Checking a BMW M5 for signs of rust, check at the bottom of the windscreen area, also the rear wheel arches, along the very edges of the boot lid. Now the plastic sill skirting covers, they will hide some rusty inner / outer sills, also jacking-points, plus bottoms of the front-wings and the A-posts. Do also check the fuel flap aperture too. Poorly repaired, or crash damage is very common too; as it’s very easy to get a BMW M5 sideways on a slippery road.
That BMW straight-six engine, will easily clock up an impressive 200,000 miles, only if looked after properly. If the original BMW coolant hoses are fitted, then it’s worth renewing them. Other cooling issues are; a leaky water pump and failed thermostats, as well as viscous fan couplings. The BMW 3.8-litre engine suffers piston and/or con rod failure, because of a badly maintained car.
BMW M5 drive train, is pretty much un-known that a rear axle will fail, but do check for any leaks, all cars get a limited slip diff standard. The BMW clutch ought to feel nice and light. If not, then get it changed. Both the 5 and 6 speed gearboxes are very strong, listen for any clattering when the vehicle is idling, and also with your foot completely off the clutch pedal. Should a rebuild be needed, it will be around £1200.
The BMW M5 exhaust is not made of stainless-steel, but reasonably long-lived. The key is listen for any noisy silencer baffles, which would indicate that a new pipes needed soon. Replacements are quite costly, at about £1200 – make sure too that the catalytic-converter is not damaged.
Any pattering over bumps indicates worn dampers; the front replacements are around £180 mark per corner, that`s for 3.6-litre cars, but with the self levelling rears dampers about £600 per side. The BMW 3.8 has the Electronic Damping Control, (EDC) some parts are now un-available; BMW last listed them at £1000 a corner, so do check for any leaks and the corroded pipes. Swapping out the SLS or EDC type suspension, for the conventional Bilstein dampers is very common, which does improve the BMW handling.
Bushes and joints
Any wear on inner edges of front tyres, will indicate worn ball joints. But if just the centre part of say the rear tyre has worn, then the rear sub frame bushes need to be replacing; they`ll typically last 100,000 miles. BMW replacement wish bones are £250 per side, but rear suspension bushes only £78 per side. Any vague steering feel might just be worn track rod ends, or maybe a tired old steering box. The box could be adjusted, but the steering box`s unique to BMW M5 model, a box from any BMW 5 series will sure be a different ratio.
Some BMW M5s actually came with cloth trim, others got luxury leather. The extended leather was less common, but a more expensive option, this meant everything was actually covered with expensive nappa hide, that`s except for headlining. Whatever it`s fitted with, it should last very well.
All BMW M5s got air-conditioning, so do check that it works, because the compressors and condensers do fail, and if they need doing then the bill will easily reach £1000. Most BMW front seats will have electric-adjustment; but you need to see it works properly. If there`s electrical faults, then firstly check the wiring where it passes up through the boot hinge. Any chafing there leads to bare exposed wiring and an array of electrical issues.