Engine Noisy @ Idle

[veedub_tdi]

Hey folks, I have an AHU TDI and since the beginning of the year the car was noticeably loud at idle. When comparing it to other TDI's there was a definite difference. Well recently I had to go into the dealer to get a new glowplug, and they told me that the loud idling was due to a tensioner that needed to be replaced. Apparently this is a very common part they replace, on our style of engines.

I thought I would share this with you, just in case some of you have the same problem.

If you look at the serpentine belt, there is a tensioner (idler) pulley, that presses against it. If you follow the arm which it is connected, across to the right to the end of the mounting bracket (your alternator is mounted to this bracket), you will see the spring tensioner. Its black, its held together by two 6mm hex bolts on the sides, and one 5mm in the middle. I was told that the spring inside tends to wear out which causes the idler pulley to shake violently at idle, when its supposed to be pushing against the serpentine belt.

The part costs $62 CDN (or something like that +tax of course). I've replaced it and the car idles sooooo quietly now

its like its brand new all over again

.

Hope this helps someone out there

 

[Andrei Rinea]

What exactly did you replace? The whole tensioner? Is the serpentine belt the one that drives the alternator ?
(that's what I think - english is not my native language thus some technical vocabulary is missing)

I've seen my tensioner (the alternator belt tensioner) "jumping" in sync with the engine but I thought it is normal..
Should it stay in place with the engine running?

what can happen let's say (not related with the topic) if the alternator belt would break? How bad can it be? Would influence the timing belt or anything important? (besides running out of the battery since the alternator is not getting any more power)

Yes, my engine is kinda' loud at idle and vibrates a little too much for my taste at idle (only at idle).

PS: Which is the V-belt and which is the Serpentine belt? I know there are three belts in my car: Timing belt (the most important one), alternator belt and powersteering belt. Any other belt? or these v and serpentine belts are among the ones I listed?

TIA!

 

[Steve Addy]

the belt and tensioner on my car was replaced at 65k miles when the timing belt was changed but I've noticed that it idles kind of weird. I should check this as well.

The biggest negative consequence of a broken serpentine belt would be to the cooling system, the water pump stops circulating coolant. Also you'd lose power steering and the charging system. Coolant circulation is by far the biggest concern though.

steve a

 

[Andrei Rinea]

Originally posted by Steve Addy:

The biggest negative consequence of a broken serpentine belt would be to the cooling system, the water pump stops circulating coolant. Also you'd lose power steering and the charging system. Coolant circulation is by far the biggest concern though.

steve a

<font size="2" face="Verdana, Helvetica, sans-serif">tnx4nfo!
Ofcourse coolant circulation stopping can fry an engine but if the serpentine would break I would notice right away and not drive it right? At least I would see an icon flashing on dashboard (battery icon right?) and power steering missing.

I would stop imediattly and investigate.
I'd have it towed or call my mechanic to fix it there and no other damage ? That is my concern about

BUT THE TB would be allright right?

 

[naturist]

Andrei, first the disclaimer: I have never seen a TDI as sold in Romania, so there may be differences I don't know about.

BUT, the "serpentine belt" is NOT the timing belt. "Serpentine" refers to a belt that runs several things, thus it has to act like a snake and make several bends. On US TDI's the serpentine belt runs the water pump, the alternator, the power steering, but NOT the camshaft or fuel injector pump, so if the serpentine belt broke, you would only lose power steering, water circulation, and battery recharge. Assuming you were paying attention, you would know something was wrong, and you would stop, but there would be no damage beyond the belt itself.

Needless to say, if you ignored the new lights on the dash, the temperature guage, and the hard steering, you could fry the engine from excess heat. But of course, you wouldn't do that.

 

[Andrei Rinea]

Originally posted by naturist:
Andrei, first the disclaimer: I have never seen a TDI as sold in Romania, so there may be differences I don't know about.

BUT, the "serpentine belt" is NOT the timing belt. "Serpentine" refers to a belt that runs several things, thus it has to act like a snake and make several bends. On US TDI's the serpentine belt runs the water pump, the alternator, the power steering, but NOT the camshaft or fuel injector pump, so if the serpentine belt broke, you would only lose power steering, water circulation, and battery recharge. Assuming you were paying attention, you would know something was wrong, and you would stop, but there would be no damage beyond the belt itself.

Needless to say, if you ignored the new lights on the dash, the temperature guage, and the hard steering, you could fry the engine from excess heat. But of course, you wouldn't do that.

<font size="2" face="Verdana, Helvetica, sans-serif">1) TDIs sold in Romania are (most of them 2nd hand and 100% all new) made and assembled in Germany so there aren't usually problems regarding assembly and quality.

And yes, it is the same car as there in terms of functionality and which belt is placed where etc etc

2)I know the serpentine belt is not the TIMING BELT but I wanted to make sure that breaking one does not interfere in ANY WAY with the TB. That was all. I know which is which but never were sure of any interference between these two belts.

Any way, thanks a lot for giving me peace of mind

My serpentine belt? or alternator? or whatever... is making some noise at cold startups which noise is getting louder and louder (or it seems to me) every day. I inspected firstly the TB and it seems ok (no abnormal wear, dirt or oil)
TB and tensioner changed exactly 10.000 miles ago so I wouldn't bet (and hope it's not) the TB tensioner.
Can the idler pulley from the TB make such a noise? If so how can I make sure it is that? Just changing it?

 

[James Black]

Thanks for this message - I bought my 96 TDi about 4 months ago now and the idle noise was terrible - it was so bad that I had it looked at by several independent garages who couldn't figure out if it was the tensioner or the alternator so then I had it checked by a VW mechanic and he advised me that it wasn't the tensioner as they it wasn't a known problem. I was convinced that it was that tensioner as I could see it vibrating - however I spent £75 on a recon alternator but have still got the same problem!! I can still return the alternator so thats not such a big deal - but does anyone know how to change the tensioner as I have looked at it and it doesn't look that straightforward as it may seem as the tensioner is surrounded by other parts of the engine. Any help would be most appreciated. Also - I think I priced the tensioner up at the time and it was around £100 (UK) (USD$150) or thereabouts which is a rip off for a friggin tensioner - they're normally around £20 (USD$30).

Thanks a ton for confirming my initial suspicions.

 

[veedub_tdi]

My disclaimer: Keep in mind, that this solution worked for me, other issues might be causing your engine to idle loud.

Anyways, to change the tensioner, requires you to take two 6mm hex bolts from either side and one 5mm in the middle. The 6mm closest to the front of the car is pretty straightforward, and the 5mm is pretty easy to get at too. Just takes some patience and some long allen keys. Now the last 6mm, the one closer to the back is a pain in the arse.

If you got a 6mm hex socket, and an extension, you might be able to reach it from further out the side better. It just takes alot of patience and alot of scratched knuckles. Pull the tensioner straight-out. There is a metal bar that runs the length of the bracket, and its impossible (or damn near impossible) to wiggle it out because of tight tolerances.

[ December 16, 2002, 17:33: Message edited by: veedub_tdi ]

 

[jag60mk2]

veedub,

With the increase in noise, did you get an increase in vibration at idle also?

Matt Ross
1997 Passat TDI

 

[veedub_tdi]

jag60mk2,

Its very hard to say, the engine itself always "looks" like its vibrating at idle in my opinion. Im going to say no, b/c I think the loud idle plays tricks on you, making you think that your engine has a bigger problem then it really has.