Jd 6420 transmission overheating

Pwquist · May 24, 2011

12r syncroplus transmission over heats after 3 hours or so pulling 926 mower conditioner heat gun reading up to 230f. Changed fluids and filter. No cleaning screen visible at larger filter as indicated by manual. Any ideas of what my problem may be. 1500 hours on tractor. Thanks

madmikey76 · May 25, 2011

there is a internal suction screen usually on the front of the trans. There will be a cover with 2 bolts and an o-ring. I would check there first. It definatly sounds like there is a restriction somewhere. I have seen hydrolic oil get op to 800 degrees due to a restriction in the suction screen.

Tx Jim · May 25, 2011

Have you ever cleaned the hyd oil cooler?

Tx Deere · May 27, 2011

I know there is an internal air pump in the front of the transmission if it is not working the trany oil will overheat. You need to check and make sure the oil level isn't overfull because that will cause overheating for sure.

bobhill · May 28, 2011

I have a 6420 with IVT transmission which overheated after using a HX15 bush hog for about 3 hours. The problem turned out to be an incorrect setting on the remote hydraulic outlet PLUS my putting the hydraulic control in the cab in the float position. I think I was dead heading the pump. What position were your outlet settings and control valve in?

Maynard Reece Byrd · Jul 1, 2011

bobhill said:
I have a 6420 with IVT transmission which overheated after using a HX15 bush hog for about 3 hours. The problem turned out to be an incorrect setting on the remote hydraulic outlet PLUS my putting the hydraulic control in the cab in the float position. I think I was dead heading the pump. What position were your outlet settings and control valve in?

How do you like the IVT. I have a couple of 7330's with IVT I am looking at for a loader tractor.

tjnoonanndt · Jul 1, 2011

Hi make sure your rad is clean and that the oil cooler is getting enough coolant flow. On earlier 20 series rads gave trouble mixing hot coolant (system one) with cold coolant(system two) causing rear end to over heat. check which rad in your tractor. Easy way to check if oil cooler getting coolant make sure intercooler not red hot just lukish warm and hoses returnin from cooler are warm do yhis with cab heating off. best of luck

bobhill · Jul 8, 2011

Maynard Reece Byrd said:
How do you like the IVT. I have a couple of 7330's with IVT I am looking at for a loader tractor.

I,ve driven a couple dozen John Deere tractors over the last 57 years with collar shift, synchronized shift, hi-lo, hydro, power shift of the 8 and 15 speed types, power quad, and lastly the IVT transmission. It is far and away the best transmission I have EVER used. It has any speed you want between a small fraction of 1 MPH and 26.5 MPH and is incredibly smooth with absolutely no perceptible shifting. I particularly like the economy mode where the control system adjusts BOTH the throttle and transmission ratio to give you the ground speed you set with varying loads. I use the 6420 IVT tractor primarily to pull an 11 row 1780 soybean planter and a 15' HX15 rotary cutter - don't have a loader on this tractor, though I'm thinking of getting a 673 self leveling for it.