BMW Engines- is there one thats the most 'reliable'?
Discussion
If you are looking for a snotter, then the old 12 valve 6 is a strong motor, however everything comes down to maintenance at the end of the day.
A "midlands minicab" that has been topped up with oil from the cash and carry wont last long, but a well maintained motorway cruiser will pass 200k with ease.
I'd be looking for a bargain basement E34 520 or 525
A "midlands minicab" that has been topped up with oil from the cash and carry wont last long, but a well maintained motorway cruiser will pass 200k with ease.
I'd be looking for a bargain basement E34 520 or 525
I would reccommend the M30 "big six"- 2.8 litres to 3.5 -fitted in earlier E34s, E32 7 series, E24 6 series E28s, E23s etc etc.
Chain driven OHC, 12 valves operaed by rocker arms. Not much goes wrong with these.
The M10 4 cylinder is a 4 cylinder version of this (as fitted to old E30 316s and 318is) but I would rate the M30 higher by virtue of its 'duty cycle' in day to da duties being less stressful
Next I'd put forward the M50, M52 and M54 range of 24 valve twin cam sixes. Arguably more robust than their M20 predessors- the only real problems these have had have been water pumps going suprisingly early (plastic impellers-big deal), and studs pulling out of the head if someone stupidly overheats the aluminium block versions.
Chain driven DOHC.
Finally I'd reccommend the M20 belt driven six cylinder 12 valver. There are lots of examples of these that have covered HUGE mileages. They tend to harden their oil seals and burn oil, and if thrashed from cold they can suffer valve guide wear. Other wise very tough and easy to work on. As fitted to E30s, E28 (later 170 Bhp models) E21s etc. Probably the smoothest sounding of all of the above engines
Chain driven OHC, 12 valves operaed by rocker arms. Not much goes wrong with these.
The M10 4 cylinder is a 4 cylinder version of this (as fitted to old E30 316s and 318is) but I would rate the M30 higher by virtue of its 'duty cycle' in day to da duties being less stressful
Next I'd put forward the M50, M52 and M54 range of 24 valve twin cam sixes. Arguably more robust than their M20 predessors- the only real problems these have had have been water pumps going suprisingly early (plastic impellers-big deal), and studs pulling out of the head if someone stupidly overheats the aluminium block versions.
Chain driven DOHC.
Finally I'd reccommend the M20 belt driven six cylinder 12 valver. There are lots of examples of these that have covered HUGE mileages. They tend to harden their oil seals and burn oil, and if thrashed from cold they can suffer valve guide wear. Other wise very tough and easy to work on. As fitted to E30s, E28 (later 170 Bhp models) E21s etc. Probably the smoothest sounding of all of the above engines
From wikipedia http://en.wikipedia.org/wiki/Straight-six_engine:
BMW introduced its first straight 6-cylinder engine in 1933. It developed straight-six engines for the post-World War II era by adding two cylinders to its M10 four-cylinder design. In 1968, it introduced a M30 straight-six design with the same 30-degree slant, overhead camshaft layout, and 100 mm bore spacing as the four. It originally intended to follow up with a V8 engine line in the early 1970s, but when the 1973 oil crisis hit, BMW canceled its V8 plans and concentrated on refining and enlarging its straight-six lineup.[11] These included a smaller straight-six in 2.0 and 2.3 litres (120 and 140 cu in) displacements (the BMW M20), versions of the larger BMW M30 up to 3.8 L (230 cu in) (the S38B38); and beginning in 1983, a series of M21 straight-six diesel engines. In 1986, BMW introduced the M70 V12 which was essentially two 2.5 L (150 cu in) straight-sixes on the same crankshaft. In the mid-90's, they produced a series of straight-6's based on the M50 architecture, the ultimate of which was the 330-360 hp S54, used up to 2006. Currently, a straight-six is offered in the BMW 1 Series, BMW 3 Series, BMW 5 Series, BMW 6 Series, BMW 7 Series (Euro models), BMW X3, BMW X5, BMW X6, and BMW Z4.
My money's on a straight six.
Also see this article from Ward's (whoever they are).
http://wardsautoworld.com/ar/auto_story_behind_war...
BMW introduced its first straight 6-cylinder engine in 1933. It developed straight-six engines for the post-World War II era by adding two cylinders to its M10 four-cylinder design. In 1968, it introduced a M30 straight-six design with the same 30-degree slant, overhead camshaft layout, and 100 mm bore spacing as the four. It originally intended to follow up with a V8 engine line in the early 1970s, but when the 1973 oil crisis hit, BMW canceled its V8 plans and concentrated on refining and enlarging its straight-six lineup.[11] These included a smaller straight-six in 2.0 and 2.3 litres (120 and 140 cu in) displacements (the BMW M20), versions of the larger BMW M30 up to 3.8 L (230 cu in) (the S38B38); and beginning in 1983, a series of M21 straight-six diesel engines. In 1986, BMW introduced the M70 V12 which was essentially two 2.5 L (150 cu in) straight-sixes on the same crankshaft. In the mid-90's, they produced a series of straight-6's based on the M50 architecture, the ultimate of which was the 330-360 hp S54, used up to 2006. Currently, a straight-six is offered in the BMW 1 Series, BMW 3 Series, BMW 5 Series, BMW 6 Series, BMW 7 Series (Euro models), BMW X3, BMW X5, BMW X6, and BMW Z4.
My money's on a straight six.
Also see this article from Ward's (whoever they are).
http://wardsautoworld.com/ar/auto_story_behind_war...
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