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Discussion Starter · #1 ·
I got a 4230 John Deere with a quad range about a year ago now and after about 50 hours on it the front hydraulic pump seized because the transmission pump was so wore out. So over the winter I replaced both pumps and everything seemed to be good again but now recently I went to go mow out a pasture with a small 6 foot rough cut but I had the problem that the pto wouldn't stay engaged and it would hardly pick up the mower. Now I went to try and figure out what was wrong and went and tested all the test ports I am getting 40psi at the oil filter bypass valve, 140psi at the clutches and 2300psi at the scv's. I also took the main pump feed hose off and put it in a bucket to see how much oil was coming out and in about 40 seconds it pumped about 3L which seems way too low. The oil is clean and so is the filter and the screen. I also took the transmission pump drive shaft out to see if it was stripped off but it looks fine and the when I spun the pump by hand I could feel it build resistance. Is it possible when I had the rock shaft housing off that something fell in and is causing a blockage? Other than that I'm at a loss and I really don't know where to look elsewhere. I'm open to any advise.
 

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Ok so the supply to the front (main) pump is your problem.
So first, You said that your pickup screen is clean? The round foot long screen that is approximately one inch in diameter behind the plug that takes a 1/2 drive to remove it?
Second is your hyd filter bypass valve stuck open? It is in the small bolt on housing right behind the hyd oil filter.
Question Dear offer's a 10 micron hyd oil filter to use after repairs like yours, did you happen to use it?
Third have you changed the hyd oil filter sence you have had the problem?
If none of that works I will look in the book.

Sent from my Moto G (5) Plus using Tapatalk
 

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Discussion Starter · #4 ·
Ok so the supply to the front (main) pump is your problem.
So first, You said that your pickup screen is clean? The round foot long screen that is approximately one inch in diameter behind the plug that takes a 1/2 drive to remove it?
Second is your hyd filter bypass valve stuck open? It is in the small bolt on housing right behind the hyd oil filter.
Question Dear offer's a 10 micron hyd oil filter to use after repairs like yours, did you happen to use it?
Third have you changed the hyd oil filter sence you have had the problem?
If none of that works I will look in the book.

Sent from my Moto G (5) Plus using Tapatalk
Thank you for telling me that Deere offered the special filter, I did not use it but then I got to thinking that maybe the filter was just plugged and so I took out the filter just to see what would happen and sure enough it was just the filter the whole time. I knew I should have just replaced it but it looked like just a clean filter. Anyway thank you again for your help.
 

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RodWil just reiterated why when diagnosing problems it's so important to perform the ""simple things 1st"" utilizing the KISS theory. (y)(y)(y)
 
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