural result of being exposed to air. Since vinegar is an acid, it was probably eating away at the zinc which should have now stopped.

Don't worry about the oxidation.

    Bookmark   October 25, 2013 at 6:05AM
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Zinc, not aluminum?
Ok, I was not expecting Platinum, but Zinc?
Isn't that even more reactive than aluminum?

It does seem to have slowed and stopped.

    Bookmark   October 25, 2013 at 11:19AM
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Well, I picked up something called "Metal Rescue" last week for cleaning the rust off of the steel parts.
I looked it up again and in the FAQ it says it will also remove Zinc Oxide.
I'll give it a try and see how it works.

Any suggestions on protecting the cleaned part, or preventing further Zinc oxide formation/corrosion on the inside?

I purchased some 500 degree high temp paint for the engine block, head and tin with the intent to paint the carb as well.
I assume that is good enough to protect the outside of a Zinc carb.

    Bookmark   October 25, 2013 at 12:57PM
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If you can find high temp clear coat, use that. I wouldn't do anything at all. It's a waste. The oxide is what protects it.

    Bookmark   October 25, 2013 at 5:00PM
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Remember when Tecumseh used to instruct not to dip for more than 15 minutes as to not remove their coating ;-)

    Bookmark   October 25, 2013 at 6:29PM
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everything you wanted to know about zinc, but was afraid to ask!

Oxidation occurs when metal is exposed to air or water, and electrons from the metal transfer to the oxygen.

Read more:

Die-casting alloys typically contain 96% zinc and 4% aluminum. The die-casting process uses a two-piece steel die and a casting press to hold the die halves together during injection of the molten metal. Inside the steel die is a cavity that has the negative image of the part to be cast. The molten metal is injected into the cavity under pressure, accurately filling the entire void. The metal cools, and the press opens the die halves, revealing the formed part. The zinc cast parts are very close to the desired shape, requiring little machining before they are placed into an assembly. Typical applications include copier, aircraft, and medical instrument parts. Automobile makers use zinc die castings for emblems, moldings, door handles, and brackets. Zinc die castings are easily chrome plated for durability and appearance.

Read more:

One unique application of zinc takes particular advantage of its ability to transfer its corrosion resistance properties by electrical contact. This application is called a "sacrificial anode." The anodes, made of almost

pure zinc, are bolted to aluminum marine engines. During operation in water, especially salt water, the oxidation forms a weak electrical current, which may corrode the hull and engine parts. Since zinc is easily oxidized in the presence of this electrical current, it "sacrifices" itself by corroding quickly, consuming all of the electrical imbalance in the ship. The remaining aluminum hull and engine are not corroded as a result. As it is consumed, the anode must be replaced to assure continued protection.

Read more:

    Bookmark   October 25, 2013 at 8:39PM
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As best as I can find, I should clean the excess Zinc oxide with the Metal Rescue, then, strangely enough, coat it with Zinc chromate primer, then paint it with the "high temp" (just because it will match the rest of the generator) Detroit Diesel Alpine Green.
I could have just pulled the fuel system and cleaned it.
As it was so neglected, I decided to tear everything down for inspection and fresh paint.
Nothing else was wrong with it except for a bunch of carbon built up on the piston from the foam air filter that was sucked into the engine bit by bit as it deteriorated.
I punched a hole in the metal end of a Tecumseh TAF-115 cone shaped 8hp pleated paper filter to sit on the carb gasket rather than the foam one.
I used a 4" Stainless Steel dish from a magnetic parts holder (Harbor Freight item #90566, magnet removed), as the lid.
It kind of has a period look to it.

So, is the rest of the cast engine and generator housing most likely also made of Zinc?
It is a 1979 Dayton 1.7 kw generator with a Briggs & Stratton 4 hp engine.

In the picture the head and exhaust was pulled before I remembered to start taking pictures.

This post was edited by archangel2003 on Sat, Oct 26, 13 at 1:04

    Bookmark   October 26, 2013 at 12:55AM
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Most likely the rest of your assembly is made up of aluminum and steel.

    Bookmark   October 26, 2013 at 6:47AM
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Here is the $7.00 filter I made.
I guess we can only post only one picture at a time.

    Bookmark   October 26, 2013 at 7:59PM
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Pretty clever! You can post multiple pictures if you upload them to Photobucket, for example, and use the img. links in your paragraphs.

    Bookmark   October 26, 2013 at 9:39PM
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