990 implematic no lift

[eytonfarmer]

Hi

i have no lift from the 3pt linkage, i slackened the pipe feeding the ram cylinder and there is no oil, but when i took the cover above the pto off the pump is supplying a nice flow of oil to the pto gears, could it be a burst pipe as when in the lift postition i can't hear the pump.

It has had a new crossbox but i have doubled checked the distance for the sensing cable so i dont think it is that.

any help or tips would be much appreicated

thanks

[Guest]

I have a PDF file on the Implematic hydraulic system from the manual, PM me your email address and I'll send the file to you so you can study it, the text should enable you to sort it out.

[ollek]

Sticking of the hold and by-pass valve in the up (lowering) position is a common failure in Implematic hydraulic systems. Remove the plug on top of the PTO and have a look at the nut. Lever down: nut in the up position. Lever up: the nut shall go down. If this does not happen, tap very lightly on the nut an see if it goes down. But be careful, hammering to mutch will damage the T-bar that lifts the valves.

[eytonfarmer]

i have that already, i have looked through the troubleshooting part for no lift, the thing that is confusing is there is no oil to the three way valve thus no oil to ram, the only thing i haven't done is to take the plug out of the pto casing to see if the valve on the pump is moving when the lever is in the raise postion.

thanks for the offer anyway

[Guest]

No problem, just a thought. I believe that on this system the feed oil pipe from the suction tube from the filter to the lift/lower valves via the pump curves around the crown wheel and is very close to it, this pipe can, as it did with the earlier models on occasions, come into contact with the crown whell which made a hole in the pipe resulting in hydraulic failure. May pay to check this out before tearing the pump apart.

[eytonfarmer]

is it a big job to get at this pipe?, can i get at it by removing the pto casing

[jimc1390]

make sure the valve is moving first 99% of the time on these thats the problem

[db2d]

Do not get misled into a major strip down at this stage. If you have oil flow to the PTO gears it is because the pump is working and the Leak-Off Valve is open.The first thing to check is the is the override control lever it could be disengaged and in hold position,then check valve movement

[eytonfarmer]

Right guys

I now have lift, it was that stuck valve under the cap in the pto casing. now i have another problem, the arms go stright up to the top and lock, i have tried the overide lever in both positions in and out but with no joy. if i turn the engine off and turn the brass knob on the left of the tractor the arms come down. is this a sticky valve?

Problem number 2, when i tried to take the plate off on the right hand side of the tractor while it was running it was spraying oil out everywhere, i turned the tractor off, took the cover off and on the back of the control vale there is a brass screw slightly above the inlet union, when i put pressure on the arms to make them go down the oil was coming from behind the head of the screw. Should this be happening?

Also the overide control lever moves with the arms even when pulled out, shoul it do this?

Sorry to ask all this questions, but i thought they might be connected by one problem.

Iam going to take pto casing off this weekend to give all the mechanisms a good clean.

thanks for the help so far guys

[db2d]

Problem 1 is not a sticky valve. I have sent a PM

[db2d]

Problem 1 is not a sticky valve. I have sent a PM

[eytonfarmer]

no pm yet

[eytonfarmer]

just a quick update i had the topper on the back of the 990 today, it lifts and lowers it fine but the only problem i am having is the arms go up with out any weight on them, this is quite a dangerous problem as when i take the topper of it i have to turn the tractor off and push it forward so that the arms dont catch on the topper, i thought it might be one of the valve on the pump not closeing completly, what do you guys think?

[ollek]

The valves on the pump are closed when the hitch lifts. The by-pass valve is open when the hitch is in hold position and the hold valve is open (and also the by-pass valve) when the hitch lowers. The only thing I can think off that creates a pressure big enough to lift almost empty lower links is the TCU valve. A sticking TCU valve will build up a constant low pressure in the system.