Holy #$%^& - Need help, I completely messed up my 46mm PMO carbs!!!

[Wayne 962]

I'm so pissed. So, the 914-6 with the 2.8RSR had some gummed up carbs from just using this crappy CA fuel for 20+ years. So, I took them off and tried to clean out the "pertinent" parts - that didn't work. So, I decided I would "do the right thing" and clean them out completely. I disassembled them and took everything apart, and put them overnight in a bucket full of POR-15 Degreaser (which I have used very recently to clean out gas tanks with *very* good results).

I left the parts overnight and pulled them out today. They look pretty much completely ruined. They are completely coated with some type of calcium-like material. I thought maybe there was some contamination - no clue. The shiny aluminum chokes that fit in the throat of the carburetors are completely covered this thick, hard calcium-like coating. I tried scraping it off - some of it will come off with my fingernail, other sections will not move.

The active ingredient in the POR-15 degreaser is potassium hydroxide. A friend of mine found a chemistry lab experiment that talks of the formation of potassium salt X (whatever that is). I did taste the stuff - it's not "salt" as we know it (NaCL) - it's completely tasteless. Again, it appears identical to the "hard water deposits" that form on the inside of the heater coil of my whole-house humidifier.

I created a new batch of the stuff and I dumped one of the aluminum chokes into the new solution, and I'm letting it sit overnight to see what happens. This may or may not answer the "contaminant" question. If the coating / residue disappears, then there might have been something in the batch of parts that caused this to happen. Right now, the degreaser is in there and it appears to be "bubbling" away on the coating. We'll see.

I also ordered a bucket of the Berryman carb cleaner that I will try tomorrow. I will also perhaps take a look at CLR, which I've used to remove calcium build up on my humidifier with great success in the past. No clue if this is the same stuff - perhaps the water was so hard that this stuff made it de-calcify? Note - the mixing instructions for the POR-15 degreaser did not say anything about having to use distilled water.

Wow, I'm flabbergasted and really pissed. These are not inconsequential parts!

Any suggestions or enlightenment?

Thanks in advance,

Wayne

P.S. Photos of the mess. There are some before and after shots here:

[Wayne 962]

More photos of the carnage:

[ian c2]

Looks a little like galvanic reaction to me .
Used to see it quite a bit back in England on aluminium parts mixed with steel parts/hardware etc that had been in the elements for a while .

[Wayne 962]

Here's the ingredients. Again, used it previously no problems whatsoever!



-Wayne

[ian c2]

If you are going to experiment some more with solvents etc , you really should remove all the steel hardware and dissimilar metals .
I’d suggest a nylon bristle brush and demon water to clean what you have before you experiment any more

[Reiver]

Originally Posted by ian c2

Looks a little like galvanic reaction to me .
Used to see it quite a bit back in England on aluminium parts mixed with steel parts/hardware etc that had been in the elements for a while .

Yes, looks the same to me also and simply accelerated by the degreaser.

[ian c2]

Originally Posted by Wayne 962

Here's the ingredients. Again, used it previously no problems whatsoever!



-Wayne

Yes , but have you used it on single metal assemblies , or assemblies of dissimilar metals ?

[ian c2]

Call Jack sachette tommorow, and see if you can get advice off him or get him to put you in touch with Shawn geers .
They’re used to working with old Weber idas and are local so might be able to offer help . *
https://jayceevw.com/48-special-vw-drag-racecar/

*
They used to be , but it’s been a decade or so since I spoke

[Wayne 962]

Originally Posted by ian c2

Yes , but have you used it on single metal assemblies , or assemblies of dissimilar metals ?

Insides of gas tanks. The last time was a stainless steel gas tank.

On the other test that I'm doing over night - there's no steel - just the aluminum choke tube.

Seems like this is the absolute wrong product to use on aluminum, from what some people have already texted me. No where on the bottle is there any warnings about not using it with aluminum! I'm fairly pissed.

-Wayne

[ian c2]

It might be just fine on aluminium, the problem is when you add steel it kinda creates a battery and you get mess ….

You can even add sacrificial diodes to oxidize to protect the valuable steel , not really needed on a socal car , though every underground metal pipe in California should have protection

Looks more surface so hopefully it’s not all badly pitted ….

[Wayne 962]

Originally Posted by ian c2

Looks more surface so hopefully it’s not all badly pitted ….

It's not really pitted at all, but the stuff is all over - I'm not going to be able to get it out of the inside passages without dissolving it, I don't think...

-Wayne

[ian c2]

Tumbling or media blasting might be an option .
I don’t really know , I’m neither a chemist nor a materials finishing expert .
It does not look like it eaten into the aluminium , so I’d seek expert advice .
The guys I mentioned are local and are used to working on vintage Weber carbs so can maybe offer good advice or contacts .
good luck and good night

[Arlo911]

Hi Wayne, tumbling nor media blasting will get completely inside the passages. I'd dunk them in a quality (not a Chinese 150$ one, but a heated one with correct cleaning liquid) ultrasonic cleaner and see if that helps.
Or you need to find something that dissolves the oxidation without attacking the aluminium.

[Wayne 962]

I did some more poking and tried to get some off with a wire brush. I’m not sure but they look a little pitted in those spots. I have a bad feeling - like I could spend 100 hours cleaning these and then the car would still never run right.

Wayne

[mikedsilva]

Originally Posted by Wayne 962

I did some more poking and tried to get some off with a wire brush. I’m not sure but they look a little pitted in those spots. I have a bad feeling - like I could spend 100 hours cleaning these and then the car would still never run right.

Wayne

See if vapourblasting or wetblasting can remove it. I think it should. Hopefully the buildup is on top of the base metal and will be removed, leaving the base undamaged.

[OSC911]

I would try some household vinegar on a small section to see if it loosens it up a bit. Pretty safe and does a nice job on cleaning calcification off aluminium parts and also steel bolts. Worth a try before you get too serious with blasting etc. if it looks like it will work, try soaking them in it for a few hours.

[Porchdog]

Potassium Hydroxide is Lye. That will absolutely attack aluminum. It's a good component for degreasing though.

I don't know anything about Webers - are they anodized?

It might be worth reaching out to Shaun @tru6.

[wjdunham]

Edit - as pointed out below, my chemistry is wrong - the ingredient in the POR product is KOH (Potassium Hydroxide), not NaOH (Sodium Hydroxide). I'll leave the post as is below anyone want's to refresh their high-school chemistry.

Did a little google searching, unfortunately this may not be good :-( Potassium Hydroxide chemical formula in the reaction below is the NaOH)
https://www.nmfrc.org/pdf/sf2002/sf02a01.pdf

"When placed in a caustic soda (NaOH) solution, aluminum dissolves according to this chemical reaction: 2Al + 2NaOH + 2H2O ⇒ 2NaAlO 2 + 3H2"

Bill

[Porchdog]

Potassium Hydroxide is KOH. NaOH is sodium hydroxide. The effect on aluminum should be similar.

I expect what Wayne is seeing is tightly adhered aluminum oxide - if it was steel we would call it rust. Guaranteed there has been some loss of the base metal. The big questions are how to clean it up without doing further damage, how to determine if the parts are still usable, and, if so, how to get them looking decent and protected going forward.

[wjdunham]

Originally Posted by Porchdog

Potassium Hydroxide is KOH. NaOH is sodium hydroxide. The effect on aluminum should be similar.

I expect what Wayne is seeing is tightly adhered aluminum oxide - if it was steel we would call it rust. Guaranteed there has been some loss of the base metal. The big questions are how to clean it up without doing further damage, how to determine if the parts are still usable, and, if so, how to get them looking decent and protected going forward.

Oops, that's what happens when I do chemistry before having coffee in the morning.