MF 2640 low hyd. pressure problem ?

[VaKA]

Hello everyone,

I've had this MF 2640 4wd (attached pic) for the past 4 yrs. Last winter I installed a new hydraulic pump, new filter and all new hydraulic oil. The pump is Vapormatic pump, the hydraulic oil I used is Fanfaro STOU SAE 10w-30, (is this the correct oil type?), this was available. Thoroughly cleaned the oil radiator and completely bled the system for air, brakes, clutch, steering, radiator. It worked fine during spring last yr and by autumn it started to get lazy.
The symptom is as follows, when i start the engine leave it to warm up a bit, it needs a bit of revs to freely use the steering, similarly it need high revs to use auxiliary hydraulics to lift, same for the lifting arms, when the tractor is normally warm. When in the fields after working all day the auxiliary hydraulics simply don't work at all, high revs or low revs, the oil at this moment is hot and almost water like in viscosity, it barely sticks in the dip measuring cap of the reservoir, so I end up leaving the attached equipment in the fields.

So now we're done with seeding and field work for a couple of weeks and I'm planning to open it up, drain the oil and take my time to find the issue.

I've read that the o-rings of the intake hose from the filter can cause problems and introduce air to the system (attached pic), also the directional valve tends to get stuck occasionally. I couldn't find anything related to pressure and relief valves, so if anyone had similar problems any info would be appreciated.

We don't have an certified workshop for this so I will need to do it myself. What should I know before I start with this process.

Thank you everyone in advance, any help would be greatly appreciated.

 

[masseybreaker]

is the filter the early cartridge type or spin on type ? if its the early type check the o ring in the bottom of the filterhousing and the one around the top

 

[VaKA]

Hi masseybreaker,
Thanks for the quick reply, the filter is a spin on actually and its merely a couple of months old.

 

[masseybreaker]

just check the o ring on the top of it sometimes you can leave the old o ring on the filter housing and when you put the new filter on you have two o rings and they can draw air between them

 

[rob h]

Have you a spool valve sticking open slightly.causing the oil to heat up and also diverting flow away from other services.we had one and the steering always went heavier when lifting the linkage

 

[VaKA]

@masseybreaker hmm that didn't cross my mind before, i will check that. It be interesting so this being the case.

@rob h so my mf 2640 has three spools. The first being in the danfoss directional hydraulic valve (photo 01) The second is in the filter head controlling the return of the oil in the filter and reservoir (photo 2). The third is in the rear differential lock mechanism (photo 3, i have used this just 3 days ago, stuck in the field, seemed to engage and disengage fine). I have cleaned up the spool in the filter head before and it seemed to make the hydraulics better but not good enough. Also when I installed the new pump, I've cleaned the danfoss directional valve also.

 

[VaKA]

What would the best way be to test and repair these. Does cleaning them thoroughly do the job or should i look for new ones ?

 

[rob h]

When you replaced the pump had it worn into the casing leaving metal filings in the pipes.if so it could be any one of them. I had problems with sticking valves mainly the lift valve when I had a worn out bearing in the gearbox.it kept jamming the spool.took it of cleaned it out there were bits of metal in it. Worked ok for a few days then did it again I took it apart 3 or 4 times over a 2week period.each time it worked ok then did it again till eventually the noise in the gearbox told us why.we also had a 6150 it chewed the hydraulic pump .putting bits of metal all over the hydraulic system.it took many goes to get it working as bits kept going around

 

[VaKA]

when i replaced the pump it had worn the casing and i assumed that it had left metal filings in the pipes and reservoir, so i used diesel to clean up some of the pipes the pump casing and command and also the radiator... my problem is mainly the auxiliary i can't lift the disc harrow for transport and when ploughing it needs high revs to lift the arms but it rotates the plough pretty easy... i dont have much trouble with steering though, gearbox feels very smooth and theres no noises coming out... couldn't figure out why the pump broke though prior...
i will start by checking on the filter o-rings and also open up and clean all the spools to make sure and hopefully i wont have to open her up.

 

[rob h]

Is it electric linkage controls or manual

 

[VaKA]

its manual linkage control

 

[rob h]

i had the linkage controll spool sticking with metal filings .might be worth removing it and stripping and cleaning it.just check the easy things first o rings /pipes etc

 

[Speedstar]

Sounds like one of the O rings in back hyd control valve cover is leaking , the one right behind the fuel tank

 

[VaKA]

@rob h @Speedstar i haven't opened this control spool ever, not even after replacing the pump, so i will start with this, strip and clean and go on with the rest of the spools.

@speedster this would be the hyd control valve you are talking about. Maybe one of the o-rings of the tubes that go in the control spools?

I will get back to you guys, let you know how this goes.

 

[rob h]

@rob h @Speedstar i haven't opened this control spool ever, not even after replacing the pump, so i will start with this, strip and clean and go on with the rest of the spools.

@speedster this would be the hyd control valve you are talking about. Maybe one of the o-rings of the tubes that go in the control spools?

I will get back to you guys, let you know how this goes.

Yeah that’s the one easy to remove just need a clean area to work

 

[Speedstar]

@rob h @Speedstar i haven't opened this control spool ever, not even after replacing the pump, so i will start with this, strip and clean and go on with the rest of the spools.

@speedster this would be the hyd control valve you are talking about. Maybe one of the o-rings of the tubes that go in the control spools?

I will get back to you guys, let you know how this goes.

Change all the number 12 , 14 & 16 O rings

 

[VaKA]

So here i am today, started tearing, cleaning and repairing.
As you can see in the photo the rear linkage control is quite oily, should it be ? I am replacing the 12, 14 and 16 o rings.
I’ll keep you posted.

 

[VaKA]

Update, teared apart the linkage control valve, the o rings are fried and one of the 14 orings is missing... also all the pipes o rings are pretty much gone...

 

[rob h]

Have you checked to make Shure
the piston works freely .or better still had all the internal parts out and checked for any signs of damage

 

[VaKA]

@rob h so i tore down the whole valve, removed all the pistons and im going to replace all the o rings before reassembling.
The large piston (marked red in the photo) had metal residue in it quite a lot, the piston itself is in good shape no damage in the groves.
The main controlling piston (marked blue in the photo) had no residue and moves freely, there was a very small dent in one of the grooves, ill attach the photo tomorrow.
There are two other pistons (number 5 and number 30) both of them move freely and there was no apparent residue. Also no residue in the needles (number 18 and 26). I cleaned the case thoroughly with pressured diesel and oil cleaner, cleaned the large piston housing (marked red) and all the oil ways.

Tomorrow I will replace all the o-rings in this and clean the directional valve and the filter head valve also for any residue and start it up to see if the pressure is back.