8N Hydraulic Problem

bobclancy · Jan 26, 2019

'48 8N, went to plow snow, and it would run only with the clutch in. Otherwise, the trans was locked up. Thought about water in the oil.... eventually got it thawed out and in the shop, sure enough. Changed the oil, put in TSC 'Renew'. Then the hydraulics would work, but had no position control, even with the lever up/vertical. Put the quadrant to raise the blade, and it would go completely up even if you put the quadrant lever back down. Same with lowering it. It would only stay all the way up, or down.

Soooo, pop the inspection plate, and with the quadrant all the way down, see photo 1.

Raise the quadrant and it moves forward and contacts that rod coming out of the pump at about 2/3 of the way up, but the rod is frozen in place (engine off). Quadrant can be put all the way up, but there's some resistance. Loosened the 4 quadrant bolts and tapped it as far back as it would go, that helped a bit but not nearly enough. Photo 2.

I'm thinking there is a problem with the cam follower pin up in the top lift cover because the rod that goes from there to the pump is so way out of whack. Also, should that rod at the pump end that it pushes on be able to move? I can't get it to budge even reaching in there and pushing. Any ideas would be much appreciated before I start diving in!

(Yes, that yellow stuff is the brand-new oil).

R Geiger · Jan 26, 2019

That rod that you can not move is the intake control valve. It should move, it has a spring in it and I am not sure how easy it should move. If it was working ok before it froze, I would be looking for something that is bent.

looks like you will be in for some work. I don't mind taking the top off, but I sure hate to drop the pump.

mike-ga · Jun 26, 2019

Did you resolve your issue? I have a similar issue.

Thanks

(quoted from post at 09:20:48 01/26/19) '48 8N, went to plow snow, and it would run only with the clutch in. Otherwise, the trans was locked up. Thought about water in the oil.... eventually got it thawed out and in the shop, sure enough. Changed the oil, put in TSC 'Renew'. Then the hydraulics would work, but had no position control, even with the lever up/vertical. Put the quadrant to raise the blade, and it would go completely up even if you put the quadrant lever back down. Same with lowering it. It would only stay all the way up, or down.

Soooo, pop the inspection plate, and with the quadrant all the way down, see photo 1.

Raise the quadrant and it moves forward and contacts that rod coming out of the pump at about 2/3 of the way up, but the rod is frozen in place (engine off). Quadrant can be put all the way up, but there's some resistance. Loosened the 4 quadrant bolts and tapped it as far back as it would go, that helped a bit but not nearly enough. Photo 2.

I'm thinking there is a problem with the cam follower pin up in the top lift cover because the rod that goes from there to the pump is so way out of whack. Also, should that rod at the pump end that it pushes on be able to move? I can't get it to budge even reaching in there and pushing. Any ideas would be much appreciated before I start diving in!

(Yes, that yellow stuff is the brand-new oil).

Hobo,NC · Jun 27, 2019

control valve stuck,,, remove the drain plug see if you can get it to sliding in and out freely if not the pump needs to come out. If its not stuck and slides free the spring that keeps pressure on it is broke...

bobclancy · Jun 27, 2019

Thanks for the info. No, I haven't gotten into it yet. Just too many more pressing things to fix! I need to bail out of "retirement", go back to work, and take a break.

Btzj02 · Dec 2, 2019

(quoted from post at 06:21:24 06/27/19)
Thanks for the info. No, I haven't gotten into it yet. Just too many more pressing things to fix! I need to bail out of "retirement", go back to work, and take a break.

Kind of late responding to this but maybe you have not had time to fix. I had the same problem. I found that the pin at the front of the control valve had "vanished". Don't know where it went but the spring came out the front side of the hydraulic pump and would not push the control valve back. A new cotter pin fixed the problem. I did have to drop the pump to find this!

Btzj02 · Dec 2, 2019

(quoted from post at 06:21:24 06/27/19)
Thanks for the info. No, I haven't gotten into it yet. Just too many more pressing things to fix! I need to bail out of "retirement", go back to work, and take a break.

Kind of late responding to this but maybe you have not had time to fix. I had the same problem. I found that the pin at the front of the control valve had "vanished". Don't know where it went but the spring came out the front side of the hydraulic pump and would not push the control valve back. A new cotter pin fixed the problem. I did have to drop the pump to find this!

bobclancy · Dec 3, 2019

(quoted from post at 13:18:35 12/02/19)

(quoted from post at 06:21:24 06/27/19)
Thanks for the info. No, I haven't gotten into it yet. Just too many more pressing things to fix! I need to bail out of "retirement", go back to work, and take a break.

Click to expand...

Kind of late responding to this but maybe you have not had time to fix. I had the same problem. I found that the pin at the front of the control valve had "vanished". Don't know where it went but the spring came out the front side of the hydraulic pump and would not push the control valve back. A new cotter pin fixed the problem. I did have to drop the pump to find this!

STILL not into it. I can do some work (such as it is) without the height control, but I do need to get 'er done. Thanks for the info. When I get into it, I'll post about it.

8N Hydraulic Problem

bobclancy

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R Geiger

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mike-ga

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Hobo,NC

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bobclancy

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Btzj02

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Btzj02

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bobclancy

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