Upgrading the hydraulic pump on a Harbor Freight towable backhoe trencher

in this video i'm going to show how to upgrade the hydraulic pump on a harbor freight towable backhoe this clip you're seeing on the left this is the stock pump and as you can see the movements are pretty slow making working with this machine a bit tedious the clip on the right this footage is from the upgraded pump and everything's just a little bit faster the movements are a little bit more fluid you can even operate two of the controls at the same time which is something that didn't really work with the stock pump the total cost for this upgrade was about 175 and it was a pretty simple job to complete so jumping in let's take a look at the details of this upgrade here you can see the stock pump it is i believe the size is 2.7 cc's and the upgraded pump that i used was 4.1 cc's uh based on my research it seems like something within the range of 4 to 4.5 is what you can upgrade to without going over capacity on this machine in addition to the pump you're also going to need two adapters because all of the hose connections on the backhoe are in metric but the pump itself is using standard threads so these adapters will allow you to make the necessary connections at the inlet and the outlet of the pump so once i had all my supplies i started by disconnecting the outlet hose from the pump next you want to disconnect the inlet hose on the bottom if you just twist this hose and face it up towards the sky gravity will prevent it from leaking out in my case i was going to be changing the hydraulic fluid anyway so i just had it going into a catch pan down below next to remove the pump you just got two bolts one on the top one on the bottom uh pretty straightforward i think the trickiest thing is just that there wasn't a lot of clearance it was a little hard to get a wrench around those bolts next up you need to remove the coupler that's on this pump so you can move it to the new pump and that's just held in place by a little set screw that takes a t t25 torx bit so here are the two pumps side by side the new one on the left just a little bit bigger than the stock pump on the right the other noticeable difference is the shaft on the new pump it's a little bit shorter and the ridge on the bottom of it sticks up a little bit higher and this caused a problem when i tried to put the coupler on here you can see in the old pump the coupler slides down and it sits nice and flush uh with the pump there's no gap there when you put the coupler on the new pump though that ridge on the bottom of the shaft prevents the coupler from going all the way down and you have this gap and when i tried this like to test fit it against the backhoe itself it made the whole pump stick out a little bit it wasn't sitting flush with the machine so to address this i just took the coupler and used a step bit to just make a little recess on the underside that that extra material on the shaft could fit into so it could sit flush and here you can see the finished product i don't know how much material i took off i basically just took a little bit at a time and just kept testing it on the pump until it sat flush so here's reassembly adding the key to the slot on the shaft and then threading the coupler on top of that and then tightening down that set screw then when you put the pump back on the machine you just have to line up the coupler so it fits in the slots inside of there next up you want to thread on your smaller adapter on the top of the pump i just put a little bit of hydraulic fluid to lubricate the threads i didn't use any teflon tape here because it does have a little rubber gasket so i think that's what's sealing it i don't think we need teflon tape at this junction so i mostly hand tighten this and then just give it a little bit of extra turn with the wrench you don't want to crank it down too hard because then it's just going to squish that gasket next up you're going to thread that 90 degree adapter that you took off of the stock pump and there's no rubber washers here so you can see it did have teflon tape on it and what i should have done is i should have taken off the tape cleaned it up and reapplied new tape because later when i go ahead and start this up it does have a leak here and i do have to undo it and put new teflon tape so save yourself that extra step and just clean things up put brand new teflon tape on it and should work the first time and then just go ahead and repeat those same procedures for reattaching your hose on the bottom of the pump and here you'll notice that there's there's no teflon tape on this 90 degree adapter on the bottom and there wasn't any to begin with and that's just because this is not the high pressure side of the pump this is where the fluids coming in so the you know it's not going to be as prone to leaking as the top side where it's coming out under pressure wouldn't hurt to throw some teflon tape on here just to protect the threads but not necessary and i didn't get any footage of this but of course you want to re-tighten that hose clamp down so it doesn't fall off the connector so after everything was put back together i went ahead and started it up and as you can see pretty neatly had an obvious leak at the top so i went ahead and undid that top connection so i could take it apart and remove all that old teflon tape completely clear out the threads and then put a nice new layer of teflon tape on it [Applause] and this time when i started up no leaks so we were good to go so here's some footage i was just testing it out uh moving it around seeing how much faster it was uh definitely a noticeable difference from what it was before uh it does kind of like throw the machine around a little bit more it's much jerkier i think like you almost have to get accustomed to the faster movements i will say though that when i've used it on projects since and you're you're actually working with it you notice it less especially because typically you've got it in the dirt and that's going to prevent some of the jerkiness so all in all a big improvement for relatively little cost and uh because i'd definitely recommend it if you have this machine to go ahead and make this upgrade you

Channel: Stick Wall Farm

Views: 77,490

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Id: VIQbUcIsBvg

Length: 10min 1sec (601 seconds)

Published: Thu Sep 02 2021