Trying to do a leak down test on my cylinders.

This forum is dedicated to the Live Steam Hobbyist Community.

Moderators: Harold_V, WJH, cbrew

Emfinger
Posts: 202
Joined: Tue Oct 01, 2019 3:30 pm
Location: Yucca Valley, CA

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

Post by Emfinger » Sat May 01, 2021 10:02 am

Gra2472 wrote:
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.
Nothing is being forced. I just want to see the piston move via air pressure.

User avatar
Bill Shields
Posts: 6616
Joined: Fri Dec 21, 2007 4:57 am
Location: Somewhere in the World
Contact:

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

Post by Bill Shields » Sat May 01, 2021 12:03 pm

Can you rotate the wheels a full 360 degrees with no air pressure applied?...

Before you do any pressure tests you need a freely rolling drivetrain
Too many things going on to bother listing them.

Emfinger
Posts: 202
Joined: Tue Oct 01, 2019 3:30 pm
Location: Yucca Valley, CA

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

Post by Emfinger » Sat May 01, 2021 12:25 pm

Bill Shields wrote:
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.
OK top coming off today.

hoppercar
Posts: 383
Joined: Sun Jul 22, 2018 4:09 pm

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

Post by hoppercar » Sat May 01, 2021 1:18 pm

Your putting air into the steam chest....you can rock the drivers back and forth, and you say at no time, is the piston under pressure ??.....either your port spacing is wrong, and your not admitting air to the cylinders, or your passageways to the cylinders are blocked, not letting air into the cylinders

User avatar
Bill Shields
Posts: 6616
Joined: Fri Dec 21, 2007 4:57 am
Location: Somewhere in the World
Contact:

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

Post by Bill Shields » Sat May 01, 2021 2:00 pm

Occum's razor...the valve is stuck?
Too many things going on to bother listing them.

Emfinger
Posts: 202
Joined: Tue Oct 01, 2019 3:30 pm
Location: Yucca Valley, CA

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

Post by Emfinger » Sat May 01, 2021 3:54 pm

bore.jpg
OK guys I ran the engine just days before I tried to do a leak down test. I'm testing because I feel the torque is uneven and a little on the light side. I'm way past any zebras, and I do agree with Occum.
I have torn the whole damn thing apart. I know the left front never saw any pressure..PERIOD.

The bore could use a good hone job, just for S&G. This Stephenson Linkage system is OK, I guess, but the slide valve is a poor design. Is there anyway I can change to a more positive valve system? I don't understand how this damn things seals.

Tom

download/file.php?mode=view&id=83769
bore.jpg

hoppercar
Posts: 383
Joined: Sun Jul 22, 2018 4:09 pm

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

Post by hoppercar » Sat May 01, 2021 4:30 pm

The valve should not be a tight, or , snap fit on the valve stem....it needs to fit loosely with a few thou, clearance.......it has to be able to move on the valve stem, so steam pressure, keeps it pushed down on the valve seat...

User avatar
Bill Shields
Posts: 6616
Joined: Fri Dec 21, 2007 4:57 am
Location: Somewhere in the World
Contact:

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

Post by Bill Shields » Sat May 01, 2021 8:38 pm

So it ran but you feel uneven...weak on one side..and you are sure that the valve settings / travel are the same on both sides...?

This is not an easy thing to check on Stephenson gear..and you admit that your experience in these matters is limited...something as simple as a slipped eccentric is very difficult to check.

Careful with honing with a spring loaded automotive type of hone. Best to to it...if needed..with a lap or sunnen type of hone if a available.

Rings or seals on the pistons are what? Cannot tell from the photos.
Too many things going on to bother listing them.

User avatar
NP317
Posts: 3042
Joined: Tue Jun 24, 2014 2:57 pm
Location: Northern Oregon

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

Post by NP317 » Sat May 01, 2021 10:59 pm

If you can post pics of the slide valve surfaces and system that would help us understand the situation.

I do note that the ports from the valves open to the front and rear of the cylinders through 5 holes.
And it looks like the head seals may be o-rings (?) which will block the connection between those 5 ports and the cylinder ends.
Better pictures will reveal more.
If the cylinder head gasket seals those passages, then no steam/air will get to the pistons.

RussN

User avatar
David Powell
Posts: 450
Joined: Thu Mar 13, 2003 10:38 pm
Location: Pickering Ontario Canada.

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

Post by David Powell » Sun May 02, 2021 6:55 am

Looking at your photos it seems that the end cover you show completely blocks off the 5 drilled holes when bolted up. Perhaps the builder simply forgot to mill a way through for the steam. Try taking the end cover off the good cylinder and comparing the two. David Powell.

Gra2472
Posts: 87
Joined: Sat Jan 25, 2020 8:02 pm
Location: Monte Rio California

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

Post by Gra2472 » Sun May 02, 2021 7:15 am

Looking at the photos, it is difficult to make a specific diagnosis. I would like to see the steam side of the cylinder head, and the valve and valve face. But, I can agree with David and np317 that it appears that the steam ports are sealed from the cylinder when the cylinder head is on. I cannot see a passage from the 5 ports to the cylinder. It looks like this is a homegrown design that may not have been finished.
7.5" Allen Mogul
3 x 7.5" West Valley Baldwin Westinghouse Electrics
The Mrs. wants her railroad around the house!
G. Augustus
Monte Rio, Ca.

User avatar
makinsmoke
Posts: 1976
Joined: Thu Jul 10, 2003 12:56 pm
Location: Texas Hill Country

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

Post by makinsmoke » Sun May 02, 2021 7:28 am

It was running, guys.

Post Reply