The Infrequent use will wreak havoc with the race oriented BMW M1, now the biggest issue is with the dry-sump, an oil tank that’s located over to the right in the engine bay: any long periods standing that allow any condensation that`ll form on the inner face ( that`s above the oil line inside the engine), the water and the rust falls into the engine oil so that when the time comes and the engine is started, all the moisture is sucked right into the bearings as well as the seals with absolute disastrous effect. If you`re buying a BMW M1 that`s not been run or used for quite some time, and hasn`t had the oil tank replaced, it`s foolhardy to start up the engine at all, without the first job being the replacement of this tank. It is quite a complex structure, there are internal baffles and such, the BMW genuine price is very high.
The BMW M1 space-frame can and does rot, this is very difficult to check and inspect as it`s pretty much enveloped by glass fibre panel work: but you need to put it on a ramp, you`ll have a chance and see that all is visible is the a full width under tray – in fact endoscopes as well as cameras will be needed see or inspect anything properly.
The front bulkheads and too the tubes right along the door sills are mainly the first places that`ll rust. The corrosion will also hit up around in the engine bay, this is where the heat from the exhaust will cause the powder-coating to lift, thus leaving some bare steel very much open to the elements.
COOLANT AND BRAKE PIPES
The brake and coolant pipes run right through the steel central tunnel that`s inside the vehicle, these also corrode. Again here use a camera or endoscope to inspect these difficult sections properly, if any attention is needed, then you need to budget for the engine and of course the interior to be removed before any of the repair work can begin.
The engine derived from racing, a CSLs back in 1974 the IMSA series in fact, with a double damped steel forged crankshaft that`ll rev past the 7000rpm mark. It is mounted very low, but vertically up between the seats rear transaxle. You`ll have to strip out the interior just to get to inspection hatches for working on the front of the engine, for most jobs and setting the valve-clearances, you`d have to remove the engine.
Unlike the other supercars of the day, the BMW M1’s engine is quite robust and is very capable of some high mileages. Probably it will need the timing chains at 100,000 miles but if neglected it will develop more trouble, like worn piston rings and head gasket problems. Do check the coolant system for any signs of a cylinder head gasket leak, this may also indicate cracked cylinder heads.
Any oil leaks from the engine need to be assessed, they are common to leak so if severe enough may warrant some attention, again the engine will need to be removed. There could also be leaks from the gearbox.
The BMW M1 glass fibre panels that are around the engine bay, are quite fragile and they often get broken, they are extremely expensive to replace / reinstate accurately. Though they`re made well and to very high standard as new, the glass fibre bodywork is very thin, you see its gelcoat, and that`s making it very costly to restore; any cracks and crazing do tend to be found around the sharp corners, such as in the front – the ‘boot’ lid and the pop up headlamps.
Beware of any cars that past resprays have actually rubbed through the top gelcoat – if you get it positioned right you`ll be able to check the glass fibre matting right under the paint surface. The original paintwork wasn`t of high quality, there were runs in places so not really uncommon.
The ignition module made by Magnetti Marelli can often be troublesome if they are infrequently used, than those that reached higher mileages. The replacements are actually unobtainable; but it’s possible that the unit can be rebuilt, but the actual process is very time consuming and very expensive.
The BMW M1 clutch has generally a very short life, and as you can imagine is very expensive to replace; due to so many part needing removal. The parts are very costly and the BMW specialists often complain of very long waits for these items to turn up from Germany.