Breaking Down: What Causes an M3 Overheating?

BMW M3 F80: Power Unit Source

Despite its popularity, the BMW S55 turbocharged inline-six has been subject to scorn stemming from it supplanting a V8 in the famed M3. Notwithstanding that, this motor is quite dependable and able to manifest quadruple-digit horsepower. Similarly to other engines though, if improperly treated, the S55 can give out. In the teardown video presented here, it is distinctly evident that the S55 was affected by overheating – an issue which has previously triggered various problems for BMW engines.

Signs of distress can be seen near the outset with visible seepage of coolant and heat tabs that have melted, yet to be certain, a thorough dissembling would uncover everything.

2016 BMW F80 M3 Twin Turbo S55 Bad Engine Teardown. Bogus Rebuild?

The presenter of the video first gave the crank a spin to assess whether there might be damage to the assembly. As opposed to most of his dissection projects, the S55 rotation was successful. He then removed the spark plugs too – although they revealed their age, less than satisfactory condition, no alarm bells were raised.

The F80 was the pioneer BMW M3 generation to manipulate forced induction, but prior to this disassembly, the turbos had already been taken off from the engine. Thus, without turbos to examine and dismember, it was time to move on to eliminating the intake and exhaust manifolds, which exposed no relevant problems. In a similar manner, once the cam cover was eliminated, minor deterioration was noticeable, but so small that the camshafts could still be resold and employed for another assemblage.

It can be quite astonishing to come across the cylinder head gasket still intact during dismounting of the block, as this is usually the first thing to suffer any damage when the motor exceeds its optimum operating temperature. Though the gasket appears to be okay, marks on the pistons indicate that the valves have struck up against them – this might take shape as a consequence of transforming the RPM beyond tolerable limits or an ill-fated timing predicament.

The final components to be appraised are the bearings and crankshaft, which get the thumbs up. The conclusion is that even though the engine did overheat, it was also mistreated following a rebuild, possibly resulting in the warped valves. High-powered motors are constructed to handle maltreatment, however, even the most dependable engines will decline if they aren’t maintained properly.

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