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740 automatic water level
Posted by: (
Date: July 25, 2007 05:06AM

As many of you will be aware I (and my college) have obtained possession of the WA museum's 1923 74 stanley. we are busy overhauling the mechanicals and are about to overhaul the boiler fittings.
Now we have figured out how it works, but is there any way of checking it prior to firing up the boiler? ie with out it being hot.
Alternatively, is there any technical information (more detailed than the owners manual) regarding the 740's?


Re: 740 automatic water level
Posted by: Jeff Theobald (Moderator)
Date: July 25, 2007 07:07PM

Hi Dave,

This information was originally posted by Pat Farrell..........

With 300 lbs. Steam pressure on the boiler and the water level at the normal sight, jack up the right rear wheel, see that the hand by-pass valve is open, disconnect the copper tube leading from the side of the automatic by-pass valve back to the water tank so that you can see when the water comes through the valve. Run the engine slowly, and see that the expansion tube of the automatic by-pass is cool. If it is hot, it shows that the water level in the boiler is not high enough. When it is cool, the water thrown by the pump should pass through the valve freely.

Water Automatic Adjustment: Open the right front blow off valve which is connected into the bottom of the boiler in the same line at the front and that the automatic by-pass is. This should have the effect of heating the expansion tube and should close the valve. If it did not, slack up the rear adjusting nut at the front end of the automatic by-pass rods and take up on the front nuts until the valve closes. Be sure that you leave the blow-off valve open long enough so that the expansion tube is very hot. Now shut the blow-off valve and pour some cold water on the expansion tube until it is cool and see that the valve opens. If it does not open when it is cool, it shows that you have the adjusting nuts set up too far. Slack these up one square, that is one sixth of a revolution, and try it again, and see that the valve closes when it is hot and opens when it is cool.

The nuts at the back end of the rods, which make a tension on the coiled springs, should be set up so that the valve will close with full pressure on the boiler, and yet have space enough between the coils so that the springs can be compressed at least 1/16 of an inch without coming together.

Hope this helps, Jeff.

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