AOC coupling
 

XC90 2009 205,000 miles. 3 months ago blown turbo repaired by dealer and going very well since. New turbo fitted at cost of £2,500.
Recent noise like a wheel bearing problem has been diagnosed by the dealer as a worn AOC coupling. The dealer has quoted £3418 to fix it. We have a reasonable indie not far away but I don't think he has up to date diagnostics, which is why I went back to the dealer.
Everything else is working very well. We live up a Welsh mountain and use winter tyres until about now; the AWD is very useful and the car is better than anything else we have had in snow / ice.
How important is it to fix this? Can I be sure that they have then right answer? Hearing about Volvo's that do 300K+ my plan was to look after it and keep going. Still cheaper than buying a replacement, is the thought.
Advice please. Very many thanks, John

The AOC couplings are normally very reliable. As such, they are not too expensive or difficult to obtain second hand. They are not uniquely coded (and you can swap over the electronics from your old one anyway) so I would go to an indie and them to either have your AOC refurbished or put in a second hand one.

I would also get them to check the diagnosis as well. You should be able to get this sorted for under £1k. But it may still be a wheel bearing so get another opinion...

This chap refurbs Haldex units for Land Rover, he may be able to do a Volvo unit. I've used him in the past with good results, he's well regarded on the Land Rover forums : http://www.bellengineering.co.uk/freelander-2-products/

John,

Had, what sounds like, a very similar experience last year. Sounded like rear wheel bearing but couldn't distinguish which side. Booked it into Volvo for Wheel Bearings got call from the dealer to say it was the Haldex unit. £3500 for the Haldex and including some other bits and Labour £5k+.

They told me it was definitely the Haldex unit as their master technician (30 years experience) had been looking into it (t doing a lot of listening along the drivetrain).

To cut a very long and tedious story short...Diff bearings were at fault. Rear Diff sent to refurber and now quiet as a mouse. One very embarrassed master technician especially as they now had a £3.5k paperweight in their parts department. Significantly less beer tokens spent as well!

I've been told by a reputable expert that the AOC coupling (Haldex) doesn't have any bearings in it. The AOC module is electronic, so your grumbling will be coming from the rear diff.

Cheers

Martin

Very many thanks for this story.
How much did the diff refurb cost, and are there specialists who do this?
I'm not a mechanic myself so have to pass the work to professionals.

I personally don't see how one could definitively isolate a bearing noise to the AOC or diff since they are essentially a single assembly. Also Volvo don't "open up" either, they will just replace with new. There is a bearing in the Haldex unit at the front to support the input shaft and flange.


hence an experienced specialist is the way to go...

I agree and in order to assist in the diagnosis I bought a second hand "known good" AOC coupling with a matching part no. which had done 107000 mile and asked the Volvo dealer to try fitting that first. This showed that the noise was still apparent even with the new Haldex fitted, this then prompted them to get the Diff off and checked by a specialist and subsequent diff bearings replaced.

There are loads of specialist gearbox and diff refurb companies out there that usually do a swap +cash (£300 - £500) for your old one. Google is your friend!

The company that Tannaton gave the link do the Haldex's as well (I didn't find anybody at the time, but I was in a blind panic at having to fork out £5.5k on a car that was only worth £3.5k).

I think, but don't quote me on this one, Landrover and Volvo at the time were owned by Ford (Premier Automotive Group - PAG) so shared a lot of common parts. The AOC coupling/Haldex was one of them and the picture of the Gen3 version on their website looks identical to what was in my 56 Plate if that helps.

If you do replace it get a new pump and filter as well.

There is a guy on Ebay "xc90heaven" (Simon) in Warrington who I bought my second-hand Haldex from. He breaks one XC90 at a time in his garage and sells the good bits on-line, maybe see if he is a cheaper option for bits. You won't get a guarantee like you will from a refurber though.

I hope this helps a bit. You problem may well be different to mine but I'm just passing on my experiences.

Cheers

Martin

Hi Martin,
Further to your helpful comments above I eventually found a good independent near Chester. He listened with a stethoscope and found definite noises from the rear differential. He also says that the Haldex unit does not have a designated service interval but it should have, every 50K he reckons. He has changed the filter and the oil and it is working fine with no noise. The differential was the problem: when he removed it he was pressing out the bearings and exposed a fracture in the main casing. The differential has now been replaced and everything is working quietly. Slightly painful on the pocket but I'm glad the diff didn't split while the car was moving.
He also found holes in the rear exhaust and offered to try to weld it, but when he came to it this was not possible so I have a new silencer. I opted for a Volvo one although he offered to try for a cheaper one, because I aim to keep this car for a while yet.
He then asked about the Auxiliary Belt Tensioner. I have looked at the correspondence about this on the forum. He currently has 3 cars in his yard whose engines were wrecked because the tensioner went. He says it is crazy not to replace the tensioner at the same time as the timing belt. Makes sense to me as apparently it is the tensioner that does all the damage when it goes.
I have asked the helpful people at the dealers exactly what they did at the last service. I've a feeling that the first timing belt change was done late so they may be waiting for the next service, and clearly this needs to be dealt with on time.
I'm seeing this message to each of you because I don't know how to send it to you both together!
Thanks very much for the help. Total cost of the above was £3115 which included the new exhaust and diff. If I had stuck with the dealer's advice I would be £3,500 worse off with new Haldex unit, a hole in the exhaust and a rear diff in danger of blowing, so I think the money was well spent.
I shall use this indie for everything in future; you actually get to talk to the guy who knows the problems and fixes them himself, and they are very obliging. The expertise is really in one person's hands, but he is a lot younger than me so should see me out.

Haldex unit
 

I have replied to the messages below, but somehow created a second message here which it wants some character is so here they are. Am also replying to you Tannaton thank you. It was very reassuring to get these thoughts which helped me in my resolve not just to accept the dealer's advice.

There is a ball bearing to support the shaft in the AOC about £15 ,, any mechanic familiar with gearboxes would find it an easy repair . Dealers never try repairs these days ...