Log Splitter Diagnostics.

[Robb55]

I have an MTD 24BF550B029 log splitter which seems to be a very common and frequently relabeled model. The cylinder goes up and down. But, it refuses to split and it doesn't seem to strain the motor. I replaced the pump seals which didn't fix it. Then, I rigged a pressure gauge on cylinder line thinking it was the control. But I registered 3000 PSI and strained the engine. That doesn't leave much to suspect but the cylinder.

The cylinder rod doesn't leak oil. So, would it be reasonable to conclude that the piston seal is blown? Does that happen very often and is there some test I can do to confirm that?

Also, is 3000 PSI a reasonable amount of pressure for a 27 ton splitter cylinder or

 

[muddstopper]

to check the cylinder, Extend the cyl all the way out, make sure cyl is all the way extended or you will make a big mess. Remove and plug the hose from the rod end at the cyl. Try to extend cyl with control and see if any oil squirts out of the open, rod end, port. If it gushes out oil, then the seals are blown.

 

[NSMaple1]

You said it doesn't seem to strain the motor - but when you put the gauge on it strained the engine?

Clarification?

 

[Robb55]

You said it doesn't seem to strain the motor - but when you put the gauge on it strained the engine?

Clarification?

I use engine and motor interchangeably sometimes. It has an gasoline engine. I deadheaded the output hose with the gauge assembly which forced the pump up to the maximum pressure as permitted by the relief valve. Since the gauge indicates almost exactly 3000 lbs and it nearly stalls the engine, I believe that the pump and relief valve as well as the control valve are working correctly. When I rebuilt the pump, I torqued the relief valve cap to manufacturer's specifications. It's a Haldex two stage pump.

 

[ChoppyChoppy]

What seals would you have replaced in the pump? There usually isn't anything serviceable in those cheaper pumps.

If it's able to make 3000psi at the cylinder when trying to split, it wouldn't be the piston seals. If those seals were bad, it wouldn't make pressure. (would bypass the seals instead)

 

[Robb55]

What seals would you have replaced in the pump? There usually isn't anything serviceable in those cheaper pumps.

If it's able to make 3000psi at the cylinder when trying to split, it wouldn't be the piston seals. If those seals were bad, it wouldn't make pressure. (would bypass the seals instead)

It has three 3 rather small rubber O rings that can get brittle and leak and I checked it for pitting and other wear and made sure the relief valve was in good shape and properly adjusted. It's not a particular difficult task. It has special gaskets between the sections that fortunately didn't have to be replaced. If it is leaking internally, you can usually see marks. Everything looked clean.

 

[NSMaple1]

What seals would you have replaced in the pump? There usually isn't anything serviceable in those cheaper pumps.

If it's able to make 3000psi at the cylinder when trying to split, it wouldn't be the piston seals. If those seals were bad, it wouldn't make pressure. (would bypass the seals instead)

From his last post it sounds like he unhooked the hose feeding the cylinder on push stroke, and hooked the gauge to the hose end. Which means no oil going to cylinder when pressure tested. I thought at first that he T'd a gauge in as would typically be done.

 

[ChoppyChoppy]

From his last post it sounds like he unhooked the hose feeding the cylinder on push stroke, and hooked the gauge to the hose end. Which means no oil going to cylinder when pressure tested. I thought at first that he T'd a gauge in as would typically be done.

Ah, ok that make sense.

T into the line and see what it's making for pressure. Should be able to dead head the cylinder and make the same pressure.

I'd suspect that the piston seals are bypassing, but would be wise to confirm by testing before tearing apart the cylinder. Some wood splitter cylinders are welded at both ends, need to cut the gland off (normally done on a lathe)

 

[Robb55]

What seals would you have replaced in the pump? There usually isn't anything serviceable in those cheaper pumps.

If it's able to make 3000psi at the cylinder when trying to split, it wouldn't be the piston seals. If those seals were bad, it wouldn't make pressure. (would bypass the seals instead)

It has three 3 rubber O rings that can get brittle and leak and I checked it pitting and other wear a

 

[Robb55]

Ah, ok that make sense.

T into the line and see what it's making for pressure. Should be able to dead head the cylinder and make the same pressure.

I'd suspect that the piston seals are bypassing, but would be wise to confirm by testing before tearing apart the cylinder. Some wood splitter cylinders are welded at both ends, need to cut the gland off (normally done on a lathe)

I would like to put a T in the line if I can find a fitting. I've been rigging things with brass and galvanized parts which let me test before and after the control valve. I sure hope it isn't a welded cylinder. What a pain that would be to service.

 

[NSMaple1]

Brass & galvanized? Sounds like plumbing parts? 3000psi can blow those up before you know what's coming at you. Be careful.

 

[Robb55]

Brass & galvanized? Sounds like plumbing parts? 3000psi can blow those up before you know what's coming at you. Be careful.

Yup. I'm a redneck making do. So, I only run it up briefly and try to stay out of the line of fire.

 

[Yarz]

I just watched a video recently that showed how to test the internal seals, and explained why:

 

[Robb55]

Another day and more information. I did rig up an in line gauge as suggested. And then....it didn't stall. It split a log and then another. So, in order to make it fail again, I took back to the field. I split a few logs and then the cylinder stalled. The gauge read about 600 PSI while it was stalled. I worked the lever up and down a couple times and it kicked in and finished splitting the log. I got it to do this a couple of times and then it started raining and I had to pack it in. According to the specifications for the Haldex two stage pump, the second stage is supposed to take over at 450 PSI.

One difference between now and before is that it has warmed up a bit. When it failed before, it was below freezing outside and now its 45 degree F.

Can the pump be intermittent? Is there a way to fix that? I already replaced the O rings in the pump.

 

[Robb55]

Another day and more information. I did rig up an in line gauge as suggested. And then....it didn't stall. It split a log and then another. So, in order to make it fail again, I took back to the field. I split a few logs and then the cylinder stalled. The gauge read about 600 PSI while it was stalled. I worked the lever up and down a couple times and it kicked in and finished splitting the log. I got it to do this a couple of times and then it started raining and I had to pack it in. According to the specifications for the Haldex two stage pump, the second stage is supposed to take over at 450 PSI.

One difference between now and before is that it has warmed up a bit. When it failed before, it was below freezing outside and now its 45 degree F.

Can the pump be intermittent? Is there a way to fix that?

 

[triptester]

On a 2-stage pump the high pressure or second stage is always producing flow or kicked in. The low pressure section will by-pass at a preset setting of 600-900 psi.
One reason it may work inside and not outside is that the fluid level maybe low and if the splitter is tilted slightly the wrong way the pump could be starved for hydraulic fluid.

 

[kevin j]

600 psi might be a clue.

As trip said, the small section is always connected to output. The larger section adds to the output when the load is less than the unloader setting. The output is ‘high flow’ the sum of the two sections.

When load pressure rises above the setting the large section unloads back to its own inlet and output is only the small section, low flow. There is a check valve between the large section and the output to keep the small section from going back to the unloaded valve. If that check valve sticks open, the entire pump will max out at the unloader valve setting.
Check this by adjusting the unloader setting on the pump. It will be under a cap usually. Move it up or down and see if the gauge reading follows. then it is likely the check valve leaking.

If it does not change, it might be cylinder seals. Test as described by others.

 

[Robb55]

I see from the diagram for the pump that there is an adjustment screw under a cap by the low pressure inlet. I will fiddle with that and see what happens. Thanks for your help.

 

[Robb55]

600 psi might be a clue.

As trip said, the small section is always connected to output. The larger section adds to the output when the load is less than the unloader setting. The output is ‘high flow’ the sum of the two sections.

When load pressure rises above the setting the large section unloads back to its own inlet and output is only the small section, low flow. There is a check valve between the large section and the output to keep the small section from going back to the unloaded valve. If that check valve sticks open, the entire pump will max out at the unloader valve setting.
Check this by adjusting the unloader setting on the pump. It will be under a cap usually. Move it up or down and see if the gauge reading follows. then it is likely the check valve leaking.

If it does not change, it might be cylinder seals. Test as described by others.

I took it out this morning and split a few pieces until the cylinder stalled again and then I remove the cap and adjusted the check screw up and then down. The low side pressure went up until it nearly stalled the engine at around 800 PSI and went down as I turn screw back. But, the high pressure side of the pump did not kick in. So I guess it's time for a new pump unless someone knows how to fix that. I already replaced the O rings in the pump.

 

[kevin j]

Take the check valve out and inspect. It is usually a hex cartridge with no adjustment.
The unloading valve is the cartridge you adjusted.
Cartridge checks usually can’t be taken apart, but there may be a wire ring holding it together or maybe you can blow through with cleaner or air.
The orings around the outside of the cartridge are not usually an issue, it is some junk inside the ball or poppet or spool and the seat.

I doubt they sell parts separately or if so, might be half to 3/4 cost of new pump, but it is worth checking online somewhere.

If it is broke now, you can’t make it worse.