I just got a new 12 ton press. Its from Harbor Freight http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=33497. I never had one before so I thought what the heck, it would make my life easier with my front end bearing swap. I just set it up and tried to press out the lower control arm bearings. Once you get a little resistance, the hydraulic "jack" unit hisses and there is no more pressure. My first thought was maybe the bearing is stuck in some way. But, I was able to remove it with my 'c-clamp' type ball joint tool fairly easily. Then I thought maybe the hydraulic unit is defective. I took it out from the frame and used it to 'jack up' a spare engine block I have here (just for weight) and no problems. My first question is, this tool should be able to generate enough force to press out a bearing, right? I mean it has to generate at least as much force as a ball joint clamp you turn by hand, right? If so, then I wonder if I am doing something wrong, or is it likely that the unit is defective. I can return it without much hassle, but it will involve at least an hour drive and back. Any help would be appreciated.
Thanks!
Mike

Check the oil level.
It may be low and will only supply enough for a short stroke of the piston or you may have reached the end of the travel when the jack was in the press??????????

Levon, thanks I will check the oil level (as soon as I figure out how to do that). The distance I tried seems to be about only half of the overall piston length. Is there any test I should try? I wish I had another piston jack I could swap in to compare.

I have the 20 to and have had no issues with it. Call HF and see if you can return the jack for a replacement. The hissing could be an internal leak, I had a floor jack from them that did the same thing.

Take the jack out and pump it up all the way. See what the stroke is. Then you will know whether or not the pistion is reaching full extension outside of the press.

Then do it in the press without a load. See if they are the same.

There should be a screw or bolt somewhere on the body of the jack which, when removed, will let you fill oil to that level. Make sure tyou use hydraulic oil if you have to add.

Let us know how it works.

I would just return it myself.

Yeah, I can't even find where the hissing is coming from. Though it is a little scary, sounds like somethings gonna blow! I am going to call HF now and see what they say. I am hoping I can replace only the jack, and not have to lug the whole frame back. I checked the travel both out of the frame and without a load, and they are the same. Once the press has a load though, one pump and it starts hissing, then the piston has no pressure on it. We'll see what they say at HF. I will post what I figure out. Thanks again for the help!

Levon, thanks I will check the oil level (as soon as I figure out how to do that). The distance I tried seems to be about only half of the overall piston length. Is there any test I should try? I wish I had another piston jack I could swap in to compare.


Mike, After the fluid check try lifting a known value such as under the rear axle of the pickup.

I'll give it a try. I just borrowed my neighbor's bottle jack and swapped it in. No problems, so mine must be deffective (or low on fluid). I am going to have to buy some hydraulic fluid, or maybe get a new one from HF (depending on which turns out to be easier).

Not to sound stupid but is the valve closed all the way?

Harbor should give you another jack. If not just buy one. My Harbor Freight 12 ton press is on its second jack. The first one leaked after 10 years. Bought another and it seemed to be be the exact same model.

Thanks for the replies. I ended up just exchanging the whole press for a new one. No questions asked. Hopefully this one is better. BTW I did check that the valve was closed all the way. The hissing wasn't really coming from the valve anyway..but I can't say from where exactly.

Does sound like the previous one was leaking, good thing HF took it back. I have a Grizzly 12 ton press that when pushing out bearings from my riding mower arbors from the wrong way (against some retainer nubs) shattered the bearing into hundreds of chunks, if 12 tons cant press a bearing out nothing can :)