New 870 owner, got some issues

hogdog05 · Sep 30, 2014

I bought a 870 4x4 with hydraulic steering. Has about 1200hrs on it. Cranks and runs fine but it will puke oil out the blow-by-blow tube ever so often. Not sure why this would be or what I need to start looking at. I will try to post a video. It has the common problem with the fuel and temp gauges not working. And finally the steering is slow to react and when it does it seems like it turns all way. I mean I have to turn the wheel like 5 times before it starts to respond, then it just turns to full lock. New fluids and filters. Any help would be appreciated.

zzvyb6 · Sep 30, 2014

Have you pulled the valve cover to see if the oil drain holes in the head are plugged with sludge?

bmaverick · Sep 30, 2014

Your John Deere 870 was actually manufactured for Deere by Yanmar in Japan. The engine is the Yanmar 3TN84. This is one of the popular engines too.

At about 2200 rpm a normal Yanmar engine will have around 35-60 psi of oil pressure when at normal operating temperature. At idle the pressure will typically drop to around 17-20psi.

With that said, Hoye Equipment has a knowledge base for the Yanmar tractors and engines. Here is #71 about the vent tube and oil blow-by ....
Oil leaking from crancase vent tube

pmsmechanic · Oct 1, 2014

I'm wondering if a good steady load on a warm day would't clean up the blow by. Something where you are pulling 80 -100% of rated horsepower for about 6-8 hours. If the tractor has only ever done light work and never been thoroughly warmed up then they will slobber out of the breather tube. A good quality oil will also reduce slobbering. Just a few thoughts.

hogdog05 · Oct 1, 2014

When I bought this tractor the injection pump had been taken off. They said it idled real high and would not idle down. They got it shut off and it would not crank after. So I reinstalled pump. The number 2 delivery valve was hanging. A light tap and got the valve to moving. Tractor fired right up, but when I gave it throttle it would just keep reving up. After running tractor and working everything it freed up. Called it good. So I went and mowed about 8 acres that was thick. Good hard days worth of work. After that is when this issue started. I have not checked the drains in head or the baffles in breather. My other question about the steering kinda confuses me. I'd think it should be more responsive and tight like.

Tx Jim · Oct 2, 2014

Here's the parts schematic of the steering valve. One things for certain the steering valve isn't very cheap. AM876679 Valve - VALVE ASSEMBLY ADD 1,189.66 USD

JD5210 · Oct 2, 2014

If you have not already purchased the tech. manual you may want to look at this site as the manual is downloadable for $24.95.

870 970 1070 Tractor - TM1470 - SelectManuals.com - Workshop, Repair and Service Manuals

You may already know about this site, but here is the parts catalog.

John Deere - Parts Catalog