Power Gear 500384 hydraulic jack teardown

During our pre-purchase inspection of our New-to-Us Southwind,  I noted the two front jacks were different, 500384HR on the passenger side, and a 500384 on the drivers side.  I also noted that the drivers side foot pad stuck down a little farther than the passenger side.  At the time,  I attributed it to mounting differences between the two different jacks.  (wrong)

After doing preventive maintenance on the jack system,  CLICK HERE, I noted that the drivers side front jack (500384) would leak when extended all the way down.  When it was retracted, it stuck down about 1 inch.  I read in one of the on-line forums where someone had a similar problem with a different model jack, it didn’t appear to be retracting completely. When they disassembled the jack,  they discovered the top shaft guide that’s screwed to the top of the shaft had unscrewed.  I suspected I had a similar problem.  (Well, almost)

When looking for a re-build / overhaul kit for my jack, Power Gear had deemed the 500384 as obsolete and no parts were available.  Their recommendation was to upgrade to a newer jack, # 500384HR, GULP,  $1,600.00   Before buying a new jack cylinder, I’ll tear mine apart and see if it could be fixed.  HEY, its a hydraulic cylinder, these things are as common as the cold…

DISASSEMBLY

I downloaded and reviewed several Power Gear documents. These were helpful in figuring out what I had and what I needed to do.. CLICK HERE  and HERE

I removed the jack from the Southwind and tore into it.  To unscrew the base (gland) of the cylinder, I pulled the shaft about half way out of the cylinder so as not to damage it from the heat. I heated the base of the cylinder for several minutes with a torch to soften any Locktite that may have been used during assembly.   Using two pipe wrenches,  the base unscrewed fairly easily.  Have a lot of rags or paper towels ready as the cylinder holds a lot of fluid,  even when compressed.

As I pulled the shaft out of the cylinder, a lot of small pieces of something came out.  Obviously, something made of plastic had broken inside. When I got the shaft out, I  noticed there wasn’t a guide on top of the shaft..  HUM…    I looked up inside the cylinder and could see the top shaft guide (or something) stuck all the way up inside at the top of the cylinder.  To get the broken piece out, I’d slam the bottom of the cylinder against a piece of wood. I could see the piece moving down every time I slammed the cylinder against the wood block.  After several minutes of slamming,  the broken top guide finally popped out of the cylinder.

The shafts top guide isn’t a piston, its a guide that keeps the shaft centered inside the cylinder as the shaft moves up and down. The guide also acts as an end stop when the shaft is fully extended, preventing the shaft from over extending and popping out of the cylinder.  With the top guide broken off, nothing prevents the shaft from coming completely out of the cylinder.  I was VERY LUCKY.

With the the top guide broke off, this caused three problems:

1) When the shaft was extended,  it would go past the normal end stop and past the sealing o-ring at the bottom of the cylinder.  When it did this, hydraulic fluid would squirt out the grease hole and the bottom scrapper. This explained why the cylinder seemed to only leak when it was fully extended..

2) When the jack was retracted, the shaft would retract up inside the cylinder and jam against the broken shaft guide at the top of the cylinder..  This is why the jack didn’t retract all the way, sticking out about a inch when it was supposed to be fully retracted.

3) A careful inspection of the bottom gland, the part that screws into the bottom of the cylinder, had some minor damage where the shaft rubbed against it.  With the top guide missing, there was nothing to hold the shaft centered inside the cylinder.  When extended the shaft could shift inside the cylinder and come out at a slight angle. This allowed the shaft to rub against the gland and do some minor damage to the gland. I used a small file to take care of this. Fortunately there was no damage to the shaft.

THE FIX

The fix is easy,  just replace the broken top shaft guide.  The problem is, Power Gears doesn’t support this jack with parts or a kit.  Instead,  they want me to buy a new jack, 500384HR to replace my 500384.   We’ll see  !!!

I suspect Power Gear doesn’t want the plastic shaft top guide out there, so they upgraded to a metal guide on the HR version.  I may do the same,  I took measurements of the plastic guide and will either make a new plastic one,  or I might make an aluminum one and groove it so it has a guide in it.  The o-ring, seal, and scraper should be standard.  I’ll check with my o-ring supplier this week.

I got my o-rings and seal from a local company that specializes in o-rings and seal..

https://www.zatkoff.com/

ED NOTE – I was able to make a new shaft guide and install new o-rings cost, $35.  READ HERE