hydraulic pump testing L48

brain55 · Mar 20, 2014

Customer complained that the loader didn't seem to have the power it once did and was slow lifting a loaded bucket. Not being from the school of "put a pressure gauge on it" I usually skip all that and eliminate the pump first.

Here's my flowmeter installed. At 2000 rpm the no load flow was about 10 gpm. At 1000 psi the flow had already dropped to 7 gpm and at 2000 psi the flow was less than 5 gpm. Had I put a pressure gauge in the system I'm sure it would have read real close to spec. Whatever that may be. With the flowmeter I don't need to know. If I would have still had 8.5 gpm or more at 2500 psi I would have started looking at other possible problems. Pumps can make pressure all day long but with no flow they won't do any work.

Brian

wdchyd · Mar 20, 2014

That's the right way Brian.....been doing it that way for over thirty years

I generally use 50 percent efficiency at max operating pressure (in your case 5 gpm) a point of absolute replacement.....new pump at 85-90 percent would be ok.....anything in between is a judgement call from the customer

I like to use the flow meter for monitoring after a new pump install too, the load valve makes a good break-in tool

brain55 · Mar 20, 2014

70% is usually my threshold for replacement, especially if they are complaining about performance.

Brian

brain55 · Mar 21, 2014

The one part I didn't like about the job was telling the customer that he needed a $1000 hydraulic pump plus the oil, filter, and labor. Fortunately he didn't hesitate, wince, or blink, he just said "do it". I like that kind of customer. He puts about a hundred hours a year on this machine and never hesitates to make proper repairs including cosmetic repairs. When you're a plumbing contractor you can't afford to show up with a shoddy machine in his opinion.

Brian

oldnslo · Mar 21, 2014

Brian,
How many hours are on this machine? If the pump is that shot I would be looking for the reason why.

brain55 · Mar 21, 2014

It only has about 1300 hrs. When I pull the pump next week I will definitely tear it apart and have a look inside. It went about 8 years where I wasn't the guy doing the maintenance so it may have missed some fluid changes. It didn't show any signs of cavitation when I had the flowmeter on it, but that doesn't mean that it didn't at another point.

Brian

rScotty · Mar 22, 2014

brain55 said:
It only has about 1300 hrs. When I pull the pump next week I will definitely tear it apart and have a look inside. It went about 8 years where I wasn't the guy doing the maintenance so it may have missed some fluid changes. It didn't show any signs of cavitation when I had the flowmeter on it, but that doesn't mean that it didn't at another point.

Brian

I'm following this with a lot of interest and wondering if anything crosses over to the M59. Did the customer say that there were any symptoms leading up to where he brought it in? Did he say it made any odd noises? or anything?

So far our M59 seems to be fine, but the pump will whine until it warms up - then it's silent. It does make me careful to let it warm the pump and fluid for a bit before putting it in gear for use. I also use a block heater in the winter and that works nicely. Maybe being over-cautious. It didn't do the cold whine thing when new; the cold pump whine started at about 300 hrs; now over 500 and no change that I can tell so ...... might be normal wear.

Say, that's a nice flowmeter. Looks handy. Who makes it?
rScotty M59, JD530, some others

brain55 · Mar 22, 2014

I believe it was gradual until it was problematic. It didn't sound like it worked one day and not the next. Though it wasn't mentioned when I was there in January working on some of his other equipment.

Not sure of the brand on the flowmeter. I bought it from the first dealer I worked for when he went out of business back about 1993.

Brian

rScotty · Jan 14, 2015

brain55 said:
It only has about 1300 hrs. When I pull the pump next week I will definitely tear it apart and have a look inside. It went about 8 years where I wasn't the guy doing the maintenance so it may have missed some fluid changes. It didn't show any signs of cavitation when I had the flowmeter on it, but that doesn't mean that it didn't at another point.
Brian

Brian, I was looking through some old posts and wondered if you remembered anything about this repair... How did it turn out when you opened up the pump?
rScotty

brain55 · Jan 14, 2015

rScotty said:
Brian, I was looking through some old posts and wondered if you remembered anything about this repair... How did it turn out when you opened up the pump?
rScotty

The pump was worn out from being worked. It didn't look like it was a lack of oil or cavitation.

Brian