when I pick up a load of dirt or something on forks it will drift down. the rear bucket will drift down over an hour or two. there is no fluid leaking out of equip
In my experience with my 2 420Eit machines, the cylinder piston seal is worn out. Many items can cause the drift, but, I've definitely repacked the front cylinders on both before 5k hours, and on my 416Cit and 426Cits, I've repacked most of the rear cylinders. Always for drift, never for external leakage, except the rear swing cylinders. They usually leak external.
I like the idea of cylinder seal vs some internal bypass or relief valve. thanks I'll do that.
The easiest thing probably would be to pressure test cylinder and DCV separate with hand pump, even from Harbor Freight body kit ( the fitting on that one looks like NPT but it’s actually BSPT and you gonna need to use short roll pin to push on check valve spring if you will be using hose other then comes with kit). Most of the times it’s cylinder piston ring, but sometimes it can be o rings on port relief valves on DCV! If you will go to trouble of removing DCV - just get the kit and rebuild the whole thing!
I have a similar issue with my 426. The boom drops very quickly. One member made a great suggestion to know if it is the cylinder or not. Start it cold and hold the control valve in one position and see if the cylinder gets warm. In my case the boom drops very fast. I had a thread going HeavyEquipmentForums I have been told it can also be the resolvers. I bought seal kits from HW Parts along with a couple tools. Hopefully the tools work and the kits are good. Could not really find any reviews but the prices are significantly less the OE Caterpillar. I figure Cat buys seals from a manufacturer to their specs. The kits came in two days.
Hercules is OK, although they getting slower on processing orders! I will not deal with Bulldog ever again: first - they lied to me about having a kit in stock which nobody else had! Second: kit supposed to take only two days to get to me, but week later when I called my quote was still a quote which never turned in to order!
Hercules prices were more or less the same as OEM. I hope the HW kit is good but if not I have learned my lesson. I would be willing to bet that most of the kits all start in the same factory. How many companies really make seals?
Never dealt with HW, just wanted people to know about Bulldog!
I am going to start the process of elimination. meanwhile I will keep working with it.
Keep us posted. My 426 boom drops so quick you have to hold the valve in the lift position to move the machine. I have all the parts and tools here. Hope to get some time in the next few weeks to work on her.
If your machine doesn't have a boom lock you could weld on some hooks and chain it up when you're not using the hoe. Seals will probably last a lot longer.
On my machine there is a boom lock but it won’t lift it high enough to engage. Comes up about 6-8 inches short.
That’s a common problem on those, my buddies 580 is the Same way, have to push against something and use bucket or push with other piece of machinery to lock it!
Then you'd lose your money. There are more manufacturers making hydraulic cylinder seals than you could shake a stick at.
Depending on what model that 580 is it may have an over-center boom lock. The lever has to be changed from the boom up to boom down position at the right time and it will continue to travel to the lock position. I ran a Case 590 and it had it. It was easy to lock the boom once I figured when to push the boom lever.
This exactly! It takes a bit of practice but the boom will come back far enough on its own.
Tried whichever way possible, holding the lock lever was the first thing that we did, it comes off very nice, but just cant bring that boom close enough. Once I’ve done it while machine was parked on hard incline nose down on the trailer ramp!