Fiat 90-90 hydraulics

vanderbadger

hey
had my 90-90 serviced there before silage season, first noticed then one evening wrapping that the hydraulics kinda stopped working in both directions, bale aram would lift but not go down, has happened a few times since, example, yesterday evening had hydraulic toplink on back onto spool valve, it would open but not close, had to swap hoses around and then it worked again but same thing happened again later, tractor has 2 spools but only ever use 1 set as one of the connectors on the other pair is damaged..any ideas anyone?

pakalasa

Hi vanderbadger,

I work a little with hydraulics but I don't know the hydraulics on the Fiat & my own tractor only has manual spool valves.

Have a look at the following
http://www.hetacfluidpower.com/images/screen_shots/float_spool.jpg

This shows an electric double acting spool valve, with A and B to tank at centre.
Most valves work on this princible. The spool (metal pin inside) moves from side to side and is activated by either - (A) 2 solenoids as shown,(B) one solenoid with a spring return or (C) manually by levers.
It sounds like the spool may be sticking on yours. That could be from some dirt, metal burr etc. These valves work to very tight clearances and so don't like dirt. If you open it up check for scratches on the spool.

Check also that the solenoids (if there) are getting voltage when they should be? ...use a voltmeter

vanderbadger

cheers
id say Fiat would be manual valves as well, everything else is manual on her
I suppose something blocking it would make sense, feck hate the prospect of having to open stuff

pakalasa

Do you have to work a lever on the valve itself for up/down, if so then it's manual. If it's manual then it isn't sticking as you would feel it in the lever.

Are you sure it's not the pump itself getting blocked at the suction side. This could be due to dirt, oil sludge from the service. That happened before on our tractor after I changed the hydraulic oil. Propably some dirt that hadn't worked itself around to the filter yet.

If you think it's the pump just leave it for a few weeks and see if it works itself ok.;)

feargall

I have a 90-90 and it sounds like a problem with the spool valves. If it was the pump the hydraulic toplink would not work in either direction, if it was the filter then it would probably just be slow at performing lifting / wrapping tasks. The problem that mostly happens with mine is in the linkage between the lever you push with your hand and where it attaches to the chest/spool valve. The studs that hold the linkage to the spool valve tend to vibrate loose so that when you operate the lever it doesnt actually operate the spool valve. this usually only happens in one direction which would explain the non operation of the toplink and also the wrapper as the flow and return for the wrapper supply is not fully opened. to try this out stand at the back of the tractor, put your hand in to the right hand side of the quick release connectors and find where the levers attach to the valve/spool chest. leave the toplink attached as before and operate the chest with your hand. the chest is in a very confined space so be prepared for a little blind feeling around. this problem happened me regular so I put some loctite on the allen head bolts that hold the linkage the linkage together and have had no problems since.

vanderbadger

thanks for the info, must check it out, had looked from the back of the tractor and as you say the valves are a bit far back but will take a better look

marlyman

sounds like dirty or worn quick release couplings. i think this is because you problem is so intermittant and cant be pinned to one specific system in you tractor.

i.e. if the female section of your spool valve is worn when the force of pressure comes on the male section may stay closed, or it may open, giving you full pressure or no pressure. cause you didnt say you had no pressure or slow hydraulics this is the most probable problem.

check the male ends on your hoses and the female ends on the tractor for signs of wear. a good indicator is to listen to the tractor, if you rev up when using the spools and the spools dont work but you can hear the revs dipping and the pump driving then everything is working but the oil is not getting out.

pm me if you need a new spool end for the tractor

vanderbadger

marlyman wrote: »

sounds like dirty or worn quick release couplings. i think this is because you problem is so intermittant and cant be pinned to one specific system in you tractor.

i.e. if the female section of your spool valve is worn when the force of pressure comes on the male section may stay closed, or it may open, giving you full pressure or no pressure. cause you didnt say you had no pressure or slow hydraulics this is the most probable problem.

check the male ends on your hoses and the female ends on the tractor for signs of wear. a good indicator is to listen to the tractor, if you rev up when using the spools and the spools dont work but you can hear the revs dipping and the pump driving then everything is working but the oil is not getting out.

pm me if you need a new spool end for the tractor

Now that you mention it one of the female ends on the tractor is missing some of those little ball bearing type bits that hold the hose in I guess, would that casue the issue do you think?
the tractor is originally a dutch import, of the 4 hydraulic connectors on the tractor I use the 2 top ones, of the bottom 2 one of the connectors seems to be a screw in type head different from the other 3, so I always just used the top 2, not sure why one connector is different

marlyman

vanderbadger wrote: »

Now that you mention it one of the female ends on the tractor is missing some of those little ball bearing type bits that hold the hose in I guess, would that casue the issue do you think?
the tractor is originally a dutch import, of the 4 hydraulic connectors on the tractor I use the 2 top ones, of the bottom 2 one of the connectors seems to be a screw in type head different from the other 3, so I always just used the top 2, not sure why one connector is different

thats the problem so.the hoses are not coupling together giving you eratic hydraulic services, the screw in end is not commonly used in ireland on that model. id suggest replacing all the female ends, and a hyd filter change.

Casinoking

vanderbadger wrote: »

Now that you mention it one of the female ends on the tractor is missing some of those little ball bearing type bits that hold the hose in I guess, would that casue the issue do you think?
the tractor is originally a dutch import, of the 4 hydraulic connectors on the tractor I use the 2 top ones, of the bottom 2 one of the connectors seems to be a screw in type head different from the other 3, so I always just used the top 2, not sure why one connector is different

When you say you use the 2 top ones, do you mean you plug both hoses of your wrapper/top link into the top couplings? If so then that would be your problem, the spools work in pairs of top and bottom for flow and return. At least they do on the vast majority of tractors. It's a long time since I used a 90-90 but I don't remember them being any different.

scudster

As mentioned above, its more than likely worn quick couplings. Ive seen this a few times before. To check this, make sure your tractor is turned off and pressure is released from the hydraulic system by wiggling all your hydraulic spool valve levers. Then press in the nipples in the quick couplers and see if any of the nipples slip to one side easily and stay there or not return fully to their original position. If they do just replace them. Also if the top of the nipples look worn down then this will cause the same problem.

vanderbadger

ya it was the coupling, some of the little balls ere missing so I guess the hose was connecting properly, new coupling fixed it