The rot hides away very well in the BMW E30. The sills, scuttle and the wheel arches, they`re the real problem areas to look at. Just feel up around the front arch and the rear arches for any crustiness, more especially if you`ve noticed that car is freshly undersealed. The inner wings corrode behind the front wheelarch guard so do open up the bonnet to check for any rust up along the very top edge at the inner wing. The front suspension turrets do rot badly from the base. Always check for signs rust up on the main bulkhead area by first removing the electrical fuse box. Now, find rust here, then walk away.
Do open and check the boot area, remove the vehicle jack, and If there is rust here it`ll have made it`s way up all the way from rot in the rear inner wheelarch. Take a screwdriver and magnet to the sills area. Do lift carpets inside the boot area and the footwells. Any rust in here is difficult to cure. Be very wary of sunroofs too. Any rot up in the metal roof skin is game over, so you must watch out for any bubbling here.
BMW E30 engines are very well known for reliability, but only a well maintained BMW engine. Fully documented detailed service history is an absolute must. Cambelts ought to be changed every 60,000 mls, or at least 4 year intervals. If it isn’t documented, then budget to get this done. Start the engine up from cold and carefully listen for any noisy tappets. If you still hear the sound when warm, then the tappets need to be adjusted. The valve clearances ought to be set roughly every 15,000 miles. When improperly adjusted, the valves can often break the rocker arms.
Do check the oil and coolant levels. Look closely for any signs of oil mixed in the coolant, and any mayonnaise muck around the inside of the oil filler cap. These could suggest that there`s headgasket failure. Then try to carry out a full compression test before you buy. You must llow the vehicle to idle, wait until warm and listen for the cooling fan to cut in. If not, then you can assume that car has over heated, in so warping the cylinder head.
Check in the engine bay, make sure that the colour does match the exterior of the vehicle. Any fresh paint could suggest that the car has had accident damage, so you need make sure that you ask the right questions. You must get a up to date HPI check. Due to low book value, BMW E30`s are crash damaged vehicles that are written off as what most would be considered light damage. So there are an awful lot of very decent looking cars out there on the roads that have in fact been registered as a Cat C or a Cat D. So Beware!
You need to check all the rear subframe bushes for any excessive wear. This is going to have an effect on the handling of the vehicle and be very dangerous to drive. It’s a huge time consuming job that`s beyond the amateur. Listen for any whining noise and a clunking from the rear diff. These mounts could also be perished, but its more likely that it’ll be a worn out diff. The replacements are easy to find, but a limited slip diff will cost a premium. Check for excess play when changing gear. Please avoid the high mileage cars, they`ll jump out of gears and probably have worn synchromesh. Look out for 4 matching tyres, a sign it’s been cared for properly.
BMW Interiors are generally pretty hard wearing, but they`ll be well past their best with 20 plus years. The leather does crack over time, and the cloth seats do wear particularly badly, especially the driver’s bolster. BMW replacement seats are relatively plentiful, but as you can imagine good quality seats will be at a premium, especially if in leather. BMW switches tend to give up with regularity, but secondhand units are easily sourced. BMW odometers can die anytime beyond about 100,000 miles, due to the worm gear deteriorating. The replacement gears are quite cheap, but very fiddly to replace. Remove the cardboard shelf that`s below the steering column. If you see any fluid that`s dripped on this, it hints at a clutch master cylinder problem. The slave should really be replaced also at the same time.