Replacing the oil pump chain on a Mini One.

[nicebubby8]

I would want to enquire about the feasibility of replacing the oil pump chain without causing any interference with the camshaft pulleys. While it may not be a significant problem, I am attempting to prevent the need for another visit to BMW by acquiring two more bolts after recently replacing the...

[CyberMage]

The only method to do this task is to locate a chain link. However, I have not personally attempted it.

[nicebubby8]

Thank you. I was anticipating that removing the tensioner would provide sufficient space to extract the cam drive gear, but my familiarity with the engine is limited.

[CyberMage]

To remove the crank bolt, first secure the crankshaft with a pin and attach locking tools to the camshafts. Then, remove the tensioner and proceed to remove the crank bolt. It is important to note that you will need a new crank bolt, specifically a single-use stretch bolt. To remove the oil pump chain and sprocket, first detach the sump and loosen the oil pump drive bolt. Then, you may take off the bottom sprocket of the timing chain and push the chain upwards to access the oil pump chain and sprocket. If the oil pump chain is stretched, it is advisable to replace the whole timing chain assembly.

[nicebubby8]

Thank you one again. The previous owner had replaced the timing chain, but I had to rebuild the engine due to the worn valve stem seals and the poorly honed block. However, because of my haste, I neglected to give sufficient attention to the oil pump chain. Upon closer examination, it is clearly in a state of significant wear and tear.

[CyberMage]

Even new ones seldom break since they have some flexibility. However, it is not ideal to grind the link plate, fit it, and then weld the end plate back on the link before it functions well.

[nicebubby8]

Task completed, albeit it was more challenging than anticipated. In order to create sufficient tension in the chain, I had to remove one of the camshaft sprockets.

The engine emits a subtle buzzing sound at present. It would be unexpected if the issue was connected to the camchain or oil pump chain, but it still need more investigation. During the engine rebuild, I replaced the water pump, friction wheel, and drive wheel, so I don't anticipate any problems with those components. The alternator belt was reused and of unknown age, but it seemed to be in satisfactory condition, as did the alternator.

I will remove the belt and see whether it has any impact.

[CyberMage]

It is probable that the belt will wear down over time when it is used on a worn pulley, since the new belt will have a different wear pattern. This is most noticeable in the morning when the belt tends to come loose easily. Additionally, I like to wait for 24 hours before adding oil and allowing the sump sealant to dry. This helps prevent any future leaks.

[nicebubby8]

Thank you. I will attempt it.