Timing cover leaks solved
Minis can leak oil from just about everywhere, but the timing chain cover is a common culprit. Here’s how to sort it.
Minis are renowned for ‘marking their spot’ with drops of oil, but even the smallest leaks can get out of hand quickly. A main culprit is the standard timing cover, which can be prone to leaks between its mounting flange and the engine front plate, and via the crank pulley to cover oil seal. Or, in many cases, both!
When an old steel cover is tightened up, the flange can distort, making it difficult to achieve an oil-tight seal to the engine front plate without use of a quality gasket sealer. Putting an already damaged cover on will accelerate the issue, as will using incorrect bolts as they are of different lengths depending on their position. It’s imperative the cover is arrow-straight and the gasket is correctly positioned, or you’re wasting your time no matter how much sealant or how many gaskets you throw at it. New covers can be purchased for the tensioner-type setup, but it’s worth checking for straightness.
As for the oil seal, that can also be a victim of wear and/or poor installation. It can leak as a result of the seal lip going hard, distorting or a groove worn in to the crankshaft pulley. Again, it’s vital to make sure it’s installed correctly or it’ll leak in no time. The best way to ensure the seal doesn’t leak is to fit the cover loose, fit the pulley, do up as many bolts as you can and then remove the pulley to get to the remaining bolts. This allows the seal to centre on the pulley correctly. With the gasket, put a thin bead of sealant on both sides, making sure you also put a bead around both flanges of the timing cover and around each of the bolt holes.
While it’s much easier to perform this task with the engine out of the car, most will be working with the engine in situ, as we are here. To gain access to the cover, you will need to drain the coolant and remove the radiator on pre-MPi models, and on all models the nearside engine mount needs to be undone and the bracket removed while the engine is safely supported.
Fitment to a later MPi model is similar, maybe easier, as the header tank, radiator and coolant hoses can remain in place. The most difficult task is likely to be removing the lock washer on the bottom pulley bolt, as space is tight with the engine in the car.
Overall this is an achievable job for a reasonably competent home mechanic, providing you have the right tools. Read on for the full process.