intermittant knocking from the rear somewhere...?

[CraigG]

so my car has starting making a knocking noise randomly at the rear, seems to be worse under load, and kinda goes away when coasting its not happening all the time however, it will be fine when then it will start knocking for a bit, then will stop.

had abit of a search, and it seems the 2 most common problems are the center prop bearing, and the rear topmounts.

now the fact that it kind of goes away when coasting points towards prop bearing as opposed to topmount, but placing my hand behind the rear ashtray on the transmission tunnel, the knocking doesnt feel very 'close' if you get my meaning.

and with the topmount, it dont start it after ive been going over a bump or anything like that, i was driving up a perfectly straight dually today and it started doing it. surely if the topmount was buggered, it would be more likly to start knocking when you go over a bump..? which it does not..?

so any ideas? i was also thinking maybe its the exhaust hitting off something.


as its pissing it down with rain, i havnt had a chance to get under and have a proper look at it, so im hoping with the info ive provided one of you guys can give me a definite/pretty damn sure, answer to the situation

cheers
craig

[SGP]

Topmounts most likely,they can be checked by pulling the boot liners out of the way and removing the rubber domes covering them.If you then bob the car up and down you should be able to see excessive movement of the strut top if they are b******d.

[Morat]

They make quite a difference to the handling when you replace them and the shocks!!

[bimmaman]

Doesn't sound like top mounts, but without hearing it, it's hard to tell... I am experiencing my own dodgy noises from the rear.., check this link, and see if it sounds like your prob... http://www.e30zone.net/modules.php?name ... highlight=

[E30Mark]

Top mounts were replaced 2 - 3 years ago, i can't remember exactly when! i used the E46 cab mounts which are supposed to be stronger and last longer! worth checking them though, they might have gone again...

Does it ever stop raining in Scotland?

[Ziggy]

Needs more description of the 'knocking' really... When it does it, is it a repetative / regular noise? Does it do it as you pull away? When you go round a bend? When you lift off then accelerate again?

Potential candidates that I can think of (other than those already mentioned), would be Subframe bushes, Trailing Arm bushes, Diff bush, Diff itself, CV joint, Loose bolt (propshaft, driveshaft, wheel), Wheel bearing...

Exhaust's pretty easy to test (to some degree) - grab the tail pipe, give it a waggle & listen for whether it hits anything!

[Rosc0PColtrane]

Perhaps the body in the boot isn't as dead as you thought?

[dazleeds]

i have a very similar prob

is it more noticeable during gearchanges???

ikm thinking its the trailing arm bushes on my touring

put car in first and pull away very slow whilst hanging out the door
on mine when i do this you can see some movement of the wheels in the arches

axle bushes seem fine hence im guessing trail arm bushes

hth

Daz

[bigdek]

had a similar prob.

nearside driveshaft was fooked

[CraigG]

this is the thing, it starts randomly, and stops randomly, dont start after you hit a bump, or go round a corner, brake or anything, ive just drove up the M9 to stirling and back, and it never made a noise....

when it is knocking, when you lift off it goes away slightly, and comes back when you apply the throttle again. but i cant get it to 'start' on cue

its just spitting atm, so im going to check the topmounts and the exhaust, see if we cant take those out of the equation

[320Touring]

Any update on this dude? If you want i'm sure we could meet up and have a poke about the motor to find out if anything is obvious

[CraigG]

exhaust is fine, no knocks

topmounts, a bit of movement, but tbh well within what the should be moving, no knocks either..


when i went to move the jack tho, it made a solid metallic knock on the metal at the side while in its holder, gave it abit of a shake and sure enough it started knocking away happily, so ive wedged my map down the side of it to stop it hitting, and ill guess we will see in due coarse if that was infact the knocking Razz

im up the garage on sunday so i can have proper little mosey undernethe then.. Smile


i posted the reply in the wrong thread