Cast iron cylinder jug cleaning tips?

[billw]

Most of my engines are from the late 40s through the 60s and thus have aluminum blocks. In the past, I have had a P30 and a couple of lightfours, among others. Most had the jugs either cracked wide open or totally plugged with scale, all of which were discouraging to me. Today, I happened pleasantly onto what will be my second, Montgomery Ward, chipmunk cheek 1.0 hp, complete with side covers and a whole skeg!! . It has a cast iron jug. Much time has passed, since I messed with one of those. Any ideas on cleaning out the cooling passages? (I don’t even know whether they are plugged up yet, or not….)

Long live American manufacturing!

• This topic was modified 3 years, 3 months ago by billw.

[Mumbles]

Soaking in muriatic acid works good on cast iron. It’s powerful and nasty stuff so be careful if you use it.

Some single cylinder motors had a water tube cast into them and if it’s aluminum, the acid will eat it away. Any iron or steel parts are OK with the acid.

[The Boat House]

• This reply was modified 3 years, 2 months ago by The Boat House.

[billw]

Very nice line-up, Tubs! The Sea King runs great, just like my first one does. They seem to be good little motors. My first one didn’t need any serious cleaning of the jug, either. I wonder if the material used on those little ones is more corrosion resistant than some of the bigger, older engines? Also, thanks for the muriatic acid idea, Mumbles. I have used that stuff before on concrete and on a snow blower crank shaft, to remove bits of a thrown connecting rod. I know that you cannot be too careful with it! I am surprised the general public can still buy it!

Long live American manufacturing!

[The Boat House]

• This reply was modified 3 years, 3 months ago by The Boat House.

[need2fish]

I’ve had luck disolving scale with CLR — it’s essentially Lactid Acid and is good at dissolving salts – rust, aluminum oxide, lime scale for example.

Have you opened the crankcase and separated the jug ? If so, soak the jug in full-strength CLR for a couple of hours at a time, pull it out and dunk it in fresh water, repeat until you don’t have junk in the water.

Caveats: The CLR is likely to have a galvanic reaction with the cast iron, and you’ll end up with black iron oxide on your jug. No point in removing it from the water passages — it actually creates a layer of dead zone that will resist rusting. However, it can be hostile to paint — dulling the top layer.

[billw]

I have not taken it apart, yet. Could I remove the black iron oxide from the outside with bead blasting or is that a no-no? At work, we have Ridlime, which I think is similar to CLR……

Long live American manufacturing!

• This reply was modified 3 years, 3 months ago by billw.
• This reply was modified 3 years, 3 months ago by billw.

[Mumbles]

Glass bead is an excellent media to use on cast iron or aluminum. Degreasing the parts first will help with the cleanup. If working with cast iron or steel, I have one bucket of soapy water to clean the grit off in and another bucket of really hot water ready to rinse the parts with. I make sure my air compressor is fully charged and ready as the parts will start developing surface rust as soon as they come out of the rinse water. A light blow dry and a quick spray with WD 40 will prevent this from happening. Before painting, the parts can be cleaned with brake cleaner or lacquer thinner to remove any trace of the WD or oil on the surface.

[Author]

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