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How the hell do you refill a floor jack???

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Talking Head

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Discussion starter · #1 ·
My 3-ton Craftsman floor jack is low on oil...I went and got jack oil at my local parts house, but I can't figure out how to fill it! :mad3:

OK, it has a fill plug half way up the body of the jack just like my cherry picker and press...SOP on those is to pop the plug when the ram is all the way down, fill til it seeps out, let it sit a few minutes, replace plug, and you're ready to go. The floor jack ram, of course, works on its side. Sooo, first thing I tried was to stand it up (like you'd use a regular jack) and pull the plug, only to have oil run out even though it was low. Obviously that was not the right position. So next I laid it back down on its side, turned it 90 degrees (so that the fill plug is on the side of the jack rather than pointing straight up as it would be installed on the jack assembly), filled it, let it sit, put in the plug, turned it as it would be installed, and tried it...and it operated just like it did before I put oil in it.

Am I missing something?? It has been seeping for quite some time around the plunger that "jacks" the ram, but it really crapped out shortly after I lifted the front of a diesel Super Duty...yes, a SD is heavy but picking up one side at a time is surely less than the jack's trated capacity. I'm just trying to figure out if the ram is shot or just low on oil...a quart of oil is cheaper than a new jack.

Any help is greatly appreciated.
 
#5 ·
Have you cracked open your pressure valve aka the screw/rod that holds/releases pressure lately? I believe quite a few bottle-type floor jacks have a check ball in the turn rod mechanism, that you turn left/right to release/hold pressure. I have seen a few of these balls get corroded and reduce their sealing/holding pressure cabilities, especially after they have been sitting up for a while with low fluid levels.
 
Discussion starter · #8 ·
Wow, that link is a great one! Thanks! I only wish I'd run across that site last night. Trouble is, I messed with both of the check valves that the diagrams on the site clearly say never to touch.

I might mess with it for a little while longer tonight but I have a sneaking suspicion that its probably fubar now even if it wasn't before I messed with it.

The check / release valve seems to be working fine. However, I inadvertently discovered that you can pull out the plunger that "jacks" the ram by hand, or at least you can on mine. That introduced more air to the system, I'm sure, and so the cycle continues...
 
#9 ·
LOL!! That is what I did to. I have never got the jack bled correctly since then. I have tried with no luck. Its on a cheap floor jack, but I still can not bring myself to toss it. I swear a trip on it once a week.
 
#11 ·
I spent 1 1/2 hours rebuilding mine and it worked great for about a week. I don't like admitting defeat, but they really are not worth the time to fix. If it's the same jack Sears has a $99 special on every christmas. Save some money and buy a better quality jack, especially if you lift a SD on a regular basis. On the bright side - at least the jackstands it came with are still useful.

If you fill the jack sideways like you tried, it won't work. You were doing it right the 1st time if I read correctly. Open the release valve and pump it very slowly to help flush any air bubbles.

You can pull the plunger on your jack and replace the O-ring. That will stop the seeping/leaking. Pull the handle pivot bolts and the piston/plunger will lift right out. the handle return spring is the only tricky part of reassembly. Just take the old O-ring to a good hardware store and match it. It's a fat one so you may need to search a bit. Use O-ring lube or some petroleum jelly when you reassemble.

If the handle isn't trying to come back up (check ball) try screwing down the relief valve slightly. It's the one all the way to the right viewed from the rear that has a plastic cap over it that says "do not adjust". The relief spring on mine was set ridiculously light from the day it was new. Count the turns to fully seat it so you have a reference to go back to.

If you decide to take the whole damn thing apart (nothing to lose - leaky floor jacks aren't worth much). use a small magnet to lift the check balls out and try to flush as much of the old contaminated hydraulic fluid out as you can- they will usually have a fair amount of rust/casting junk floating around inside. To reseat any of the balls, drop them in their seat and give them a tap with a drift and hammer. This will break up any rust or crud on the seat that's allowing them to leak. You won't dent the balls - they are hardened steel. You don't need to beat the crap out of them - just one good tap will do. The pressure relief ball is tiny, so go easy on that one, or you can deform the seat. If you see a shiny "ring" 360 deg. around the seat/hole, the ball will probably seat correctly.

Just be safe and don't kill yourself - stay clear from under anything you are jacking and always use good jackstands. Good luck.
 
#12 ·
I recently used the link and tips to fix my engine hoist and 2 floor jacks.

Engine hoist - the pump rod had a blown O ring, so I found one rom AutoZone that was a close enough fit to work. I drained all of the fluid and refilled with the jack standing up, fully compressed.

The hoist now works better than it has in YEARS, and a couple of bucks for an O ring and a bottle of jack oil saved me from $80-100 for a new ram from Harbor Freight.

The floor jack was a bit trickier - the location of the fill plug was such that the jack had to be mostly disassembled to get to it. All of the seals looked ok, so I just drained then refilled this one, reassembled the jack and again - it is operating better than it has in years, finally able to fully extend all the way up again.

One tip on refilling both floor jacks that the web site link did not say - on mine I left the jack laying down in the normal (in relation to the jack) position, fully compressed ram, and filled the fluid reservoir pretty much full (the fill plug was facing "up"). This worked great - and trying to fill the jack as if it were a vertical jack does not work (at least on mine).

Anyway - I'm happy as can be, with 2 good working floor jacks and an engine hoist that are back in business and a TON cheaper than just buying new ones.
 
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