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Looking for an education on an off-colour product - JD 8650


Ian Beale

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Neighbors had one , they only wear yellow underwear over there . He's had to do many head gaskets. I've been told that the issue is not a frame really and the front axle mounts to the oil pan basically. If you go over rugged terrain while using horsepower pulling something hard they flex and cause issues. 

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The 8650 was the best of that series. like mentioned on here the head gaskets. Were a issue. There is really no space between the sleeves with any casting for the block on the 619. The 619 was the 531 5020 block updated with a larger bore. The head gaskets problems were really more man made after the mechanics changed one they usually were going to leak bad then. The same engine was used in the 60 ,70 series mounted on rubber and they seemed to last. The 8650 head improvements in rear end they had the biggest axles, bigger planetary, front frame split for easier engine service and so on. They basically had the 30 series design the best it was going to be by then. If you treated them okay they did last if you abused them they were a money pit.

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I have one. I’ve had quite a bit of engine trouble with it over the years. A lot of my problems stopped when I got a different head and put on it. Mine has over 10,000 hours and the transmission/final drives have never been touched. It has had the high/low clutch pack replaced. They all have the Deere quad range transmission as the only option. They were ok tractors, but are getting old now. I have an 8640 that has a Kinze 855 Cummins conversion on it and it is a much better setup than the original Deere design. If I was going to buy another 30/40/50 series Deere 4wd it would have to be pretty reasonable or preferably have a Kinze repower on it. The steering and handling of those tractors is better than any other 4wd of that vintage, much better than my Steiger of the same age. 

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The dozer blade isn’t a real concern. If they had a blade made by John Deere or degelman. The mounting frame actually connect the side frames , axle mounting holes to the front hinge casting. Made a subframe if you want to call it that. A 4 x 6 tube frame with 4 bolts  on hinge and a extra frame and bolts connecting axle housing , block to frame. A Leon blade used a pin on hinge area , so it wasn’t as strong. The myth that tractors had no frame isn’t all truth. There is a plate steel frame 24 inches wide tapered to the front that is a frame member. This should have been 1/2 or thicker with a couple more cross links would have stiffened things up well. The axle mounted to the block supports that bolted to the side frames though. On the early 30 series , these were the only ones effected by block twisting the main bearings. It was more in western , hilly ,rolling land. Tractors would cross gullies or ravines under power and the main bearings would tighten clearance. the fix was a more looser fight main bearing and it stopped those problems. Really by the time the 50 series tractors were out they were pretty reliable and the shortcomings were addressed by then. This engine went on for two more series with very good reputation and 350 hp so it was sorted out by then.  I had every part and piece of a JD 4wd in my hands at one  point or the other from the front headlight casting to the rear PTO shaft nothing that caused lots of pains that weren’t fixed by the 77  model year 30 series which essentially was a 40 series as they had made many minor changes in them. 

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1 hour ago, dale560 said:

The dozer blade isn’t a real concern. If they had a blade made by John Deere or degelman. The mounting frame actually connect the side frames , axle mounting holes to the front hinge casting. Made a subframe if you want to call it that. A 4 x 6 tube frame with 4 bolts  on hinge and a extra frame and bolts connecting axle housing , block to frame. A Leon blade used a pin on hinge area , so it wasn’t as strong. The myth that tractors had no frame isn’t all truth. There is a plate steel frame 24 inches wide tapered to the front that is a frame member. This should have been 1/2 or thicker with a couple more cross links would have stiffened things up well. The axle mounted to the block supports that bolted to the side frames though. On the early 30 series , these were the only ones effected by block twisting the main bearings. It was more in western , hilly ,rolling land. Tractors would cross gullies or ravines under power and the main bearings would tighten clearance. the fix was a more looser fight main bearing and it stopped those problems. Really by the time the 50 series tractors were out they were pretty reliable and the shortcomings were addressed by then. This engine went on for two more series with very good reputation and 350 hp so it was sorted out by then.  I had every part and piece of a JD 4wd in my hands at one  point or the other from the front headlight casting to the rear PTO shaft nothing that caused lots of pains that weren’t fixed by the 77  model year 30 series which essentially was a 40 series as they had made many minor changes in them. 

I’d have to go look again at my 7020 but it seems like JD went backwards from the 70/7520 to the 30 series in regards to how the front axle was mounted. I didn’t know about the block twisting until the internet either.  

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2 hours ago, Big Bud guy said:

I’d have to go look again at my 7020 but it seems like JD went backwards from the 70/7520 to the 30 series in regards to how the front axle was mounted. I didn’t know about the block twisting until the internet either.  

The 404 on the 7020 was a bit narrower than the 7520 531 and 8630 and up 619s. You could see more or the bolts holding the engine to axle cast cradle. The 466 equipped 84 series were like that also. One thing a 20 had nice going for it was a universal joint on front driveshaft. They were easier to get pan off. The worst thing to do on those was a inframe. It didn’t take much longer maybe 3 hours to have engine out and back in. On the 86xx if the cradle bolts were bad you had to pull frames to get bolts out. The 8650 had a split front frame to take care of this. But in all reality to pull fuel tanks, side frames and rad cluster was as easy as just pulling front axle. Plus it was a lot easier to work on engine just sitting out front or in a stand.

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