The BMW E38, a classic German designed performance sedan and the matching BMW M73, matching German built V12 engine, two great tastes that tastes great together. Nothing quite says “autobahn cruiser” like a big German V12, and nothing is more comfortable for use driving than the E38 body.
The BMW M73 is a V12 SOHC piston engine which replaced the M70 and was produced from 1993-2002. Compared with its M70 predecessor, the M73 uses an aluminum engine block and cylinder heads. While most other engines in the BMW range had switched to DOHC and 4 valves per cylinder, the M73 used SOHC and 2 valves per cylinder, and two separate Bosch Motronic engine management systems, think of it as two BMW 6 cylinder engines joined together at the hip.
This BMW 750iL car presented with a rough running, engine misfire at idle and low speed during the warm up phase. The problem was not always present, and vanished as soon as the engine had been in operation for a few minutes. A number of maintenance items relating to the secondary ignition system were identified and corrected, and the final piece of the puzzle was the leaking intake manifold buffers. This was not an easy diagnosis, and could be confirmed with a teardown as it was not detectable under a normal “UV Smoke Test” of the intake system, but was lated discovered after a more extended and extensive version of that test protocol.
You’ll note the cracking in the rubber buffers, and the compression set loss of the sealing ring around each port. After 15 years or so, these items have simply reached the end of their useful lifespan, unfortunately they are located in the center of the engine, and this is not a chore for the easily discouraged, your want a BMW Service professional to tackle this repair. The Atlantic Motorcar BMW service team was up the task, and the buffers, sold as 4 sets of three, were installed and updated, and the engine reassembled. Despite the superlative design of these engines, the tolerances are rather tight, and even a small upset in fuel mixture, especially at the critical engine warm up phase, can lead to pronounced drivability problems.
Here in a photo essay, is the repair and service process, illustrating the wondrous design of the BMW V12, one of the most complex, yet elegant BMW designs we’ve been privileged to service at the Atlantic Motorcar Center in Maine.
Just because someone uses the name “Specialist” does not mean that they really know, or care about your particular car. There are ethical shops out there, but judge by the reviews online, by meeting the service team, by asking friends. Out of our area (we cover Falmouth, Freeport to Camden), call and ask for a referral to one of our service network members. Your car, and your pocketbook will thank you. And so will the AMC Team.
Feel free to call or stop by find out more on how we can help you get your car back to the condition you both deserve! Earning your trust, every time you turn the car…that’s what we do…every day…for the last 30 years.
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If you have questions, or if we can be of further assistance, just call us at (207) 882-969, we’d love to meet you, and your car!
Bruce and the AMC Service Team