450E transmission 3rd time around Help needed!

[deey]

Let me start with the history. The first problem occurred after the dozer got hot. While pushing if I shifted from high to low while under a load the transmission would sometimes not shift it would seem to neutralize, or if it did shift to low it may push for a short time and then stop just like it was shifted to neutral. When the problem occurs there is no slippage that I could feel and if shifted to high the transmission would start pulling again. I used the machine this way for about a month and the center of the engine clutch broke and required replacement. Upon tear down I found the transmission input shaft badly worn and decided that since I was going this far that it would be a good idea to check the HLR clutch packs as well. I replaced the engine clutch, pressure plate release bearing and pilot bearing. The transmission pump, clutch oil manifold, all steel and fiber plates and piston seals in the HLR assembly were replaced with new parts from J.D.
The machine was reassembled and did not have oil pressure from the transmission pump. Second time around I found that J.D. sold me the wrong transmission pump gears. The replacement gears were for another transmission and were to thin for my application and would not pump oil. Now for the third time. The dozer was put back together and seemed to work well until it gets hot now I have the neutralizing problem in both high and low range same symptoms as the original concern now only worse because both ranges are affected. Due to my frustration I hired a John Deere technician to come diagnose this problem so that I would know what to look for on my third try. He hooked his pressure gauge and found no pressure with the engine running and both shifters in neutral. He then told me that this indicated a large internal pressure leak. He advised me to again tear down the transmission look for any cracks blown seals etc. The transmission is now apart and upon visual inspection no problems are seen. Upon calling him today he asked how the steering worked the last time I used the dozer since the steering system shares oil pressure with the transmission. I told him that the steering clutches both worked well while using the dozer. He said that he was very busy and it would be a few weeks before he could get by to take a look. He seemed as perplexed as I am. If anyone has any suggestions as to what I can look for next send me an E mail at deey@bellsouth.net and if your willing to talk send me a number.

[JWB Contracting]

We had a similar problem with a 450C. The mechanic is on the right track - look for the pressure lines feeding the steering cluches as they have o-ring / rubber conectors between the pipes/case to channel the oil. This is the problem that we had. We bought the machine at auction in the dead row. Someone had done a complete rebuild on the tramission and steering cluches but could not get it to move. It took us two tries to fix it.

[deey]

The 450E is still down due to the transmission problem in my previous post. I have closely inspected all of the HLR parts I see no signs of cracks, all seals and o rings were inspected and found to be O.K. I have a pressure loss in high and low, pressure will start at 165psi and as the dozer heats up the pressure will fall off and then the transmission will neutralize, sometimes a touch of the clutch will be enough to make the pressure rise again and sometimes not. The transmission always has pressure in reverse. There is no pressure with the HLR lever in neutral, and the J.D. tech I consulted with says that I should have the 165 psi in neutral and this indicates a large pressure leak. I cannot find a pressure spec in my manual for engine running transmission HLR lever in neutral. I would like to confirm his statement that I should have pressure in neutral. The tech also said my pressure loss could be in the steering circuit of the dozer, if this is so can I block the line from the transmission to the steering clutch valve and see if my pressure comes back in neutral ? I would also mention that the dozer always steers perfectly. Any Ideas are appreciated.