Do we need to preventatively change serpentine tensioner?

[eugene89us]

Good morning, all,

I was changing the oil on the Passat this weekend, and noticed that Diselgeek's Green serpentine accessory belt has turned black on its back. It caught my eye, since I wondered how it can lose it original green-ness within 10 months/10k miles. The only thing that touches the back of the serpentine belt is the tensioner. I decided against replacing it during TB job, since it still looked pretty good. However, it has plastic parts, such as the roller itself made of plastic and I believe there is some kind of plastic piece in the spring itself. As I am noticing that over last 10 years since the car came off the production line, the plastic components are the weakest link in this entire vehicle. Everything that broke so far, such as valve cover leak, oil cooler leak, a couple of door lock actuators - all kicked the bucket due to plastic becoming brittle.

Looking at the belt, it is moving smoothly with the engine, there is not any wobble or inconsistency with it. So I can't blame the one way clutch of the alternator or the tensioner itself. But of course my worry is that if the plastic tensioner wheel is indeed the weakest link, I would hate to see it fail causing serpentine belt to be swallowed into the timing belt, causing major engine damage. Seeking expert recommendations as to your perceived longevity of the tensioner, and whether it is worthwhile to change it preemptively? Is there a shortcut to replacement, because reading ErWIN manual, you basically have to remove everything in front of the bolt. If that is the only way, I may decide to do both the tensioner as well as replacement of thermostat while I am already there.

Edit: Another thing I considered is buying a tensioner and just replacing the plastic wheel itself primarily to renew the plastic while I am sure the print itself would last until next TB change. But once again, I am not sure of tensioner failure rates and whether I should just leave it alone for another 100k miles.

 

[Lightflyer1]

That is the problem of doing an incomplete TB job. You basically have to do it again if there are any issues. Generally all parts in the TB path should be replaced at the same time, just for this reason. Are you having any other issues than the green is gone? If it worries you then do the whole thing over again replacing everything this time. Or just wait and see.

 

[eugene89us]

Well, the timing belt job was complete, all idlers replaced, tensioner, water pump. That was followed perfectly, I posted a guide here on the forums. I am talking about accessory belt that runs alternator and A/C compressor, which is on the outside and visible. That tensioner had a bolt that is located behind the intercooler. To "properly" replace it, I would have to drain the coolant and remove intercooler, among a few other parts. I replaces serpentine belt just in case as I was replacing TB, but original is black belt. This was green belt from Gates, I think they advertise it as long lasting fleet belt. Weird how the paint comes off, I am contemplating going with Contitech and replacing just in case. I am really pleased with Kevlar Gates timing belt, but the serpentine one does not instill much confidence.

 

[Lightflyer1]

Sorry to sidetrack your thread.

 

[eugene89us]

@Lightflyer1 No, not at all, man, you're trying to help. I realized I may not have made my question clear, since there are two belts to replace. I think that would certainly be an insanity to change out the timing belt and keep the tensioner the same. Especially as much time, sweat, and tears as that job entails. Thankfully, serpentine belt is easier to replace. I am just scared of whether or now a wait and see approach is a good idea with the serpentine tensioner. And how to really know whether it is on a brink of failure or not. Being that the roller is plastic, it already feel flimsy just spinning it. LOL

 

[AverageAndy]

Well, @eugene89us got me thinking (not a good thing as I have already been thinking about how my car runs on the warm side) so I grabbed a couple of pics for you. This is my belt with about 14,000 miles of service. It is decidedly not a lovely green color. Not sure if this helps or hurts your case for tensioner replacement.

Accessory belt2.jpg

• AverageAndy
• Apr 10, 2023

Accessory belt1.jpg

• AverageAndy
• Apr 10, 2023

 

[pedroYUL]

I did replace the serp belt on both my 2015 Passat and GSW when I did the timing belts. Never thought of the serp belt tensioner.

Now, the logic on older cars Mk4 and such was, if the tensioner is bouncing around, then have a harder look at all components, including the tensioner. If the belt was just going round smooth, then motor on. I just motor on with both my cars.

 

[eugene89us]

Andy and Pedro, thank you for your input. Yeah, the belt does look somewhat like yours, Andy. I was looking at it yesterday, and I noticed there is some of the "belt fuzz" that has poked in one part of the belt. Some fuzz is acceptable on the sides, I think, but this fuzz came out about 20% into the belt. It is just a small piece that poked from the back. Once again, further concerns me. I went ahead and ordered Contitech serpentine belt from FCP, I will replace the Gates one with it and will leave original tensioner as-is for now. Once I do so, I will post a photo of the fuzz I am talking about on this thread.

I opened the timing cover to check on Gates timing belt, and it still looks great. I was worried about it being thinner than Contitech that was originally on mine, but as I read, Gates has aramid fibers, which makes it a Kevlar belt. I use Kevlar in my chainsaw chaps to protect my life, I certainly think I can trust Kevlar to last on timing belt. Brian (Oil Hammer) has mentioned in past threads about his trust in both Conti and Gates for TB, as they are both OE suppliers. But as it comes to serpentine belt, I think I will go back to Conti. FCP did not have $14 Conti belt, so I had to spend $25 on VW-stamped Conti instead. Eh, what the heck, I get "lifetime replacement", if the car lasts another 100k miles, I will get me a free OEM replacement.

 

[greengeeker]

The green Gates serp belt turning black isn't abnormal.

You ask a good question on whether you should preventatively replace the accessory belt tensioner. I've seen half a dozen common rails with timing belt failures due to the accessory belt being pulled into the timing belt path. It's a stupid, expensive failure. I'm almost getting to the point where I recommend the tensioner and the thermostat be replaced with the timing belt. It's a "while you're in there" situation to address two common failure points.

On another note, I am very much done with Gates timing belts. I just had my 2nd premature belt failure come in....both of them sheared teeth off at 90k miles and ~3 years after installation. One a BRM, one a CKRA.

 

[eugene89us]

Well, Nick, now you got me worried about that Gates timing belt. Though I have also seen posts of people swearing they would never pick a Conti belt after a failure. It would be terrible if that happens to one of us here. And yet, I drive a Bimmer with N47 engine, a very popular diesel engine that is known for its timing chain failures. Sometimes I wish I bought a Toyota! LOL

 

[06bluebeetletdi]

Im not sure i would replace the thermostat with the timing belt/water pump/serpentine belt, if you are doing the oil filter housing, then yes, i would replace the thermostat as you are not far from the thermostat when the intercooler has been removed. I would test the thermostat first to verify it opens and closes, my replacement thermostat was stuck wide open, not a job I enjoyed doing twice.

 

[740GLE]

On our 2015 I replaced the serp tensioner and belt at 90K I was tracing a rattle when the AC is on (the new tensioner didn't solve the rattle), the serp tensioner was easy to replace, I did remove the fender liner and a combination of short extensions got the old one off and new one on.

I sourced the tensioner and belt from Idparts and I think its a conti belt. I forget if the old tensioner was plastic wheel or metal.

Not sure if the 2012-2014 tensioners are much different than the 2015.

 

[GolfSW98]

On our 2015 I replaced the serp tensioner and belt at 90K I was tracing a rattle when the AC is on (the new tensioner didn't solve the rattle), the serp tensioner was easy to replace, I did remove the fender liner and a combination of short extensions got the old one off and new one on.

I sourced the tensioner and belt from Idparts and I think its a conti belt. I forget if the old tensioner was plastic wheel or metal.

Not sure if the 2012-2014 tensioners are much different than the 2015.

Can you describe the rattle noise? Did it sound like a worn out spray bottle but with a ratcheting noise, short pauses in-between? with a hint of snoring? I am positive it isn't TB related on my car. Serpentine belt is two years old, but the tensioner is original.

 

[740GLE]

only noticeable at idle and radio down due to its quiet nature. It is cyclical comes and goes every 5-10 seconds that is 100% tied to the AC compressor load. Shut the AC off, noise is gone. My hope was that it was AC load inducing a sound on a weak tensioner.

I'm now thinking something is up with the compressor, but its been doing it for the past 60K so hard to say it's an imminent failure.

 

[otep858]

I will add in here that with my 15 with 170k on the car it thru a belt at maybe 20k on the newest belt so I replaced it thinking that it was just a defective belt. 500 miles later it tore up the new belt. The 2nd replacement belt made it maybe 1k. Mind you that all pullys ran smooth and the tensioner had no play that i could find while it was in the car. But going farther into it I removed and replaced the tensioner after the 3rd belt in 1500 miles. Took it to the vise, put it under pressure and could get some play out of it however it wasn’t much at all. I put a new tensioner on and new belt and it’s been great since. Coming up on 190k miles now. Mine had the plastic tensioner. My vote would be to replace it before you get stranded in the middle of nowhere like I was the first time. Especially if you are getting close to the mileage mine was when it started chewing up belts. The part that really thru me was that there literally was hardly any play in it

 

[greengeeker]

^^ that's the best case scenario: you just tear up your accessory belt and it doesn't get pulled into the timing belt. That being said, VW recognized this failure mode and change the timing belt cover somewhere mid life cycle on the CKRA which has a rib molded in which prevents the accessory belt chards from being pulled in. Your EA288 (all 2015 TDI variants) timing belt cover has this newer design so hopefully this failure mode is isolated to the CBEA, CJAA, CKRA engines. I'd highly recommend those owners upgrade to the newer cover style. I believe there is an aluminum aftermarket version available but like I said, VW has a plastic version as well.

HTH

 

[Mozambiquer]

One of the components not mentioned is the alternator clutch pulley, after seeing them fail and causing serpentine belt failure, I now change them every timing belt change. They are not expensive and they have a life that pretty close to matches the timing belt life, though it seems the 2015s seem to wear out just a bit sooner because of the smaller diameter pulley they have. It often does make the sound that @740GLE describes.

 

[eugene89us]

@greengeeker Can you please show exactly what you mean by molded rib on a cover? This may be the best prevention strategy. Hopefully, 2014 being end of CKRA engines, it may be equipped with what you're talking about.

 

[AverageAndy]

@eugene89us I found this one Common Rail TDI Lower Timing Belt Cover – Whitbread Performance Innovations, LLC but would probably have to call the company to verify fitment.

 

[eugene89us]

Dang it, now I really want this aluminum cover. It is definitely going to be impossible to penetrate should something cause the accessory belt to fail. I will send them an email, I realize replacing a tensioner will cost less than this, but in consideration of time and how busy I have been lately, this will be a reasonably priced insurance against larger failures.

 

[greengeeker]

@greengeeker Can you please show exactly what you mean by molded rib on a cover? This may be the best prevention strategy. Hopefully, 2014 being end of CKRA engines, it may be equipped with what you're talking about.

03L109147D

Timing Chain Cover 03L109147D

wolfautoparts.com

2014 Volkswagen Passat 2.0L TDI DIESEL A/T TDI SE Sedan Engine Timing Cover (Front, Lower). 2012-14. Passat; Lower - 03L109147D - Genuine Volkswagen Part

Engine Timing Cover (Front, Lower). 2012-14. Passat; Lower. 2014 Volkswagen Passat 2.0L TDI DIESEL A/T TDI SE Sedan. Genuine Volkswagen Part - 03L109147D (03L-109-147-D, 03L109147B)

parts.vw.com

The smaller, earlier CKRA version [without the rib] is the "B" revision.

Anyway, I believe D revision would work on the CBEA, CJAA but replace the two separate metal covers.

HTH

 

[eugene89us]

I see exactly what you mean! I called Whitbread Performance, they don't have experience with CKRA engines. From what I can gather, I have the ribbed version of the cover. Our cover on CKRA has upper and lower pieces. Other engine models had upper, middle and lower covers. The Whitbread cover replaces just the lower of the 3 covers. If we were to use that, we would most likely need to modify our lower portion to remove the circular piece and figure out how to basically create a "middle" cover.

 

[greengeeker]

You'd just need to obtain the CBEA/CJAA metal middle cover.

 

[740GLE]

One of the components not mentioned is the alternator clutch pulley, after seeing them fail and causing serpentine belt failure, I now change them every timing belt change. They are not expensive and they have a life that pretty close to matches the timing belt life, though it seems the 2015s seem to wear out just a bit sooner because of the smaller diameter pulley they have. It often does make the sound that @740GLE describes.

Whats the easiest way to test that alt clutch pully? Is it an easy part number?

Thanks.

 

[740GLE]

looks like a new pulley is in order

 

[2ManyKMfor1Tank]

On our 2015 I replaced the serp tensioner and belt at 90K I was tracing a rattle when the AC is on (the new tensioner didn't solve the rattle), the serp tensioner was easy to replace, I did remove the fender liner and a combination of short extensions got the old one off and new one on.

I sourced the tensioner and belt from Idparts and I think its a conti belt. I forget if the old tensioner was plastic wheel or metal.

Not sure if the 2012-2014 tensioners are much different than the 2015.

How the heck did you get at that tensioner bolt without removing half the front of the car?? Any pics or descriptions would help, as I have to change mine.

 

[740GLE]

2015 has all the bolts (2) right in the clear (you can see the top one on the left side of my picture above) only issue was solved by pulling the wheel liner. Getting under neath and setting the tensioner in the locked position is a two handed job with little room, but do able.

 

[eugene89us]

Well, folks, tell me I am not the luckiest guy with this Gates green Micro-V serpentine belt from Diesel Geek. Remember, I did that with TB change at 110,000 miles. Car has 130,000 now, so basically in 20k miles this is what happened. You can argue that Gates themselves do not show the green belt as the option for CKRA when you search for parts, only black standard, but they advertise green as the long lasting belt and this is what came with highly recommended Diesel Geek kit.

Installed OEM after this, I know I overpaid for the logo, but what the hell? And despite the other side looking good, it leaves the nasty black residue on my hands. My hands were washed clean before I started to photograph the belt. Any hypotheses why I got so lucky? Andy, you may want to keep an eye on this green abomination. Now I am even more concerned with Gates quality --- after all, my TB is the Gates one from diesel geek kit. And that cannot tolerate poor quality, which can cost me an engine... Almost sounds like there is some kind of quality control problem in the factory.... Or the green belt is just not the best choice. The original belt may have been old with 110k miles, but it was not this awful.

Replacement belt:

 

[Mozambiquer]

Well, folks, tell me I am not the luckiest guy with this Gates green Micro-V serpentine belt from Diesel Geek. Remember, I did that with TB change at 110,000 miles. Car has 130,000 now, so basically in 20k miles this is what happened. You can argue that Gates themselves do not show the green belt as the option for CKRA when you search for parts, only black standard, but they advertise green as the long lasting belt and this is what came with highly recommended Diesel Geek kit.

Installed OEM after this, I know I overpaid for the logo, but what the hell? And despite the other side looking good, it leaves the nasty black residue on my hands. My hands were washed clean before I started to photograph the belt. Any hypotheses why I got so lucky? Andy, you may want to keep an eye on this green abomination. Now I am even more concerned with Gates quality --- after all, my TB is the Gates one from diesel geek kit. And that cannot tolerate poor quality, which can cost me an engine... Almost sounds like there is some kind of quality control problem in the factory.... Or the green belt is just not the best choice. The original belt may have been old with 110k miles, but it was not this awful.

Replacement belt:

We have had a ton of issues with the gates greenback belts on our trucks.
So far, the timing belts are good, but their idlers, tensioners and water pumps are GARBAGE! My first TDI I put a Gates timing belt kit on. The idlers were GMB made in China. One of them locked up less than 40k miles after installation and the timing belt started to tear. No more gates kits for me!

 

[watatrp]

Well, folks, tell me I am not the luckiest guy with this Gates green Micro-V serpentine belt from Diesel Geek. Remember, I did that with TB change at 110,000 miles. Car has 130,000 now, so basically in 20k miles this is what happened. You can argue that Gates themselves do not show the green belt as the option for CKRA when you search for parts, only black standard, but they advertise green as the long lasting belt and this is what came with highly recommended Diesel Geek kit.

Installed OEM after this, I know I overpaid for the logo, but what the hell? And despite the other side looking good, it leaves the nasty black residue on my hands. My hands were washed clean before I started to photograph the belt. Any hypotheses why I got so lucky? Andy, you may want to keep an eye on this green abomination. Now I am even more concerned with Gates quality --- after all, my TB is the Gates one from diesel geek kit. And that cannot tolerate poor quality, which can cost me an engine... Almost sounds like there is some kind of quality control problem in the factory.... Or the green belt is just not the best choice. The original belt may have been old with 110k miles, but it was not this awful.

Replacement belt:

It looks like the grooves are almost completely worn off.