Backhoe Boom Cylinder Leak

   / Backhoe Boom Cylinder Leak #1  


Super Member
Feb 10, 2007
Willis, Texas
Mahindra 6520 4WD
I figured I would share my plan to rebuild my backhoe's (Bradco 511) boom cylinder. The cylinder is enclosed in the boom structure. 5-7-20 Boom Cylinder Intallation.jpg5-12-20 Backhoe Angle Of The Dangle.jpg To get it out, I had to dig a deep pit so the rod could be removed while leaving the cylinder base installed, buried inside the boom. 5-12-20 Backhoe In Hole.jpg5-12-20 Backhoe In Repair Hole.jpg5-7-20 Hole For Boom Cylinder Rebuild.jpg

I have rebuilt all the other cylinders while leaving the cylinder bases installed. 5-12-20 Backhoe Uplock.jpg I wasn't sure if just being in a hole would work, so I backed the tractor in 90 degrees to the hole. Then I swung the boom to the left and lowered the bucket into it's new temporary home. I then loosened the gland nut enough to know I could unscrew it, without taking it all the way out. Next I went to remove the pin on the rodend. I couldn't move it.

So I went to my welding shop friend and asked for advice. He said he could help the next afternoon, so I wouldn't need to buy a torch to heat it myself. Well, he was busy and I decided to hire a heavy equipment outfit to take the pin out.

The heavy equipment guys were swamped in their shop, but they could send a truck today. 4 hours mininum. I told them to send the truck out.

Long story short, the mechanic didn't have all the "right" experience to take it out with a torch. I told him I requested pin pusher service. He left after an hour to bring a track pin pusher tomorrow. Two hours later, while I was doing a 50 hour inspection on my sawmill, two heavy equipment trucks came rolling up the driveway. All I thought was the pin was gonna come out for sure, now.

A 60 something old guy drove the second truck. He proceeded to instruct the younger mechanic all about heating and banging out "small" pins. It was a small pin, as their pin pusher was a 100 ton unit and would have pretzeled my swing post structure and his smallest pusher pin was way bigger than my "small" pin.

Anywho, they banged back and forth heated, heated, heated and had it out after about an hour. Then I saw $$$. I was paying for the old mechanic to train the younger mechanic how to remove my pin!

Shortly thereafter, I had the backhoe in the hole and the rod out.5-12-20 Backhoe Rodend Pin.jpg5-12-20 Cylinder Rodend Apart.jpg

It's all apart now. I'll pick up the new pin and orings tomorrow.

hugs, Brandi
   / Backhoe Boom Cylinder Leak
  • Thread Starter
I lifted the boom with the CAT to drain all old fluid out. 5-13-20 CAT Holding Boom Up.jpg Then we stabbed the rod in with no problems.5-13-20 Boom Cylinder Rebuilt.jpg I used a smaller dia. bolt to leak check and to take her out of the weather. 5-13-20 Boom Cylinder Bolted Temporary.jpg No leaks. Yippee. Then I put her in the barn to polish up the grinding marks from dressing the pin for removal. Then I painted it all red again. 5-13-20 Kingpost & Rodend Painted.jpg
hugs, Brandi


  • 5-13-20 Boom Cylinder Empty.jpg
    5-13-20 Boom Cylinder Empty.jpg
    1.7 MB · Views: 55
   / Backhoe Boom Cylinder Leak
  • Thread Starter
I still have to "polish" out the kingpost hole a little. I need to go buy some barrel sanding drums from Graingers. I thought I had some at home, but that small size is back in the hangar in my tool box. The new pin goes in except 1/4 inch, where the hammer hit during the pin removal.
hugs, Brandi
   / Backhoe Boom Cylinder Leak
  • Thread Starter
I purchased a 1 inch dia. sanding expanding drum mandrel and 80 grit spiral bands from Grainger Industrial Supply - MRO Products, Equipment & Tools.5-14-20 Pin Bore Sanding Drum.jpg I used my high speed router and buffed the end of the bore that the pin was hanging on. A couple of minutes use and the pin slide home.5-14-20 Pin In.jpg Now, back to digging that water line.
hugs, Brandi
Last edited:
   / Backhoe Boom Cylinder Leak
  • Thread Starter
Hi, nice detailed post. Interesting.
Thanks. I have seen a bunch of questions lately, in various threads, on cylinder leaks. Hope this helps someone.
hugs, Brandi