Update on all 7520s

[chandler37]

Brian;

Yup that would have been my guess; now I will have to convince the dealer that there is one. Thank you for the info.

Blu;
MY Manual says "# indiactes that the must be done at specified hrs."
page 84. Sounds like a glove box story. Spent the big $'s and am trying to do it right. I think the screen is going to wait.
Tractor is at the dealer getting the turbo replaced; noticed oil leaking down the exhaust and down the engine side. dealer had me take pitures and email them to him for conformation. He told that district service had not had a turbo go bad on this model and where ??? it before sending a replacement.
Still I am very happy with the tractor and waiting to get it back home.

REminded the wife that when we bought a new chevy PU it went back the next day with a radiator leak. the Tahoe wouldn't start after a week and needed it second battery. Things happen.
Noticed in the Farm Trader the the prices on new/ demo/ left over 05 & 06 Kobota's and Jd's are coming down. I wounder if "other brands" are having a effect on them.

Chandler

 

[SPYDERLK]

Blu 82 et al, Any words on slow loader issues??
I am homing in on this as a true indication of lower than specd hydraulic delivery. I have incorporated a pressure gauge to sample pump pressure directly at the output of the hyd pump. I think this will be handy for many system checks, but in the instant case i was thinking the feed lines to the loader might be limiting full flow by causing excessive back pressure. They are not. - Full rpm full speed lift of the loader shows less than 1000psi at the pump. This is not enuf to make any difference in the pumps output, nor is it enuf to push anything past the relief valve that is set at 2500. From lift rate of the loader and volume of the cylinders, I calculate 11or12GPM delivery. I am going to ask Mahindra for the specs of the pump. That would be the easiest way for them to prove their 17GPM claim for the hydraulic system - as specd seperately from the 5GPM steering system in the sales brochures.
Larry

 

[Blu 82]

Larry--I haven't timed the loader, just got it back from the shop to fix some hyd leaks (main system and pwr steering) underneath the tractor. Nothing major but needed to be fixed. On the main hyd system the line was leaking from a fitting on the lower right side of the tractor just before it goes underneath the tractor in the back. We tried to tighten the fitting but it wouldn't tighten. On the pwr steering, the line was leaking at a fitting on the left front and it was fixed by tightening the fitting. I have been clearing land and the tractor is doing its job. Tough on the tractor compared to just plowing fields or mowing I imagine, but that is what I bought it for.

I will try to time the loader and see how the times compare to the specs. I know that the loader is strong and has helped me move some pretty large trees using a forklift. I haven't had a problem w/speed on the loader. Maybe that is because I don't have any experience and it seems ok for me but I will time it. If the hyd are not as advertised though, I think Mahindra should acknowledge it and give us some satisfaction.

Was using the backhoe the other day and it does fine in my sandy soil. I had to replace one of the backhoe hyd cylinders. Good news is the cylinder was only about $378--I thought it would be much more. My dealer doesn't mark up the tractors or parts a whole lot and is easy to deal with.

Because of the hyd leaks and BH repair, I feel like I should drain and replace all hyd fluids. I know the manual doesn't call for it at 50 hrs. I do know that the Kubota/John Deere dealer replaces all filters and fluids at 50 hrs and the MF dealer recommends the same. Not sure if that is just a way for the dealers to make more $. My Mah dealer said I didn't have to do that and I may not change all the hyd fluid. The eng oil is really black though and I will prob ch it and the filter. Is there a seperate hyd pump for the pwr steering? Where is it? Also, how do you drain the pwr steering fluid? I will also ask my dealer the questions too but don't mind asking here also. My dealer showed me where the eng oil drain plug is--well hidden in the protective cover for the front wheel drive shaft and some hyd lines (I think).

Thanks for keeping up on the hyd issue. I sure wouldn't know how to check the pressure. Will let u know what times I come up with next time I get out to my land.

rob

 

[SPYDERLK]

Hi Blu. Never saw your answer. Probably since the day you answered my engine broke at 174hrs. I was running a wood chipper when I noticed smoke coming from the crankcase breather that exits down by the starter. No leaks, all gauges normal, but within a few seconds the engine missed, began to clatter and stutter. I cut the key. After checking everything I could and finding nothing amiss, I try restart. It just spun. Turns out the cam stopped turning. There was a problem with factory assembly. Im losing optimism.

Re slow hydraulics - The 20 Series Brochure lists for the 7520:

Steering

• Type - Hydrostatic Power & tilt steering
• Pump output - 5.2GPM

Hydraulic System

• Type - Open center, full live hydraulic, with position and draft controls
• Pump Output - 17GPM

The brochure lists 5GPM and 11.4GPM respectively for the 6520.
I test drove a 6520, and its slow loader convinced me that the 7520 was the way to go, particularly since 17GPM is enuf in a pinch for skid steer implements. Imagine the disappointment on getting my tractor and finding it equally slow. Loader cycle time on my tractor indicates 11 or 12 GPM. While it is in the shop I will press for remedy.
When you check yours, be sure not to slam it against the top. What I did is find a stop point near the top and measure an amount of rod extension to get there from the lowered position. I used 22.5" extension. This works out to 5.213liters [5.516qt] delivery considering the 2 cyls. This and your time will give you the delivery rate. Warm it up, rev it up, lift it up and time it. Experiment with escalating times to get near this extension cuz beyond it there isnt much safety factor. Six seconds flat would be 55qt/m or 13.75GPM and mine wont even do that.

There is plenty on the good side - it just has to meet spec and keep working so you can maintain focus in that direction.
larry

 

[Raddad]

"ground engaging work? " Who calls using a rear blade "ground engaging work"?

 

[SPYDERLK]

"ground engaging work? " Who calls using a rear blade "ground engaging work"?

I would, but who did?

 

[DavesTractor]

Spyder, have your dealer remove the rubber hose on the return (suction) line going back into your pump. Sand the paint off of it where the hose fits, then replace the hose. Apparently some of these are sucking in some air at that point, yet they do not leak oil, so it's not noticable. It is said to have a profound effect on loader speed. Sorry you are having problems, they are not typical.

 

[SPYDERLK]

Dave, thanks for the pointer. I had heard about this and have doubled up hose clamps on the joints. I would prefer, before going into this system separation at the dealer, to know that the pump is capable of 17GPM. Can you tell me its spec for the steering and the main hydraulic sections. I need cubic inches per revolution for each section, and the speed at which the pump turns at 2400 or so engine rpm. Looking at the pump from the outside the two sections are a ratio of 2 to 1 in length. This suggests a 2 to 1 delivery ratio. This makes me think it may have a 6520, 11.4/5GPM pump rather than a 7520, 17/5.2GPM pump. This lower capacity is verry close to what I have observed. Full ID and spec of the pump would have a much better chance of sending us quickly in the right direction for remedy. Thanks for your help!
larry

 

[CuzPat62]

Hi all,
Haven't been around in a while. Thanks Larry for the e-mail/pm inquiring about me. I have had 3 foot surgeries and just got off of crutches from the last surgery just 2 weeks ago Tuesday. Hope my foot is on the road to recovery now.

All I have done this winter with my tractor is put out round rolls of hay for my cows each week. I did do the 50/100 hour service on it back in November. I now have 82 hours on the tractor and a brand new problem has surfaced. It kind of worries me.

Here's what is going on. I never noticed it until the weather turned cold. My tractor has started smoking and when it does it it is pretty bad. The smoke is a bluish gray color. It does not do it on a continuous basis. It will smoke a while and then clear up and run without smoking. Then it will start back up to smoking again. If you let it sit and idle it will smoke really bad. It seems to do it worse when it is cold. Yesterday, the weather warmed up quite a bit here and it was not cold at all. I put out hay with it and it did not smoke at all. At times, this $30,000.00 new tractor smokes worse that my 1966 John Deere that I sold that was still running the original engine!

I have already contacted the dealer about this problem. He stated to me that they had recieved several complaints on this issue from other Mahindra owners. He said it had something to do with the Intake manifold heater for starting in cold weather. I believe he said that they had to order some type of device to install in the circuit which has a switch or relay in it. I think he told me it was a timer that had to be installed.

The dealer has not seen the tractor on this problem, I've just talked to him on the phone. He is hoping that this is what the problem is. Looks to me if it was an internal problem with the engine it would smoke all the time.

Anyone else had this problem with their tractor? Or can Dave or anybody else enlighten me on this issue? Thanks for the help.

By the way, the loader is as slow as it ever was. It really disappoints me. My BIL has a Kubota M6800 with loader and his loader will work circles around mine! That's Sad!!

Glad to be back here again. Ya'll take care!

 

[SPYDERLK]

Quote: By the way, the loader is as slow as it ever was. It really disappoints me. My BIL has a Kubota M6800 with loader and his loader will work circles around mine! That's Sad!!

CuzPat, good to hear from you. Glad youre recovering. A working foot comes in handy-especially this time of year coming up. I think I have the same type of smoking problem you do. It comes when the tractor is worked real easy in the cool. Its called "cold stacking" I believe. I put some multi perforated cardboard in front of the radiator to bring up temperature and it helps. You may note from my posts on various threads that my intake heater has not worked since I got the tractor because its relay was sticking. It deadened the batt so I unplugged it. It occurs to me from what you said, that it could be used to help warm the manifold to correct T and prevent the smoking. It would require a thermostatic control and I dont see one in the wiring diagram. I think its a minor problem, but OMG! mine had it and didnt at first - and my cam stopped!!. Could have been related to slips in cam timing?

As you can see Im hot on the slow loader issue as an indication of less than specd hyd output. It should be very simple to lay this to rest. At this point I want to see the pump specs and its gear drive ratio. After that works out to 17GPM we can then look for malfunction. I havnt heard anyone who has used a loader before refer to it as other than slow. Mahindra is calling it air leaks in the suction line. That could do it for sure, but it seems to me that there would be much more leakage at high RPM since it would be sucking harder. That should show up as a loader that remains sluggish even as the engine revs. Mine on the other hand, speeds up pretty linearly with rising rpm but never gets anywhere near fast enuf for 17GPM.
Take care. Get better.
larry

 

[Dougster]

By the way, the loader is as slow as it ever was. It really disappoints me. My BIL has a Kubota M6800 with loader and his loader will work circles around mine! That's Sad!

As a retired mechanical engineer with considerable positive displacement fluid systems design experience and performance testing experience (not to mention interest in this particular tractor), this 7520 hydraulic flow / loader speed issue continues to intrigue me. This should not be a particularly difficult problem to investigate and (hopefully) resolve. But can I just ask one question: Did you folks notice this slow loader issue at the time you were shopping and buying? Or did it show up later?

Not trying to be cute or difficult... just trying to understand whether this is a machine design issue or a maintenance/wear problem.

Dougster

 

[SPYDERLK]

Dougster, to be cute but hopefully not difficult, pls read #64 down near the bottom. Some dont get the chance to even get that close and rely on spec alone.
larry

 

[Dougster]

Dougster, to be cute but hopefully not difficult, pls read #64 down near the bottom. Some dont get the chance to even get that close and rely on spec alone.
larry

Hi Larry - I think I've read every post on this issue (Yes, I do need a real life!!!) until I was blue in the face as this was my former occupation... i.e., testing & troubleshoooting fuild systems albeit on a much larger scale. Believe me when I say that I'd like to help. Even more, I'd like to know the answer to this mystery as the 7520 is my post-lottery winning dream machine! But first, I'd like to know if the problem was there from day one... i.e., a design issue that everyone experienced... or something that only some experience... or something that generally got worse after a time.

Forgive me if I've forgotten some of the particulars over time. I am old.

Dougster

 

[SPYDERLK]

Dougster. It was slow on my tractor from day one. I was not able to find a 7520 to test drive despite inquiring with a Mahindra sales rep I met at a dealer and getting no help at all. In deciding, I went by extrapolating specs from the 6520 I was able to locate on my own. The loader speed has neither improved nor worsened. I suspect mine has the wrong pump.
larry

 

[Dougster]

Dougster. It was slow on my tractor from day one. I was not able to find a 7520 to test drive despite inquiring with a Mahindra sales rep I met at a dealer and getting no help at all. In deciding, I went by extrapolating specs from the 6520 I was able to locate on my own. The loader speed has neither improved nor worsened. I suspect mine has the wrong pump.
larry

Two more questions please: 1) If you can see the hydraulic pump you can photograph it and post it here. Unless the 6520 and 7520 have pumps that are visually and dimensionally identical, wouldn't that solve the mystery of the potential wrong part right away? and 2) This is not rocket science... so why can't a simple flow test be conducted to measure hydraulic flow?

Dougster

 

[bindian]

Dougster. It was slow on my tractor from day one. I was not able to find a 7520 to test drive despite inquiring with a Mahindra sales rep I met at a dealer and getting no help at all. In deciding, I went by extrapolating specs from the 6520 I was able to locate on my own. The loader speed has neither improved nor worsened. I suspect mine has the wrong pump.
larry

Larry,
Take the part number off of your pump, then ask a Mahindra parts guy the part number on the 17 gph pump that is suppose to be on the 7520. Two different capacity pumps can look alike on the outside. Other than that, you could have some obstruction or trash blocking a line or oriface in the cylinder. Airliners use 3000 psi in their hydraulics and every now and then, something gets caught in a check valve or restricted check valve or even an actuator. A by-passing cylinder can also give slow response time. Raise the loader all the way up and leave it for a day or so. If on start up, you can raise the loader, it is fluid (and pressure) by-passing the cylinder piston causing all or some of the problem. With out having a schematic of the hydraulic system it is hard to pin point what is doing on where and when. All I have is the Ops manual on the ML275, which is on the 6520 and 7520. Basically, any port or fitting that has small inner diameters could cause an obstruction. A bad line that is coming apart internally is another thought that can cause a slow response.
hugs, Brandi

 

[SPYDERLK]

Dougster. I was told by a tech rep when I 1st brought this up that they are putting the 17GPM pumps in both the 6520&7520. A picture would merely confirm the same pump - not its volume. The pump in mine is a two section pump showing identical cross section front to back. The main hyd section is about twice the length of the steering section. These two things suggest to me that they are a 2to1 volume ratio - not a 3to1. When you combine that with my measurement of fluid delivery of 11to12 GPM based on timed lift rate of the loader, you are led to the conclusion that the steering and main outputs have been combined for the 17GPM figure. Mahindra reps make statements to the contrary. We need the pump specs and geared/crankshaft ratio. Thats all we need in order to know if we should look for a malfunction or an inflated claim.
larry

 

[SPYDERLK]

Brandi. You have good suggestions. Pls see #62. I believe its all been covered except for a leak on the suction side, or inadequate pump displacement or incorrect crank to pump gearing. I want the pump specs. The p/n would just tell us it is the one they mean to be on the tractor.
Oh - just thot about what you said re a check valve being off its seat. On further thinking I think thats ruled out too tho. When my engine broke I used the starter to turn the engine and raise the loader so I could tow it. Anything but the smallest leak anywhere would have used all of the meager pumped fluid.
larry

 

[Dougster]

When you combine that with my measurement of fluid delivery of 11 to 12 GPM based on timed lift rate of the loader, you are led to the conclusion that the steering and main outputs have been combined for the 17 GPM figure. Mahindra reps make statements to the contrary. We need the pump specs and geared/crankshaft ratio. Thats all we need in order to know if we should look for a malfunction or an inflated claim.

I do sympathize... and I can certainly understand your suspicion. But... mechanical engineer to mechanical engineer... even the pump specs are not nearly as good as one accurate, instrumented pump flow test... including accurate measurement of engine RPMs. You have already conceded that there is no way to tell the difference between a 6520 pump and a 7520 pump... or that there may be any difference at all if you, in fact, have a 6520 pump. Indeed, they may be the same pump with different drive RPMs at spec engine RPM (as you have implied).

Forget about the loader for a bit. Spend the cash and do the pump flow test.

That's my last word on this. Now I'll shut up and fade back into the wallpaper.

Dougster

 

[bindian]

Hey guys,
Something doesn't add up between the 6520/7520 4WD sales broucure and the Model ML275 FEL Operator's Manual. The broucure shows a 9.3 second time to raise the boom on the 6520 and 6.2 seconds on the 7520.
My KMW ML275 Operators Manual specifications shows that both the 6520 and 7520 at full rpm will raise the boom at 6.2 seconds. So some advertised spec is wrong somewhere. Has anyone timed the 6520 4WD FEL yet? 11.4 and 17 gpm should show a good difference in time. I played with the 6520 4WD and raised the loader. It seemed fine for me. But I have only ran a FEL on a Kubota L3400 before. I will time it this week while at the dealer. So let me get this striaght. Time it from level on the ground to full height? Is this right? The broucure says RPM is 2500. The ML275 Ops manual says at full rpm. Which have y'all been using? My 6520 Ops Manual shows a photo of the tack and it redlines about 2750. Which is fast as I will rev it. So I will time at 2500 and redline.
Also, the broucure shows the 6520 4WD weighs 7300 pounds. My Ops Manual says it weighs 6141 pounds. Is the broucure weight with the FEL? I haven't found a seperate listed weight for the ML275 FEL. One of the first trailer trips I will make with my 6520 4WD,FEL, and BH will be to the local salvage yard's scale.
hugs, Brandi