7520 Broken cam gear

[dnetherland]

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

 

[JerryK]

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...

 

[DavesTractor]

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.

 

[dnetherland]

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

 

[DavesTractor]

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.

 

[JerryK]

GREAT...!!! Sounds like a pretty fair shake to me....

 

[SPYDERLK]

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

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

 

[DavesTractor]

...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.

 

[Texan4Life]

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.

 

[civesnedfield]

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.

 

[BeltfedGoodness]

I'm seriously looking into Mahindras for several tractors.....this is good customer service to say the least. Another plus for Mahindra in my book.

Looking at the gear design itself. the lightening/handling holes were too close to the hub and the web is too thin. Obvious flexing occured as other posters have pointed out.....what i see is a very repairable situation. if in the future the SHTF, i would not be afraid to weld it back together and use a reinforcing disc for the patch on it. Seeing the part is avaialble, i wouldnt do it now...just saying if the SHTF and you were on your own with it.

 

[SPYDERLK]

But how would you assemble it without the holes? A new design is needed. This one, at the 2007 snapshot, is showing to be a latent defect. There can be well over 30HP crossing that idler counting the 17GPM main pump, 5GPM steering pump, alternator, fan, and cam.
larry

 

[BeltfedGoodness]

Not sure how the holes play into the assembly of the gear......never had one in front of me to really know.

Usually holes in the web of a gear or pulley are for a desired heat treat effect on the inner or outer parts of a gear, handling holes or racking holes for processing during manufacture, simply lightning holes or to save material in the blank casting process.

In this case, if the breaks of the webs could be aligned again, there could be a disc or a basic "patch" welded in so it could be used again.......this would only be attempted in a situation if no replacement could be found.

I've been looking at the Mahindras specifically for simplicity. if we have bad times ahead in this country and no parts are avaialble, one has to improvise.....and i'm pretty good at that.

 

[SPYDERLK]

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

How is it going? I have been looking at the pictures and the little I can see of the lovejoy coupling to the hyd pump looks to be damaged. Could you check and confirm.
Thanks,
...larry

 

[dnetherland]

Larry,

Lovejoy coupling seems to be OK.

Sorry it's taken a while to update but this has been a complicated process.

As i noted before Mahindra goodwilled a new camshaft. Valves and head were checked. Mechanics started to put the tractor back together and water pump didnt fit with the timing cover. After much debate turns out Mahindra sent the wrong timing cover. Cost another two weeks of down time. New gasketst totalled about 600.00. Labor and other parts $2084.00. So all in all I'm out about $2700.

The tractor was run at the shop for a day. I picked it up and ran it about two hours around the house when i noticed the alternator light was on. When I checked the main pulley was not turning. Seems it is swedged onto a shaft with a bolt. It was originally locktited and torqued to specs per the mahindra dealer. Mechanic came out and re-torqued. Ran it a while and loaded it and took to the farm. After 30 minutes of bushogging bolt backed off and threw a belt. No fan or water pump so couldn't even drive it to camp. Chained it to a bulldozer and pulled it to camp.

Brenda at Mahindra customer service had called once during the repair to check on progress. Well now I am frustrated so I call Mahindra customer service. Brenda and Steve put me on speaker phone and proceed to tell me how they can't warranty work from anyone other than a dealer. I tried to explain that I understood that and that I now felt that this tractor was a lemon. At 500 hours a cam gear should have never sheared. All I was really looking for was company intervention to help determine value and intervene with a dealer to make sure that I get a fair trade-in and move on to a new tractor. Well today Brenda called again to tell me that Mahindra would not goodwill any additional parts. Again I reiterated that my goal was help in determining value and getting a fair trade-in. I was told that they just had no way to do that since they would have to look at the tractor etc, etc.

I like the weight of the Mahindra. I really like a 5 year warranty. I was hoping that a Mahindra dealer would give a better trade-in than another brand. I now truly question reliability and now I retract the good things I have said about customer service.

The tractor is in the shop and will be fixed but I likely will shop for another tractor.

The tractor is a 2007 7520 4WD with a canopy and ML275 loader. If condition is rated like cars are for Kelly Bluebook, I would rate it as good. It has 500 hours on it and has been kept in a storage container since new. Tires are R1 in good condition. No real mechanical problems until this. I am going to local dealers for trade-in value but if any dealers that frequent this site can give ranges on price I would appreciate it.

Thanks
Don Netherland

 

[SPYDERLK]

How is it going? I have been looking at the pictures and the little I can see of the lovejoy coupling to the hyd pump looks to be damaged. Could you check and confirm.
Thanks,
...larry

Larry,

Lovejoy coupling seems to be OK.

Sorry it's taken a while to update but this has been a complicated process.

Thanks
Don Netherland

Wow. I thot pictures didnt lie. I guess I mis interpreted that a tooth was missing on the elastic coupling.
... Sounds as if youve had significant follow up problems. The work was not done by a dealer. Unfortunate. Mahindra certainly has an out there. They didnt pay as close attention to yours as mine got - perhaps since it was out of warranty. On mine the work was done by a dealer mechanic with the Mahindra tech rep participating. They were very interested in the problem and took the failed parts to study. It seems they are less interested in the problem of inadequate design margin at this point. I guess theyve made their stab at correcting the latent design defect and arent expending any more effort on a discontinued model. Bummer. ... These things should last the life of the tractor. Mines still lasting, but cracks might be growing ...
larry

 

[dnetherland]

The saga continues. My mechanic talked to the local Mahindra dealer. He ordered a new pulley and belt and the bolt that holds the pulley on. 5 days later the parts arrive. Lo and behold they don't fit the tractor even though he had the serial number of the tractor when he ordered. This is the second incident where wrong parts were sent. Took the old parts to the dealer so he could measure and re-order. Parts have finally arrived and should go on next week.

Have talked to 3 dealers about trade-in. I'm getting offers of 10-11k on a 2007 tractor with 500 hours and in very good shape. This seems a little low to me. I would still be interested in the opinions of dealers who frequent this site. I am currently looking at other brands but I am having trouble finding a comparable weight tractor in the 85 HP class without a cab. A lot of my work is in the woods and I don't think a cab would work.

Thanks
Don

 

[DavesTractor]

The dealer experience is a big factor in this deal. If the tractor was at a top notch Mahindra dealer with experienced mechanics and parts people (so as to hopefully get the right part the first time) I think you would have been much more satisfied. And I am not saying your shop isn't real good, but there are advantages to working on rigs for which a guy is familiar and experienced. We work on all brands, and I am quite sure we struggle diagnosing and/or fixing an issue occasionally that would be a cinch had the customer gone to his OEM dealer. If that is the case, we charge a fair price to the customer, and charge ourselves a little for the learning experience.

And if you will take $10-$11k for it and it is nice, I'll arrange a truck and ship it across the USA and resell it and make good money on it. Get it fixed and use it. And if you decide it needs to go, sell it or consign it to a Mahindra dealer. That should get you maximum $$.