Intermitent Knocking from prop or gearbox
 

Hi All
I have a 320i 1992 and it's been as good as gold untill the other day when it developed a horrible noise from under the car that lasts for approx 10 to 20 secs then goes and she drives great again. It sounds like metal on metal thats gauging against each other and jolts the car, which is pretty bad but i cannot see what the problem is. I have stripped off the exhaust and looked at the centre bearing on the prop and it looks fine can anyone help..

Niggles UK

You need toprovide more info when this occurs - low speeds, when accelerating, braking, cold, hot what RPM level??? We'll give you our best possible advice if you can provide as much info as possible.

It happens at low speed hot or cold I have not tried it at high speed as it sounds dangerous. It makes no difference if the gear is engaged or not nor the engine running or turned off. Could if be the bit that sits at the back of the gear box, sorry i don't know the name of it as i'm new to BMW's

Niggles UK

possible gearbox/transmission mounting broken or worn you could do with getting the car up on a lift for a thorough inspection.

Cheers Stevo but the mounts look good do you know if the middle bearing on the prop has a metal bearing in it or is it just a spline??

Cheers

Niggles UK

not to sure on that one, i would imagine its just a spline.......

It could be something as inocuous as a loose heat shield; similarly, I experienced a rattling sound from the engine compartment that turned out to be some bracket, the connections for which had corroded, and the thing fell onto the exhaust pipes. I only discovered this when jacking up the car to do a coolant change myself. You'll have to get yours up on a lift and check all sorts of things, engine mounts, transmission mounts, exhaust brackets, etc., etc., etc.

Thanks guys but i think the gearbox has to come out for a closer look she is now on ramps with all heat shields removed aswell as the whole exhaust to get access if i find anything i'll let you know and if poss if anyone has anyother ideas as to what this could be please let me know. I am getting very suspicious about a fractured flywheel or clutch plate even thow it all works fine it's that sort of horrible noise and seeing as it makes the car jolt then release it has to be in that sort of area. I was looking for a better relationship with my Beemer but i tell you what it knocks the spots off my old ford cabriolet so the work will be worth it.

Cheers

Niggles UK

good luck niggles, hope it doesn't turn out to be too expensive, stick with it you will love your beemer once she's running right.

Good news, after closer inspection and a very procarious 40mph while on axle stands it turns out that the shoes on the o/s handbrake mechanism had collapsed so all the transmission is fine. Still cannot believe that the handbrake made a noise like the gearbox was about to explode. Thanks all for your help.

A Much Happier Niggles UK

Just a quick update, the parts cost me £6.75p and took 1 hour to fit

RESULT

She's driving fine now guys

Niggles UK

nice one niggles, what part of the uk you in?

Hertfordshire.. You??

I know where that is! I lived near macclesfield though if you know where that is.

Does that make you a lancs man or a yorks man i can never tell