whistle after timing belt change 1.8T 20V

[sambb]

Hi,

I recently did a hydraulic to mechanical tensioner conversion on my 1.8T 20V in a Polo Gti 9N3. The tensioner I used is the KR series 1.8L 16V one. I'm getting a whistle noise when I get up it. If I progressively bring up the revs even to say 5000rpm its fine but If I accelerate hard the noise will kick in. I had initially thought boost leak but its the wrong sound and I have only just done the belt. It sounds a bit like a slipping ancillaries belt but I replaced that yesterday for no joy. I'd set the belt for 90 degrees of twist but that's pretty subjective and its entirely possible that the belt is too tight creating the whistle. So do the noise symptoms I've described sound like an over tensioned belt?
thanks for any help
sam

[Bora Sport]

I don't know about a whistle but a timing belt that's too tight can definitely cause a whining sound. 90 degrees of turn doesn't sound tight. I assume the tensioner was new.

[sambb]

yep new tensioner and the IE billet bracket/idler assembly that replaces the hydraulic unit. I just tensioned it as though it was a 1.8L 16V. Just finished pulling it mostly apart just now. I rechecked the belt and I can get 90 degrees easily enough and it definitely doesnt feel tighter than the hydraulically tensioned belt on my other 1.8T. I refit all the guards and fit a new ancillaries tensioner and belt and checked all the IC piping while I was at it. We'll see I guess - could be a dud tensioner roller who knows. Just thought I'd ask you guys as I'd read that an over tight belt could whire/whine/whistle if too tight and your engines give you a lot more experience with manual tensioners. thx

[h100vw]

A tight belt on a KR could be heard from down the street back in the UK. So that would be the first thing I'd look at .

[Umai Naa!!]

Was the tensioner pulley offset correct?

If it's not lined up with the other pulleys, there'll be friction on the edges of the belt.

[sambb]

Alright I backed the belt tension off so that I could get 90 degree twist on the belt without difficulty and it was still doing it. I then backed it off again so that I could get 90 degree twist just with my fingers alone (ie not moving my hand at all). I thought that'd do it but the noise is still there. Thing is, I've subsequently notice the belt is much looser when the car is stone cold. I'd noticed this on one of my previous goes - easy 90 degrees, 2 or 4 rotations of the crank pulley, re-check marks and tension aok, but once its warm it was much tighter and 90 degrees almost unattainable. ie today when I got to work I couldnt get 90 degrees and there wasn't much deflection, 5 hours later it was easy and the belt was floppy. Since when does a warm belt get tighter? Could it be that the 1.8T belt has some special properties that match with the hydraulic tensioner? I'm not a numpty but this has me a bit f**&ked.
The pulley lines up exactly with the IE spacer that fits under the tensioner roller and everything tracks spot on. Checked clearance to the covers etc too.
Even if I could pin down the source of the noise I've kind of had it with this tensioner and don't trust it with what seems like really variable tension. I have an ABF 2.0L 16V manually set sprung tensioner so I'm going to chuck that in instead.

[sambb]

I have a theory. I could be way off but would I be wrong to think that the variation in belt tensions is due to head expansion. Obviously the KR tensioner worked on an alloy 16v head but was the change in belt tension cold vs hot maybe why they went to a sprung automatic tensioner on the ABF 2.0L 16v? Did KR series 16v ever loose belts at startup more so than when hot?
im actually starting to think that my noise is more boost leak related as it's happening only when I really stamp on it, but the fact that the belt is noticeably slack when fully cold vs when up to temp has me thinking that maybe the ABF tensioner is more appropriate for me. Thoughts?

[sambb]

Follow up. I found the source of the noise and it wasn't the cam belt tensioner. Was the turbo to dump pipe gasket leaking. Not sure what's going on there because I checked those bolts recently. Why that coincidentally started right after I did the timing belt I don't know but definitely it sent me on a tangent and I kept hearing about how manual tensioners can be noisy.
So tensioner is good from a noise perspective, but still the belt seems a little looser than OE (cold) when set up as per the Integrated Engineering 90 degree recommendation. In recent emails they assured me that there's no way it can jump a tooth if its set up like that so I'll just keep an eye on it, re tension after a couple of thousand kays and then forget about it hopefully. thx

[karmen]

get the cover on right can avoid noises too btw lol

[h100vw]

Never heard of tensioners issues on kr engines, except the odd one that was set too tight. ABF motors were pretty rare, my mk3 16v never missed a beat but was serviced at vw before I bought it. Including a new belt