John Deere 450c dozer transmission issues

[SChunter1991]

I am the proud owner of a john deere 450CC Dozer sn #: 195007T with unknown hours and unsure of machine history. I have changed the transmission fluid(used tractor supply john deere equivalent), cleaned the screen and replaced the filter I noticed fluid inside the bell housing when making the adjustment after fluid change. I believe I may have over filled the transmission as the level appeared high on the dipstick. I drained fluid out until it was at the proper level. I used a boroscope to inspect inside the housing and there appeared to be 2-3” of fluid in the bottom of the housing. I then dropped the skid plate and cleaned out the drain port at the bottom of the bell housing. After getting the fluid level right I haven’t noticed anymore accumulation of fluid in the bell housing.

I went through the HLR adjustment and found the pressure to be low. I removed the pressure control valve cap and found there were already shims stacked in side the cap. I was only able to add one shim and still get the threads to catch. After adding the shim the pressure was in range per the spec. I then went back through the HLR adjustment procedure. Initially, the machine would push and shift great. Both tracks would spin when pushing against an immovable object. However after running the machine for approximately 20 minutes it became weak and unable to push much of anything. The shift also became sluggish. I have used the machine several times and each time it performs the same. Strong initially, then progressively weaker. What else do I need to look at?

[Jim B]

Welcome to the Boards.

You may have some seals starting to fail. Cold oil can hide some leakage. As the oil and components warm leakage will increase. The other thing is a pump that is worn generally drops off as it warms. If you leave the gauge in place does the oil pressure change as it warms up?

[NIKinNZ]

Hello, i have the exact same problem, when you say a seal issue, do you mean the seal between the transmission and engine? Also does anyone know where to get a pressure tester? or what the specs are for making one up?

[Jim B]

Oil in the engine clutch area can come from a leaking engine rear main seal (oil will be the same color as the engine oil on the dipstick) or the input shaft seal of the transmission (oil will be the color of the oil in the transmission).

There should be a cotter pin hanging out of a hole in the center bottom of the clutch housing. It should be loose in the hole. It is a "jiggle" pin, being loose in the hole it can move around to keep the hole open to allow any oil to drip out and not build up and contaminate the engine clutch. Dirt can get built up around them and the hole plugs. That sounds like what SChunter1991found on his.

Have you done the adjustments and diagnostic steps in the manual? As when you have asked before, that is the only way to narrow the possible causes down. The "pressure tester" is just a pressure gauge, your manual should tell you the pressure range needed. There is generally a section that give specifications and special tools at the end of the section group (should be in the powertrain section in this case) You should be able to get gauge(s), hose(s), and fittings locally. I believe a 300 psi gauge will work.

[NIKinNZ]

Thanks Jim, i just need to make up a pressure tester to do all the diagnostics, but i have a similar situation, from cold it starts up fine and pushes and moves well but after 5 mins or so (once warmed up) it loses all pushing and moving power and i have noticed oil dripping out of the cotter pin hole, i presume that would mean the main seal between the transmission and the bell houseing (i presume there is one) has failed? i will get a pressure tester and test a few more things.

[Jim B]

SChunter1991,

I should have noted before that if you found a lot of oil in the clutch housing, it could have contaminated the engine clutch. The clutch might grip when cold and slip as it warms. Install your pressure gauge and leave it in while running your crawler to see if the pressure is dropping when it gets warm. If the pressure comes up to your setting and it still has trouble moving that could be the engine clutch slipping.