MINI N47 ENGINE REBUILD
MINI COUNTRYMAN ENGINE KNOCK
We recently had a MINI Countryman with the 2.0 N47C20A in for an engine rebuild. This vehicle was producing a loud knocking noise indicating a suspected bottom end failure, we later concluded this was in fact correct.
This engine can fail in various different ways including timing failure, spun conrod bearings and spun main bearings. This vehicle suffered from 2 spun conrod bearings and 1 spun main bearing. We started by removing the engine from the vehicle, removing the ancillaries and stripping down the engine.
After the engine was stripped it was clear that 2 conrod bearings and 1 main bearing had spun. The customer stated the vehicle had very little oil after a recent service, it looks like this oil change was done incorrectly as they did not refill the oil to the correct capacity.
The lack of oil circulating around the engine meant important components were not receiving the lubrication they require to operate efficiently. So after driving for some time with a low oil level the bearings at the crankshaft journals could no longer support this environment of low lubrication and began to spin.
N47C20A ENGINE REBUILD
After the failure had been identified we began the process of rebuilding this unit with new parts. Firstly the block needed to be sent to the engineers for line boring as one main bearing was spun. After the engine block had been returned and all parts thoroughly cleaned the bottom end assembly could be built.
We carefully installed a new crankshaft with main bearings into the block after installing the oil jets. 4 new pistons and conrods were installed along with a new set of bearings and piston rings. The lower timing assembly and oil pump was built up with new parts along with the front and rear seals and sump. A new head gasket was installed upon attaching the cylinder head. New rocker arms, hydraulic tappets, camshafts and carrier were installed and the upper timing assembled. Finally the rocker cover was installed with a new gasket to make the bare engine assembly.
After this process the ancillaries needed to be reattached to the engine so this could then be refitted to the vehicle. Once back in the car a new oil filter was installed and new oil & coolant were added. Once the vehicle was completely reassembled this was tested to ensure a successful rebuild.