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Repowered Deere 4WD
Farmers at the recent World Ag Expo near Amana, Iowa,crowded around a Deere 8630 4-WD tractor displayed in the Kinze Manufacturing exhibit. The first thing they all noticed was the tilt-up hood, made possible by side-mounted exhaust and air cleaner stacks. If they looked a bit closer they also noticed that this Deere tractor didn't have a Deere engine.
Jon Kinzenbaw, presidentof Kinze Mfg., with the help of employee Jim Spaid, repowered the Deere 8630 with a Cummins 855 engine. "The 619 engine in Deere's 4WD tractors has been a disaster. Many of the engines, in early model 8630 and 8640 lasted only 2,500 hrs. or less. Deere replaced them at a fraction of new cost but with the same engine. Most farmers who own one of these tractors have already faced - or will face in the future - a complete overhaul that can cost as much as $11,000 or more. Our repowering kit makes the tractor better than new."
Kinzenbaw has been repowering Deere tractors since the late 1960's when he came up with a "kit" to repower Deere's 5020's. "It had a very heavy-duty transmission and rear end but the 535 cu. in. 125 hp. engine was under-powered. We converted 200 to 300 tractors with a Detroit diesel engine, including conversion kits we sold to farmers and machine shops around the country.
"When Deere introduced their new generation 4-WD's in the mid-1970's, it had the same basic engine used in the earlier 5020's but was rebored for more power. Many owners had trouble right away with the block, head, head gasket, cylinder sleeves, and soon. Deere tried to get more powerout of the engine by installing turbochargers, coolers and other add-ons, but they weren't enough. If they had taken the time to design anew engine with about two more inches of length they could have solved many of the problems," says Kinzenbaw.
"I know one farmer who rebuilt the engine in his 8630 last winter and then, less than 200 hrs. later during planting, it blew up and he had to buy a new engine for $14,000. Two other local farmers blew up the engines in their 8630's this summer. They had no choice other than to install Deere engines and parts because the tractor is built so that the engine is an integral part of the frame. No other engine can be used without a major rebuilding job," says Kinzenbaw, adding that so far as he knows he's the first person to install a non-Deere engine in an 86 Series 4-WD. "It was a very complicated job that took us 4 months to complete."
The modified tractor looks almost like an unmodified 8630 except for the exhaust and air cleaner stacks which mount off to the side of the front hood. The side-mount positioning allowed Kinzenbaw to put a front hinge on the engine hood so it can be easily tilted up for service. "Taking the hood off this tractor was a big chore because if you couldn't unbolt the muffler you had to lift the hood up over the exhaust pipe."
To mount the Cummins engine (fitted with a variable speed governor) in the tractor,Kinzenbaw first built a 2-in, thick adapter plate on back of the Cummins engine to match up with the bellhousing on the Deere driveline. Because the tractor has an oil clutch, the plate had to be double-sealed to keep clutch oil out of the engine and engine oil out of the clutch housing. Kinzenbaw also had to adapt the Deere clutch to the back of the Cummins engine , which was one of the trickiest parts of the conversion because of tolerances as tight as 10,000ths of an inch.
A sub-frame runs around and beneath the engine from the 2-in. adaptor plate up to the front of the engine where it supports a frontmounted hydraulic pump and fastens to the front axle. Originally, the Deere engine functioned as part of the tractor frame, mounting directly to the front axle. That unusual design - along with the bell housing that's unique to Deere - is the main reason owners have not been able to install other engines in the tractor, notes Kinzenbaw.
One big advantage of using the Cummins engine is that it's so widely available. "It's much more reliable and inexpensive to service than the Deere engine because 3 out of 4 semis on

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1988 - Volume #12, Issue #6