1997 BMW 525tds AirCon this time!

Yes, absolutely correct. Have you actually checked under the bonnet to see whether the clutch engages when the air-con is switched on? If it doesn't (and I suspect it won't) then I'd say your guess is spot on.

Dave

The low on gas could be a possibility, but if it was a hot day and it was slightly low on gas it would have probably cut out anyway. The first thing to look at is if its fitted with a compressor over temperature switch, mounted on the compressor itself- this is the last "straw" in the electrical supply to the clutch. It will be a round or square encapsulated switch probably held in contact with the compressor body by a spring clip.

Tim..

If this was caused by low gas, it's usually not an instantaneous thing, but the system looses efficiency gradually before finally stopping working. The aux electric fans on these cars should run all the time the A/C is selected - but often give problems. This is based on the petrol ones - I've no experience of diesels.

Thankyou once again Tim.. and Dave for the above. I have only had info via the telephone but will get the car a week saturday to replace the upper & lower control arm bushes. I will then check it as you both describe and report. Pete

Ah. The dreaded E39 wheel wobble? What's the mileage? I'm trying to keep track of when this happens on the various models.

Will let you know when I get the car. Helen [daughter] has been complaining about it for about a year now, that and tramlining, but steadfastly refused to let me drive the car as it would only be TP on my cover.I'm her dad for Christ's sake, would I crash it?

Will put in new repro botton arms and Powerflex polyurethane upper control arm bushes. Pete

I'd like also then to know what wheels and tyres it has. Tramlining isn't a common complaint. But as the wheels go up in size, so do the problems.

Heh heh, it's the safest car I've ever had by a mile - the DSC makes it near impossible to unstick.

I'd be careful about aftermarket bushes making the ride harsh or noisy.

In news: snipped-for-privacy@argonet.co.uk, Dave Plowman decided to enlighten our sheltered souls with a rant as follows

mine tramlined like a, er, tram when the tread got low.. it had the 17" Sport alloys and suspension.

until the bloody ABS sensors pack in... again. Great fun in the wet that was. Makes the Capri feel so much better balanced!

I'd just shove oe ones in from GSF or wherever.

......I'm replacing the fronts, knackered because of shimmy problem , the size is 235.45.17

..... I understand that there is a slight increase in road noise but compensated for by better handling and up to 10 times longer bush life, which is required because her hubby grows horns when he gets behind the wheel and she kerbs it! Pete

As I thought. There's little or no tramlining with the 'standard' suspension and wheels.

I'm afraid that's mainly the cause of your problem. For some reason anything above 16" gives this problem earlier, and the original 15" are better still. You pays for fashion...

Even with the largest wheels, it's usually about 60,000 miles before the shimmy starts, and the cure is to replace the bottom control arms. It is possible to replace the joints only with decent workshop facilities.

However, of course damaged wheels will cause problems too, and ones with ultra low profile tyres are the easiest to damage.

If she regularly kerbs this car, I'd suggest some driving lessons, given that the handling is so good even in bog standard form. ;-)

......... Alignment and balancing, swap front/rear all tried, definitely the bushes. She doesn't understand how they work, nor does hubby. Nor do they care, so it's taken some time to get where we are today.

..........I'll leave that to you :) I've had just one headache in the last 8 months - I drove 100 motorway miles with her - never again! And I used to navigate on rallies back in the 70s & 80s

Just a follow-up on the above.

I replaced the lower control arms complete. The old arms had knackered bushes, both sides had cracks and were 'blistered'. The ball joints were 'loose' but no play both would have passed MoT.

It was difficult to say whether the compliance bushes on the upper control arms had 'gone off' but these were replaced in situ by drilling and sawing out the old bushes and replacing with the PowerFlex polyurethane bushes which are a doddle to fit.

There is now absolutely no shimmy, the steering is positive and there is NO discernible increase in noise level.

Altogether a happy outcome!

Pete

Addendum to below

------------------ Car had done just over 65,000 miles when problem was first noticed. During the time up until I replaced items as per below various fixes such as tracking - balancing - new tyres - swapping front to rear were tried with marginal success. The mileage is now 80,548 so should last for a few more years. Pete

That's about par for the course on an E39 with large wheels. Standard wheels seem to take it to somewhat over 100,000 miles.

It's a weakness, but I'd guess it's what you pay for the good road isolation.