Combines 81 N6IJ what do yall think

The price seems right for the unit. Has it had the rod bolts and bearing done yetIJ The 81 and older are 1500 hour machines until the underhaul. The extra 200 rpms of the Roosamaster fuel system is hard on the 670HI engine. The hydro on the 81 N6 was lighter than the later Series 3 N6. If it has been well maintained N6 with a good service and update record you should have a good machine if you do the recommended service and updates and get the engine slowed down. I bought an 82 N6 that was well maintained and it made 3100 hours before the rod bolts and bearings were done. Because of good maintenance it didn't need the underhaul yet but was cheap insurance from getting a hole in the block, or spun bearings. A VERY HAPPY N6 Owner

I have a 81' N6 and for the most part I am very happy with it since I hyperized it. The first season with the stock set up was a nightmare, no capacity and poor sample. The next year I did everything but the grate and had a completely different machine. like John says you need to slow the engine down 200rpm for insurance. lee at Midwest Diesel 515_576_5501 in Fort Dodge, Iowa can recalibrate your pump. If the hours are correct and it had a good home the price doesn't sound too bad. E-mail me if you have any other questions. Pete Hinrichsen

John, I just bought a 84 N6 how many hours before a underhaul should be done, it has had good maintenance, but the hour meter quit. It probably has around 2800hrs. Thanks

The 670I engine when maintained good should get attention between 2500-3500 hrs. The rod bolts on my 3100 hour engine were not stretched and the bearings showed mild wear for the hours. I had it done because I didn't want to encounter what many N6 670HI engines(early machines) did and just tightened and renewed things for many hours to come. Several hundred dollars of underhaul costs are much cheaper than a new or retrofitted engine. The regular service by the previous owner really made my N6 a wonderful machine. It has made my harvesting a real pleasure over the past few years. The hyperizing of the machine has made it fun to run in high yielding corn. My 21 yr old combine smokes the neighbors brand new machines with ease. Can't ask for any more than that!

What are the differences between the earlier 670's and the one in my '84 N6IJ Thanks for your earlier comments John, I'm estimating 2000 sep. hrs. and 2800 eng. hrs.

The 670HI was turning about 2800 rpm wide open and 2550 rpm loaded and the 670I and 670T turned about 200-300 rpms less. Also the later 670I had dual sumps for the oil pump, helped keep the oil flowing no matter how hard or what angle the machine was running at. Better oil flow and slower engine rpms made a huge differance in the engine life. At 2800 engine hours, if it has been maintained, the underhaul should get your engine out to between 5-6k hours for an overhaul or replacement(Cummins). My underhaul cost 20% of what an overhaul would have at the time, not bad to almost double the engine life. As you would tell your teenager, SPEED KIllS, and it sure did with the 670HI in the early N6, 7080, 7580. The 670I and T in all applications at the lower rpms was a much more reliable unit.