Log splitter pump blew fitting out - need some help!

[Kao]

Older home-made log splitter been working great for years until the hydraulic pump seized up last year.
I thought the engine had seized, but after disconnecting the lovejoys, the little 7hp engine runs just fine. Turns out the pump was seized.
I replaced the pump with a new one. Same fittings and roughly the same size and ratings - 13gpm, 3000psi, 3600 rpm.
However, after the first cycle, the 1/2" fitting blew straight out of the pump. Oil everywhere! What a mess.
The threads didn't look damaged on the pump, so I went to Northern Tool and bought a new fitting. Snugged it in tight - but not over tight or cross threaded.
And it happened again. After a cycle or two - blew the fitting right out of the pump housing.

After reading some other posts on this forum, my guess is maybe a bad/rusted pressure relief valve fitting on the detent valve. But that's just a guess.

Anyway, can you offer some advice on how to test and diagnose this? Really don't want to keep shooting oil all over my garage!

I am returning the hydraulic pump and getting a new one and a new outlet fitting just to be safe on the threads.

Thanks!

 

[Dave M7040]

Please provide Northern Tool product number for both the pump and the fitting.

Dave M7040

 

[WranglerX]

If you blew the fitting out of the pump body twice it would be my opinion the threads in pump are compromised and no amount of futzing with them is going to fix the issue.....

You might be able to disassemble the pump and chase the treads a bit deeper with proper tap, but its probably not going to be real/best solution...

IF control valve moves freely in both directions it pretty sure its not a rusted control valve or detent assembly...

Dale

 

[wdchyd]

My guess is you have the wrong fitting for that pump. Maybe you are using a 1/2npt fitting on an ORB #8? Or something like that?
Fittings do not just blow off for no reason.

 

[Kao]

Please provide Northern Tool product number for both the pump and the fitting.

Dave M7040

Fitting

Pump

If you blew the fitting out of the pump body twice it would be my opinion the threads in pump are compromised and no amount of futzing with them is going to fix the issue.....

You might be able to disassemble the pump and chase the treads a bit deeper with proper tap, but its probably not going to be real/best solution...

IF control valve moves freely in both directions it pretty sure its not a rusted control valve or detent assembly...

Dale

I agree. I thought about tapping it to 5/8, and getting a 5/8 fitting, but have since decided against it.
The control valve seems to move properly. I'm really not sure why it would blow out like that.

My guess is you have the wrong fitting for that pump. Maybe you are using a 1/2npt fitting on an ORB #8? Or something like that?
Fittings do not just blow off for no reason.

The fitting definitely fit good and tight. I brought the pump to northern with me to make sure of the fitment. Maybe I got a pump with bad threads or something.

 

[WranglerX]

OK... By link (part number) of fitting you provided, you are trying to use a SAE STOR (Straight Thread O-Ring) fitting in a NPT (National Pipe Thread) port on pump..... Wrong fitting for pump body and since pump body is aluminum I would not trust threads in it after two blow outs...

I think this is proper fitting that you want, 1/2in. MNPT x 1/2in. FNPT Swivel 90 Degree if hose connection side is NPT swivel .... BUT hose may be 1/2 inch SAE M STOR, you will have to check it out to be sure of correct hose end (female side of fitting) ...

Correct Fitting

Spec sheet for pump states outlet port is 1/2 inch NPT. The NPT fitting male end is tapered thread and seals by how tight it "wedges" in to taper of female port. STOR fitting are straight thread and depends on "O" ring to seal the connection.... Its the mismatch of thread types of 90° fitting that seems to be culprit... Use PTFE tape or high pressure hydraulic approved "dope" on tapered fitting to get good seal...

Fitting types (threads) defined here...

Hydraulic Fitting Thread Chart | Hydraulics Direct

Dale

 

[Kao]

OK... You are trying to use a SAE "O" ring fitting in a NPT port on pump..... Wrong fitting for pump body and since pump body is aluminum I would not trust threads in it after two blow outs...

I think this is proper fitting that you want if hose connection side is swivel...

Correct Fitting

Dale

Excellent! Just the kind of advice I was hoping for. Thank you. I'll try that fitting when I get a new pump.
Should I go with a steel housing pump instead of aluminium?

 

[4570Man]

I’d say you could tap the threads just a little deeper and be fine especially if they aren’t damaged to bad.

 

[WranglerX]

Excellent! Just the kind of advice I was hoping for. Thank you. I'll try that fitting when I get a new pump.
Should I go with a steel housing pump instead of aluminium?

Please reread my post I did some editing to it as I may have identifies the wrong fitting that was your wrong fitting and corrected and added some more information...

Aluminum or steel pump, can not advise you there as I have had not much experience with any pumps.... Personally I would rather it be steel for my applications but that is my old skool thinking...

Dale

 

[lennyzx11]

I’d say you could tap the threads just a little deeper and be fine especially if they aren’t damaged to bad.

I agree with this. The wrong fitting would have been a little smaller going into the NPT tapped hole.
A new correct NPT threaded fitting and pipe dope rated for hydraulic pressures may very well work.

 

[Dave M7040]

What is puzzling me is that the link to the eBay pump you provided talks about the pump being designed for electric 12 volt DC motor operation.

From Ebay web site.
Perfect replacement pump for 12VDC controlled hydraulic systems, designed for horizontal mounting, capable of quick oil output.

The rpm is 3,600 and the out port 1/2" NPT.

The fitting you have been buying is the wrong thread. It is 1/2in. F NPSM and uses an O ring.

NPT is a simple old style pipe thread with a tapered design and no O ring.

As other have said, the fitting has been blowing out because it is the wrong one!!

Dave M7040

 

[WranglerX]

What is puzzling me is that the link to the eBay pump you provided talks about the pump being designed for electric 12 volt DC motor operation.

From Ebay web site.
Perfect replacement pump for 12VDC controlled hydraulic systems, designed for horizontal mounting, capable of quick oil output.

The rpm is 3,600 and the out port 1/2" NPT.

The fitting you have been buying is the wrong thread. It is 1/2in. F NPSM and uses an O ring.

NPT is a simple old style pipe thread with a tapered design and no O ring.

As other have said, the fitting has been blowing out because it is the wrong one!!

Dave M7040

The whole web page is a full of contradictions.... Typical of seller who does not know anything about products he sells, just cuts and pastes from any source the looks impressive....

Dale

 

[Kao]

The whole web page is a full of contradictions.... Typical of seller who does not know anything about products he sells, just cuts and pastes from any source the looks impressive....

Dale

Yeah, I was trying to cheap out and go through ebay. The seller seemed to have a pretty good rating.
I had also brought the pump with me to Northern, and they fitted and sold me the fitting that I used...so a little bit of this is on them.

I'll pay a bit more and get a good pump and new fitting.

Thanks again.

 

[crazyal]

I think the patent ran out on the 2 stage pump design and now we are getting flooded with Chinese clones. Those selling them are just using the information the Chinese company making them provides. Often they just copy and past the mistakes. Since you have the pump I would use it. Other than making a mess if the fitting comes out again what do you have to loose. Not knowing how it's constructed (and I'm sure the seller has no clue) I can't offer any advice about being an aluminum body. I would expect that aluminum would wear faster unless you stay on top of changing the oil and filter. But it could be made with a steel liner like how some small gas engines are made.

 

[Kao]

I think the patent ran out on the 2 stage pump design and now we are getting flooded with Chinese clones. Those selling them are just using the information the Chinese company making them provides. Often they just copy and past the mistakes. Since you have the pump I would use it. Other than making a mess if the fitting comes out again what do you have to loose. Not knowing how it's constructed (and I'm sure the seller has no clue) I can't offer any advice about being an aluminum body. I would expect that aluminum would wear faster unless you stay on top of changing the oil and filter. But it could be made with a steel liner like how some small gas engines are made.

I already have a return authorization for the pump and a full refund. I just don't trust it now. I'll get a new pump and fitting and see how she goes.

 

[crazyal]

I already have a return authorization for the pump and a full refund. I just don't trust it now. I'll get a new pump and fitting and see how she goes.

That's great the seller is taking it back. Of course they probably will resell it.

 

[triptester]

Typically nearly all the aluminum body 2-stage pumps are made in China even when sold as US OEM . These same pumps are manufactured for many different countries which use similar looking hydraulic fittings that do not match SAE. The pump could have been built for sale in another country, even in the US there are multiple styles of fitting used.

 

[WranglerX]

Any resolution to this problem?

Dale

 

[LD1]

THey dont make a "steel" housing pump to my knowledge.

But they do make cast iron bodied pumps. Get one of them. They arent a whole lot more money for a knock off cast iron pump.....but even a concentric brand pump is only $200, and that pump should last the average homeowner log splitter a lifetime.

 

[RickB]

My guess is you have the wrong fitting for that pump. Maybe you are using a 1/2npt fitting on an ORB #8? Or something like that?
Fittings do not just blow off for no reason.

Exactly my thought. A -8 ORB male will screw in a 1/2 NPT female port or fitting and hold minimal pressure before it spits out.