Ask The Mechanic

Hard Starting Solved With "Destroker"

(Progressive Farmer image by Steve Thompson)

READER: I have a John Deere 4630 tractor that I bought new in 1977. It is nearing 9,000 hours on the engine. I only use it now to pull a 12-row planter. I also have a 1984 John Deere 4840 tractor. I use the recommended 30 weight oil in both, but I would like your opinion on changing grades of oil to help with cold-weather starting up here in Ladoga, Indiana. Both tractors are hard to start and sometimes will not start in the winter unless I use the block heater, which is impossible out in the field. Can you help me with this troublesome starting problem?

STEVE: I would stick with the oil you have been using for the last 9,000 hours and not change the grade of engine oil. Your hard-starting problem in the winter can usually be corrected with a "destroker kit" for your hydraulic pumps. The closed-center systems on your tractors are building "standby" pressure when you are cranking the engine. Building hydraulic pressure and an extremely cold engine put a huge load on the starter and batteries. The "destroker kit" keeps the hydraulic pump from pumping, which allows the engine to start much easier. The kit comes in an electric and manual version. The manual version is less expensive, but with either one, you will find that your starter and batteries last much longer. The John Deere part number for the electric kit is RE 40463, and the manual kit is AR 96625.

READER: I have a Ford 4600 that has a unique problem. It starts fine when the engine is cold. However, if you kill the engine after it warms up, it won't start again until it cools off a couple of hours. This is usually not a real problem until I ask someone to help me in the field, and they forget and kill it -- never at a good time. Even though I tell them not to kill it, they forget. Then, no hay gets raked for a couple of hours. My grandson killed it one day, but a friend of his showed up with a cooler full of cold refreshments. He told his friend the problem, and they decided not to "Ask The Mechanic" before they poured some ice water on the injector pump, but it started. I don't think this was a good idea. What do you think?

STEVE: Wow! You are right. You got lucky. Pouring cold water on a hot injector pump is a bad thing. I never wash off a hot engine. I wait until it has completely cooled before washing. You got lucky that the pump was not damaged. You need to take the pump to a reputable rebuilder and have it repaired. More than likely, the kill portion of the pump is a little tight, and it sticks from thermal expansion. I bought a Ford 4000 new, and it did the same thing from the factory. The dealer repaired the pump, and I had no more trouble.

Safety Tip of the Month:

Hot weather can be hard on engines, AC units and batteries out in the field. It pays big dividends to keep one eye on the temperature gauge. Protection from the heat and sun is also important for equipment operators on open tractors. My farm dog is my latest hired hand out raking in the field. Grandpa's old straw hat protects him from the blazing Texas sun. It's hot out there. But, he never complains, and he is ready to go to the field every morning.

> Write Steve Thompson at Ask The Mechanic, 2204 Lakeshore Dr., Suite 415, Birmingham, AL 35209, or email


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