Solved! C30 alternator squealing? Nope - PCV diaphragm split

carnut222

Took the C30 to Volvo club coffee and chat morning today and we noticed when decelerating at low speeds we could hear a squealing noise... intermittent and seemed to stop when accelerating. I opened the bonnet and it sounds like it's coming from the vicinity of the alternator at idle but not 100% sure. With engine off I could easily turn the centre of the alternator pulley so I assume it has some sort of clutch like an AC compressor and only kicks in when needed? Do the alternator bearings or clutches go bad regularly? I guess the other thing I need to check is the serpentine belt tensioner although seems like that would squeal all the time not intermittently. Will pull the belt off and start fiddling.

Thoughts?

timbo

The alternator clutch does fail.

Usually you hear it as a brief chirp at startup

The pulley should drive the alternator if you turn it in a clockwise direction, then suddenly flick the pulley anticlockwise, it should free-wheel briefly.

If it's directly driving the pulley both ways then the clutch is faulty.

The belt tensioners are also a service item at 180,000kms or 10years.

carnut222

timbo
The alternator clutch does fail.
Usually you hear it as a brief chirp at startup
The pulley should drive the alternator if you turn it in a clockwise direction, then suddenly flick the pulley anticlockwise, it should free-wheel briefly.
If it's directly driving the pulley both ways then the clutch is faulty.
The belt tensioners are also a service item at 180,000kms or 10years.

Thanks for the reply Tim...however I’ve solved it. Yay! I thought could it be the PCV diaphragm, so I took the oil filler cap off (lots of suction there) and the noise stopped immediately when I pulled up the cap, and began again when I let it back down again...so time for a new breather unit or to replace the diaphragm. I think replacing the unit will be a lot easier than replacing the alternator, so I’m somewhat relieved! FWIW the car has about 146k KM on it. Guess now I just need to source either the new PCV asm or the diaphragm...must look around a bit...any comments on best option or whether it’s worth trying to replace the diaphragm instead of the unit, lemme know!

timbo

The oil filter housing has been through a few revisions since 2008 so i would replace the whole unit.

At some point Volvo started plastic welding the cap over the diaphragm so it's not always possible to just replace the diaphragm.

If your top crankcase vent hose is original it will also need replacing

carnut222

timbo
The oil filter housing has been through a few revisions since 2008 so i would replace the whole unit.
At some point Volvo started plastic welding the cap over the diaphragm so it's not always possible to just replace the diaphragm.
If your top crankcase vent hose is original it will also need replacing

Thanks Tim - sounds like it might be worth just replacing the whole unit...I’ll check it out. Seems to be a wide variety of prices for the same P/N so just need to confirm the correct P/N and see what replacement of the unit involves. Wonder if it’s available cheap through the Ford dealers? :)

timbo

Last time I priced it ford were more expensive than Volvo, but worth a try.

I usually just find an xr5 vin on Google and use that.

It's pretty straightforward to replace, only 4x10mm + 2x8mm bolts to remove housing, trickiest part is getting the stock airbox out.

hamsandwich

I just bought the diaphragm when mine went, no airbox removal and total less then 5 mins to install

carnut222

hamsandwich
I just bought the diaphragm when mine went, no airbox removal and total less then 5 mins to install

Thanks Steven. I opted to go that way as well as I figure I only have like $30 to lose by ordering the diaphragm, and if it all goes pear-shaped I’ll just do the box. I ordered the diaphragm from vanos-bmw.com and turns out it’s in Russia...wonder how long that will take to arrive? :) I saw the YouTube video of popping off the cover and replacing the diaphragm, and mine appears to be the style with the removable cap, so hopefully it’ll go smoothly. The car has always had regular oil changes using Castrol full synthetic, so I assume there is not a problem with build-up of gunk or anything in the breather box. Worth a try to save $400! :)

carnut222

The new diaphragm arrived from vanos-bmw.com today. Took about 2 weeks (from Russia!)

Removal of the diaphragm cap was straightforward after removing the 2 air inlet duct portions. I used a wood chisel on edge to pop the cap off as per something I saw on YouTube or a Google image, then the trim tool to lever it off fully.

A bit of gunk inside but not too bad. I guess that's to be expected with 1477xx km. Here you can see the tear in the diaphragm:

Reinstalling was a bit fiddly as you have to position the spring and diaphragm and get the cap on, and not much space to work under the inlet manifold. All up took me about 20-30 minutes. No more squeal! Yay! Total cost for diaphragm and postage was $27.50USD (= about $38AUD).