Draft-control valve replacement fixes all kinds of things

MikeOConnor · Aug 15, 2014

Hi all,

Remember my "1850 hydraulic pressure pulsates" puzzler a while back? Here's the link to the thread:

http://www.tractorbynet.com/forums/power-trac/313875-1850-hydraulic-pressure-pulsates-any.html

The semi-OK cure was the replacement of the brake-tender and charging valves, but things still weren't quite right. The pulsating was fixed, but the draft control that holds up the mower deck, and the seat-tilting piston, were operating at really low pressure after that. I limped along for a while but decided to start working on getting that fixed too.

The culprit of (I think) all of these problems has finally been revealed. An "old version" of the draft-control valve, which according to Terry, caused them all kinds of headaches. Replacing mine with a new one has:

- fixed the draft-control -- it's now working better than it has in years

- fixed the tilt seat -- it's now working better than it has in years

- cured a miner, but persistent, engine-overheating problem that's been with me for years

I think this rascal may have also been:

- the cause of repeated replacements of blown-seal charging-valves over the years

- the actual root cause of the "pulsating" problem

So here's a picture of my replacement one -- you can tell if you have a new one by looking at this picture. If the hex head sticks up 3/4ths of an inch like the one in this picture does, you have a new-version valve. If it only sticks up about 1/4th of an inch (about as high as where the arrow is pointing) you have an old-style one and, if you have any of those weird pressure-related problems that I listed, you might want to get a new one.

It's like driving a new tractor!

woodlandfarms · Aug 16, 2014

Ran outside and checked. I got the new one. although your cartridge is different than mine.

MikeOConnor · Aug 16, 2014

Dang! I kinda was hoping you'd have the old one...

Marks481 · Aug 16, 2014

MikeOConnor said:
Dang! I kinda was hoping you'd have the old one...

Why would you think Carl still has ANY of the original equipment that came with his PT?

OK, so he still has the original diesel, but that is probably about it.

MikeOConnor · Aug 16, 2014

<grin> Yeah, I guess I should have figured that.

But sooo many of the weird things with my 1850 went away when I put that gizmo in, I was hoping for a miracle cure for Carl too.

woodlandfarms · Aug 17, 2014

I still have the engine and some paint.

J_J · Aug 17, 2014

Carl, you don't park your PT over an old indian burial mound do you.

If so, they might be pissed off at anybody and anything.

SpringHollow · Aug 17, 2014

Carl has dead bodies on his property but I do not know if any are Indian.

Ken

woodlandfarms · Aug 17, 2014

I was bout to say... the sheriff said If they are tennis shoes call, moccassins don't.

cqaigy2 · Aug 18, 2014

Poor Carl....and his PT. :*(

MikeOConnor · Aug 30, 2014

Another update -- and a question. In my enthusiasm, now that the new valve was making everything work so well, I decided to replace the *filter* in the draft-control circuit. Argh! My sluggish low-pressure troubles returned. So just for the heck of it I unscrewed the *valve* enough to relieve the pressure on the circuit and screwed it back in again. Presto! Snappy performance restored. So I'm wondering -- does anybody have an opinion as to whether that circuit needs to be bled when a new filter is put in? And, if it does, what the right way to do it is? I have a feeling that replacing the valve may not have been what did it, but rather that I accidentally bled an air pocket out of the circuit and *that's* what actually fixed the problem. That would sure be a cheaper fix for folks with that trouble.

RegL · Aug 30, 2014

MikeOConnor said:
Another update -- and a question. In my enthusiasm, now that the new valve was making everything work so well, I decided to replace the *filter* in the draft-control circuit. Argh! My sluggish low-pressure troubles returned. So just for the heck of it I unscrewed the *valve* enough to relieve the pressure on the circuit and screwed it back in again. Presto! Snappy performance restored. So I'm wondering -- does anybody have an opinion as to whether that circuit needs to be bled when a new filter is put in? And, if it does, what the right way to do it is? I have a feeling that replacing the valve may not have been what did it, but rather that I accidentally bled an air pocket out of the circuit and *that's* what actually fixed the problem. That would sure be a cheaper fix for folks with that trouble.

Where's the filter for draft control circuit. Don't think I have one on the pt1430.

MikeOConnor · Aug 30, 2014

Bah. I was just testing you. It's not the filter for the draft control circuit. It's the charging valve filter. Sorry about that -- draft control, seat leveling and brake tender circuits all go through that charging valve in one way or another. Here's a picture of the draft control valve and the charging valve filter right below it. All roads lead to the charging valve.

woodlandfarms · Aug 31, 2014

Confused. I have this filter system as well. I guess they dropped it in 2010. Anyway... What valve did you undo?

MikeOConnor · Aug 31, 2014

Hi Carl,

Interesting that they dropped that filter in 2010. I can see why -- the maze of circuits that relies on that charging valve is unbelievably complicated. Anything that simplifies that would be a Good Thing.

Anyway, the valve I'm talking about is the draft-control valve. That's the one that controls how much the draft control lifts the mower deck. The valve is on the assembly at the top of that picture just upthread (there are two gizmos on the top of that assembly, the one on the left with a knurled knob and a locking ring is the valve). That's also the valve that is pictured in the third post of this thread. I didn't completely remove it, just unscrewed it enough to let a little oil leak out and then screwed it back in.

My evolving theory is that with all those different circuits going in and out of the charging valve, it's possible that air bubbles get in there and goof things up.

One of the intriguing things is that little nipple that shows up in the newer picture - directly below the draft-control valve assembly. I wonder if that's a bleeding point, kinda like the one we use to bleed the main intake line when we change our filters. I'll try to remember to call Terry and ask him about that after the holiday. Does anybody else know what that nipple is for? That would be a much easier way to bleed that circuit than pulling the valve - especially if it could be done without running the tractor. Kinda like bleeding the air out of a radiator back in the old days -- just open up that nipple, wait for air to escape and a little dribble of oil to come out, replace the nipple.

ponytug · Aug 31, 2014

Ask Terry?

All the best,

Peter

MikeOConnor · Aug 31, 2014

Yup, that's the plan fersure. Mostly curious if others have really dug into all the plumbing that goes in and out of that charging valve. I've replaced it a half-dozen times and I'm starting to think that it's possible that I've been maintaining all the other stuff incorrectly for all these years. I wish I'd kept a detailed maintenance log so I could go back and look up when I replaced the charging valve filter the first time. It may just be that all the blown seals and leaks were caused by incorrectly changing the filter. That would definitely fall in the "let no good deed go unpunished" category.

PTWannaHave · Sep 3, 2014

As I prepare for a PT-1430 purchase (my 1st machine with hydraulics), this is the kind of story that rattles my nerves...! :worried:

woodlandfarms · Sep 3, 2014

Owning a pt is not for the feint of heart. Either you know a good mechanic or you are not afraid to get greasy. If both are an issue you should not get a pt. This said, the machine is worth the aggravation. And in terms of aggravation in the end not a lot of us have issues. My machine was abused. Really abused. Caught on fire abused. Rotted outdoors abused. The guy I bought it from put a ton of money in fixing it up. Did a great job. But certain systems just had issues. And then I got it and I abuse equipment. Or should I say I work my machine to the limit. I take good care of it but this week I am on a 35 degree slope pulling out well over 100 trees that are over 50 ft then grinding the stumps. Couldn't do this with a regular tractor nor could I do it as quick. I feel you are making a good decision on the 1430.

MikeOConnor · Sep 3, 2014

I talked to Terry this morning.

He confirmed something Carl mentioned up thread, which is that they dropped that charging-valve filter in 2010 -- the same time they switched to the new version of the draft-control valve that they put in. So I think all this rigamarole probably doesn't apply to a new 1430.

He says that replacing the filter shouldn't require bleeding, but that if I ever DO want to bleed those circuits I should crack the port on the bottom of the charging valve. Sometimes, that's just a port, sometimes there's a hose on it. Just crack it and then tighten it back up again (essentially the same thing I did, except I did it at the draft-control valve).

Finally, he said that the nipple I highlighted in the picture is NOT the place to bleed it.

That concludes my report.