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Hi, I recently inherited free of charge a Gravely 816S complete with rear hitch and tiller and a snowblower. It's not a bad little tractor but it does need some TLC which I intend to give it to restore it to it's former glory.

Yesterday though the first problem reared it's ugly head, I got the Gravely out of the garage to do some work on it, I raised the rear hitch to move it and up it went no problem. Parked it up and went to lower the hitch and nothing happened. With some wiggling of the hydraulic lever I eventually got it to go down. I raised it again and up it went, however it just won't drop down again.

Does anyone have any idea what may be causing the hitch to stay up? I have noticed that the lever rod is contacting the release button on the hydraulic valve but it is not releasing the hitch to go down.

I haven't really done any investigating of the problem as of yet, I thought I would get some pointers first on what could be causing the problem and possible causes to look for.

Thanks in advance for any advice.

Blu
 

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Discussion Starter #2
Moderators, I just noticed there is a thread for hydraulics. My apologies if this is in the wrong place and would you be kind enough to move it if it is.

Blu
 

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No problem leaving your thread where it is, Blu. You may want to carefully check that nothing is binding. I recall having the clevis yoke on the front end of my 816's lifetable hitch rod hanging up on the transmission filler cap. Installing a longer filler pipe so that the filler pipe cap cleared the clevis yoke took care of it.
 

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Discussion Starter #4
No problem leaving your thread where it is, Blu. You may want to carefully check that nothing is binding. I recall having the clevis yoke on the front end of my 816's lifetable hitch rod hanging up on the transmission filler cap. Installing a longer filler pipe so that the filler pipe cap cleared the clevis yoke took care of it.
Hi tracktortag and thanks for the reply. I had the tractor up on the hoist and can't see anything hanging up underneath that would cause the hitch to stay up, I also managed to get the rusted old battery base plate off where the hydraulic valve sits under the plate and I cleaned it up some but couldn't see any problems. Do you know if there is a way to test the hydraulic valve to find out if it is kaput? I also checked the hydraulic fluid level and it looks okay in there.

Saying that though what I know about this tractor wouldn't cover the back of a postage stamp however I'm one who is keen to learn and I'll get to the root of the problem one way or another. Failing that I'll just take it outback and shoot it.

Again thank you for the reply.
 

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Noo, don't shoot it! :) You may want to remove the reservoir filler cap, crank the engine (spark plug wire removed from the plug), and look into the reservoir to see if the fluid is moving around while cranking the engine. No movement would mean that the pump is not working. There could also be air trapped somewhere. Doing this may help to get rid of it. If you see bubbles, you will know that there is air in the system.

Also, if you look at the top of the reservoir cap very closely you should see what is literally a pin hole tapped into somewhere near the center top of the cap. This acts as a breather for the hydraulic system, and can easily get clogged up from dirt, etc.
 

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Agreed on the test to ensure that the pump is still pumping. But it went up, earlier, so I bet it hasn't failed just now.

I'm guessing valve, or more likely actuator that controls the valve.
 

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Agreed on the test to ensure that the pump is still pumping. But it went up, earlier, so I bet it hasn't failed just now.

I'm guessing valve, or more likely actuator that controls the valve.
It could very well be, John. It would be nice if it's just some air in there for some reason.
 

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Discussion Starter #8
Noo, don't shoot it! :) You may want to remove the reservoir filler cap, crank the engine (spark plug wire removed from the plug), and look into the reservoir to see if the fluid is moving around while cranking the engine. No movement would mean that the pump is not working. There could also be air trapped somewhere. Doing this may help to get rid of it. If you see bubbles, you will know that there is air in the system.

Also, if you look at the top of the reservoir cap very closely you should see what is literally a pin hole tapped into somewhere near the center top of the cap. This acts as a breather for the hydraulic system, and can easily get clogged up from dirt, etc.
Hi tracktortag and thanks for the reply. Would I be correct in thing that the hydraulic reservoir tank is in the center of the photo below. I did what you said and saw no bubbles and apart from the vibration of the tractor turning over there was no movement in the fluid inside the tank. TBH I'm not really sure what kind of fluid movement I should be looking for.

As for the breather hole in the tank cap, well there isn't one, I've also took a photo of that and it looks like a dipstick with the top of the cap painted over but no hole on top or bottom that I can see. I had a look on the parts manual for this tractor and the tank cap is listed as "Stick,Dip Hydraulic Tank" which is what it is.

Again thank you for taking the time to reply, I really do appreciate it.

Blu
 

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Discussion Starter #9
Agreed on the test to ensure that the pump is still pumping. But it went up, earlier, so I bet it hasn't failed just now.

I'm guessing valve, or more likely actuator that controls the valve.
Hi jrd and thanks for the reply. I was kind of wondering if it was the valve as well. I really do hope not because the screws for it are well and truly welded to the battery plate with rust and they are also like rocking horse s**t to find. I do have another actuator on it's way to me as I write this. I'm one of those people that will buy parts as I find them for the just in case thing especially for old machines such as this.
 

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I'm coming to this late, but, assuming a functioning hydraulic system with the right fluid level, running at the proper pressure and with a working valve, all the "down" function does is let the fluid bypass and if there is no weight on the hitch it's not gonna down down for ya.
 

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Discussion Starter #12
I'm coming to this late, but, assuming a functioning hydraulic system with the right fluid level, running at the proper pressure and with a working valve, all the "down" function does is let the fluid bypass and if there is no weight on the hitch it's not gonna down down for ya.
Hi Yamato, The tiller is still on the hitch buddy so plenty of weight there. I think the actuator is okay because I can hear it working when I pull back on the lever to lift even though it's in the out/raised position.
The dipstick in the hydro fluid tank says the level is good

I have a suspicion it may be the hydraulic valve that has gone belly up, looking around they appear to be very scarce indeed. I did find one on partstree but they want over $700 bucks for it. There is one in Australia for $163 but I don't think that guy is going to mail it to the US.
 

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Yamato is correct. Lowering is a matter of gravity. You can control the rate at which things drop by moving the control lever slowly off the "full raised" position. At that point, two things are possible. There is some external/mechanical reason like screwed up linkage or a bit that has come loose and is blocking things from dropping. Second reason would be something in the hydraulic system preventing fluid bleed-off/bypass that normally allows things to drop. Thus far, nothing I have read points to one case or the other.

I suspect the pump is fine. The tiller raises ok. The pump has nothing to do with it dropping.
 

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Discussion Starter #14
Yamato is correct. Lowering is a matter of gravity. You can control the rate at which things drop by moving the control lever slowly off the "full raised" position. At that point, two things are possible. There is some external/mechanical reason like screwed up linkage or a bit that has come loose and is blocking things from dropping. Second reason would be something in the hydraulic system preventing fluid bleed-off/bypass that normally allows things to drop. Thus far, nothing I have read points to one case or the other.

I suspect the pump is fine. The tiller raises ok. The pump has nothing to do with it dropping.
Hi Mikey and thanks for the reply My first thoughts were that some might be hanging up and therefore not allowing the tiller to drop. I had a good look around everything and didn't see anything that would indicate a hangup. I had a good look at the hydro valve yesterday and I could see that that were the control lever contacts the valve to drop the tiller, the contact on the valve looked loose and wobbly as if something inside the valve had broken or had come loose.

I guess I'll find out soon enough if it is a hydraulic system failure as I have a new pump, valve and actuator coming from Australia of all places. They should be here within the next month or so.
 

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Discussion Starter #15
Hi guys, well it's been a couple of weeks since my last update. Since then I've learned a heck of a lot about this tractor. But still having the same problem.

To date I have replaced the hydraulic valve, the actuator the hydraulic pump and the hydraulic lines and bled the new lines. After replacing the pump it did go up and down a few times but then stopped and nothing since then, the rear hitch with the tiller attached is still stuck in the up position.

As Tracktortag suggested I made sure the it wasn't hanging up on anything such as the cap he mentioned and everything is clear and I see nothing hanging up. I have to admit that I am really stumped now as to why it won't go down.

Blu
 

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Discussion Starter #16
Hydraulic lift is now fixed and working as it should. When in doubt get the hammer out, that's what I did and it fixed the problem.
 

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Gravely1964
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So what was binding? The lift linkage for the rear hitch or what?
 

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So what was binding? The lift linkage for the rear hitch or what?
Nope nothing was binding, the problem was the hydraulic valve rod for opening and closing the valve. I was watching a video on YouTube and I had one of those hang on a minute moments. Well I noticed the rod in the video was nice and straight, the one on my tractor was bent in the middle.

Now as I said in my first post, Gravely's are new to me and I thought the bend was par for the course. So on discovering it wasn't ,I took a 5lb hammer to it and straightened it out and now the hydraulic lift is working as it should.

Ah well at least I now have a spare actuator, valve and pump should any of the new ones go belly up, just need to make sure that SWIMBO (She Who Must Be Obeyed) doesn't find out what I really paid for them is all.

Thank you all for the replies and the suggestions as to what the problem may have been, I really appreciate it guys. If anything this has been a learning experience and I now know a bit more about my Gravely.

Blu
 

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Thanks for coming back and posting what the fix was. And you can never go wrong using a BFH. Even if everything goes wrong, it feels right using it.
 
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