MolaSoak--LC or AutoRX??

[San Diego Mac]

I have two Pratt and Whitney aircraft engines, one a 985 cu. in. Wasp, Jr. and the other a 1340 cu. in. Wasp, on planes that are not being operated for a long period of time (years, in the case of the 1340) because of restoration and maintenance. These are both large bore, 9 cylinder radial (round) engines mounted on the planes and are hangared in a dry, inland San Diego climate.

My normal preservation method has been to periodically (semi-annually) spray the inside of each cylinder, using an engine cleaning gun, with Marvel Mystery oil through one of the spark plug holes with the piston at BDC on both intake and exhaust strokes (to also coat each valve in the open position). Every few weeks I then pull the prop through about 15 or 20 blades (8-10 revolutions) to keep the oil distributed on all surfaces and also pump oil through the lubrication system.

I am now thinking of spraying the cylinders with Lube Control, after the MolaSoak method to clean any carbon and/or lead (yes, I have to use leaded fuel in these engines) out of the cylinders and ring packs. My question is this: considering both the desire to clean, and the need for long term lubrication, would LC or AutoRX be the best product to use in this application?

I have always wondered why MolaKule used LC in the MolaSoak instead of AutoRX, or even MM, because I understand LC to be primarily an anti-oxidant as opposed to ARX and MM, which I believe are primarily cleaners. (You reading this Mola?)

Has anybody ever made good side by side comparisons of these three different products as long term carbon/combustion deposit cleaners?

 

[mburnickas]

Just a side note since I work with P&W daily, why note ask P&W what is the best direction to take?

 

[jamesn]

have you considered CRC aerosol spray grease? it goes on like wd40 and then gels to vaseline consistency. my brother is a machinist and they use it by the case to prevent flash rust on items going into storage or waiting more than an hour for the next machining process. they take it off with either gasoline or paint thinner.

 

[MolaKule]

Hi Mac,

Interesting question.

To my knowledge, I don't think LC or ARX has made any recommendations regarding Aircraft engine cleaning.

I can only speak to LC (and I will speaking from my own opinion) and you will have to contact Auto-RX for their suggestions, since ARX has to be used while the engine is running or in operation.

My put (and LCD may have their own) is to spray the inside of the engine with LC and put some LC into the spark plug holes and let soak for a few days while occasionly turning prop. For those cylinders on the bottom side of the radial, your spraying will have to done in repeated steps, of course. Drain as much of the LC as possible from the crankcase and combustion chamber before replacing fresh oil, since we don't want to dilute the 50 or 60 weight engine oil.

And use a respirator or mask while spraying; as with any hydrocarbon so you don't inhale any of the mist.

 

[San Diego Mac]

Thanks for the suggestions. And for the advice to use a respirator. I never thought of that, and, as you can imagine, there is a lot of mist floating around from this procedure--which is why I use the engine cleaning gun with a lot of air pressure. Heavy mist comes out the carburetor and air intake and the exhaust stack. I figure it is coating everything with a nice layer of MM and stopping any rust or corrosion

It sounds like ARX needs heat from a running engine to clean, whereas the LC cleans just by cold soaking for awhile--is this correct?

Since these engines have dry sumps and huge oil tanks (11.5 GALLONS on the 1340), I always flush the tank and system with Marvel Mystery Oil until it runs out clean, and allow it to drain thoroughly before putting all the plugs back in and filling the tank.

 

[darkdan]

Yes, auto-rx cleaning comes from esters.

LC20s cleaning ability comes from it's solvency.

 

[San Diego Mac]

Thanks, Dan,
So esters need heat to become effective?

 

[MolaKule]

All cleaners can use help from heating, but for ARX, heat helps to mix the cleaning esters with the engine oil much better.

The LC seems to soften carbon at any temp.

 

[San Diego Mac]

Now I understand much better, thank you.

Do you think it is still a good idea to rinse it all down with MM after the MolaSoak has done its job? I thought this might help to carry away the softened carbon, etc., and drain it all out of the engine and cylinders before I put fresh engine oil in.

As an aside, I have been using the Phillips X-Country 25-60 multi-grade aviation oil, as recommended by P&W, in both of these engines. I used to use 60 weight and wait about 45 seconds after engine start for oil pressure at a 70°F ambient cold start, after pulling the prop through by hand about 10 revolutions (20 blades). With the 25-60, oil pressure is now indicated by the time the first cylinder fires. Oil temperature is also quite a bit lower.

 

[MolaKule]

I find that LC seems to do a great job of carrying away it's own carbon, but thinning the fluid coating as a final rinse should be the coup de'tat.

In fact, not so long ago our STLE section attended a seminar on Aircraft Oil from a Phillips rep.

 

[San Diego Mac]

Thanks again, Mola. YOU DA MAN!!

 

[San Diego Mac]

Frank,
Read the initial post for this thread. I am using this as a long-term COLD cleaning soak without operating the engines.
Bill

 

[NovaMan]

What aircraft are these engines in?
What octane does the wasp need?

Awesome stuff, man!

 

[XS650]

quote:

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Originally posted by NovaMan:
What aircraft are these engines in?
What octane does the wasp need?

Awesome stuff, man!

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http://www.pratt-whitney.com/about_history_classic_r1340.asp

 

[Bio-T]

quote:

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Has anybody ever made good side by side comparisons of these three different products as long term carbon/combustion deposit cleaners?

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Auto-Rx is not designed to be used in the combustion chamber as a cleaner, hot or cold. Crankcase, trans, diff, pwr. steering, yes.