HF/US General 67408 Jack Fluid Fill and Bleed Help

[alpine]

Long time lurker and first time poster Realizing that I have never replaced the hydraulic jack fluid in my jacks I decided to tackle this job. First jack was my Craftsman 3 Ton floor jack. "Typical Japanese/Taiwanese/Chinese" jack with oil fill port on the reservoir. Removed the plug, tilted jack an drained fluid, filled fluid, bled properly, etc. Everything works great on this jack.

Moved on to my Harbor Freight/US General floor jack (SKU 67408) and I am having trouble. Here is the jack in question and the diagram of the hydraulic unit

I removed "A31" Oil fill plug and removed the old fluid. Now I am trying to get the new fluid in and it will not pour in. I have the release unscrewed all the way and no fluid will enter. I tried to jack it once and it did **** the little bit of fluid in that was sitting in the fill hole. It seems inside the fill hole there is a tiny hole that leads to the reservoir and another tiny hole connected to the check valve?

Does this floor jack require a different filling method? I wasn't sure if this was a factory filled unit and would require opening of the actual hydraulic unit to "fill" it and then bleed.

 

[Hiball]

Whenever the fill hole needs to travel thru the block to get to the reservoir it's uphill trying to fill them. If you have the hydraulic unit out of the frame you can remove the release valve, which will vent the unit and essentially keep 2 way traffic (air/oil) from having to use the one way street. Outside of that.. Pumping the handle while filling the jack will help or being patient.

Hope that helps

 

[alpine]

Success! Thanks so much for the tips Hiball

I removed the hydraulic unit from the frame and then removed the release valve (for those doing this, be sure to watch for the tiny steel ball as it will come out). I then used a tiny funnel that fit just inside the tiny reservoir fill hole while leaving the other tiny "air" hole open to vent. While slowly pouring the new fluid in to the funnel I repeatedly nudged the piston which helped burp the system and **** up the fluid. Eventually it filled all the way and a bit of fluid started to weep from the release valve hole. I put the steel ball back in, screwed the release valve back in a bit, and then tightened up the oil fill plug. Jack now works again

 

[DPDISXR4Ti]

If only for future searching reference, it would seem that Harbor Freight / US General #91039 is the same as model# 67408. My #91039 is currently working but leaking. Trying to figure out what seal to replace.

 

[beyeriii]

LOCATION OF THE OIL FILL PLUG
=====================

IMPORTANT: DO NOT CONFUSE THE OIL FILL PLUG WITH THE
SAFETY VALVE. THEY ARE THE SAME SIZE AND SHAPE.

WHEN VIEWED FROM THE FRONT OF THE JACK, THE SAFETY VALVE
IS ON THE LEFT HAND SIDE AND THE OIL FILL PLUG IS ON THE
RIGHT HAND SIDE.

!!! DO NOT ADJUST THE SAFETY VALVE. !!!

Strangely, the manual for the 67408, i.e.
images.harborfreight.com/manuals/67000-67999/67408.pdf
is for two different jacks.
Pages 1 thru 8 are for a trolley jack, while pages 9 thru 11 are for the
floor jack.

The 67408 manual shows the location of the Oil Fill Plug on page 9.

The manual for the HF US General 96562 is very similar to the 67408,
but having a additional LED light, i.e.
images.harborfreight.com/manuals/96000-96999/96562.pdf


IMPORTANT, the 96562 manual has a typo in Figure A
on page 6 showing the oil fill plug as being on the left side when viewed
from front of the Jack.

Page 8 describes for correct location of the oil fill plug, i.e
"Oil Fill Plug is the one on the right hand side when viewed from
front of the Jack."
and the Assembly diagram on page 13 shows the correct location
of the Oil Fill plug (part number 61).


CHANGING THE OIL
============
Newer Harbor Freight jack manuals recommend changing jack oil
every 3 years.

Use good quality Jack Oil, Harbor Freight sells Sta-Lube, i.e.
harborfreight.com/15-oz-hydraulic-and-jack-oil-40709.html
one bottle is more than enough.

The 67408 and 96562 are particularly difficult to do an oil change.
See Hiball's answer for changing the oil by removing the hydraulic unit.

The following steps might work to change oil without removing the
hydraulic unit (Disclaimer these instructions are from memory)
1. Lower the saddle
2. Clean area around oil fill plug
3. Turn handle clockwise to close release valve
4. Remove oil fill plug and turn jack face down over a drain pan
5. Pump the handle, oil should exit the fill hole
6. Turn jack face up
7. Fill a clean plastic syringe with jack oil
8. Pumping handle down will purge air
9. Use syringe to add oil while pumping handle up
10. After oil is full, raise jack to vertical with front wheel on the ground
and back two wheel in the air.
11. Repeat steps 8 and 9 until completely full.
12. Lay jack down with handle raised and replace oil fill plug.
13. Test raising and lowering the jack.
14. Jack should come down smoothly, if it skips / jitters while coming
down, then there is air in the system.
15. Raise handle, and remove oil fill plug, if oil is not translucent
(milky / cloudy) then there is air in the system
16. Replace oil fill plug.