timing belt squeal

[sleeprs6]

hi everyone, I just finished doing my 35k timing belt service, stern motor mounts, serpentine belt with idlers and tensioner, oil and coolant, and I have a slight problem:

I replaced all of the timing belt idlers and tensioners, water pump, and belt. I used the stock continental belt because I read that the gates belt squeals. With the car running there is a pretty loud squeal though. I took everything apart and it looks like it's coming from the small idlers on either side of the water pump. I'm afraid to drive the car with the belt rubbing like this because after enough rubber gets removed from the back of the belt maybe it will break? Or maybe the idlers will loosen up with use. Any advice or suggestions are much appreciated.

I used the kit from europa parts: https://www.europaparts.com/timing-belt-kit-s6-rs6-c5-s8-d2-4-2l.html

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[mrdave]

Yeah that's definitely not good. My guess is that you got a bad batch of idlers or they somehow got installed incorrectly. Either way I wouldn't drive it until those get replaced.

[Aronis]

Hope you get it sorted out......

Mike

[sleeprs6]

I torqued them to the spec in the service manual, new OEM bolts, so I'm pretty sure they're installed correctly. I just contacted EuropaParts and will update when they reply.

[RS6 rick]

The rollers looks like there dragging. Did you spin everything by hand to check before you installed the belt ? GL. If all else fails go to your local Audi dealer and replace. As others have said don't drive it till it's fixed !!!!!!!!!!!!!!!!

[Bigglezworth]

There shouldn't be anywhere near that much rubber transfer. IMO, this visually appears to be the result of the belt heating up (thus the squeal). You aren't "slipping" as this is a ribbed belt. I'm of the opinion you have a situation where the belt tension too tight. How did you adjust/set the tension on the idler pulley? There is a set procedure for how to adjust that prior to releasing the pin to engage the tensioner. Too tight and you're putting a lot of strain on the rollers.

[sleeprs6]

Europa parts rep responded to my inquiry, but he offered no resolution. Just assured me that there's no issue with the rollers:

"I do not necessarily see anything at all wrong there. Double check the idlers that the center bolts are to proper torque specification. We have had zero issues with any of these items. The Hepu pump is what we have always sold for those 4.2’s of that era, and zero issues. A bit of rubber coming off of the gummy rough surface of a brand new timing belt onto the idlers initially is not anything that I would be concerned about, as long as the idler is properly torquedand there is no resistance on the pulleys. I don’t know about “squeeling”, not sure what to make of the entire scenario without being directly at the car to examine first hand what the situation may be, but to have one of those rollers an issue would stun me, let alone both on one car. The Hepu pumps have been perfect Nothing is impossible, perhaps something is over torqued, perhaps an idler may be out of spec, but I have never seen this issue prior, and as you know, all of those components are OE and have never been an issue for me prior."


The rollers spin without the belt on and are torqued to 22nm as specified in the service manual. They spin with the belt on too, since there is rubber evenly covering the whole circumference of the roller. However, they don't spin AS EASILY as the ones I took off. Just a bit more resistance, which I attributed to them being brand new (noticed this before I put them on the car).

The eccentric tensioner is torqued against the belt to the 6nm spec, using the T40009 tool. Too much belt tension could be the cause, this would be determined by the hydraulic tensioner though? The eccentric tensioner sets the extension of the hydraulic tensioner when the locking pin is removed, more tension and the hydraulic tensioner compresses, less tension and it extends. That's the point of having a tensioner right? Constant force applied to the belt. The tensioner is extended 6mm, the spec is 5mm +/- 1mm. So maybe the new tensioner is applying too much force?

Not really sure what to do at this point, since the europaparts guy is not helping. I guess I'll reinstall the rollers, reset the timing etc. again this weekend.

[P1054]

I can't say for sure what the problem is in your situation, but I did have a similar experience. I performed the full timing belt/water pump/pulleys service and installed a Gates blue racing belt. It squealed, but not super badly, and not continuously. I wasn't sure at first what was causing the noise so I drove it for a bit, and then took everything apart again. I had a minor amount of rubber on the pulleys (much less than in your pictures) and a bit more on the water pump pulley. The first thing I tried was a different belt, and the problem was solved. I ended up going with a Continental ContiTech belt, nothing fancy, and never had any more issues, either squealing or rubber build-up.

[CBeau]

Damn I was going to do a Gates belt soon. Bad idea? I've used them many times before on many cars, mostly Porsche, and never had any issues.

[P1054]

Some people have had good luck with Gates belts on their RS6s, but I (and some others) didn't. So I don't know, maybe it was a combination of the Gates belt and some of the other parts I used? All I know is that switching from the Gates belt to the Continental belt solved my issue.

[Dmb408]

I realize your pics point to it not being this, but just opening because I had a squeal once on beast 1, it was the covers put back on wrong.

[G2]

Looks like a typical issue of not being clean enough and/or a residual leak. Was the cam sensor cam seal replaced? It's right over the idler pulley shown.
Meaning if there is ANY grime that gets on the backside of the t-belt it will start to gum up. A coolant leak can and will delaminate a belt causing failure. Coolant is very sticky. Avoid even one drop on a belt. Otherwise not a big cause for concern in my viewpoint. Not ideal, but long as the symptom doesn't further degrade should be fine. With that said would say the situation was avoidable.

I have noticed over the years that old stock/parts will have more resistance. New rollers always have higher resistance. The rep is basically saying nothing worth while, sounds like a nice guy however. It's true that OE/INA parts are basically failsafe in terms of defects.

The eccentric idler torque may not be correct, if I understand the statement. Torque is much higher like 45NM range. It does not affect (appreciably) belt tension, simply used to alter the hydraulic tensioner position and tweek cam timing. I typically set tensioner gap on the low end of the spec. I do not see how a slight setup variation would - again appreciably - increase tension enough to affect the roller. The decimal place must be pretty far to the left.

Gates belts are a bit noisy at times. Noticing it on my car now that it's getting cold out. Quiets up once warm. The belt is truly overkill,but convinced it won't stretch as much. It forces a complete timing syn'c, by requiring cam sprocket removal. (Don't use the Gates belt if you want to avoid this step.) And Conti is getting iffy on their sourcing. If it's not German or EU/UK I won't use/install/sell it. The belts tend to walk more and the edges are not as well finished. Who knows what else.

Clean off the pulleys with brake clean. Ensure the belt is perfectly clean. That's half the job of doing it right at a pro level. It's basically equivalent to dentistry. One of reasons I got a $4K parts washer few years ago. Everything is squeaky clean for assembly. Some things are crucial like cam sprocket to cam snouts. I use a ton of surgical gloves (have several types) to prevent cross contamination of grease, loctite, or in just handling something.

The scenario is starting to reignite a prior motivation to create a solution for those skimpy upper idler rollers.

[Bigglezworth]

i like what Gary has outlined above. The more I go through all the steps in my head, you really cannot get a belt too tight. The eccentric idler is torqued to snug and ensures accurate crank to cam timing. The hydraulic tensioner cannot put enough pressure on the belt to do this.

While we're on the topic of idler rollers, does anyone know why the BCY engine has two and other 4.2's have only one?

[G2]

Appreciate the hat tip BW.

I'd gander the double rollers are to avoid any potential belt fluttering.
'Suppose the higher turbo charged cylinder pressures might put more kick back to the cams? It's been awhile since doing auto match but thought BMEP was around 400 PSI on a NA engine. Have to assume with 5 valves and all the surface area perhaps it was a concern for the engineers. It may not matter in the real world. Can imagine that testing was rigorous with extended dyno runs, endless laps at Nordschliefe, 2am AutoBahn/Strada runs. Who knows maybe they had a belt or two fail and said or yelled "Nein"?

Nice to own a Halo car, eh?