70 Powr-Trol Gasket Question

Patatrcc

Member
I've got a 70D that I used last year and noticed the 3 point leaked down slowly. I have had this problem with 3 other JD's and it's always been the gasket on the rock shaft cylinder to housing that's blown out in a small area. Replaced the gasket and everything was fine. So, I planned ahead last fall and got the gasket and rear end gasket from JD in advance and got everything pulled apart today. I took the cylinder off and there is a copper gasket there. Is this a homemade fix or can this gasket be bought somewhere that is copper vs. paper? It's a tad bent up in the center hole and the sq. hole at the bottom doesn't look 100% perfect, which leads me to think someone made it. It doesn't show any blow-out, but if you look at the one pic, there is a shiny "V" from the cylinder to the sq. hole, which might have been leaking, but hard to say. So IF it did work, then it's leaking down somewhere else. I took the piston out, checked the O ring and gasket there, and they look good. No scoring on the cylinder wall or piston. Has anyone ever seen/used a copper gasket here? I wanted to hold off on putting this back together until I got some feedback.
Pat in Montana
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I don't think JD offered a copper one. Likely homemade. Shiny area is suspect.
A better "fix" might be to have that area machined for an o-ring or square packing and forget using a gasket all together.
I would also check your relief valve pressure in case it is too high. Someone might of increased it to lift more.
 
That is what I was thinking. After looking at it a bit closer, it's not evenly cut on the outside and there are some "fish hooks" on the inside of the center hole, so it's homemade most likely. I don't think it was sealing between the cylinder and the sq. hole. You can't really see that V with the naked eye, but it definitely shows up on film with the camera flash. This gasket is par for the course on this tractor. It had been cobbled and hacked by the last owner or two, and it probably should have been parted out, but I decided to put a few bucks in it and get it back to running again. A few bucks, then a few more bucks, then a few more bucks.....
 
Sounds like EVERY tractor I ever bought ! LOL. I just end up tearing them completely apart so I know what I have. Got too expensive so I had to stop completely.
 
This one I bought for $900 4 yrs. ago. Thought I stole it. I have named her Mis-Match since then. I just put a new Titan rear tire on y'day and that should put me close to $8000. If not, after I put new 90w and new Powr-trol oil in it later today, I'll be there. It just got abused and neglected from the last owners and a lot of it didn't show until you got inside. I got going on it and had a few thousand in it and then you get to a point where you can't stop and leave it half fixed, so you put a few more $$ in it, and then find another issue, then more $$ and so forth. Then you're past the point of no return. Right now, if this gasket fixes my leak down, it's slated to pull the disk in a week or so. New tires all the way around, replacement block, new rings, new bearings, rebuilt P/S, Taper-Loc Flywheel, new injector pumps, head redone, new brakes, new electrical on the Pony, carb kit, new gauges... You know the routine. She's a runner, she just needed some TLC.
Pat in Montana
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I did my 720 D electric start model way back in 1985-1986
I started finding a lot of issues which started with an oil change and metal pieces came out. I had just drove it home several miles so everything seemed to work ok ? I got mad at it and swore I'd fix it right. I tore it 100 % apart ! Every bearing, bushing, seal and timing gears and several other parts later I had $ 5,000 in it in parts IIRC. But that was 1985 prices. I'd sure hate to do it today. I'm sure several parts I got you could not get today. There are a few things I can get now I could not back then like proper decals and gauges. I have went back and redid a few things with the newly avail. reproduction parts I can get. They sure do run and work a lot better when fixed right.
 
I don't doubt that a bit. Just this week: $700 15.5-38 Titan, $140 at NAPA, add in the gaskets and O-ring, and it's almost a $1000 week. It adds quickly, doesn't it?. 2 years ago I thought I just about had things finished up (mechanically) and was going to take the 13.6-38 off the left rear and get a matching 15.5-38. It came that way (13.6 on one side, 15.5 on the other). Anyway, I order the $700 tire, get the old one off and realize the 13.6 is on a 12" rim and I need a 14" for the new tire. So I had to scurry around on the Internet, find a replacement rim in Washington at the last minute, get it shipped here and that was $300. Add that to the tire, and it was another $1000 week in the blink of an eye. Then, after getting the new 15.5 Titan on, I see that the tractor is now sitting about 3" out of whack because the old 15.5 Goodyear had a much shorter sidewall than the new Titan. Murphy's Law, I guess. So, it got parked and this week I finally broke down and got a matching 15.5 Titan so that it's level and the tires are both the same size. It's just been one of those projects.
 
My 720 had mismatched rear tires. I saw where it worn the diff. shaft. It likely ran that way a long time.
 
UPDATE: Got the replacement fiber gasket put in and checked the O-ring and leather cup gasket around the piston and they looked good. Got it back together and it still had a slow leak down when I had the disk hooked up to it, so did some reading in the manual and checked the throttle valve. It was supposed to be about two turns out and was out to the max. and barely threaded in. I don't think the spring and ball had enough pressure on it to hold anything. I got it adjusted and it holds fine now. Don't think that copper gasket was working 100%, but having that throttle valve out all the way was part of the problem, too.

Pat in Montana.
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