Confirmation on B7800 valve adjustment specs and procedure

[DieselBound]

First time to do this...

I've got 0.145mm to 0.185mm as the adjustment spec on both(?) intake and exhaust: reference here; I found this in a thread here on adjusting B7800 valves, but there's no clear model spec and I don't feel comfortable accepting this blindly. Can folks verify that this is correct?

Also, no way am I going to be able to follow the procedure's recommendation to turn the crank in rads. I've only ever adjusted valves by slacking both intake and exhaust valves. Pretty sure that this is sufficient but want to run it by others just in case/for feedback.

 

[orezok]

Here ya go.

 

[DieselBound]

Thanks! Seeing the page header (identifying it as being from the B7800 manual) is assuring!

Maybe one day I break down and get a manual for this tractor. I've got one for my NX (and everything else).

I think I "get" their instructions for setting up for adjusting the valves. The "3cyl" and "4cyl" columns were confusing until I realized that they're showing for two different engines (a 3 cylinder and a 4 cylinder): duh. And after adjusting the specified valves when at true TDC just do one complete crank/revolution (360 degrees) and adjust the rest of the valves. No matter, I am pretty sure that if necessary I could get it done a cylinder at a time if necessary (though a bit slower).

 

[diesel85]

Depending on how many hours you have on your machine, you might find it doesn't need any adjustment. So don't be alarmed.

My D905 only needed cylinder 2 adjusted, and even then, I could've left it because it was well within the tolerances defined.

 

[DieselBound]

I've got around 1,850 hrs It had just under 750hrs when I bought it. A neighbor has a smaller Kubota that has over 3,000 hrs (if not 4,000!) and has never adjusted the valves. I'd have adjusted them at the correct interval had I not had some other (high) number in my head: wasn't until a while back that I realized that the hour number I had in my head was WAY off. Be interesting to see what the valve spec is before I adjust.

 

[DieselBound]

While juggling a bunch of stuff I managed to finally get the valves adjusted (lots of other maintenance on the B7800 as well). Three of the four intake valves were in-spec, with one being out at 0.305mm. All exhaust valves were loose, ranging from (approximately) 0.203mm to 0.356mm.

Not sure if it's my imagination, but the tractor sounds a lot nicer now. I suspect it's a bit psychological in my feeling better about finally getting around to this long-put-off task. Anyway...

Many thanks for the help!

 

[diesel85]

Tightening the exhaust valves will make a slight change in the noise.

At least it's all set now!

 

[DieselBound]

I was surprised to see how clean everything looked when I'd popped the valve cover. Initially I'd freaked when I saw green on the top of the head. Kubota looks to have used something there to help the oil flow off/away.

Don't feel negligent now