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.