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  1. #1
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    Mahindra 4005

    Default 7520 Broken cam gear

    I have a 2007 7520 with 500 hours on it. The tractor recently died while driving it to my camp. The engine sounded like it had no compression. When we pulled the timing cover the camshaft gear had sheared off the camshaft. Has anyone had similar problems. This tractor only has 500 hours and has been operated by me 95% of the time. It has been worked but not abused. Of course it is out of warranty, but I noticed that Mahindra discontinued the two piece camshaft and replaced it with the one piece gear and shaft. I suspect they either realized the original was poor design or had problems with it. Pictures are attached, I think. It appears to me that a gear that would shear like that is either due to faulty materials or design. Any suggestions/ comments would be appreciated.

    Thanks
    Don
    Attached Thumbnails Attached Thumbnails 7520 Broken cam gear-2012-08-08-16-45-a   7520 Broken cam gear-2012-08-08-16-45-a   7520 Broken cam gear-2012-08-08-16-45-a  

  2. #2
    Veteran Member JerryK's Avatar
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    Mahindra 5035 HST TLB, 2555 HST Cab, JD 420 HST

    Default Re: 7520 Broken cam gear

    I would check to see if there is any end to end play in either your crank, cam, or any other gear that contacts the cam gear. Just a guess, but looks like the cam gear was being acted on by a side force that flexed/cracked it near the cam shaft over time. Also, this 'looks' like it could be called a one piece design... [ not an expert here, but had lots of years working on stuff ] Good luck, Jerry...
    78" Mahindra front blower, 48" CID QA forks, 6' EverythingAttachments Land Plane, 78" JRW rear blower, homemade 1 ton rear weight, 6' Ford rear blade, big homemade 3pt box/carrier, 8" wood chipper

  3. #3
    Elite Member
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    Default Re: 7520 Broken cam gear

    Back in 2006 or 2007 I think there was a failure like this reported on TBN. But I haven't seen one since. I think that fellow thought the cam gear was getting too much side load from the hydraulic pump...but I am stretching a poor memory. They have since updated the cam with a shrink fit cam gear instead of a bolt-on gear, which is of course stronger. It is only sold as a cam/gear assembly. The cam is also extended and is now supported additionally by the front cover. It is just a more robust design. Your dealer can pull up the service bulletin and let you know what you will need as far as parts to update to the new system. Keep in mind the manufacturers have a right to continually improve designs, and that does not mean that a failure out of warranty becomes covered.

    If this is a defect, that is exactly what a warranty is for, defects in material or workmanship...but the kicker is that even if you can prove a defect and absolutely no neglect on your part, reimbursement is still limited to problems that manifest themselves in the time period (time or hours, limits on both). If you have a 2007, you had a three year warranty, so you are out by maybe 2 years. Just giving you a heads-up on how that normally works, so you do not think the fact that this has been upgraded is a smoking gun leading to coverage.

    The good news is that the new design is super stout, and if you can do the repairs yourself it should not be all that expensive and you won't have to give that cam gear another thought.

    Talk to your selling dealer and see how he can help. I just looked it up and the kit is part number 006004516F91 and is not as expensive as you might think since it looks like it comes with the cam/gear, cover, gaskets, bearings, compatble hydraulic pump gear, etc. Looks complete. We have sold quite a few 7520's and we have not seen one fail, so it isn't common. We have never installed the kit ourselves.

    I hope this helps, and good luck getting this going. Sorry this has happened to you, but at least the fix is an improvement.
    Dave
    Dave's Tractor, Inc.
    Red Bluff, California

  4. #4
    Member
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    Tractor
    Mahindra 4005

    Default Re: 7520 Broken cam gear

    Update on cam gear failure. After discussions with Mahindra dealers it appears that this is rare on the 7520, however Mahindra appears to have changed the design on several models and beefed up the camshaft and gear. The tractor was out of warranty by two years (three year warranty at the time of purchase) but would have been covered if purchased more recently since they now carry a five year warranty. Mahindra has agreed to cover the cost of the camshaft, front cover and bearing. I am still out transport and labor but overall I feel that was fair treatment. Hopefully this will solve the problem on a tractor that otherwise I have been very pleased with.

    Thanks
    Don

  5. #5
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    Default Re: 7520 Broken cam gear

    Quote Originally Posted by dnetherland View Post
    Update on cam gear failure. After discussions with Mahindra dealers it appears that this is rare on the 7520, however Mahindra appears to have changed the design on several models and beefed up the camshaft and gear. The tractor was out of warranty by two years (three year warranty at the time of purchase) but would have been covered if purchased more recently since they now carry a five year warranty. Mahindra has agreed to cover the cost of the camshaft, front cover and bearing. I am still out transport and labor but overall I feel that was fair treatment. Hopefully this will solve the problem on a tractor that otherwise I have been very pleased with.

    Thanks
    Don
    Seems like a very fair resolution. Thanks for the update.
    Dave
    Dave's Tractor, Inc.
    Red Bluff, California

  6. #6
    Veteran Member JerryK's Avatar
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    Default Re: 7520 Broken cam gear

    GREAT...!!! Sounds like a pretty fair shake to me....
    78" Mahindra front blower, 48" CID QA forks, 6' EverythingAttachments Land Plane, 78" JRW rear blower, homemade 1 ton rear weight, 6' Ford rear blade, big homemade 3pt box/carrier, 8" wood chipper

  7. #7
    Super Star Member
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    JD2010, Kubota3450,2550, Mahindra 7520 w FEL w Skid Steer QC w/Tilt Tatch, & BH, BX1500

    Default Re: 7520 Broken cam gear

    Quote Originally Posted by dnetherland View Post
    I have a 2007 7520 with 500 hours on it. The tractor recently died while driving it to my camp. The engine sounded like it had no compression. When we pulled the timing cover the camshaft gear had sheared off the camshaft. Has anyone had similar problems. This tractor only has 500 hours and has been operated by me 95% of the time. It has been worked but not abused. Of course it is out of warranty, but I noticed that Mahindra discontinued the two piece camshaft and replaced it with the one piece gear and shaft. I suspect they either realized the original was poor design or had problems with it. Pictures are attached, I think. It appears to me that a gear that would shear like that is either due to faulty materials or design. Any suggestions/ comments would be appreciated.

    Thanks
    Don
    Quote Originally Posted by DavesTractor View Post
    Back in 2006 or 2007 I think there was a failure like this reported on TBN. But I haven't seen one since. I think that fellow thought the cam gear was getting too much side load from the hydraulic pump...but I am stretching a poor memory. They have since updated the cam with a shrink fit cam gear instead of a bolt-on gear, which is of course stronger. It is only sold as a cam/gear assembly. The cam is also extended and is now supported additionally by the front cover. It is just a more robust design.
    If this is a defect, that is exactly what a warranty is for, defects in material or workmanship...but the kicker is that even if you can prove a defect and absolutely no neglect on your part, reimbursement is still limited to problems that manifest themselves in the time period (time or hours, limits on both). If you have a 2007, you had a three year warranty, so you are out by maybe 2 years. Just giving you a heads-up on how that normally works, so you do not think the fact that this has been upgraded is a smoking gun leading to coverage.

    The good news is that the new design is super stout, and if you can do the repairs yourself it should not be all that expensive and you won't have to give that cam gear another thought.

    Talk to your selling dealer and see how he can help. I just looked it up and the kit is part number 006004516F91 and is not as expensive as you might think since it looks like it comes with the cam/gear, cover, gaskets, bearings, compatble hydraulic pump gear, etc. Looks complete. We have sold quite a few 7520's and we have not seen one fail, so it isn't common. We have never installed the kit ourselves.

    I hope this helps, and good luck getting this going. Sorry this has happened to you, but at least the fix is an improvement.
    Your memory is good Dave. That was me with the early failure -- at around 200HRs. Dons failure looks just like mine and pics fit your description of the improved design I think. On my replacement the web portion of the gear was about 0.010" thicker and finished better in the holes where cracks would start due to the helical profile and the inherent continuous opposing thrust loads following the idler/cam gear as it rotates under load.
    Those holes are needed to get to those bolts to remove and install the cam assembly and they are the demonstrated weak point. I use my loader a LOT and hit system relief pressure dozens of times per hour sometimes. The tractor now has 1100hrs and seeing this failure on Dons later model 7520 has me pretty worried.
    ...Dave, do you know if the design shown in Dons pics is representative of the final upgrade?
    Thanks,
    ...larry
    This side of 40
    JD2010, Kubota L3450/FEL w SK QC, L2550 w FEL
    Mahindra 7520 [Pinky] /FEL w Skid Steer QC/w Tilt Tatch & BH, BX1500 [Mighty Mouse]
    IH37 Baler, CCM165 Drum Mower, JD Rake
    JD 127 bushog, Flail, SK Tilt Tatch , KK tiller, Rhino rear blade, Post driver, post auger, chipper, pallet fork, Grapple/Loader Buddy, Homemade Splitter/DC Welder

  8. #8
    Elite Member
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    Default Re: 7520 Broken cam gear

    Quote Originally Posted by SPYDERLK View Post
    ...Dave, do you know if the design shown in Dons pics is representative of the final upgrade?
    Thanks,
    ...larry
    Larry, I don't know. We haven't had a failure on one so I have not seen it up close. Sorry.
    Dave
    Dave's Tractor, Inc.
    Red Bluff, California

  9. #9
    Gold Member
    Join Date
    Sep 2007
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    321
    Location
    Texas
    Tractor
    Mahindra 2810, IH Hydro 70, 706

    Default Re: 7520 Broken cam gear

    Quote Originally Posted by dnetherland View Post
    Update on cam gear failure. After discussions with Mahindra dealers it appears that this is rare on the 7520, however Mahindra appears to have changed the design on several models and beefed up the camshaft and gear. The tractor was out of warranty by two years (three year warranty at the time of purchase) but would have been covered if purchased more recently since they now carry a five year warranty. Mahindra has agreed to cover the cost of the camshaft, front cover and bearing. I am still out transport and labor but overall I feel that was fair treatment. Hopefully this will solve the problem on a tractor that otherwise I have been very pleased with.

    Thanks
    Don
    wow thats great. They really went the extra mile IMO. I would be one happy camper.

  10. #10
    Platinum Member civesnedfield's Avatar
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    2007 Mahindra 4530----1972 Massey Ferguson 1100

    Default

    It's what is called in the industry a "Good Will" warranty. Mahindra is finally coming to the realization that a little good will goes a LONG way.

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