szabon

So, I recently had my turbo rebuilt because there was this wirring sound coming from where the turbo was. I took it all apart and sent the turbo out the get rebuilt proffesionally to avoid anything going wrong. Just put her back together again, and there is no change! There is still the same wirring sound from the same spot. It gets louder as the engine gets hotter. I have no clue what this could be and I am a bit terrified of it, since I do not have the means to pull and engine and rebuild it. The turbo replacement was about my limit...

Any ideas?

I don't even know what to do next...

Gator_86_951

Post a video so we can see. I would very helpful. Have you driven the car/

944meister

Most likely balanceshaft bearing noise from the belt being tensioned incorrectly. As the aluminum block warms up, it expands and would effectively increase the tension making the sound worse.

xsbank

What car?
Cam chain tensioner (if you have one)?
Balance belt?
Power steering pump?
Alternator?

My belts whirr and they have been tensioned.

John_AZ

OP Vid Post,

https://rennlist.com/forums/924-931-...ine-noise.html

I cannot tell by the video.

GL
John

carlege

At least you have a rebuilt turbo.

Jfrahm

Hard to tell from the video but if it follows the engine RPM it can't be the turbo. It could be the alternator bearings or. as was suggested, the BS belt. Might as well pull the accessory belts and see if that helps, if not check the BS belt. The balance shaft belt when 'tight' is pretty loose feeling.

I have an alternator that whined pretty good, sounded similar.

-Joel.

szabon

It's a 86 944 turbo. When I bought the car, the po gave me records saying a porsche shop did the belts, but I have found a ton of stuff that these guys missed while going through the engine, so I am not 100 percent that they did a good job. I have not done the belts yet, is there a write up on how to do this? Which belts are accessory? How do I check the BS belt? This sound also started up after driving the car for a few months with no sound at all. Can this still be the belts?

BeerBurner

I haven't watched the video so I am going only on what people have said.

The accessory belts will be the alternator, AC and power steering belts. Maybe just drop the belly pan and pull them off to see if the whirring goes away. If it does, then it is either the belts themselves, the tension of them or something bad in the belt-driven components. You can narrow it down by putting one belt at a time back on, running it and see if the noise comes back. When it comes back you'll be closer to the trouble area and then if it is still there after properly adjusting them and the belt is in good shape then you'll have a better idea of where the problem is.

If that doesn't do it, I have the tools to do the balance and timing belts so we can always check the tension on those. My life during the next month is booked but if you can't find anyone else to help you I can head over and we can check all of that once my summer vacation starts.

BB.

szabon

I think I will take you up on that offer if I cannot figure it out. Do I need to tension the accessory belts, or can I literally just pop them off, run the car, and pop em back on?

BeerBurner

You don't need any official tension reading on them. Typically, I aim for about a half inch of deflection at the longest point on the belt with a reasonable amount of thumb pressure. Someone will probably post a different number for that but this is what has worked for me.

But really, the car will run just fine for a few minutes without the belts so just eliminate that variable all together and completely remove them.

BB.

szabon

Ok, I tried searching, but I guess i am an idiot. I only see two belts, and I cannot figure out which one to remove to check the accessory belts. I am afraid of taking off the timing belt and then turning the engine on, as I hear this would be bad...

BeerBurner

If you are looking at a timing belt diagram then don't look at that. The accessory belts are the the alternator, PS and AC belts that you can see by looking at the front of the engine.

BB.

szabon

gotcha. so remove the 2 belts I can see, start the car up, then see if it whirrs again. I imagine I should warm the car up first to get the sound to start again, yes? Any tips on taking these two belts off?

BeerBurner

If having it warm makes the whirring louder then yeah, warm it up first.

They are pretty straight forward. Pull the belly pan for access and you'll need two sets of 13 mm and 17 mm (I think) wrenches or something adjustable. You'll see two adjusting turnbuckles that are locked in place with a second nut. Loosen the nut, back them all the way down and then spend some time turning the turnbuckle to loosen the belts. Nothing difficult... just a little time consuming with all of the turnin'.

BB.