Trying to do a leak down test on my cylinders.

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Emfinger
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Location: Yucca Valley, CA

Trying to do a leak down test on my cylinders.

Post by Emfinger » Fri Apr 30, 2021 2:08 pm

Hello and thank you all for your help.
Thanks to you I now have a well controlled oil burner and have good control over the steam it generates.

But I can't seem to do a leak down test on the cylinders. If you look at the attachments you will see the way I'm trying to do the test.
When I put 100PSI of air into the valve chest nothing happens. No matter where I put the valve rod I can't get the piston to move. I have the wheels chocked (well blocked from turning) with the air on I can rock the drivers back and forth. I have added a lot of oil to the steam chest without change...What am I doing wrong?
Thank you
Tom

Emfinger
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Re: Trying to do a leak down test on my cylinders.

Post by Emfinger » Fri Apr 30, 2021 2:23 pm

cylinder.jpg
Exhaust.jpg
Leak tester.jpg

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Bill Shields
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Re: Trying to do a leak down test on my cylinders.

Post by Bill Shields » Fri Apr 30, 2021 4:51 pm

you would not expect the piston to move if the wheels are locked...

however...if you are moving the valve rod (by hand) and getting no reaction whatsoever from the piston, then I would suspect that there is a problem with the valve...maybe totally disconnected from the valve rod...

or stuck up and away from the valve surface (for some reason)....

however if the valve is away from the surface then you would be getting all your air straight out the exhaust pipe...

I would start by taking the cover off the valve chest for a look-see

note of caution:

If things don't work as expected at 10 psi..putting 100 psi on it is not going to tell you much more. Should things get away from you at that pressure..things are going to start happening in a big hurry.
Too many things going on to bother listing them.

hoppercar
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Re: Trying to do a leak down test on my cylinders.

Post by hoppercar » Fri Apr 30, 2021 5:03 pm

Are you getting a big, constant "whoooosh". Of air up the exhaust nozzle ?...if so, all your air being fed into the steam chest is leaking under the slide valve and escaping up the blast pipe ?....if not?....and your able to move your driver's like you say, then with the main rod connected, I am assuming the piston is moving in the cylinder......,...is there any chance your steam ports from the slide valve face to the cylinders are plugged with anything ?...food for thought, I had a set of cylinders once, that had the passage ways cored in....and I had the same thing happen, that sounds like what your having here......I found some of the passage ways still plugged with core sand ?....

hoppercar
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Re: Trying to do a leak down test on my cylinders.

Post by hoppercar » Fri Apr 30, 2021 5:06 pm

Rereading your post, am I understanding correctly?...you have the drivers chocked where they can't move ?....or are u able to rotate them ?

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NP317
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Re: Trying to do a leak down test on my cylinders.

Post by NP317 » Fri Apr 30, 2021 7:38 pm

I would remove the valve chest covers for internal inspection on ANY locomotive I acquired used.
Just standard operating procedure, based on my own challenging experiences.
Until you are sure the valves and linkages are OK, don't even think about applying air or steam. Just my approach.

Yes, bad things can happen all too quickly:
In 1981 was involved in a challenging situation when a 22" diameter piston under steam got away and busted the cast cylinder head to smithereens!
We ended up steaming the locomotive 10 miles back to the shop under just one piston. It was a 90-ton Heisler, so we were able to block off the steam pipe to the inop cylinder.
Yes, several times at road crossing stops we got stuck on TDC and has to jack the locomotive off that to get moving again.
Never again...

Insect inside those valve chests first.
RussN

Emfinger
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Re: Trying to do a leak down test on my cylinders.

Post by Emfinger » Fri Apr 30, 2021 7:57 pm

OK, the drivers can rotate 1" back and forth....with 100 PSI into the valve chest and anywhere I put the valve rod no pressure to the cylinder. Nothing is plugged. How do I make the slide seal the ports?

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Bill Shields
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Re: Trying to do a leak down test on my cylinders.

Post by Bill Shields » Fri Apr 30, 2021 8:06 pm

Take the valve chest apart and see what is going on.
Too many things going on to bother listing them.

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makinsmoke
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Re: Trying to do a leak down test on my cylinders.

Post by makinsmoke » Sat May 01, 2021 6:39 am

Maybe I’m off my nut, but are you putting air pressure onto the top of the slide valve and not the input port?

Gra2472
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Re: Trying to do a leak down test on my cylinders.

Post by Gra2472 » Sat May 01, 2021 7:22 am

Sounds like you need to disassemble it completely and have a good look around. If it won't move under 100 psi then you're not doing yourself any favors trying to force it.
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Bill Shields
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Re: Trying to do a leak down test on my cylinders.

Post by Bill Shields » Sat May 01, 2021 8:47 am

Top of a slide valve chest is the input area...
Too many things going on to bother listing them.

Emfinger
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Re: Trying to do a leak down test on my cylinders.

Post by Emfinger » Sat May 01, 2021 10:01 am

hoppercar wrote:
Fri Apr 30, 2021 5:06 pm
Rereading your post, am I understanding correctly?...you have the drivers chocked where they can't move ?....or are u able to rotate them ?
I can rock the wheel 1" back and fourth otherwise I wouldn't know it the piston was under pressure.

At no time has the piston been under pressure ????

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