Muriatic acid / Oxalic acid / Water mixture effectiveness?

[brico]

I have not done it and am asking those that have, how effective is it?

I have my expansion tank removed and heat exchanger element taken out. I've used some Zep "Bath tub and Tile Cleaner" (Home Depot Canada) and managed to remove some of the growth on it, but not completely. Would the soaking it in "Muriatic acid / Oxalic acid / Water mixture " as per Detroit Diesel instructions really clean it to shining metal? Or would the Phosphoric acid mixture do better?

I might as well try and clean it as best as I can now that I have it out.

I am attaching the photographs of the heat exchanger core before and after using Zep "Bath tub and Tile Cleaner" (Home Depot Canada) 166681666916670

can it get cleaner than what it is now?

[brico]

here is the second "before" cleaning with Zep "Bath tub and Tile Cleaner" (Home Depot Canada) forcomparison.

[MikeP]

The DD recommended mixture will clean it to new/shiny in 5-6 minutes. It is far stronger than the other methods--with the appropriate cautions necessary re mixing acid/water, disposal, etc

[bobk]

If you are using muriatic (hydrochloric) acid, you should do it off the boat to prevent corrosion by the volatile acid fumes. If on the boat, phosphoric is better because it is not volatile and will work as well but might require a few extra minutes.

Bobk

[MikeP]

I agree - and it is much easier/safer to do off the boat as opposed to futzing around in the ER with a bucket of acid.

[brico]

The DD recommended mixture will clean it to new/shiny in 5-6 minutes. It is far stronger than the other methods--with the appropriate cautions necessary re mixing acid/water, disposal, etc

Thanks Mike,

I do have the Muriatic acid but not the Oxalic acid that DD manual calls for. I am unable to find that stuff. Would it work with two parts water and one part Muriatic acid only?

In addition manual says to pull it out when the foaming/bubbling stops, usually in 30-60 seconds, while you are saying 5-6 minutes?? I am OK to work with chemicals I am however afraid what effect will the Muriatic acid have on the heat exchanger core / element? It looks like it is made of some sort of stainless steel so it should withstand the acid a bit better than the bronze/copper tube type heat exchanger.

My main goal is to get rid of the thin coat of scale that has coated the raw water side. The way it looks now is way better than when I opened it up, but since i have it apart while awaiting gaskets and 'O' rings from J&T i want to try and clean it as best as I can.

So, do i just go by foaming/bubbling indication and when it stops I pull it out and flush with a lot of fresh water.You seem to have had it done yourself hence the questioning ;-)

[bigbill]

brico, the oxalic acid is available at most hardware stores and home depot/ lowes it is the same as wood deck cleaner

[Boatsb]

brico, the oxalic acid is available at most hardware stores and home depot/ lowes it is the same as wood deck cleaner

Or wood Bleach usury in a powdered form.

[MikeP]

Time necessary will depend on the concentration of the acid and how bad the HE core is plugged - Just do it until the boiling stops. The first time I did it - with cores that looked like yours, it took 5-6 minutes until the boiling stopped (I'm estimating - I didn't actually time it). Subsequent cleanings didn't take more than a minute or two at most. As noted, Oxalic is available at most hardware store.

[oldboat]

the oxalic acid is available on amazon. they sell it in different quantities. i can't find it at hardware stores these days. i don't know if it can be shipped to canada.

http://www.amazon.com/gp/product/B007HUR0EK/ref=oh_aui_detailpage_o07_s00?ie=UTF8&psc=1

[brico]

Thanks guys, i'll continue search for the oxalic acid and make the bath for the core to clean it. I'll try and make few photographs for reference. (if i do not forget)

[Boatsb]

Thanks guys, i'll continue search for the oxalic acid and make the bath for the core to clean it. I'll try and make few photographs for reference. (if i do not forget)

Or take it to a radiator shop.

[brico]

So I did find the Thompson's wood cleaner and brightener which is based on Oxalic acid and comes in a gallon container. In Canada it is hard, if not impossible, for ordinary public to buy dry chemicals for mixing. As per MSDS it is 6% by weight so i guess it comes close to that Detroit Diesel's recipe that calls for 0.5 lb per 2.5 gallon of water/muriatic acid solution.

Lets see how it turns out when i soak it in.

[Canuck Dennis]

I believe Lordco parts sells similar product to ospho, is put out by the auto body paint people PPG ?for cleaning metal prior to painting etc.

[dsharp]

What does the oxalic acid do? I always soaked the coolers in diluted muratic acid for 5-10 minutes then rinsed with water.

[Boatsb]

What does the oxalic acid do? I always soaked the coolers in diluted muratic acid for 5-10 minutes then rinsed with water.

Different acids will dissolve different things. Ospho is phosphoric acid. Wood Bleach is usually oxalic acid. Muriatic is hydrochloric. Then there's nitric, hydronic .....

[Canuck Dennis]

Brico, another solution you might try is to contact a medical gas supplier like BOC gases, they should carry pickling solution, pre mixed ready to use. They use to pickle medical copper pipe etc so it has to work really well.

[brico]

Thanks everyone for suggestions and tips especially to Mike who shared his first hand experience soaking the H/E element in DD recommended solution.

I did it yesterday evening and left it in about 4-5 minutes by which time bubbling stopped completely. Rinsed it well over 30 minutes with copious amounts of water (could have just left in the rain, it was pouring down here in Vancouver). The results are astonishing. Not a trace of scale could be seen and the element is bright and shiny viewed from the raw water side. The coolant side is much more dense and could not be viewed through it but am sure it is as clean.

Definitely worthwhile experience. Seeing how easily the scale if coming off, if there are bigger pieces that fall off and do not get dissolved/reduced in size they may clog the holes on the shower head and cause it to block, so not sure how advisable is it to do this in situ. My exhaust elbow is retrofitted SS piece and I have no idea how many holes are on it and how big are they to accommodate the crap that may come out of the H/E element and piping.