Hydraulic press oil leakage

Sometime ago I noticed that the oil was leaking out of the hydraulic
jack of my press… However, it seems to be working fine now, and I am
able to get it up to the desired pressure.

I was under the impression that one could refill the jack with oil
if it is needed. I notice a small opening at the top of the jack,
presumably for oil but I have been hesitant about adding any as the
jack seems to be working.

My press is one that I had made following the instructions in the
Susan Kingsley book. I got the jack from an automotive supply place.

I wonder if this is the same kind of jack that comes with the Booney
Doone press, in which case I wonder if Oil could be added if
necessary. Mine is a 20 ton jack.

Alma Rands

Hello Alma

Yes oil can be added easily. I use a bottle with a tube to squirt
oil into the hole. I get a Quart of Jack oil from any hardware or
automotive store.

You can fill it up to the hole opening and let excess drain out
before replacing the screw/bolt.

The piston and the cylinder in the jack have some O rings that start
leaking but it works fine.

If it is really bad then replacing the Jack is not a bad idea.
Personally I find that Harbor Freights 20 ton Jack is really cheap
and freight is not expensive it came by US Mail and the last time I
got a 30 ton jack a just little bigger in diameter.

Kenneth Singh Khanduja

Alma; They can lose oil around the gasket where the handle goes into
the jack. the Bonnie Doone is just a modified jack of the type you
speak. I don’t know if the gaskets are interchangable between brands.
You can check the level of your jack fluid by removing the top plug
and bending a paper clip and inserting into the hole I can’t remember
the exact amount but I believe the proper level is about 1/2 inch
below the hole. At least on the Bonnie Doone model so I assume other
brands would be similar. Try calling the tech people at Rio as I
think they are the ones carrying it now. If you add fluid or change
the gasket turn it on its side to remove bottom gasket or at a 45
degree angle to add fluid. It will take very little hydraulic fluid
to fill it back unless you had a major leak which it doesn’t sound
like you do. Hydraulic fluid is available at any auto parts store.

Dave Owen


Another suggestion for adding hydraulic fluid is to go to a farm or
vet supply place, and get a couple of 60CC syringes. Actually, get a
bunch, they’re useful to have around. They don’t come with needles,
and they’re way too big for anything a human’s going to want to
shoot up with, so most places don’t control them. Load the oil into
the syringe, open hole in side of pump, proceed to squirt. The oil
will trash the rubber gasket on the syringe eventually, but long
after you’ve topped up the pump. Throw it out after use, and save
the rest for future uses. They make great glue applicators too.


Hi Alma,

There is a way of filling the jack with hydraulic oil. That is the
little rubber or plastic plug about 3/4 the way up the jack. Pop out
the plug and fill it with oil. The trick is to use a small bottle of
hydraulic jack oil with a small spout that will fit into the hole.
You should replace the oil every year or so under heavy use but do
not let more than 3 years go by even if you don’t use it. The oil
does have a shelf life. Empty all the old oil out through the opening
that lets the ram come back to the down position, but remember there
is a ball bearing in the hole so make sure you catch it and replace
it after the jack is empty. Once the jack is empty fill it with fresh
oil level to the bottom of the plug hole. (with the ram completely
down). Then put the rubber plug back in the jack.

Once the jack is full run the handle up and down a few times to get
all the air out of the cylinder then re-check the oil level.

That should do it. If you have any other questions you can go to the
Bonny Doon Engineering web site and click on the New Forum button
and talk to all us presskatiers and get loads more

David B. Anderson


Hydraulic jacks are fairly simple and much construction is of a
similar type. I found the following.pdf file that might be of some


Good luck!
Mike DeBurgh, GJG
Henderson, NV


Hydraulic jacks are fairly simple and much construction is of a
similar type. I found the following.pdf file that might be of some


Good luck!
Mike DeBurgh, GJG
Henderson, NV

Hi Gang,

If you don’t feel comfortable repairing/working on the hydraulic
jack in your press, check your local yellow pages.

Many locations have a listing under Hydraulic Repair. Most hydraulic
repair shops have a supply of gaskets, O rings and other items
needed to repair a jack.

They also have the knowledge, experience & tools to do the job


Thank you all for the very helpful suggestions you have made
regarding my leaking jack. I appreciate the time you all took to help
me. So far the jack is working well, but if there is any more leakage
I now know how to deal with it.

Thanks again. Alma