Powershift acting "sluggish"/hes on JD 350C after

[davb38967]

Hi Fellows,

I'm new to this stuff, forums and all like that. I just found this forum & joined a few weeks ago. I stayed on here a couple of days just looking at pics & reading. This place is great. I've bought me a little dozer that I really like. 1st dozer that I've ever owned but it's got a problem. Hope someone can shed some light as to what it might take to fix it. It is a 1978 John Deere 350C. It is a diesel with a powershift and a 6-way PAT blade. I bought it a couple months ago on e-bay & traveled to TX from my home in MS to try it out, pay for it & bring it home. The new gravel parking lot that had just been finished with this dozer was way too nice to mess up said the mgr & I understood. I did drive it around some while steering enough to tell that it would pull left & right but couldn't give it a real workout. When I got home with it, I started using it on my place just pushing some butt cuts of a big oak tree into a pile and skimming the ground a little & it seemed to perform OK. A few weeks later, I loaded it up and took it to a deer hunting camp where some guys wanted me to shape up some of their back country roads that they used to get to their hunting spots. This is where the problem started showing up. As I started using it to push some wet clay dirt out of a mud hole & the hydraulic fluids got up to operating temp, I noticed that the powershift became real "sluggish" & had a lot of hesitation when changing from Forward to Reverse. I never noticed this happening at all during the 1st few days upon arriving home from TX w/it while pushing the tree & all, even when using it a couple hours at a time, but I never did load it down. Does this sound like maybe a fluid & filter change might solve the problem.
Thanks,
David B

[pdmech08]

Dave: Certainly a complete oil and filter change wouldn't hurt. Including engine and hydraulics as well. After all you don't really know what the previous owner did. As far as fluid and filter change correcting the problem.......possible but unlikley. In many cases once the reverser becomes sluggish and clutches begin to slip the damage is done and there is no quick fix. I would recommend changing fluid and filter and then doing a pressure test according to the book. You do have the tech manual right? If not I suggest you get one. A parts book will be very helpful as well. After doing the pressure tests, you can try following the adjustment procedures to correct any pressure problems. If the correct pressures cannot be obtained then the reverser will have to come apart. Don't worry, you're not the only one with these problems. They are common with the 350's and 450's.

[jdemaris]

Hi Fellows,

It is a 1978 John Deere 350C. It is a diesel with a powershift and a 6-way PAT blade.

This is where the problem started showing up. As I started using it to push some wet clay dirt out of a mud hole & the hydraulic fluids got up to operating temp, I noticed that the powershift became real "sluggish" & had a lot of hesitation when changing from Forward to Reverse.

Does this sound like maybe a fluid & filter change might solve the problem.
Thanks,
David B

It's a common malady and changing the oil and filter won't make it any better. Verify it's not low, though. Changing the oil and filter is a good idea anyway - especially since the filter is made of paper and blows to pieces pretty easy.

You need to check the obvious first . #1 - pull the floor-"boards" off - and look closely at the clutch pedal and linkage where is attaches to the reverser-control-valve assembly. It is an area that is subject to getting dirt and sticks stuck in it - and thusly prevents the clutch-linkage from returning all the way back when you foot is not on it. There is also a large spring that helps pull it back - and often that spring has been overstretched and ruined (during past mechanical work).

After you've verified the reverser is not low on oil, and all that linkage is clear and returing all the way back as it should - do this.
Run it - get it well warmed up. Then - open up the rate-of-shift adjuster screw. Opening it is to turn it counter-clockwise - or if you are British - "anti-clockwise." When it is adjusted properly - your crawler when hot - engine at full throttle - transmission in 2nd gear - should give a firm shift on-the-go without touching the clutch pedal. The more you open up that adjuster- the faster and firmer it will shift. If it trys to snap your neck when it engages - it's open too much.

Keep in mind that on a 350C - the main reverser clutch pressure also powers the steering clutches. If it's low - the steering clutches will slip before the reverser will and the fibers will get ruined. You might want to stick a gauge in the main-clutch-pressure port when hot and check.

If - when opening the rate-of-shift screw - you get it to shift faster - but not completly smoothly - it's due to some internal wear which you can't fix easily from the outside. When the accumlator spring - piston- and stop-bolt are out of adjustment - the shift will be almost in two parts. It will start to shift - then hestitate - and then - slam in. Other worn parts - or adjustments can also do the same thing. Many 350Cs when brand new did it - I had to fix many before they got sold.

Rate-of-shift screw is at the bottom of the reverser control valve assembly. You reach in through the track - and there is a pipe-plug you remove. Once the plug is out - there is a jet inside that takes a flat -bladed screwdriver to turn. A small stubby screwdriver works fine. When you first pull the pipe-plug out - there might be a little oil leakage - don't worry about it. The screw-adjuster inside is sealed with an o-ring a but still often leaks a little. The leakage doesn't affect anything - and once you're done and put the pipe-plug back in - all will be fine.

[davb38967]

Thanks pdmech08 & jdemaris,
I was out of pocket yesterday & did't get a chance to logon the forum. I really appreciate your help. I am going to try & get me a tech manual this week. I'll send a progress report when I have some new news & probably have some more questions before it's all over.
Thanks Again & Best Regards,
David B

[davb38967]

Hello Again Fellows,
I'm excited because I was able to purchase & download my 350C tech manual thru the JDtech website. Boy, is it packed full of stuff, 837 pages. I burned it onto a cd for safekeeping. Actually, to be honest I had my youngest brother do it for me. I'm not that computer savy.

I have been reading thru on the power reverser section & now can start to understand what you guys were trying to tell me in the earlier post.

I hope that I can get started troubleshooting real soon. I really could use it right now. The weather is starting to get nice & hot.

Just wanted to let you guys know where I was & Thanks again.
PS: I'll probably be back with some more ?'s even though I have the manual

Best Regards,
David B