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My 302 AC started squeaking and I could see that it slowed down in sync with the squeak.
It seems to be the piston that pumps the air to the smoke unit and makes the chug sound. If I move the piston by hand it seems to intermittently rub or bind in the cylinder. I believe I read somewhere not to lubricate the piston and cylinder, but nothing about how to clean it. As usual any help here guys will be greatly appreciated.
 

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Not sure if cleaning will help but you can try using contact cleaner inside and wiping with paper towels and Q-tips. Once you've cleaned it, check for smooth movement by hand at first before reassembling. I am sure I read somewhere that a very light coat of vaseline was alright to use, but don't do it just because I said so here. I could be wrong with that assumption. I'd also check for a bent piston rod/lever, piston connection pin, loose or binding connection on the drive gear and alignment within the chassis.

If the issue continues and it is not the piston, you might want to check your drive wheel linkages. When the wheels are out of quarter, they tend to bind. However, you would have had to remove drive wheels/linkage and reinstall them out of quarter for this to happen unless one (or more) is (are) loose or stripped on the axle.
 

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Yup, the cylinder was streaked with black stuff...looked like the same stuff that the piston is made of..whatever that is. Cleaned it out with goo-gone then electrical cleaner like you said. Tested and works great and no squeaking. I held off on the lube for now. Thanks for the response.

Oldfeller
 

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I'm not sure either...carbon maybe?? If you choose to, replacement ones should be fairly cheap -- Port Lines has them for $7.50 each. But nearly all steamer engines have the same part. So any junker will have one that should suffice.
 

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What I do to clean the inside of the smoke unit is this: Dremel makes a small red scotch-brite pad on a 1/8 shank shaft. It fits into the piston chamber like it was made for it! A few revolutions and the piston bore is spotless, and it doesn't affect the diameter of the bore. Use a thin coating of vaseline inside the piston bore, not as a lubricant, but as a sealing agent. Works every time.:thumbsup:
 
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