The good news is that the replacement process is relatively easy, providing you have the right information, and the right parts. First, disconnect the battery. The radio harness has constant voltage supplied to it, and you don't want to accidentally blow any fuses or damage any electrical components. If you're replacing the battery tray, what else is needed. The real OEM page has a hell of a lot of clamps and brackets etc. also http://www.realoem.com/bmw/enUS/showpar Id=41_0137 r/E30. Join. • 24 days ago. For $30 in spray paint and some lack luster cleaning, I'm pretty happy with the results. Not a show car anyway 🤷🏻‍♂️. 1 / 3. r/E30. Join. • 28 days ago. I suspect you have a bad crank position sensor. If it's bad, nothing will work except the starter spinning the crank. You'll have no fuel pump power, no injector pulses, and no spark. If it won't now fire on starter fluid there's a 99.9% chance the CPS is dead. Ken Kanne, Silverhill, AL, SuperMod/Admin. If you are looking for a durable and reliable marine battery, you might want to check out the NBH-31-SSC-OPT Optima Battery Tray on Amazon.com. This product is designed to securely hold your Optima BlueTop battery and protect it from corrosion and vibration. You can also read the customer reviews and ratings of the Optima BlueTop battery on Amazon.com and see why it is a popular choice for This Genuine BMW Trunk-Mounted Battery Tray (Mfg#51711922158) fits BMW E30 325e, BMW E30 325es, BMW E30 325i, BMW E30 325is, BMW E30 325ix. Products protected by Valves adjusted (another must for M20's), New valve cover gasket. Replace rocker shaft seals. New oil pan. New oil pan gasket. New battery. New timing belt/tensioner (a MUST for M20 engine BMW's) Changed engine oil (10W-30 synthetic) Changed rear diff fluid (75W-90) / Diff: Redline Synthetic GL-5 Gear Oil. Genuine BMW - Battery Trays - Electrical - BMW E30 M3 (1988-1991) 2.3L Old batteries can leak caustic and corrosive fluids destroying your car's metal. Battery trays are used to protect the car's metal from the potential caustic damage that can happen from an old battery. rhSJk3.