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Stock Problems/IssuesDiscussions related to warranty related issues and repairs, or other problems with the OEM parts and software for MINI Cooper (R50), Cabrio (R52), and Cooper S (R53) MINIs.
My mini over the summer has developed a very faint knocking or (duh duh duh duh) noise after the AC has been on for awhile. You can hear it in the cabin, not so much outside, and it only happens with the AC on (not immediately after it turns on but usually after 20 mins of driving it starts). Also after you shut the AC off, the noise is still audible for maybe 30 seconds before it finally faints away.
Does anyone know what could be causing this noise?
Hm can you elaborate on why you think so? Perhaps when the AC is on and engine under heavier load, the crank pulley is under heavier stress / starting to deform?
I was hoping i'd have some time left before tackling the crank pulley given the car is only at the 65k mile mark, but definitely going to take a look during the next auto change at it's conditions. I read to look for any tears in the pulley but are there any other signs its starting the fail?
edit - also wanted to add about 2 months ago, after getting off the highway and stopping at a light, the car stalled right away (its an auto). Christmas tree of lights came on but it fired right back up and i was on my way. No codes were thrown either and hasn't happened again since. Wondering if this is related?
You can check the crank pulley by starting it up and watching it with a flashlight. If there is any wobble whatsoever it is going bad. Or you can remove your belt and check by hand if you can move the outside grooved portion relative to the inner core. Mine went bad at 68,000 so it’s deginitely possible. It is a very poor design. Some more of that German Uber engineering.
Hm can you elaborate on why you think so? Perhaps when the AC is on and engine under heavier load, the crank pulley is under heavier stress / starting to deform?
I was hoping i'd have some time left before tackling the crank pulley given the car is only at the 65k mile mark, but definitely going to take a look during the next auto change at it's conditions. I read to look for any tears in the pulley but are there any other signs its starting the fail?
edit - also wanted to add about 2 months ago, after getting off the highway and stopping at a light, the car stalled right away (its an auto). Christmas tree of lights came on but it fired right back up and i was on my way. No codes were thrown either and hasn't happened again since. Wondering if this is related?
It is not the miles. It is the age! rubber loses it flexibility and starts to separate from itself. Sometimes slowly and sometimes completely right away. Quite often, the damage is not visible, but if you get under the car and see if the dampener is worn on the inside, where it can hit the engine. If there are any wear marks visible, it has failed.
It is not the miles. It is the age! rubber loses it flexibility and starts to separate from itself. Sometimes slowly and sometimes completely right away. Quite often, the damage is not visible, but if you get under the car and see if the dampener is worn on the inside, where it can hit the engine. If there are any wear marks visible, it has failed.
It is miles too. This damper is essentially two metal cups with a ring of rubber glued between them as the only connection. The constant torsional twisting of the rubber connection is this dampers weak point. Normal driving is one thing but if the driver is on the gas pedal hard all the time then the torsional stress is increased leading to earlier failure. A better design is the rubber ring sandwiched in between an outer and inner metal ring such as it is on early American V8s. I just replaced the original damper on my sons 71 Chevelle.
So finally had the chance to do some diagnosing and here is what i noticed...
1) The crank pulley itself does not seem to have noticeable play but the crank pulley bolt definitely wobbles while the car is running. Is this normal? The actual pulley is pretty dead on center/true, just the bolt doesn't move in a perfectly circular motion.
2) The knocking noise is definitely coming from the pulley area and only happens with the AC on. Very audible (faint but audible) when listening from the passenger wheel well with the plastic splash guard removed. Even with a stethoscope it was hard to pinpoint where exactly. That being said, my recent blackstone oil report came back with higher readings of lead (generally associated with bearings), nothing too concerning that im going to stop driving the car but something to look out for. Would a failing crank pulley in turn affect the crank bearings?
The crank bolt should not wobble at all. Either it’s loose or it’s bent. A bad crank pulley shouldn’t cause bearing wear. That usually happens form oil starvation or just normal wear. I would definitely check the crank pulley. I would go ahead and remove and replace if you have any amount of miles over 60,000.
Last edited by Tgriffithjr; Oct 1, 2018 at 05:25 PM.
The crank bolt should not wobble at all. Either it’s loose or it’s bent. A bad crank pulley shouldn’t cause bearing wear. That usually happens form oil starvation or just normal wear. I would definitely check the crank pulley. I would go ahead and remove and replace if you have any amount of miles over 60,000.
Thanks tgriffithjr, it turned out to be a loose crank pulley bolt. I did a quick zip with my impact gun and it stopped wobbling and spins truly round. Its weird since i dont believe this part has been serviced before, and the prior owner had meticulous detail of service records and never mentioned about this either, so unsure why it would loosen.
i need to suck it up and order a new crank pulley soon, but hoping this tightened bolt can hold me over till after winter.
The crank bolt should have loctite or whatever the BMW equivalent is on it to prevent it from loosening. Probably blue loctite would work but I believe there is a heavier duty version designed for larger boots.
