Mystery Engine Whine Sound

[Crozzy 19]

Kia ora team,

 

So the old 328 has developed a less than fantastic gurgley whine in the engine bay. It's most noticeable at idle, particularly in Drive, and doesn't occur at all until the engine is warm. While stationary if you put the vehicle in Park the sound reduces dramatically.

My ear-omitor says it's coming from somewhere near the power-steering reservoir, but I can't place it exactly. The fact that it only happens once the engine is warm makes me think it's a fluid, and the power-steering fluid was looking a bit muggy so I sucked it out and topped it up with fresh fluid while going back and forth to full lock on the steering. I did that about 4 times, and although the fluid looks cleaner (although admittedly still cloudy) the sound remains. Could it be air bubbles stuck in the power-steering still? Or perhaps the reservoir needing replacement (I understand they have inbuild filters)?

Since in the 20 odd years of this model being around I can't be the first person puzzled by this sound, so I figured I'd see what you guys think!

Cheers!

[Eagle 1662]

Sounds like a worn tensioner pulley. Long screw driver placed on tensioner housing with ear attached should confirm.

EDIT: Or idler pulley, forgot you have a TU

Edited April 1, 2019 by Eagle

[Olaf 3320]

yep, serpentine belt tensioner most likely suspect!

 

[M3AN 4016]

I'd say if that's a pulley then it's in very bad shape and I wouldn't drive the car until it was replaced least you lose a belt. Pulleys normally give a telltale high-pitched whine long before the bearings fail. Also a pulley noise will change with the revs, does that happen?

You can test them yourself by slacking off the belt and spinning them with your fingers to listen for noise and feel smoothness. if you're going to do that you might as well loop the belt off the accessories also (keep a track of routing) and check the alternator, water pump and power steering pump by feel also.

If it's not something belt related then I'm sorry but I can't offer any other suggestions.

 

[Crozzy 19]

Update: Thanks for the replies, much appreciated! Took the intake scoop off and moved the air filter out of the way to get better access to the belt and pulleys, and used the screwdriver scope (Thanks @Eagle) and it's definitely the tensioner pulley! The idler pulley seems to be alright.

I've ordered one and will fit it when it arrives. I really should've checked them when I did the waterpump/thermostat job..

Cheers guys!

[Crozzy 19]

Alrighty, I finally got some free time, so update time:

I pulled the fan and shroud off and took the belts off to check the pulleys. They didn't seem too bad turning them by hand, but as I had the replacement pulley on anyway I put that on the tensioner as the noise is definitely originating from there. After putting the belts back on it's still unfortunately making the noise. Out of curiosity I removed the belts and ran the engine for a bit and the sound is definitely from something driven by the belts. After a bit of listening through the screwdriver-scope and some observation, it appears the tensioning spring itself is the cause of the noise. Is this possible? At this stage I'm planning to purchase a whole new tensioning unit but I thought I'd see if you guys had any thoughts. Would it be worthwhile spending the extra bit for the hydraulic conversion?

 

Cheers!

[M3AN 4016]

Short answer: yes replace the mechanical tensioner with a hydraulic one, the mechanical ones will just keep failing.

You need a few extra bits to do the swap but all can be had off a wreck if you've got a couple of spanners and a little time. I think I paid $15 or $20 for mine from Zebra when I replaced the mechanical one on my 328 - much better than the cost of a new one and the hydraulic ones are pretty much lifetime.

Here are the parts you need: https://www.bimmerworld.com/Engine/Pulleys/Hydraulic-Tensioner-Update-Kit-E36-E46-E39-E60-X3-X5-Z3-Z4.html

 

[Crozzy 19]

2 hours ago, M3AN said:

I think I paid $15 or $20 for mine from Zebra when I replaced the mechanical one on my 328

Thanks for the info. I took a quick trip to Pick-a-Part this arvo and managed to find ONE e36 with the hydraulic tensioner (I checked against the kit you attached, seems identical and should fit the e46 too) installed instead of the mechanical, but unfortunately I didn't have any tools on me, and by the time I go to the shop to grab them and head back it'll be closed.

Looks like a mission for next weekend!

[Crozzy 19]

Final update for this thread, in case someone encounters the same issue as me and stumbles across this thread:

This Saturday I went back to pick-a-part and grabbed the hydraulic tensioner I spotted the weekend before. Here's it off the old block. $11

And the old mechanical tensioner and pulley I pulled of my motor

 

It seems the tensioning spring in the mechanical unit was worn and making an unpleasant sound. It was doing its just still, but admittedly did sound a lot like a failed pulley. Worth saying though, if you think you have failed pulleys and you still have the mechanical tensioner, you''re better off replace the whole thing with a hydraulic tensioner.

 

Unrelated, I also picked up a oil level sensor from another wreck at pick-a-part for $29 as the one in my vehicle is faulty. Figured it was worth the try to see if it works by replacing my definitely broken one next service. I'll be sure to replace the o-ring though.

 

Anyway, that about wraps things up. Thanks to those that offered insight and/or advice, helpful as always.

Chuuurr!!