Re: 674 questions (PTO, Brakes, and Range)

Hi Tipper, usually it is the control mechanism from the lever that becomes siezed up and dosen't close the vlave properly. But since you disconnect the control lever that can't be the problem. So is it ON all the time or in the SOFT start position?
I believe the PTO clutch pack has a piston return spring that when the pressure is released the spring forces the piston back so the clutch goes against the PTO brake. When the tractor has been off for sometime can you turn the PTO shaft with your hand. Normal is only turn up to 1/2 a rev., just enough to align a PTO shaft.
There are adjustments in the book for the lever and for the PTO pressure when engaged. But your problem would appear to have pressure on the clutch all the time.

JimB

When the tractor is off--as soon as I kill it, I can turn the pto the standard half turn or so until the brake ring contacts the boss inside the housing. And the PTO clutch should be good to go. Out of curiosity last week I went ahead popped the mcv and pto clutch out of the tractor. Clutch pack now has new seals, steels, clutches, and springs. It checks good with air, and honestly, it didn't need replacing. It was cheap to do, and well, what the hell, I was in there. The big issue I found with the tractor was the parking brake band. It was chewed up, and lining material was everywhere inside the case. I cleaned everything best I could--changed hyd filter and cleaned pickup screen on transfer pump. I was expecting to find a torn gasket on the mcv, but no such luck. I'm am going to grab a gauge today to see what is going on w/regard to pressures. BTW, from what I can tell, the PTO is engaged and not in the feather position-well, it may functionally be in the feather position if it is getting partial flow when off. After cleaning the PTO lever mechanism, it now behaves as it should--automatically returning to the "off" position anytime the handle is released before the break over point in the linkage.

It certainly didn't hurt that I cleaned up the housing and did the pto job, but after not seeing anything obviously amiss, I was really hoping it would magically fix itself. Unfortunately, that was not the case.

And just to confirm, with the PTO off, I should have 0psi on the line going out of the MCV into the T for the PTO feed, yes? Or is there a certain amount below that is acceptable?

And again, with fluid going to the PTO the only valves that [i:5ecdebc81e]should[/i:5ecdebc81e] matter are the PTO and pressure regulator. And if the PTO valve is functioning correctly, the pressure regulator should not be able to cause an increase in pressure when the PTO is disengaged.

Last thought for the morning- with the lever unhooked, is there a point at which the pto valve starts to feather as the spool is raised--basically beyond the off position? If that doesn't make sense... Going from fully engaged with the spool pressed fully down, is there a point going up just past the disengaged position that the feathering position is encountered for a second time? I doubt that is the case, but I figure I should ask.

Sorry for the long post and babbling, but it is early--and I'm curious.

Tipper, re feathering, it should only occur during that wide slot area at the PTO lever, going forward from the OFF position.

I think the solution is putting a pressure guage at the output of valve.

I am travelling and don't have my book with me but I would suspect that when the PTO lever is in OFF position there should be no flow at output of PTO valve.

Re parking brake band, was the parking brake drum chewed up as well? My brother's 684 has the same problem. He had a summer student work for him a few years back and you know the rest of the story. His local IH mechanic told him that replacing the band didn't always work if the drum is baddlly damaged. He just changed the hydraulic filter many times and I guess the rest of the junk has settled to the bottom. His solution was to drill a hole in the foot rest and install an eye bolt between brake foot pedals and when he wants to lock the brakes on he sticks a pin thru the eye bolt. I am sure this dosen't meet code as parking brakes have to mechanical and not rely on hydraulics.
Did you lift the 3pt hitch housing off to change the parking brake band.

JimB

Actually I decided not to replace the band just now. I'm going to run this for a year or so, and just see how things go. Considering the crud inside the housing, I figure another fluid change when things are apart down the road won't be a bad thing.

I hooked up a gauge, and it shows in the ballpark of 45psi when the valve is supposed to be off. When engaged, pressure is where it should be--225ish. So now the million dollar question-what is there to do with a valve that won't shut off? I know CNH offers a valve, but if it is the MCV housing that is worn, that won't help. I think I'll pop the valve back out and see what there is again. Maybe there is still some trash in there that I didn't notice on the first go around.

Ready for the million dollar answer? When nothing seems to actually be wrong, pull the valve again. I popped it out, measured it, found nothing wrong, and put it back in. AND IT WORKED. 0psi when off and 225 when on. The funny part is that I could have probably done that before doing the pto clutch job, but oh well. New clutches never hurt anyone. So that won't need to be done again for 30+ years. Anyway, I'm thankful for your help. Everyone I have been talking to has been telling me to check things I've been checking. I'm glad I went for another look at the valve.

I'm going to look at it this way: If I didn't change the fluid and clean things out, I probably would have had the same issue spring up again shortly. Again, thanks for the help.

Hi, have you change the hand brake cable? Bernard le mécano

No, have not changed the hand brake cable, but it shouldn't be too difficult--if that is what you are asking. It disconnects right outside the rear housing. There is a pin with a cotter key. Someone cut my cable before I acquired the tractor, and quite frankly, it isn't much of an issue with me. Now that the PTO works, I get to tackle the newest interesting feature--plugged filters/lines. It gets enough fuel to start up and run for 5-10 seconds before it dies. Wait a minute and repeat. That is a job for tomorrow.

Hi,i've ask you that, because, the bracket that hold the cable, near the transmission housing, can be turn upside down.If the bracket is not on the good side, the fork make contact with the bracket and the valve don't lift enough to stop the PTO. If the gasket of the MCV is broken, the PTO will slip. I've see a trouble like yours, it have dirt in the MCV that cause the spool valve to not lift enough, the PTO don't stop.Bernard le mecano Quebec Canada

I see. My way out of dealing with the non-functioning brake (and bracket) was to remove it for the time being. If/when I fix the parking brake, I'll put it back. Until then, it can keep other things on the shelf company.

And just in case I was not clear--I did not remove the lift housing this time.

Hi, to change the park brake band, the best way, is to lift the hydrolic cover. Bernard le mecano Quebec Canada