Floor Jack Plunger O-ring

[alton]

Sears 1 1/2 ton , model 328.12002. How snug should the plunger o-ring feel? Should it fit the plunger lightly or pretty tight? The plunger OD = 0.784". The o-ring ID = 0.792". Do I need to look for one a couple of thousandths smaller than the plunger OD? Is there a rule of thumb for this measurement? Thank you.

 

[Hiball]

Sears 1 1/2 ton , model 328.12002. How snug should the plunger o-ring feel? Should it fit the plunger lightly or pretty tight? The plunger OD = 0.784". The o-ring ID = 0.792". Do I need to look for one a couple of thousandths smaller than the plunger OD? Is there a rule of thumb for this measurement? Thank you.

You want the Oring to fit the Pump Piston with a little resistance (Very Little), if its too tight it will distort the Oring and Reduce the Sealing Contact of the Oring. The Most important thing is to make sure you are using a Oring with the Correct Cross-section (thickness). If you use too small of Cross section the Oring wont seal correctly in the Gland, too big and you wont be able to install the pump piston with damaging the Oring.

 

[alton]

Thanks Hiball I guess this one is still ok.

 

[Hiball]

Thanks Hiball I guess this one is still ok.

If my Memory serves me, Im sure its a 3.0mm cross section. I actually keep that size here at home for you guys.

 

[alton]

Hiball, it is 0.143" or 3.632 MM. Thank you for the info. Alton