Trying to do a leak down test on my cylinders.
Re: Trying to do a leak down test on my cylinders.
There does appear to be a pocket machined in the cylinder cover.
Re: Trying to do a leak down test on my cylinders.
You can see a machined pocket in the cylinder head that provides steam path from the five ports to the cylinder.
Really hard to make out the ring set up. It looks like two on the piston with one missing.... iron rings?
Can have a pretty poor bore seal and still run, maybe not very powerful.
Pretty sure you had a valve timing/sealing integrity to begin with. With it all apart now you probably introduced new problems. Have you only dismantled one side?
Lets see pics of the valve faces. That is all you should have taken apart...
Really hard to make out the ring set up. It looks like two on the piston with one missing.... iron rings?
Can have a pretty poor bore seal and still run, maybe not very powerful.
Pretty sure you had a valve timing/sealing integrity to begin with. With it all apart now you probably introduced new problems. Have you only dismantled one side?
Lets see pics of the valve faces. That is all you should have taken apart...
3/4" Juliet II 0-4-0
3/4" Purinton Mogul "Pogo"
3/4" Hall Class 10 wheeler
3/4" Evans Caribou/Buffalo 2-8-0
3/4" Sweet Violet 0-4-0
3/4" Hunslet 4-6-0
3/4" Kozo A3. Delayed construction project
1 1/2" A5 Camelback 0-4-0
3/4" Purinton Mogul "Pogo"
3/4" Hall Class 10 wheeler
3/4" Evans Caribou/Buffalo 2-8-0
3/4" Sweet Violet 0-4-0
3/4" Hunslet 4-6-0
3/4" Kozo A3. Delayed construction project
1 1/2" A5 Camelback 0-4-0
Re: Trying to do a leak down test on my cylinders.
In your first photo it looks like you have air on the right side only and the piston is pretty close to the end of travel. One side would be exhausted and depending on the lead in the valve gear the other port has not opened yet.
It was running before though uneven which sounds like a valve timing problem. If it were due to excessive wear (blow by) you would have had air blowing out the exhaust port during your test and you did not comment on that.
Maybe at this point decide if any wear surfaces need attention. I would put it back together and leave the valve chest covers off. Roll it our block it up and turn the drivers slowly and watch the valves. You will be able to see the valve port open and have a good idea when steam would be admitted. I have a Clishay that looking at it I would have sworn was in time, but power was low and at low speed the motion was uneven. With the cylinder cocks open and a the tiniest bit of steam I could see when the port opened to admit steam. I had an eccentric a bit off.
It was running before though uneven which sounds like a valve timing problem. If it were due to excessive wear (blow by) you would have had air blowing out the exhaust port during your test and you did not comment on that.
Maybe at this point decide if any wear surfaces need attention. I would put it back together and leave the valve chest covers off. Roll it our block it up and turn the drivers slowly and watch the valves. You will be able to see the valve port open and have a good idea when steam would be admitted. I have a Clishay that looking at it I would have sworn was in time, but power was low and at low speed the motion was uneven. With the cylinder cocks open and a the tiniest bit of steam I could see when the port opened to admit steam. I had an eccentric a bit off.
Re: Trying to do a leak down test on my cylinders.
I was never able to pressurize any cylinder. I'll take more pictures after I tear the other side apart.pat1027 wrote: ↑Sun May 02, 2021 8:46 am In your first photo it looks like you have air on the right side only and the piston is pretty close to the end of travel. One side would be exhausted and depending on the lead in the valve gear the other port has not opened yet.
It was running before though uneven which sounds like a valve timing problem. If it were due to excessive wear (blow by) you would have had air blowing out the exhaust port during your test and you did not comment on that.
Maybe at this point decide if any wear surfaces need attention. I would put it back together and leave the valve chest covers off. Roll it our block it up and turn the drivers slowly and watch the valves. You will be able to see the valve port open and have a good idea when steam would be admitted. I have a Clishay that looking at it I would have sworn was in time, but power was low and at low speed the motion was uneven. With the cylinder cocks open and a the tiniest bit of steam I could see when the port opened to admit steam. I had an eccentric a bit off.
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Re: Trying to do a leak down test on my cylinders.
Is there any possibility that somehow the valve chest fitting is not opening the check valve in the air hose female end fitting? That would explain runs on steam but does not react to air...
- Bill Shields
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Re: Trying to do a leak down test on my cylinders.
Thick gaskets or undercut in the end caps?
Too many things going on to bother listing them.
Re: Trying to do a leak down test on my cylinders.
This may be a problem.
Re: Trying to do a leak down test on my cylinders.
Yeah, the valve faces look pretty rough.
Out of curiosity, how were the d-valves oriented in the valve chest before you removed them for these photos? Were they inline with the cylinder as shown or 90 degrees across the cylinder?
Out of curiosity, how were the d-valves oriented in the valve chest before you removed them for these photos? Were they inline with the cylinder as shown or 90 degrees across the cylinder?
7.5" Allen Mogul
3 x 7.5" West Valley Baldwin Westinghouse Electrics
The railroad is almost done.
G. Augustus
Monte Rio, Ca.
3 x 7.5" West Valley Baldwin Westinghouse Electrics
The railroad is almost done.
G. Augustus
Monte Rio, Ca.
Re: Trying to do a leak down test on my cylinders.
Hi,
A couple of things.
First, now that you have the valve cover off, check to see that air can flow through the connection into the valve chest. You need to do your checking and testing logically and step by step and also understand what you are doing in each step and why.
Step #1 is to see that air can get into the steam chest.
Step #2, With the valve cover off, When you rotate the wheels by hand, does the valve move the way it should, do the cylinder ports get uncovered at the right time and is the valve free to contact the face of the steam chest throughout its travel with very little lateral play?
Step #3, Do the cylinder and exhaust ports look right and do they match the valve?
It is hard to tell from the pictures, but as a general rule, the width of the cylinder ports should be the same as the lands between them and the exhaust port, and the exhaust port should be twice as wide as the cylinder ports. In your picture, it looks as if the lands are too narrow and uneven and the pocket in the valve is too wide. The valve pocket should be wide enough to go from the exhaust to one or the other of the cylinder ports, but not any further. In the picture, it also looks as if the valve pocket in one of the valves doesn't have a straight side.
Step #4, 100 psi is way too high a pressure to use. It can be dangerous; ie. broken fingers, parts etc. when things happen that you haven't allowed for. 10 or 20 psi. should be more than enough for testing and even then, be careful and count your fingers!
By the way, the recess in the cylinder head that connects the 5 holes to the cylinder is too deep and will contribute too much to the "dead volume." It should be half of what it is.
Hope this helps.
Richard Trounce.
A couple of things.
First, now that you have the valve cover off, check to see that air can flow through the connection into the valve chest. You need to do your checking and testing logically and step by step and also understand what you are doing in each step and why.
Step #1 is to see that air can get into the steam chest.
Step #2, With the valve cover off, When you rotate the wheels by hand, does the valve move the way it should, do the cylinder ports get uncovered at the right time and is the valve free to contact the face of the steam chest throughout its travel with very little lateral play?
Step #3, Do the cylinder and exhaust ports look right and do they match the valve?
It is hard to tell from the pictures, but as a general rule, the width of the cylinder ports should be the same as the lands between them and the exhaust port, and the exhaust port should be twice as wide as the cylinder ports. In your picture, it looks as if the lands are too narrow and uneven and the pocket in the valve is too wide. The valve pocket should be wide enough to go from the exhaust to one or the other of the cylinder ports, but not any further. In the picture, it also looks as if the valve pocket in one of the valves doesn't have a straight side.
Step #4, 100 psi is way too high a pressure to use. It can be dangerous; ie. broken fingers, parts etc. when things happen that you haven't allowed for. 10 or 20 psi. should be more than enough for testing and even then, be careful and count your fingers!
By the way, the recess in the cylinder head that connects the 5 holes to the cylinder is too deep and will contribute too much to the "dead volume." It should be half of what it is.
Hope this helps.
Richard Trounce.
- Bill Shields
- Posts: 10548
- Joined: Fri Dec 21, 2007 4:57 am
- Location: 39.367, -75.765
- Contact:
Re: Trying to do a leak down test on my cylinders.
The valves are rotated 90 degrees from operating position
Too many things going on to bother listing them.
Re: Trying to do a leak down test on my cylinders.
It may well be a timing issue and / or a valve sealing problem. So I'll surface the valve seats and valves. I want to hone / deglaze the bores and install new cast iron rings.
Anyone know where I can buy new rings 2.350" x .090" ?
Anyone know where I can buy new rings 2.350" x .090" ?
Re: Trying to do a leak down test on my cylinders.
"Measure twice, curse once."