The Unofficial Mamod and Other Steam Forum

[46u]

Will a late model Jensen #70 cylinder and piston assembly fit a Jensen #5?
Thanks
Jeff
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Jeff Member of the Georgia Steamers Association.  
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[IndianaRog]

Wish I could help you Jeff, but I don't own a 70 to check !
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Rog

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[46u]

[Stitch1615]

Easiest way to find out is call Dorita at Jensen.
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Stitch

Hot Tip: Never kick a fresh turd on a hot day.

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[46u]

[Stitch1615]

[46u]

The reason I think they crack or blow the solider out between the steam chest and cylinder on fix engines is people either over oil or get a lot of water in the engine then when they try to start it they are hydro locking and that pressure has to go some where. The reason I say that is I use to over oil my engines and ended up blowing the solider between the steam chest and the cylinder. Now I limit the oil. You could hear it knocking real bad till it cleared out.

I all so took Gil's advice and when it just starts making steam I open the steam valve and turn the flywheel slowly preheating the cylinder and piston.

All so if they are stored in a garage or unheated area where it gets below 0 for several days and have some water left in them could cause one to crack.

All so one with a reversing lever it is not good to run them fast and revers them as I bent a rod on my original #75 I received in 1964 from doing this but lucky I was able to fix it. Now if I am running fast and revers it I put it to the neural position for a split second so it slows down or throttle down.  

The number #5 with the crack cylinder I received it that way. Out of 30 or so Jensen s I have own only own 23 right now this is the first one I have ever received with a cracked cylinder.
_________________
Jeff Member of the Georgia Steamers Association.  
My YouTube channel
http://www.youtube.com/user/Jeff46u/videos

[Stoker]

You've been lucky then Jeff, as I have fewer Jensens total, but perhaps half a dozen cracked cylinders.

I'm of the opinion that the cylinder walls are a bit brittle (un-anuealed) and that the stamped brass end plates that are press fit (basically swaged) into place oft times have burrs and irregularities around their circumference that stressed the cylinder walls locally, leaving them vulnerable to splitting come any future additional stress.

... or so I think!
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[Swift Fox]

I've done the same when running my Jensen #65 & #75 with regards to cracking open the steam valve slightly to preheat the cylinder, once it is hot to the touch i open it up a bit more and spin the flywheel and it starts with no problems. That practice is used all the time on large steam engines but they often have drain cocks too.
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[46u]

Yes that is why when you see a 1 to 1 steam locomotive take off you see steam and water coming out the cylinders from the drain cocks as if they did not they would hydro lock and crack the cylinders. Same thing when starting a 1 to 1 stationary steam engine. Many of the model steam engines have them as well. Preheating helps as well as it help clear the cylinder.
_________________
Jeff Member of the Georgia Steamers Association.  
My YouTube channel
http://www.youtube.com/user/Jeff46u/videos

[scorpion2nz]

in my opinion 2 reasons for cracking cylinders
1, possibly cold start hydro-locking
2  more likely  stress caused by end caps to tight a fit and pressed in
only 2 ways to fix properly .change cylinder or clean and solder
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Cheers
Dennis