2017~2025 Rear differential failure

Why would anyone want to stay with Mazda when rear differential is a common issue at under 100k miles, and the cost of replacement on average is $5500, never mind other accruing expenses? The response from corporate is beyond irresponsible.

 

[n0m0remazda]

Unfortunately these types of issues plague every manufacturer, regardless of their reputation or past history. Some happen more often than others. Believe it or not, prior to the CX-90 and CX-70, Mazda as a brand ranks between Toyota and Honda when it comes to reliability. More recently, Honda is further down the list, and Mazda is usually very close to Toyota.

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I recognize that this doesn't help your current situation. Ultimately it comes down to the person on the other side of the phone/computer screen that has the final say regarding coverage. Some people have been able to get full payment coverage with their reps, while others get nothing more than a "Sorry, here's a free oil change". So much of it depends on who you get on the phone and how far that person is willing to go, or how much you can wear them down.

I will say that a repair/replacement done at a 3rd party shop with used parts will be closer to the $2k-3k mark. Mazda quotes the repair high because they have high shop rates and they use brand new OEM components. In my case, my rear diff failed completely, but the most I would have paid without coverage would have been just over $6k CDN, and that includes labour and parts. I have no idea where they're coming up with $8k for yours. Also, with the replacement, I got a 1-year/12k km warranty on the repair through

Thanks for the insight. That person on the other side was absolutely useless and has closed the case; I probably will go to a third party for the repair as youre right, doesnt make sense to pay premium at a dealership, especially on used. I guess the positive that came out of this, is, I know a little more about cars!

 

[CrazyHippie]

A good set of general rules is as follows:
1. Oil and filter change every 5K miles.
2. Coolant and brake fluid change/ flush every 3 years.
3. All other fluids change every 30K miles, with flush and filters, as applicable.
4. New plugs every 50K miles.

Do as much as you're able yourself and keep a log for warranty purposes. Spend your money on tools, not fools!

 

[Silly Wabbit]

Could you share what the service advisor wrote on the service order? I'm curious what this "play" is that they are talking about.

 

[BoomerZoomr]

I did try to be civil about it, made the same case as you did, that it was expected to last the lifetime of the vehicle, and that there were no maintenance information in the cx5 2017 manual. Im not a car person so I take it to the dealership every so often, and I would expect that they'd tell me what to do in good faith to maintain the car.

As they have never suggested any changes to the rear differential oil, it now has "play" and needs to be replaced. Im not even asking for full coverage, just a "hey, we hear you, we understand, here's an X amount to help you out with the costs" from a billion dollar company. The mazda folks at the dealership were real quick to refer me to a sales rep (as the total cost of repair not including the differential came out to be about 8k), but just the indignity of the situation is turning me off. If this happens at less than 100k mile with no acknowledgement or accountability, why not go to honda or toyota, where these expensive issues are unheard of.

$8,000? Does it take their mechanic a week to do this job? I would talk to another dealership, at the very least.

 

[CrazyHippie]

$8,000? Does it take their mechanic a week to do this job? I would talk to another dealership, at the very least.

A new rear diff is going to run about $7500. That's why a remanufactured one is the way to go! I'd definitely seek a reliable private mechanic in your area if I were you. They should warranty the repair if you source the parts through them. These diffs can also be repaired, and it's just possible that a private mechanic will find nothing wrong, especially if this was a surprise to you from the dealer! Have you asked if there are any related codes present in the car's computer? If there are no codes, I'd be tempted to keep driving it. If it ain't broke.......

 

[BoomerZoomr]

A new rear diff is going to run about $7500. That's why a remanufactured one is the way to go! I'd definitely seek a reliable private mechanic in your area if I were you. They should warranty the repair if you source the parts through them. These diffs can also be repaired, and it's just possible that a private mechanic will find nothing wrong, especially if this was a surprise to you from the dealer! Have you asked if there are any related codes present in the car's computer? If there are no codes, I'd be tempted to keep driving it. If it ain't broke.......

He said $8K not including the differential.

 

[CrazyHippie]

Ouch! They're not that hard to change out. I'd run. Someone is trying to take advantage of you.

 

[AL Cx5]

WOW! Thanks for posting your experience. I hope Mazda comes through for you.

If my rear diff fails, I'll look for a salvage yard rear cradle, change the diff fluid and go again. The rear cradle is pretty easy to get out, maybe an hours work on jack stands.

I'll change the fluid in the front and rear diffs at 30K. 30K intervals are going to be pretty busy, plugs, turbo thing, transmission, differentials and brake fluid. Oil/filter and air filter will be changed at that time as well.

I'll perform the above items myself. These little cars are pretty easy to work on.

I changed the oil/filter and air filter for the 3rd time last week. Now that I know where to put the jack stands it's a simple operation. I rotate the tires since I have the front up and just raise the rear. With the turbo I change the oil/filters and rotate the tires about every 4500 miles.

 

[madar]

Ya, as I obviously found out the hard way. Apparently, I can't trust the manufacuturer to release a car manual that has proper maintenance schedule. Nor should I trust my doctor to diagnose me correctly.

So, what are you actually experiencing here? "Has lots of play", is this some thing they noticed?
Problem description is vague, I'd get a second opinion. It may somebody's unprofessional opinion.

 

[sm1ke]

A new rear diff is going to run about $7500. That's why a remanufactured one is the way to go! I'd definitely seek a reliable private mechanic in your area if I were you. They should warranty the repair if you source the parts through them. These diffs can also be repaired, and it's just possible that a private mechanic will find nothing wrong, especially if this was a surprise to you from the dealer! Have you asked if there are any related codes present in the car's computer? If there are no codes, I'd be tempted to keep driving it. If it ain't broke.......

A brand new OEM rear diff is a lot cheaper. In my case, total cost for a rear diff replacement done by the dealer was approx. $6k CDN. Component costs were about half of that, the rest was the labour and the programming.

When I called around for quotes on rear diff replacement through 3rd party specialty shops, they quoted the job (including used components) at $2k to $3k. Additionally, one of the knowledgeable members here mentioned that it would probably be best to just replace the rear diff instead of repairing it by disassembling it and replacing parts, in terms of cost and part availability.

One thing that really frustrated me is the fact that when my rear diff failed, there were no codes. I drove it for a while after the rear diff gave out (meaning no more noises, and zero power to the rear wheels). Zero codes presented. So you'd never know that something was wrong until you did something like try to accelerate in snowy conditions. The front wheels would start spinning and the traction control would come on. Normally the rear wheels would engage, but because the rear wheels weren't getting power, the car continued to cut power to the front because it thinks the rears are spinning and trying to regain traction. This results in the car crawling forward very slowly, and severely limited my ability to modulate the throttle to regain traction up front. It made it very dangerous to drive, especially when doing something like merging onto a snowy highway.

I had so many shops tell me over the phone that there was nothing wrong with my rear diff because I would see codes if there was.

 

[AL Cx5]

A brand new OEM rear diff is a lot cheaper. In my case, total cost for a rear diff replacement done by the dealer was approx. $6k CDN. Component costs were about half of that, the rest was the labour and the programming.

When I called around for quotes on rear diff replacement through 3rd party specialty shops, they quoted the job (including used components) at $2k to $3k. Additionally, one of the knowledgeable members here mentioned that it would probably be best to just replace the rear diff instead of repairing it by disassembling it and replacing parts, in terms of cost and part availability.

One thing that really frustrated me is the fact that when my rear diff failed, there were no codes. I drove it for a while after the rear diff gave out (meaning no more noises, and zero power to the rear wheels). Zero codes presented. So you'd never know that something was wrong until you did something like try to accelerate in snowy conditions. The front wheels would start spinning and the traction control would come on. Normally the rear wheels would engage, but because the rear wheels weren't getting power, the car continued to cut power to the front because it thinks the rears are spinning and trying to regain traction. This results in the car crawling forward very slowly, and severely limited my ability to modulate the throttle to regain traction up front. It made it very dangerous to drive, especially when doing something like merging onto a snowy highway.

I had so many shops tell me over the phone that there was nothing wrong with my rear diff because I would see codes if there was.

How many miles/kilometers was on the diff?

Was the fluid changed per Mazda recommendations?

Asan aside, do you know if the diff drain plug has a magnet in it? I put a magnetic drain plug on the oil pan this last oil change. If the diffs don't have magnetic drain plugs, I'll replace them.

The days a long gone when we can ignore changing all the fluids per the maintenance schedule in our owners manual on any brand, period.

I feel for ya, no code, and having to drive with only front wheel drive. And TC is hendering regaining traction. Yikes

 

[BoomerZoomr]

It’s interesting how the Mazda rear differential can fail without fanfare.
I had a truck long ago, and when the rear differential failed, it sounded/felt like the gears were chewing on steel ball bearings. I could barely get off the road.

 

[sm1ke]

It’s interesting how the Mazda rear differential can fail without fanfare.
I had a truck long ago, and when the rear differential failed, it sounded/felt like the gears were chewing on steel ball bearings. I could barely get off the road.

I'm not sure if it's normal for it to fail without codes like mine did. All I know is that it happened to me and I hated driving the car like that. I had very little confidence in it.

 

[BoomerZoomr]

I am learning about these Mazdas, and there is a very good possibility that I don’t know what I am talking about here…
but doesn’t the later models of CX-5 have some type of clutch mechanism where the driveshaft goes into the rear differential?
Seems like I read the CX-5 is mostly front wheel drive, and directs power to the rear wheels when needed. So I am wondering if there is a rear differential failure without scary sounds, could it be this clutch mechanism? And if so, is the clutch serviceable or integrated into the differential requiring complete replacement?

Also, from what I understand, the transfer case is a simple gearbox that always spins the driveshaft.

 

[sm1ke]

How many miles/kilometers was on the diff?

Was the fluid changed per Mazda recommendations?

Asan aside, do you know if the diff drain plug has a magnet in it? I put a magnetic drain plug on the oil pan this last oil change. If the diffs don't have magnetic drain plugs, I'll replace them.

The days a long gone when we can ignore changing all the fluids per the maintenance schedule in our owners manual on any brand, period.

I feel for ya, no code, and having to drive with only front wheel drive. And TC is hendering regaining traction. Yikes

113k kms on my rear diff.

Mazda does not specify a fluid change interval. Only a visual inspection of the rear diff housing, and a recommendation to replace the fluid if the rear diff has been submerged in water. I had planned to change the rear diff fluid anyway, but it failed before I could. I'm unsure if changing the fluid earlier would have made any difference, but if I had done it earlier, I could have at least ruled that out as a potential cause (or a potential low fill from the factory).

An interesting note is that throughout my communications with Mazda Canada and the dealership, not once did they ever make any mention of replacing the fluid. They do not expect customers to change the fluid, and they don't want them doing it. They do this because they think the rear diff is durable and reliable enough, and to prevent outside factors from introducing potential problems (using the wrong oil, underfilling/overfilling oil, introducing contaminants, stripping the bolt threads, etc.).

The diff plug does have a magnet in it. I did a rear diff oil change on my 2022 CX-9 as soon as I bought it (used with 70k kms). The fluid was a honey-coloured and the plug had a small amount of metal on it (pics below).

 

[AL Cx5]

113k kms on my rear diff.

Mazda does not specify a fluid change interval. Only a visual inspection of the rear diff housing, and a recommendation to replace the fluid if the rear diff has been submerged in water. I had planned to change the rear diff fluid anyway, but it failed before I could. I'm unsure if changing the fluid earlier would have made any difference, but if I had done it earlier, I could have at least ruled that out as a potential cause (or a potential low fill from the factory).

An interesting note is that throughout my communications with Mazda Canada and the dealership, not once did they ever make any mention of replacing the fluid. They do not expect customers to change the fluid, and they don't want them doing it. They do this because they think the rear diff is durable and reliable enough, and to prevent outside factors from introducing potential problems (using the wrong oil, underfilling/overfilling oil, introducing contaminants, stripping the bolt threads, etc.).

The diff plug does have a magnet in it. I did a rear diff oil change on my 2022 CX-9 as soon as I bought it (used with 70k kms). The fluid was a honey-coloured and the plug had a small amount of metal on it (pics below).

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Well that's as dumb as saying the trans fluid is good for the life of the vehicle.

Mazda has a high opinion of their diffs and techs and low for the rest of the world.

We often forget that the shaft seals allow dust into the system, clutch and metal from the gears and bearings. The oil breaks down after time as well.

I'm glad to see a magnet that is picking up clutch dust.

I'm going to check my diffs fluid level soon.

On my 2500 truck the fluid is suppose to be 1/2" below the inspection hole. I made a little guage to check the level. This diff doesn't have a drain plug, rather we take the diff cover off. It's more time consuming than the Mazdas but we can inspect the gears.

 

[stickerbush]

I'm glad to see a magnet that is picking up clutch dust.

How could there be clutch dust in the rear diff?