I thought all these jacks had a T handle but this one is not. I cleaned it up and noticed a drip at the bottom plug, what is the purpose of this plug ? to access the piston ?
The gasket was cracked so I found an oring for now for it and added some oil to it. I dont see any other leak so I jack it up with no load and after 25-30 mins it is sitting bottomed out. Then I jack up my car and leave it a good 30 mins and it is still fully raised.
I dont know why that is
Anyway, whether it is an issue of valves leaking or an old piston cup not sealing properly under no load, which is totally possible, the OP should replace the seals as a safety measure instead of using the jack as it is. The jack is old and even if it working now, the piston cup can fail at any moment. I would be very wary about using any old jack without knowing the condition of the seals. If the piston cup breaks, it could well happen when one is putting the jacks stands under the car. At least scary if no one gets hurt.
This same recommendation apply to jacks owned by the same person since new and that after 20 plus years are still working. Piston cups and u-cups do not last forever.
As for the pump piston, if the bigger/upper ball leaks, the oil will flow back until the pump piston reaches it maximum extension; when the pump piston is stopped from going out any further, the lifting arm stops leaking down as now the pump piston takes the place of the upper ball and is now holding the weight of the load. If the pump piston seal happens to be leaking, then the lift arm would keep going down as the oil leaks out by the pump piston seal.
Some OS did come with a T handle. I have one with the T that I rescued from a scrap metal yard.The body is quite rusty, with lot of pitting near the front part of the body (therefore ugly) but the pump was mostly rust free.
At least two other GJ members have T handled OS or O'boys. The pictures below are from one of them. Adding the two horizontal handles should not be very difficult. You could weld two pieces of tubing or pipes to the handle.
I agree with you that the problem might be caused by a worn out piston cup that leaks under no load for the reason you explained, that there is not enough load to expand the flexible sides of the leather piston cup and make a good seal. This same situation then would be the reason to actually replace the piston cup. If it can not hold the weight of the arm, then it is not good enough. Such a situation would not happen with an u-cup. If the u-cup leaks under no load, it will most likely leak under load more so, just because the u cup lips and sides are stiffer than the leather piston cup. Not flexible enough to expand and seal against the cylinder if it is worn out as a leather piston cup could.
When I made the comment about the check valves, I assumed, for the sake of discussion, that the piston cup was in enough good shape to seal under a no load situation. Apparently, it isn't.
The idea of finding any vintage jack is to actually find one, not to find one that works with the original seals. My recommendation has always being that old jacks should be repaired when bought instead of being tempted to leave it as it is and use it if it still works. From what I have read here in other threads, there is disappointment when someone buys an old jack and it does not work. Many buyers are expecting that the old jack works like a new jack. The mind set should be to buy the jack and repair it whether it works or not. Don't even waste time testing to see if it works.
Does the O'Boy handle just remove when the bolt is taken out at the bottom (7/16 head I think)? I circled the bolt in question in yellow. I did that and my handle seems to be stuck. Maybe a little heat to get it out, or am I missing something on taking it off? Its a T handle.
The idea of finding any vintage jack is to actually find one, not to find one that works with the original seals. My recommendation has always being that old jacks should be repaired when bought instead of being tempted to leave it as it is and use it if it still works. From what I have read here in other threads, there is disappointment when someone buys an old jack and it does not work. Many buyers are expecting that the old jack works like a new jack with the old seals. The mind set should be to buy the jack and replace the seals/repair it whether it works or not. Don't even waste time testing to see if it works or not.
I'm in agreement with this line of thought completely. A lot of the vintage hydraulic jacks are pretty cool however, the old seals within them are not. You've got to replace them and tend to any other required repairs for safety reasons.
I think there are more than a few folks here that get all excited about obtaining a vintage jack only to find out that it's not always cost effective to put one back in service.
Always enjoy the discussions between you and Hiball.....well most of the time...![]()
I'm not sure if I ever seen a OS/Oboy with a T handle, some of the WS units definitely had a T handle, some only carried the straight handle. The "Complete" leak down issue is more than likely associated with a Worn Leather piston seal, due to there nature they really need "Cylinder Pressure" to create a positive seal against the cylinder wall. The cylinder pressure created from the weight of the lift arm and return springs just isn't doing it, versus the cylinder pressure created by lifting your vehicle. Highly unlikely a valve issue would allow a "complete leak down" at least with a full extension just based off the amount of oil in the cylinder would dramatically overcome the pump piston galley and valve when the return flow of oil was stopped by the seating of the lower ball. Obviously a jack of this age could suffer from multiple areas of failure, but valve issues under load are quite noticeable in regards to handle feedback. Im not sure what the purpose of the plug on the bottom was, it obviously feeds the bottom of the pump piston. I service all my OS/WS units from the top as its beveled for ease of installation. I reckon it would be quicker from the bottom though, simply remove the Clip and push it out, service the seal and reinstall, then again now that I think about it... The pump piston head is normally swollen from repeated contact with the roller, it more than likely wouldn't clear the guide. Yep.. Top End is better.