Manual transmission or clutch makes an intermittent "clacking" noise


#1

Hello Esteemed Car Talkians,



I have a 2000 BMW 328, 5-speed manual transmission, with about 85000 miles on her. She still drives like a dream but today I noticed a rather loud rattling or clacking noise when the car is in gear at around between 30 - 40 mph. If I depress (push down or in) on the clutch pedal, it stops. If I let it out again, it MAY start again. Sometimes it doesn’t come back until I stop then start again. Any ideas on what this may be?


#2

In my experience, it is either the pilot bearing or the throw-out bearing. The transmission will need to be removed to get to either. At that point, you might as well replace the rest of the clutch.

But, I would wait until the problem goes from annoying to scary. It’s a pricey fix.


#3

Thanks BustedKnuckles. I appreciate your taking the time to reply to my post.


#4

The rattling/clacking occurs when the clutch is engaged and the trans in gear - car is moving. Sound stops when clutch disengaged. I’m not a mechanic, BUT - maybe a U joint or suspension bushing? Would help to know location of noise; have someone walk beside the car to listen while idling in 1st gear, if possible.


#5

Thanks 03impreza. I appreciate your taking the time to reply to my post. Thus far the “noise” has only presented itself at speeds above 30mph so I can’t really have somebody walk along side. However, I will take it out again and see if I can’t listen for it again and try and localize it better.


#6

You’re welcome. It’s entirely possible that BustedKnuckles is aware of some clutch symptoms peculiar to BMW with which I’m unfamiliar. However, the circumstances you describe don’t fit the classic throwout bearing failure scenario of my limited experience. That is usually a metal to metal whining noise when the pedal is depressed - clutch disengaged. OTH, a failing U joint makes a knocking noise when the drive train is under load, clutch engaged, car moving.

You MAY be able to hear something outside of the car at low speed that isn’t apparent inside - try the lowspeed walkalong.


#7

BTW, your bimmer has a “swing axle”, meaning that there are more than the usual number of U joints (or CV joints, the principle is the same) - at least two on the drive shaft, and FOUR for the half-axles, where they articulate with the differential and the rear wheels on each side. U joints are cheaper than a clutch job - Good Luck!


#8

Hello again 03impreza! I’m sorry I haven’t been able to check back and see your very thoughtful responses. I will try the low speed walk-along with a friend. I think you may be on to something with this “swing axel - Ujoints” thing as the noise has not happened in the past 3 days. Do you by chance know how easy it is to check the swing axel and/or U-joints?


#9

I’m not a mechanic; this site is as much a learning experience for me as it probably is for you. So take this with a grain of salt.

If you can localize the noise toward the rear end and it occurs while the drive train is under load, it is likely in the U joints. (Another, less likely, culprit would be worn bushings in the suspension.) First, I’d check to see if the boots (the rubber covers at each of the half axles) are intact. If not, dirt has probably got in there, and grease leaked out, damaging the joint. You can put the car SAFELY on jack stands (not the tire changing jack!), NOT running, and check for play in the drive shaft, and axle shafts, by hand. I don’t know how much is permissible. There will be some acceptable gear lash, which is unrelated. At least when you take it into a shop you will be armed with a little information. Maybe someone seeing this post can be more specific.


#10

Thanks yet again 03impreza! I really, really appreciate your help. Yes, I’m going to take her in to the shop and I feel much more comforatble now with the great information you have given me. I’ll let you know how it goes!