Lift

[Billy the kid]

Ok guys could use a little advice!
I have a 8n that keeps blowing out the gasket between the hydraulic lift cylinder and the top cover?
I put a new lift cylinder on about a year ago and every thing was fine for about 3 months. The tractor gets light use, so when it came time to do a little snow removal the hydraulics started not holding pressure with the clutch engaged, removed the lift cover and found the base gasket on the lift cylinder had blown out.
I replaced it again and shortly after the same thing happened again?
Before I replace it Again I was thinking of replacing the pressure relive valve at the same time?
Looking for some thoughts as to why this is happening?
Thanks…..Bill

 

[Bruce (VA)]

Are you using any gasket sealer on it?

Did you torque the top cover correctly?
75 Tips

 

[JMOR]

(quoted from post at 10:40:46 12/12/13) Ok guys could use a little advice!
I have a 8n that keeps blowing out the gasket between the hydraulic lift cylinder and the top cover?
I put a new lift cylinder on about a year ago and every thing was fine for about 3 months. The tractor gets light use, so when it came time to do a little snow removal the hydraulics started not holding pressure with the clutch engaged, removed the lift cover and found the base gasket on the lift cylinder had blown out.
I replaced it again and shortly after the same thing happened again?
Before I replace it Again I was thinking of replacing the pressure relive valve at the same time?
Looking for some thoughts as to why this is happening?
Thanks…..Bill

ore than likely a mechanical problem than overpressure. You say "light use". The pressure is proportional to the load being lifted. Lift 150 pounds load & pressure may only be in the range of 200 to 300 PSI. You need around 1200 pound load to reach relief valve pressure, assuming your pump is that good. Use of gasket sealer, especially silicone based, can result in gasket 'push-out'. Verify flatness of both gasket mating surfaces AND the hold down bolts/bosses. If one of those contacts before proper gasket clamping force is reached, you have a problem. Do you have gaskets at all four bolt holes? If not , parts will not be parallel.

 

[Billy the kid]

The last time I, the first time I did not use any. I did torque it down.

 

[Billy the kid]

I will check, Thanks

 

[R Geiger]

Are you using all the gaskets? large main one and two small ones fore alignment.

 

[Billy the kid]

Yes both times

 

[old]

Sure as heck would not hurt to replace the relief valve since if it is sticking it would cause things to blow out

 

[Billy the kid]

I was thinking the same thing.
I will check every thing closely when I take it apart AGAIN!
But for the cost of the valve it could not hurt.

 

[Jason S.]

It shouldnt make any difference,but I know the gaskets from CNH are thicker than the aftermarket ones. I measured with a caliper and there was a considerable difference between the two.

 

[JMOR]

Can't hurt anything...true, but if you were right in saying that only "lightly loaded", it can't help anything either. It may divert your attention away from looking for the real cause, however. These relief valves are like condensers to many posters. An unknown/misunderstood/mysterious device, so hey, lets replace it! If you put a pressure gauge on the test port, under the conditions you say, you will not ever even see half the pressure needed to open that valve. Don't believe everything you read on the internet....some of those posters are French models too!

 

[Bruce (VA)]

Do NOT use any gasket sealer, ever. While the correct torque value is critical, so is the sequence in which you tighten the bolts. Do 1/3 of the final torque value in a cross pattern. If the final value is 60 lbs, do it in 3 steps: 20, 40 then 60.

I doubt you have a pressure relief valve problem.
75 Tips

 

[old]

While the relief valve may not be the root cause of the problem it could well still be part of the problem is say the control valve sticks etc. You know good and well replacing the relief valve it ALWAYS recommend any time you in the hyd system

 

[JMOR]

By someone...........and some also recommend always replacing condensers, not setting battery on ground or concrete, and not crossing path of a black cat and not walking under a ladder, and.........
Most don't hurt or help anything.

 

[old]

NO such thing as a true black cat. They all have a little bit of white hair on them.
But again it is recommended here more then most any other part to replace and it sure never hurts and after having a hyd pump blow apart due to a relief valve problem I'll still stand by what I have said

 

[JMOR]

I see no problem in standing by.

Won't fix the man's problem, though.

 

[Billy the kid]

Yah after market do seem thin

 

[Richard G.]

Had the same problem years ago on an 8N that we bought. Finally used Indian Head shellac and 2 gaskets just at the point where the oil comes up. Fixed the problem.
Richard

 

[Maineman]

I would suggest that You check the bolt holes for any thing in there that could cause the bolt to bottom out before it is fully tightened up. Oil, grit or rust could stop your bolt from drawing up tight on the cylinder. Also too long a bolt would do that.
Other than that, you must have surfaces that are not flat and parallel. Or bad gaskets.

Joe

 

[souNdguy]

if a replacement cyl.. check for uneven surface ont he bottom that may prevent full bolt up and good contact with the 1 big pressure and 2 small spacer gaskets.

 

[JMOR]

(quoted from post at 16:41:39 12/12/13) I would suggest that You check the bolt holes for any thing in there that could cause the bolt to bottom out before it is fully tightened up. Oil, grit or rust could stop your bolt from drawing up tight on the cylinder. Also too long a bolt would do that.
Other than that, you must have surfaces that are not flat and parallel. Or bad gaskets.

Joe

ow, that really would be a rare occurrence, in this instance! :wink:

 

[Maineman]

(quoted from post at 15:28:50 12/12/13)

(quoted from post at 16:41:39 12/12/13) I would suggest that You check the bolt holes for any thing in there that could cause the bolt to bottom out before it is fully tightened up. Oil, grit or rust could stop your bolt from drawing up tight on the cylinder. Also too long a bolt would do that.
Other than that, you must have surfaces that are not flat and parallel. Or bad gaskets.

Joe

ow, that really would be a rare occurrence, in this instance! :wink:

Agreed! But, I've seen it done. More than once. And it costs nothing to double check.
Myself, I'd suspect a poorly machined replacement cylinder.

Joe

 

[JMOR]

(quoted from post at 19:48:52 12/12/13)

(quoted from post at 15:28:50 12/12/13)

(quoted from post at 16:41:39 12/12/13) I would suggest that You check the bolt holes for any thing in there that could cause the bolt to bottom out before it is fully tightened up. Oil, grit or rust could stop your bolt from drawing up tight on the cylinder. Also too long a bolt would do that.
Other than that, you must have surfaces that are not flat and parallel. Or bad gaskets.

Joe

ow, that really would be a rare occurrence, in this instance! :wink:

Agreed! But, I've seen it done. More than once. And it costs nothing to double check.
Myself, I'd suspect a poorly machined replacement cylinder.

Joe

oe, I was trying to be gentle. "in this instance" was significant. Those 4 bolts are installed in through holes with a nut on the top side. Length not critical, no bottoming out possible.

 

[Maineman]

(quoted from post at 18:33:53 12/12/13)

(quoted from post at 19:48:52 12/12/13)

(quoted from post at 15:28:50 12/12/13)

(quoted from post at 16:41:39 12/12/13) I would suggest that You check the bolt holes for any thing in there that could cause the bolt to bottom out before it is fully tightened up. Oil, grit or rust could stop your bolt from drawing up tight on the cylinder. Also too long a bolt would do that.
Other than that, you must have surfaces that are not flat and parallel. Or bad gaskets.

Joe

ow, that really would be a rare occurrence, in this instance! :wink:

Agreed! But, I've seen it done. More than once. And it costs nothing to double check.
Myself, I'd suspect a poorly machined replacement cylinder.

Joe

oe, I was trying to be gentle. "in this instance" was significant. Those 4 bolts are installed in through holes with a nut on the top side. Length not critical, no bottoming out possible.

Silly me. It's been a couple of years since I did that job on my 640. I caught your inference. Just chose to ignore it!
I wouldn't tell anyone to spend money on my advise. But, to inspect something? Why not?
Thanks for your input. I always enjoy reading your responses and have learned from them!

Joe

 

[Hobo,NC]

(quoted from post at 21:08:25 12/12/13) NO such thing as a true black cat. They all have a little bit of white hair on them.
But again it is recommended here more then most any other part to replace and it sure never hurts and after having a hyd pump blow apart due to a relief valve problem I'll still stand by what I have said

How do you know its was a relief valve issue to begin with... I have never seen anyone complain their lift worked to good do you think I need to replace the relief valve...

Enjoy the peace cuzz you are going to be standing alone.....

You are correct to offer a pattern answer ( at least I learned you something) in it never hurts to replace it mostly because my time is to valuable to chase a mystery leak...

 

[Billy the kid]

Hmmm thought of 2 gaskets but thought fluid would blow threw?

 

[Billy the kid]

Well I have a new cylinder and I did clean every thing up good, I will check bolts, maybe with the after market cylinder that could be a problem?

 

[TheOldHokie]

(quoted from post at 07:08:06 12/13/13) Well I have a new cylinder and I did clean every thing up good, I will check bolts, maybe with the after market cylinder that could be a problem?

I think what I would be checking is flatness and condition of the two mating surfaces. Place the two together WITHOUT gaskets and look for any indication of a high spot or warpage. They fit should be dead solid with no gaps or rocking.

TOH

 

[Billy the kid]

That seems to be the only thing that makes sense at this point.
1st time thought maybe I messed up, but to have the problem twice now?
I hate after market parts.

 

[Hobo,NC]

(quoted from post at 15:43:09 12/13/13) That seems to be the only thing that makes sense at this point.
1st time thought maybe I messed up, but to have the problem twice now?
I hate after market parts.

This is not a common issue so look for the root of the cause and don't play the blame game just yet...

Clean both surfaces with brake clean, alcohol are lacquer paint thinner :wink: There are adhesives that will nail the gasket in place but I would not go their just yet...

 

[TheOldHokie]

(quoted from post at 09:09:49 12/13/13)

(quoted from post at 15:43:09 12/13/13) That seems to be the only thing that makes sense at this point.
1st time thought maybe I messed up, but to have the problem twice now?
I hate after market parts.

This is not a common issue so look for the root of the cause and don't play the blame game just yet...

Clean both surfaces with brake clean, alcohol are lacquer paint thinner :wink: There are adhesives that will nail the gasket in place but I would not go their just yet...

Agreed. I don't want to wish any misfortune on Billy but a thorough inspection of the parts seems to be needed. The mounting system used on that cylinder is fraught with peril. I received this piston pump gear housing from a customer - looked fine until it was cleaned in the bead blaster.....

TOH

 

[Billy the kid]

Thanks for all the input guys, Yes this is a weird one.
I will look real close when I tare down.
Thinking at this point is a none true service?
I will let every one know what I came up with or not LOL!!
Love this site got so much good info from you guys!

 

[ZANE]

Did you replace the two round one hole gaskets that go under the open end of the ram cylinder.

They must be the exact same thickness as the one under the front bolts that is the pressure gasket.

If you don't replace the two round gaskets the pressure gasket will be loose on one side and cause it to blow out.

Zane