Which of these pulleys are bad?

Continuation of the below thread, basically I have engine noise that might be the alternator but before spending money on that (it charges fine and is relatively new) I'm checking the pulleys D Thread 'High-Pitched Intake whistling sound - any ideas?' 7 Mar 2026 Watch IMG_6228 | Streamable Watch "IMG_6228" on Streamable. streamable.com This high-pitched whistling sound has been there since I got the car. It's not accompanied by any other symptoms as far as I can tell. It's now bothering me enough to want to locate the cause. First of all, this is not a normal sound, right? Second, it sounds like air to me, possibly one of the myriad of vacuum hoses? Could it be pulley whine/something else? Any ideas or experiences welcome. Dovoda75 Replies: 3 Forum: Porsche 911 996 (1997-2005) I've taken a video in the hopes more experienced people here can comment on which of these pulleys are bad Watch IMG_6311 (1) | Streamable Watch "IMG_6311 (1)" on Streamable. streamable.com AC clutch pulley, this sounds quite noisy, is it normal? Alternator pulley works fine (had it changed a year ago) but the stator makes a click inside (not audible in the video) Idler pulley top (alternator): this is harder to turn than the others, is this normal? Garage put my alternator back in (they messed up my engine mount install so no trust) so maybe they overtorqued it? Didn't think to undo it and properly torque it while I was in there Both idler pulleys and the tensioner pulley sounded noisy to me to be honest, this is why I'm asking because I'm hoping I'm being too fussy and not all of them need replacing. Any help appreciated.

And please excuse my clumsy hands in the video

I’m no expert, but when new they will hardly “free wheel” so i would say both idlers and AC.

Hard to judge noise from video alone, but based on what you’ve described: - AC clutch pulley should spin smoothly and quietly with the AC off. If it’s rough or noisy that’s usually the bearing starting to go. - Idler pulleys should all feel the same. If one is harder to turn or feels different that’s not normal and points to bearing wear, not torque. If you’ve got multiple pulleys sounding rough it’s usually easier to replace the set (idlers, tensioner, belt, and possibly the AC pulley) rather than chasing them one by one. What I would do Replace the full set of idlers, tensioner and belt, and deal with the AC pulley at the same time if it’s noisy. That saves you doing the job twice and eliminates all the variables in one go.

Put the belt back on and run the engine, squirt each bearing with WD40 in turn (not all together before starting engine!) and if it gets quieter then replace that bearing.

Get a long bar, hold one end against the centre of each rotating part, the other against your ear. Run the engine and you'll know in seconds. A long screwdriver will do or even a length of pipe.

I had a whine that was slowly getting worse recently, I took the belt off and my lower idler pulley was similar sounding to yours (dry, spinning very freely) , I replaced it (part has been superseded and now a 997 part no). Picked it up from OPC for £70 odd quid popped it on over the weekend and all better now. I replaced the belt while I was at it too very satisfying quick bit of tinkering.

Re idler pulleys - there was a post a couple of years ago where someone had identified the bearing spec and with the aid of a press swapped them over. About £18 each for the bearing IIRC.

Quotes source post: 2796023

I've researched this when I replaced the bearings in my steel pulleys on my 997.1 and when the bearding are worn they turn easily, when new they're harder to turn and don't spin much.

as mentioned above, I had steel pulley so I replaced the bearing instead of the entire pulley.

Don't leave it too long: Thread 'Tensioner Pulley left me stranded in the South of France!' 6 Aug 2023 As some will be aware, I've just been down to St Tropez with my son (to join a mate) on holiday. Had the usual couple of issues - water washer pipe came off inside the inner wing (20 minute job before breakfast to fix that) & passenger door mechanism microswitch broke - new Audi TT replacement mechanism now on order, as well as running out of fuel on the way to the beach :floor: BUT the nightmare of the holiday was the aux belt tensioner pulley failing, whizzing off into the engine compartment at 80mph. By mid holiday we returned from the beach one day to the car and as soon as I fired... Alex Replies: 32 Forum: Porsche 911 996 (1997-2005)

The thread on replacing them is here: Z Thread '996 Idler / Tensioner bearing replacement' 25 Nov 2016 For those of you interested; The correct bearing can be found here for a good price; Manufacturer: FAG / SFK Type: Double Row Angular Contact Bearing, Sealed Side; 15 x 35 x 15.9 mm Part number: 3202-BD-2HRS-TVH / 3202 2RS / https://www.bearingbasement.com/pro...ag-double-row-angular-contact-bearing-sealed/ ~ £18 / each and free shipping. Beats £60+ replacement items from porsche or OEM... Just a case of pressing out the old and pressing in the new.. Freezing the bearing and heating the pulley may help. I'll post some info when i do mine. Neil Zub-911 Replies: 64 Forum: Porsche 911 996 (1997-2005)

Thanks everyone for the replies. I've had a look, it's not as straightforward as one would imagine/hope. I'm sure now my lower idler and my tensioner are bad, the AC clutch possibly as well. Since the compressor is the original one I might as well change it now before it fails and makes mess in the system since the car is on 92k miles. Which means I might as well change the dryer, a couple of seals, etc. so project creep as always. Just a bit of info that might help someone out... - The pulleys differ between pre and post facelift obviously but they also differ on manual vs automatic. - For the 996.2 manual you need a different pulley for each of the three rollers. - Old parts were steel but have been superseded by plastic parts for the manual, you can still get metal ones for the tip. - In terms of kits, continental make one you can get it from rockauto. Rockauto is also very good, very competitive prices and some components that you don't see in Europe, it was a nice discovery as part of this debacle. You can also get an OEMatch kit from D911. Both kits seem overpriced especially if you don't need everything in the kit. - The "replace the bearings" route, I saw mixed results and you need a press, plus ensuring you have the right bearing for your engine and transmission. I'd say worth it if you're keen on keeping the metal rollers but longevity is dubious? - Autodoc sell Vaico branded pulleys for a fair price. - Heritage parts Centre sells Meyle pulleys for a good price with a 2 yr warranty, and I'm going with them. They are not listed on the relevant store page, you have to find it via "meyle parts" for the 996. - The 996 pulleys have been superseded by 997 parts that on some retailers might not appear as compatible with a 996, so worth double checking OE numbers with the D911 diagrams.

A listening stick, as I suggested, will answer your issue instantly with regards to what is worn and what isn't. If you decide you're going to do your aircon compressor YOU MUST CHANGE THE DRIER and also flush out the system and put the correct amount of lubricant in to keep it in warranty. Also, most come pre lubricated, so you really need to drain it out the new one, measure it, then put it back in, then work out how much lubricant needs to go in the rest of the system, otherwise you can easily F it up. You're right on changing the bearings yourself - unless you have the right tackle and can also check the diameters on the pulley bores, you're in for a failure.

I changed the bearing in my AC pulley last month, saved doing the whole lot as my ac works great. I’ll see if i still have the old one on the bench, and replacement required a dremel, lump hammer and vice only.