2008 Mini Cooper S In-car Engine Rebuild
This vehicle arrived with complaints of very high oil consumption, a check/service engine light on, and poor running. When the spark plugs were replaced, the vehicle would run well. However, the car would quickly go back to running poorly. It was burning around a quart of oil in less than 1,000 miles. There were also many, many codes stored in the vehicle's computer associated with the check engine light.
The initial idea was that the intake valves had become carbon coated, or "gunked up" to the point that they had damaged the valve stem seals. This is a common issue for direct injection engines, and is explained in further detail here, and here. However, the oil consumption was so high that HPMotors believed there was probably an additional oil leak either in the turbo or bad oil control rings on the pistons. Investigation of the turbo, which is possible with the car mostly together, showed it to be in fair, serviceable condition. At this point, HPMotors theorized that the carbon fouling on the valve stems had become bad enough to damage the valve stem seals. This then led to too much oil entering into the combustion chambers, and then led to that level of oil overwhelming the oil control rings. Those rings are only designed to handle the film of oil on the sides of the cylinder bore, and small amounts of oil that enter the combustion chamber through other means.
There is no clear way to see the piston rings until the pistons are removed from the engine, which basically means disassembly of the entire engine to gain access. So, knowing that the car at least needed a head service, motor disassembly began.
***Note: This project will have more videos than pictures, as we did not have time to stop and take pictures during the various steps. Instead we simply shot quick videos after different procedures were completed.***
The initial idea was that the intake valves had become carbon coated, or "gunked up" to the point that they had damaged the valve stem seals. This is a common issue for direct injection engines, and is explained in further detail here, and here. However, the oil consumption was so high that HPMotors believed there was probably an additional oil leak either in the turbo or bad oil control rings on the pistons. Investigation of the turbo, which is possible with the car mostly together, showed it to be in fair, serviceable condition. At this point, HPMotors theorized that the carbon fouling on the valve stems had become bad enough to damage the valve stem seals. This then led to too much oil entering into the combustion chambers, and then led to that level of oil overwhelming the oil control rings. Those rings are only designed to handle the film of oil on the sides of the cylinder bore, and small amounts of oil that enter the combustion chamber through other means.
There is no clear way to see the piston rings until the pistons are removed from the engine, which basically means disassembly of the entire engine to gain access. So, knowing that the car at least needed a head service, motor disassembly began.
***Note: This project will have more videos than pictures, as we did not have time to stop and take pictures during the various steps. Instead we simply shot quick videos after different procedures were completed.***
Engine Disassembly
This process will start with removing the front body work and bumper/radiator support. From there the exhaust manifold, intake manifold, and head are removed.
This process will start with removing the front body work and bumper/radiator support. From there the exhaust manifold, intake manifold, and head are removed.
Further Diagnosis and Analysis
Assembly Time
With the pistons installed, the oil pump, with a new oil pump sprocket and bolt, is installed. This is followed by the oil pan with new gasket. Now we can install the head, and timing components.
Video after head installation.
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Video after timing chain kit and turbo/manifold/oil filter housing installation.
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All Wrapped Up!
Normally we catch the initial cranking on video, but this time the battery was dead. So we put the rest of the front of the car together while the battery charged and took it on an extended test drive.
Normally we catch the initial cranking on video, but this time the battery was dead. So we put the rest of the front of the car together while the battery charged and took it on an extended test drive.
The car runs great, and did fine on the test drive home. The oil consumption issue has cleared up, while power and fuel economy are back to normal. Looks like it's time to hand it back to the customer!