2017 CX-5 Sluggish Engine Response After Belt Tensioner Replacement

[Fadkar]

I recently had the hydraulic belt tensioner replaced on my 2017 CX-5 with 68,000 miles due to a leak. A local shop performed the work, installing a new INA tensioner, a NAPA serpentine belt, and an OEM water pump belt.

Since the replacement, I've noticed two issues:

1. Hesitation on Startup and Rough Idle (Resolved): The car experienced a brief hesitation on startup and a slightly rough idle for the first few trips. This is likely due to the battery being disconnected during the repair, which can reset the learned idle mapping.
2. Sluggish Engine Response: More concerning is a sluggish engine response. The car feels like it has more drag to it. This loss of responsiveness is quite noticeable and negatively affects the driving experience considering that the NA CX-5 was never a fast vehicle to begin with... Now it feels like I really have to stomp on it to get it going.

I'll be contacting the shop tomorrow to discuss the possibility of the NAPA belt causing this issue. However, I'm also curious to hear from you all:

• Could a non-OEM serpentine belt contribute to sluggish engine performance?
• Are there other potential causes, such as a dirty throttle body that I should look into?

Any insights or similar experiences would be greatly appreciated!

 

[stickerbush]

There is no need to disconnect the battery to replace the tensioner and belts. Was there other work being done?

I can't see how the new tensioner and belts, OEM or not OEM, could have any effect on engine response.

 

[Silly Wabbit]

I think I've seen repair video where the mechanic mentioned aftermarket belts can be a pita to install. Maybe it's too tight and it's causing issue?

 

[yrwei52]

I recently had the hydraulic belt tensioner replaced on my 2017 CX-5 with 68,000 miles due to a leak. A local shop performed the work, installing a new INA tensioner, a NAPA serpentine belt, and an OEM water pump belt.

Since the replacement, I've noticed two issues:

1. Hesitation on Startup and Rough Idle (Resolved): The car experienced a brief hesitation on startup and a slightly rough idle for the first few trips. This is likely due to the battery being disconnected during the repair, which can reset the learned idle mapping.
2. Sluggish Engine Response: More concerning is a sluggish engine response. The car feels like it has more drag to it. This loss of responsiveness is quite noticeable and negatively affects the driving experience considering that the NA CX-5 was never a fast vehicle to begin with... Now it feels like I really have to stomp on it to get it going.

I'll be contacting the shop tomorrow to discuss the possibility of the NAPA belt causing this issue. However, I'm also curious to hear from you all:

• Could a non-OEM serpentine belt contribute to sluggish engine performance?
• Are there other potential causes, such as a dirty throttle body that I should look into?

Any insights or similar experiences would be greatly appreciated!

@Digbicks1234 had similar experience like you but he was using an aftermarket Gates belt tensioner:

11/20 Update (After driving 1,700 Miles):

Hey guys, I just wanted to follow up on the thread after driving about 1.7k miles. So today I think I finally figured out 50-75% of the problem I'm experiencing with why I felt that after replacing the belt tensioner, my acceleration feels worse. Previously, before replacing the belt tensioner and the water pump/serpentine belt, I had a blast driving the car especially on highways and going from 0 - 60+.

Stomping/mashing on the pedal felt effortless and it didn't really take much for the car to rev up really high and start flying past everything. However, after replacing the belt tensioner all of this fun started to disappear and today I have slightly figured it out. I think most of us are aware of the little activation button on the bottom of the gas pedal (a.k.a Pedal Kickdown Switch) once you press down all the way. I never had to press the pedal all the way down until I heard a click but today after messing around and stomping on the gas pedal repeatedly, the car felt alive again.

The very strange thing is, why did this occur after replacing the belt tensioner/water pump belt and serpentine belt? I still enjoyed the OEM belt tensioner more as I did not have to press down until I hear a click.

Here's some possibilities that I can think of that may have changed the personality of my car:

1. NON-OEM Belt tensioner: Stiffer design/different lubrication/different wheel bearings/Still not broken in? IDK
2. Maybe I didn't bleed out the air from the belt tensioner correctly?
3. Maybe there's some calibration that needs to be done?
4. Maybe that's how my car was supposed to feel and replacing the OEM belt tensioner brought my car back to the factory shape?

I'm not sure how I feel about this as I was planning to put my OEM one back in because I definitely missed that personality of the car a lot more. Also, I did try Googling around to see if anyone has experienced the same issue as me but I don't think it's very common.

View attachment 229021
View attachment 229022

OMG, THE POWER IS BACK TO NORMAL AGAIN GUYS!!

I took out the crappy GATES one and there was fluid leaking out of it. I don't care at this point anymore but I installed the INA one and went for a test drive on the highway and the power is definitely back for sure. I don't have to press down until I hear a click anymore, it's literally back to normal where I would step on the pedal 50-60% and it automatically goes into a high rev/downshifts unlike the Gates one where it would slowly/gradually build up speed.

Also, this time, I only removed the splash shield cover and I did not disassemble the entire wheel well splash shield and outer fender like last time. I can definitely see why people would have trouble trying to access the serpentine belt and performing the replacement, you are losing at least 20-40% of the view on your right hand side where the other pulleys are and you have a piece of plastic in your face. It's doable, but I had to use my hand to feel if the serpentine belt was lining up with the A/C Compressor pulley grooves. Very annoying, but I did it when it was getting dark so it was hard to see.

View attachment 233365

I would highly recommend anyone replacing this to either buy the INA one on RockAuto or get the OEM INA one from Mazda and to skip the GATES one completely.

When I was doing my research on "belt tensioners," I couldn't really find much information on whether or not a different brand would make a huge difference/performance impact but now I know after owning (3). If you go on Google, this is really the only thing that it says:



This diagram below illustrates how I feel using both. It's not supposed to be 100% accurate but it gives you an idea at the very least:
View attachment 233367

I did not disconnect my battery this time prior to yesterdays spark plug change. It has been as-is so this is a direct comparison between two belt tensioners. I'm really trying to think of some theories of why the vehicles characteristics feel so different after the belt tensioner change.

Could it be related to:

1. The type of fluid being used as a lubricant inside?
2. The rubber boot material that's different? The GATES one looks much more durable and more stiff looking compared to the INA one which is a very soft/supple rubber. I'm thinking that this is a very likely possibility.

I know that OEM hardware are typically tuned to work the best with our vehicle and using aftermarket parts may make a difference but I just can't wrap my head around this belt tensioner.

View attachment 233370
View attachment 233371

2013~2016 Belt Tensioner - Shouldn't this be a warranty item?

2013 - 2016 CX-5 Belt Tensioner + Serpentine Belt + Water Pump Belt (Install/Removal) Guide

Not sure the reason why, and you have already used an INA tensioner. At least it meant that a bad tensioner could affect the engine performance! Your aftermarket INA tensioner could be defective, or you can try a Mazda OEM tensioner ($$$$$)?

 

[Fadkar]

@Digbicks1234 had similar experience like you but he was using an aftermarket Gates belt tensioner:





2013~2016 Belt Tensioner - Shouldn't this be a warranty item?

2013 - 2016 CX-5 Belt Tensioner + Serpentine Belt + Water Pump Belt (Install/Removal) Guide

Not sure the reason why, and you have already used an INA tensioner. At least it meant that a bad tensioner could affect the engine performance! Your aftermarket INA tensioner could be defective, or you can try a Mazda OEM tensioner ($$$$$)?

Your replies are always so thorough! Thank you @yrwei52

It's good to know that a faulty tensioner could be causing the problem. I had only heard of good things about the INA ones since they are the OEM manufacturer but I might go back to the shop and get them to replace both the tensioner and the serpentine belt with OEM equivalents...

It has to be one of the two items since the car ran perfectly before that and I haven't changed anything else... Sucks to have to pay twice but I guess that's the expensive lesson for me just to dish out the extra $$$ for OEM the first time around... I'll report back if replacing these components fixes the issue or not.

 

[stickerbush]

I wonder if perhaps the shop failed to bleed the air out of the new tensioner. You might ask the mechanic if he bled it, if not it could probably still be bled and this might fix the problem. Bleeding is mentioned on this service manual page.

 

[yrwei52]

Your replies are always so thorough! Thank you @yrwei52

It's good to know that a faulty tensioner could be causing the problem. I had only heard of good things about the INA ones since they are the OEM manufacturer but I might go back to the shop and get them to replace both the tensioner and the serpentine belt with OEM equivalents...

It has to be one of the two items since the car ran perfectly before that and I haven't changed anything else... Sucks to have to pay twice but I guess that's the expensive lesson for me just to dish out the extra $$$ for OEM the first time around... I'll report back if replacing these components fixes the issue or not.

Although INA makes the belt tensioner for Mazda, but based on the discussion between @Digbicks1234 and @PatrickGSR94, we can see there’re some differences between the aftermarket INA tensioner and Mazda OEM tensioner:

2013~2016 Belt Tensioner - Shouldn't this be a warranty item?

And if you read further down on that thread, you’ll see @Digbicks1234‘s second aftermarket INA tensioner may have cut into the serpentine belt:

Mileage: 76,785

Decided to randomly check on the serpentine belt and tensioner. Not looking good, there's actually a nice slice right in the middle.

 

[Fadkar]

Well, the Napa belt didn't even last a year without cracking. The shop that installed it warrantied it with an OEM replacement and the Mazda got its pep back! Wanted to post here so other folks can be cautious with their belt choice.

I also got a set of Pirelli scorpion AS3 installed and the car is driving better than ever despite being 8 years old with 75k miles!

 

[ceric]

My '17 CX5 (43k miles) just had this replaced (tensioner).
Dealer fixed it for free as a gesture of goodwill.

Dealer did charge me $200 for the belt, which was ridiculous.
Since the tensioner was replaced for free, I did not argue with them.

No difference how it drove before and after.
Sold it to my co-worker after fixing the last known issue.

Too many vehicles in my house now. Tried to find a new home for it.
Yes, the one in my avatar.

 

[ceric]

Some might disagree, but this is a known issue for '16 and '17 Mazdas.
My '16 Mazda6 got it. My '17 CX-5 also got it.
100% failure rate among my four Mazdas.
The tensioner of my '14 Mazda3 still looks clean.
Note that, all my vehicles spend most nights in garage. CA warm weather.
Inferior OE parts are to blame, IMHO.

 

[Jmaz]

Some might disagree, but this is a known issue for '16 and '17 Mazdas.
My '16 Mazda6 got it. My '17 CX-5 also got it.
100% failure rate among my four Mazdas.
The tensioner of my '14 Mazda3 still looks clean.
Note that, all my vehicles spend most nights in garage. CA warm weather.
Inferior OE parts are to blame, IMHO.

The tensioner on my 2014 was leaking at 29K miles. Dealer said they last about 40K miles. I was just past the 3/36 warranty timewise so no free replacement but they would install a new one and new belts for a mere $450. I thanked them for their time and bought an OEM Mazda online for~ $100 and changed it myself. The belts looked great. Admittedly tight quarters changing it but wondered how their quote justified hundreds in labor when they had a lift to make the job quicker and easier. That was probably 7 years ago and the replacement hasn't leaked yet.