NAA lift suddenly stopped

Bill Seifert

New User
I have read and searched till I am ready to scream about lift problems on my NAA tractor.

I finally just took off the top cover. My question is: I started my tractor with the top cover and no oil shot out the hole that feeds the top cover/lift mech. Can the relief valve be stuck and simply bypass the oil and cause this condition?

I took off both the inlet and outlet lines on the bottom of the housing leading to the pump, thinking that something had plugged the suction line. It seemed clear.

Again, can a stuck relief valve cause the lift to stop working and cause no oil to pump out the hole to the lid? Thanks Bill
 
Bill, your is your pump the square vane style or the later round case piston pump?
It may need to be primed, but it can be tested.
Some of the guys here helped me with mine when it wouldn't work.
 
(reply to post at 21:01:04 04/11/13)
I started my tractor with the top cover and no oil shot out the hole that feeds the top cover/lift mech. Can the relief valve be stuck and simply bypass the oil and cause this condition? About 99% certainty, that the answer is no.. Make that 99.44% Your pump is not pumping.
 
Yes I have the old vane pump. I suppose it could have lost prime, but why after all these years(owned since 1988). Also using #90 grease it seems like it might not lose prime as easy as it could using lighter hyd. oil.
I know vane pumps don't have as much suction as a gear pump.

Most likely maybe the pump went bad. Although I work with hyd. systems most everyday, I did not see an easy way to hook any type of guage on to the pump. Thats because the pump has bolt on flange/rigid pipe design outlets with no easy way to T in a pressure guage.

Who can tell me where or how to check this pump without tearing it all apart? Bill
 
Sounds like what the other posts have already stated,..you lost prime on your hydraulic pump. There should be a plug on the top of the pump towards the front. You can unscrew that plug, or the hydraulic line and check for oil. Pour some in if you need to prime the pump. Also be sure to bleed the air out of the system after you have primed it. Check your hydraulic oil level at the dipstick to ensure the sump is indeed full.
I included a picture of the vane style pump. T.O.H. (This Old Hokie) on this site can give you all the info you need to get your pump primed and he also has a replacement gear style pump kit with fittings for your NAA if your pump is bad.
a111186.jpg
 
(quoted from post at 13:29:42 04/12/13) Yes I have the old vane pump. I suppose it could have lost prime, but why after all these years(owned since 1988). Also using #90 grease it seems like it might not lose prime as easy as it could using lighter hyd. oil.
I know vane pumps don't have as much suction as a gear pump.

Most likely maybe the pump went bad. Although I work with hyd. systems most everyday, I did not see an easy way to hook any type of guage on to the pump. Thats because the pump has bolt on flange/rigid pipe design outlets with no easy way to T in a pressure guage.

Who can tell me where or how to check this pump without tearing it all apart? Bill
Unlike the piston pump, there appears to be no inlet & outlet plugs on the pump itself to permit the release of air (outlet) nor on the inlet/suction to allow the introduction of hydraulic oil. This leaves the outlet release point as the test port plug on the lower right side of center casting, near foot board/right brake. You can remove that and start to see if air on outlet is keeping it from pumping. I think this is not a high likelihood. Introduction of oil into the inlet is probably a better shot at success. This is done by applying compressed air to the dipstick hole with an air compressor blow-gun to help force oil up into the pump inlet. Other option is less desirable. Remove the pump, turn it upside down and fill it with oil, work pump to thoroughly coat insides with oil, being sure it actually pulls in oil at intake & forces it out the outlet when rotated. Pour oil into the suction line...gravity will never let you fill the line, but at least some oil will now be known to be in the line. If you need pictures of the test port location, view picture.
NAA_tst_port_mkd.jpg
 
When i changed the hydraulic system oil on my NAA (original vane pump) I decided to use more viscous oil than the old stuff I drained out that seemed to be about SAE 10 (thin)viscosity. Everything was fine until winter, when the hydraulic system would not lift the snow blade. I heated the pump and suction line with propane torch for about 10 minutes and then the hydraulic system worked OK. Since then, I drained the "heavy viscosity" hydraulic oil and replaced it with thinner (about SAE 10) oil. I have used the tractor for about 3 years since that time (including winters) and have not had another "pump-loss-of-prime" incident.....hope this may help you.
 
If you are using 90 weight gear oil in the hydraulic system, that is likely the problem. In cold weather, the gear oil causes the pump vanes to "stick" and not slide out to contact the elliptical pump housing...so it won't pump. Try changing to less-viscous oil and prime the pump with air pressure as suggested by JMOR.
 
That is thanks you all of you good folks on this site.

I put the back lift back together, then removed the vane pump. I disassembled the pump and checked it over for wear ect. It looked really good. I put it back on prefilling it with heavy lube ( similar to STP) Did the air in the dipstick hole trick. I left the outlet line off till I seen oil coming through the pump using the air pressure. I then buttoned eveything up and it worked instanly.
It must have just lost prime someway, never happened in the 25 years I have owned it.

Thanks to all of you who helped me, you're the experts on these tractors for sure. Bill
 
OK guys I had it working, but it loses prime if it sits more than a day or so.

I took the pump apart and found that the main seal on the shaft is hard. I believe it is sucking air and losing prime.

I think with a speedy sleeve on the shaft and a new seal it will work again.
Problem is : Where do I get a seal for this vane pump. The avenues I have persued have so far come up empty. Any help would be appreciated. Bill
 

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