Testing Front Hydraulic Pump on 40 Series

johnyquest69 · Apr 27, 2019

Have a friend that sold a 4640 that is having hydraulic problems. 3 scv''s and 2 of them are leaking by. I think we need to cap the line going to rockshaft housing and test front pump at junction block under right hand battery box. Trying to find out threads in junction block for test gauge and also cap for line going to rockshaft housing. I'm thinking if scv's are leaking then one will need to cap line going to rockshaft to prove pump.[/quote]

Bob · Apr 27, 2019

All the info on the hydraulic fitting sizes and threads can be discerned at the jdparts website.

If you and your friend are serious about analyzing the hydraulic system, you SERIOUSLY need a factory shop manual, some good-quality gauges, and a hydraulic flow meter.

COSTLY, yes, but throwing $$$ parts at it without a diagnosis gets high $$$ soon, as well!

johnyquest69 · Apr 27, 2019

I have a shop manual I recently purchased but does not show the info I am looking for. Test port is on 24a and I think I need to cap fitting 22.

johnyquest69 · Apr 27, 2019

Also have a gauge that is acting very erratic at scv's. That is why I was wondering if I could cap line a junction block and eliminate rockshaft and scv's to prove pump. Thanks!

Bob · Apr 27, 2019

(quoted from post at 21:30:43 04/27/19) I have a shop manual I recently purchased but does not show the info I am looking for. Test port is on 24a and I think I need to cap fitting 22.

If you have a factory shop manual, it will list the thread sizes of the fittings need to check pressure.

If NOT an OEM shop manual, STOP and take a deep breath and don't proceed 'til you get a genuine/REAL factory shop manual.

I THINK this is the cap you need to cap the rear fitting, JIC cap for 5/8" line, 7/8" thread. You will have to verify it fits!

Test port is a -3 "ORB" with 3/8"-24 threads. (Maybe 1/2" on later models???)

I suggest installing a test port coupler, #RE13562, IIRC, and using the appropriate quick-connect female coupler on your test gauge to connect to it.

johnyquest69 · Apr 29, 2019

Thanks for the info Bob. Found out I can't read head and test front pump this way. I did fix leak by on all 3 scv's and solved the problem for now. Going to cap one of the scv's so it won't be a problem again.

Testing Front Hydraulic Pump on 40 Series

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