New 16 gpm pump issues on a wood splitter

[C Steffens]

Hi everyone,

First post and new to the group. Hope you guys can help.

A few weeks ago I inherited an old wood splitter with the following specs:
8 hp Briggs engine 319 cc,
4 inch cylinder with 2 inch rod,
24 inch total displacement when rod is extended,
And a Viking pump with unknown stages or gpm.

I used the splitter for a few hours and it seems so do fine except with some gnarled oak that it struggled with. The pressure gauge at max struggling showed 2000psi during these times.

After the afternoon of splitting I noticed the pump was leaking a little bit and not being able to tell it's size, I figured it might be a good time to replace it. I purchased a 2 stage 16 gpm Haldex pump from Northern. Today I changed out the pump, replaced 3 hydraulic hoses (badly cracked) and fired it up. I ran it for about 15 minutes to purge any air back to the reservoir. And went
forward and back half a dozen times for good measure.

But to my amazement, when I tried to split that gnarled oak from the previous weekend it could not split it. And the strange part is that pressure gauge only ever ready about 900 psi! How is this possible? My understanding in looking at the specs on the Haldex 2 stage 16 gpm is that it should produce 3000 psi during the second stage when the splitter is struggling with a piece of wood.

So that's my quandary. Hope I did something wrong because if 900 psi is normal, on this 16 gpm Galdex pump, I'll go back to a leaky Viking pump with 2000 psi any day of the week.

Thanks in advance for the help and replies.

Chris

 

[Mntn Man]

I was recently having the same issue. I could only get about 500 psi unless I held the cylinder against the detent. Doing that, I could get about 1700 psi. Turned out that my cylinder was bad. I ended up testing the pump by capping the line with the gauge in it. I slowly pulled the motor over and watched the pressure go briefly to 3000 psi. You can test the cylinder by fully recessing it then plug the return side of the valve and push the valve to retract. If oil comes out of the open port on the cylinder, it is getting through the (bad) packing. Hope this is understandable. Good luck.

 

[C Steffens]

Thanks for the reply. When you capped the line with the guage on it, did you fire up the engine or just pull the cord gently until 3000psi was reached? How did you relieve the pressure without uncapping the line and hydraulic fluid spraying everywhere?

I do understand what you suggest regarding the cylinder. I should mention that the psi is about the same if I hold it against the detent....900 psi give or take.

I will test the cylinder, but I am doubtful that the cylinder is the issue since last weekend I was reading a strong 2000 psi with the older Viking pump.

Chris

I was recently having the same issue. I could only get about 500 psi unless I held the cylinder against the detent. Doing that, I could get about 1700 psi. Turned out that my cylinder was bad. I ended up testing the pump by capping the line with the gauge in it. I slowly pulled the motor over and watched the pressure go briefly to 3000 psi. You can test the cylinder by fully recessing it then plug the return side of the valve and push the valve to retract. If oil comes out of the open port on the cylinder, it is getting through the (bad) packing. Hope this is understandable. Good luck.

 

[Mntn Man]

I just pulled fairly slow, I don't think it would start anyway as the pressure jumps up really fast. Pressure relieved itself. I had used a male quick disconnect just in case it didn't.

 

[triptester]

After changing pump and hoses some crud particles may have gotten into the pressure relief in the control valve keeping it from closing fully.

 

[C Steffens]

I think I've gotten to the bottom of my issue. As I face the Haldex pump shaft, it is supposed to turn clockwise, in fact there is an engraved arrow confirming the rotation. As I face my old Briggs and Stratton engine, guess what, the shaft turns clockwise as well. Putting the two together would mean my new pump is turning counter clockwise. Not good. Clearly somewhere along the line Briggs started making shafts that turn counterclockwise, but apparently mine is old enough to turn clockwise.

So the big question is did I damage my pump by running it counterclockwise for 15 minutes just idling and then trying a few logs thereafter?

After changing pump and hoses some crud particles may have gotten into the pressure relief in the control valve keeping it from closing fully.

 

[dave_dj1]

I doubt you damaged the pump, some pumps in fact can be reversed by switching around a plate in them if so equipped. I guess you'll be shopping for a new motor, the Predator 6.5 hp can be had at Harbour fright for 99 bucks.
Good luck
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[C Steffens]

That's good news. Would you happen to know if this Haldex/Concentric 16 gpm pump can be reversed as you mentioned? Any idea how to do it? I'm pretty handy and at this point I have nothing to lose before checking out the Predator engines. Personally I'd rather keep my Briggs. She's old but still running well.

Chris

 

[dave_dj1]

I don't think a two stage pump can be reversed although the internals are similar.

 

[C Steffens]

The plot thickens... She when I got home today, I double checked the rotation of my Briggs engine. I am happy to report that the shaft does indeed turn counter clockwise when facing the shaft. This makes more sense as I was dumbfounded that Briggs would have ever changed the rotational direction at some time in its past. The good news is that my new 16 gpm 2-stage Haldex pump is indeed installed correctly and rotates in the clockwise direction. Bad news it's still not producing the psi it should.

So now I am back to square one. Why, when under load, is the pump not putting out the 3000 psi it should in the second stage?

Tomorrow, barring daylight savings and these early sunsets, I will put the pressure guage right in the output of the pump to see if I can pull the engine gently and get some better numbers.

What are the chances this is a bad pump?

Chris

 

[Mntn Man]

Don't get too excited until you do the test on the output. I just about drove myself crazy because I needed to get some splitting done and money was a big issue. I ended up spending almost $300 in testing and parts and I still need to buy more oil as I lost plenty replacing things.

 

[ChoppyChoppy]

A pump doesn't make pressure, just flow. Pressure is caused by restriction of flow.

Provided the oil is fine (not sucking air) something is leaking. Pump, cylinder, valve, pressure relief.

 

[Marshy]

A pump doesn't make pressure, just flow. Pressure is caused by restriction of flow.

Provided the oil is fine (not sucking air) something is leaking. Pump, cylinder, valve, pressure relief.

Not entirely true. A pump produces flow and discharge head (psi). At any given flow there is a discharge pressure. They are inversely related so if flow goes down pressure goes up etc. Those two parameters are a direct function of the system resistance. Resistance goes up, flow goes down, pressure goes up. With the pump discharge blocked (highest system resistance) you will reach the maximum discharge pressure.

You don't really ever want to run the pump there, especially if it's a positive displacement as it will ruin the pump. Testing it like how was advised is fine though.

 

[Big_Eddy]

Assumption - you are running the engine at full throttle - correct?

Describe what happens in more detail please.
Start with the cylinder fully retracted and a "normal' log on the beam touching the wedge / log stop.
Advance the lever forward and hold.
The ram should advance quickly until it touches the log, then it might "slow down" and continue to advance at a slower pace until the log pops, then speed up again to the end of the stroke.
Watch the pressure gauge. At what pressure does the speed change? It's probably around 600-700psi. What's the maximum pressure before the log splits?
Listen to the engine. Do you hear it loading up before the ram speed drops, then "unloading" slightly as it slows down?
Or does the engine speed stay constant? Or drop off significantly as soon as the ram contacts the wood?

Now repeat the process with your tough guy.
What's different?

Exactly what model of Haldex pump did you buy?
A 16GPM 2 stage pump may be too much for your 8HP engine - especially if it's a bit tired. It will depend on where the reliefs are set

 

[C Steffens]

Here's what I found and tested this afternoon:
The pump is Haldex/Concentrics model 1001507, 16 gpm 2 stage

When I split a log as sugggested in the last post, the ram slows down slightly as it engages the wood and as you suggested the pressure briefly rose to just under 300 psi. The engine barely changed tone or effort and continually ran at 3200 rpm according to my meter. An easy split.

When I repeat with a tough piece of wood, the engine does sound like it is under stress, the rpms drop slightly but nothing close to stalling or bogging down. If I relax the valve handle the engine recovers with no issues. The psi during the attempted split is no higher than 800 psi. If I up the throttle to 4000 rpm and repeat, the pressure again does not exceed 800psi and the wood does not split.

So just for fun I took off the Haldex pump and put back my old Viking pump who's gpm I have no idea. I fired up the Briggs and went to town on the gnarled oak. As the ram hit the wood the engine lowered as it had done with the Haldex pump, but the pressure rose to 2000psi and then topped out. Still didn't split the wood but at least my psi was respectable. I strongly suspect the psi is topping out at 2000 psi due to the Brand Hydraulic relief valve which is preset at 2000 psi. If the incoming weather holds off I will adjust the relief valve higher and see what the Viking pump does.

So I'm still at a loss why this new 16gpm Haldex pump will not build to a higher pressure.

Additionally, as suggested by Mnt Man in an earlier post, before I changed out the Haldex, I capped the out line from the pump with the pressure gauge and gently pulled the Briggs starter line and interestingly enough the pressure would not build at all. The needle barely budged and did not hold pressure between pulls. The engine did not start during this test and despite 10 or multiple pulls I could not build any significant pressure.

Chris

Assumption - you are running the engine at full throttle - correct?

Describe what happens in more detail please.
Start with the cylinder fully retracted and a "normal' log on the beam touching the wedge / log stop.
Advance the lever forward and hold.
The ram should advance quickly until it touches the log, then it might "slow down" and continue to advance at a slower pace until the log pops, then speed up again to the end of the stroke.
Watch the pressure gauge. At what pressure does the speed change? It's probably around 600-700psi. What's the maximum pressure before the log splits?
Listen to the engine. Do you hear it loading up before the ram speed drops, then "unloading" slightly as it slows down?
Or does the engine speed stay constant? Or drop off significantly as soon as the ram contacts the wood?

Now repeat the process with your tough guy.
What's different?

Exactly what model of Haldex pump did you buy?
A 16GPM 2 stage pump may be too much for your 8HP engine - especially if it's a bit tired. It will depend on where the reliefs are set

 

[Marshy]

Interesting... it almost sounds like the pump isn't kicking into the second stage to build the higher pressure.

 

[C Steffens]

I was thinking the same. Hard to imagine on a new pump.

Interesting... it almost sounds like the pump isn't kicking into the second stage to build the higher pressure.

 

[Marshy]

I was thinking the same. Hard to imagine on a new pump.

I'd give the manufacture a call and see if they can help you out.

 

[dave_dj1]

Yup, sounds like the pump.
You could try to adjust it but not sure if that is a good idea or not, I would get ahold of manufacturer and see what they say. Could be a bad pump. QQ ya know!

 

[triptester]

Interesting... it almost sounds like the pump isn't kicking into the second stage to build the higher pressure.

On a 2-stage pump the high pressure / low volume section of the is in operation at all times. The low pressure / high volume section bypasses when preset pressure is met.
The key that holds one of the gears of the high pressure section may be broken or missing.