Muriatic and Oxalic vs phosphoric for H/E

[Bob Bradley]

OK, I screwed up and bought the Muriatic and Oxalic acids instead of the phosphoric. I should learn not to depend on my memory when I'm shopping.

That said, can anyone give me the "recipe", i.e mixing ratio, for this approach, now that I have it all and don't feel like exchanging it?

[MikeP]

What you bought is what DD recommends for this purpose so nothing is wrong with your memory unless you intended to buy OSpho or one of the Phosphoric Acids. In that case...

Anyway...MY memory can't recall the proportions at the moment but tomorrow I will be on the boat and will look it up in the DD service manual. I've done it with the HEs and with the Intercoolers and I BELIEVE it's 1 part Muriatic to 3 parts water and then 5 or 6 OZ of powdered oxalic added to that. BUT I AM NOT SURE! I'll let you know tomorrow - someone else may have a manual handy and look it up before then.

[Bob Bradley]

Thanks, Mike. And yes, I had planned on buying the Ospho stuff, but when I got to the paint store, well...like old Dan Partridge (or was that Quail?) used to say, "A mind is a terrible thing when it's wasted."

[Genesis]

Muriatic and Oxalic works fine and is indeed what DD recommends BUT be VERY CAREFUL with it - that stuff is WICKED NASTY if it gets on things you don't want it on (like you!)

[Bob Bradley]

Do you happen to have the mixing proportions, Karl?

[Genesis]

Not offhand, no. I will see if I can find my DD manual this evening.

Remember, acid is ALWAYS poured into water, NOT THE OTHER WAY AROUND, and make darn sure you are wearing eye, hand and body protection against splashes and spatters. A goodly amount of baking soda to neutralize any spills is a good idea to.

[Bob Bradley]

Thanks. Good advice as usual.

BTW, this seems like a silly problem, but I cannot locate an oil cooler on my 6v92's ('79 435hp). Is it always in the raw water loop? All I have is the fuel cooler. I go from pump to ss pipe, to fuel cooler, to H/E, to ss pipe, to hose, to exhaust. Am I missing something obvious? (No apparent tranni cooler either)

[MikeP]

Here is the text and acid proportions from the DD V71 manual:


"Immerse the heat exchanger core in a scale solvent consisting of one-third muriatic acid and two-thirds water to which one-half pound of oxalic acid has been added to each two and one-half gallons of solution. Remove the core when foaming and bubbling stops. This usually takes from thirty to sixty seconds. Flush the core thoroughly with clean hot water under pressure."

[Nick]

The DD manual for the 71 series specifies 1/3 muriatic, 2/3 water with oxalic acid at 1/2 pound per 2-1/2 gallons of solution. CAUTION, It is a very corrosive solution and will dissolve the salt deposits quickly, like in minutes and less. Watch for bubbling, when bubbling stops the parts are clean. The fumes are also corrosive. Do not use it indoors. Protective gear is a must. Good chemical resistant long gloves, not the vinyl cr---p, goggles, lost of fresh water to flush the acid after you dip the parts.

Nick

[SKYCHENEY]

On my 6v92's (465hp), the tranny cooler is in the heat exchanger. There is no separate cooler. Just follow the lines from the trans and see if they go to the H/E.