4250 powershift

[PHOY]

Looking for some help on a JD 4250 with powershift trans. 13 and 15 speeds are slipping and maybe 11 but not for sure. I tried the slip test in 7th and 8th but can't stop the tractor in either gear. Tractor pulls down but the brakes won't kill the tractor and it won't stop. The lube pressure drops 4 or 5 psi from 10 psi in gears 12 thru 15. Also system pressure is running low, around 160 psi. Anybody seen something like this? Any help would be appreciated.

 

[4520BW]

My 4250 lost several gears..can't remember which ones as was 10 years ago...but ended up splitting it and found a crack in a clutch pack and burnt clutch discs...wish I could remember!! I did make a set of long hoses on the gauges to read the pressure while in the cab.

 

[tim s]

Here is a schematic of the shift components..go through the speeds 1 by 1 when it's warmed up and make a note of each spd..and compare what you have with this chart and it will give you and idea of which function is failing,, there are 4 clutch/brakes applied for each speed..they are listed at the top of the chart, let us know what you find...it's a start...

 

[PHOY]

Thanks for the chart Tim s. I did go thru the speeds but I was checking the lube pressure and sys pressure. Is that what you think I should be checking? The only big thing I noticed was the pressure drop from 12 thru 15. What should I be looking for in the pressures? Sorry I am kind of new to pressure checking.

 

[tim s]

To check it correctly you will several gauges and you would mark down the pressure readings of each function I use an old 8spd gauge set plus a couple individual gauges..But if you warm it up and go through each speed trying to notice some thing not right and noting it then compare what you noted to the speeds involved on the list, it can maybe point to the clutch or brake in question to hint where to start C-2 clutch is the one that shows wear first most of the time, and it can slip from just plain being worn out or a packing leaking can cause it not to engage strong enough, they are a good transmission for the most part. Get a little more info and tell use what you find and we can point you in the right direction,,has the trans light flickered when warmed up?....

 

[PHOY]

The trans light doesn't come on at all. If the trans pressure is only running 160 psi should I shim that to get the pressure up first before I test anything else or is 160 an ok range? Tractor has 9300 hours on it so the pump may be wearing down. Thanks for the advice. I will put a gauge back on the tractor tonight and see what I get going through the gears.

 

[PHOY]

Had time to pressure check the lube pressures last night. They were as follows:
1=18
2=18
3=18
4=20
5=21
6=20
7=20
8=20
9=20.5
10=19.5
11=20
12=11
13=12
14=11
15=12
The system pressure was pretty consistent around 160. According to the chart would that lead me to believe c1 or c2 is leaking?
Thanks for the help!

 

[tim s]

Seems like C2 takes the beating mostly..