Go Bottom1999 4300 MFWD HST problems
 | mech3atgsk
Join Date: Jul 2003 Posts: 6 Wilson, North Carolina 
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2003-01-23 47979
Hello, I have recently purchased a used JD 4300 MFWD tractor with 420 loader/R4 tires from a local JD dealer. The tractor has 600 hrs on it. I first suspected a problem with the transmission when I loaded the tractor on the trailer the day I bought it. The tractors transmission gave an audible noise and would not move up the loading ramp. I had the tractor in "B" range with low throttle. I moved the range lever to "A" and increased throttle to about 1800/2000 rpm and the tractor moved on up the ramp. I did not think much of it at that time. Since then I have had the tractor in a few situations where I thought the tractor should have broke traction and wheel spin should have occured. It only gave that same audible noise and the tractor stopped moving. Now after doing some research on the internet I learned that JD had a bulletin out on some early HST transmissions that stated the HST trans would lose performance and fail. It also stated that the HST filter is too small to capture the debris, resulting in the element plugging and the filter going into relief. Water may be homogenized in the oil. It noted that JD had a new HST filter and to increase the HST oil change interval. The procedure states to: Clean the suction screen before 50 hours. Then at each 200 hours to change the oil filter. At each 400 hours change the oil and filter and clean the suction screen. Now I changed the HST filter to the new one, cleaned the suction screen and the trans seems better but I am not convinced that the problem is resolved . I also learned that the audible noise is the trans pressure relief valve unloading indicating its at max pressure, which is 6000 psi. (assumming the relief valve is in proper working order and the pump is not worn excessivily.) Without a pressure test I will not know if it is the HST pump/motor or the relief valves. Does anyone know more about this HST problem? Also can anyone tell me how to identify the new MFWD axle. Thanks
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 | Art White
Join Date: Jan 2000 Posts: 6898 Waterville New York 
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2003-01-23 47981
JD was only putting the newer axle under tractors sold with belly mowers. You may want to take the tractor back and ask them to check the pressure relief valve on the hydro. It should only take an hour at max to check it and then you will know if it is right. Not all systems are created equal and you might find that other tractors simuliar to yours has the same limitations. ....
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| TomG
Join Date: Feb 2002 Posts: 5406 Upper Ottawa Valley
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2003-01-23 47987
There's a thread in the archives under 'used 4300' that has some info. Harvey described a way to tell the new and old axles. "... To tell the difference is: the new ones only have 1 hyd cylinder toward the right side and a tie rod back to the left side. IE; two ball joints at wheel on the right and only one on the left. The older style had two cylinders, one to each wheel."
Relief valves are pretty reliable things but it would be good to check the relief pressure just to make sure that's not the problem. A test shouldn't be too difficult and a manual should give a procedure. I would check a manual first to see if special tools are required. On my Ford, a special tool for PS relief valve pressure testing turned out to be a t-fitting.
The trouble was that the fitting needs metric flares and threads on one leg and NPT on the others. No such thing is available except through NH for a cost of 634 $CDN. I bought a replacement elbow for the line with the idea of seeing if a welder thinks a 3rd leg can be welded onto the elbow but I haven't gotten around to checking.
Anyway this is just a comment to illustrate how complicated what should be simple procedures can turn out. The problem was that Ford used NPT thread for hydraulic ports (which is pretty standard internationally) but stuck with metric steel hydraulic lines (which take metric flares and fittings) and ended up with fittings that nobody else in the world uses or would want to use.
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| DICK-W
Join Date: Jul 2003 Posts: 14 WISCONSIN
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2003-01-25 48133
I also have a rig the same as yours and have not encountered what you described. Is yours under warranty yet? Even though it is a 1999 it still could be under the 2 year warranty time frame depending on when the unit was placed in service . You can take the serial # off it and take it to a dealer where they can run a history of your unit. On my used 4300 that I had bought from a JD dealer, the range lever would not stay in any range you put it in. So they put a bunge cord on the under side of tractor to hold it into C range only and said it was fixed and I didnot need the A and B ranges really. Needless to say , once I discovered what they had done I took it to a more reputible dealer and had it fixed right.
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| mech3atgsk
Join Date: Jul 2003 Posts: 6 Wilson, North Carolina
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2003-01-26 48164
Thanks for the replies guys! As far as the warranty, I assumed my tractor did not have any left being a 1999 model. Also my tractor had a very similar problem with the range lever. My tractor would hardly go into A and C range. I investagated the problem and found it to be what I think is a design flaw in the range lever itself. On my tractor the range lever has too much deflection for the limited amount of front to back movement that it requires to get it in all three ranges. The lever also did not have the correct bend to clear the parking brake cable. So I ordered a new range lever only to find out it was exactly as the old one. So I carefully reshaped the new lever and installed a new roll pin. It works great now. JD must have known of the problem because on the newer models (03-4310 HST to be exact) they redesigned the range lever, making it shorter, more rigid and relocated the parking brake cable. ....
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