Clunking sound from under only when hot.

[petey]

Hi all . A far more serious sounding noise on my 75 cdt manual. Clunking , knocking when hot and in motion but not engine related.
I drive to work 23 miles at 5am , so nice and cool, no noise. Parked for 8 -10 hours and drive home [ motorway] no noise but when i come ofF onto the A road and town it starts clunking n knocking from under. Coasting in neutrel still doing it. Got new springs ect and been checked for normal things so nothing obvious.
Strange it only happens when hot.
Any ideas ? Thanks.

[gillorasp]

Sounds a bit like the anti roll bar drop links. On my first 75 they just suddenly went and they used to make a clunking over even the slightest bump or road camber. Other clunking I can think of might be the lower engine mount. Making the sound in nutral tho I would check the drop links first.

[petey]

Thanks. Another rover i had did that but when cold too which has confused me !

[maxxpump]

Hi all . A far more serious sounding noise on my 75 cdt manual. Clunking , knocking when hot and in motion but not engine related.
I drive to work 23 miles at 5am , so nice and cool, no noise. Parked for 8 -10 hours and drive home [ motorway] no noise but when i come ofF onto the A road and town it starts clunking n knocking from under. Coasting in neutrel still doing it. Got new springs ect and been checked for normal things so nothing obvious.
Strange it only happens when hot.
Any ideas ? Thanks.

My car did this when it needed new drop links on the front, same description, too the T!

[Mike24]

I've had the same thing! usually at low speeds after a longish drive. Drop links seem OK, but I've only checked them cold - I wondered if the AR bushes might get compressed during the course of a journey and allow some movement, but as yet it remains a mystery! I hope someone comes up with a solution - it's a nasty sound, which coupled with the strut bearings make for a noisy ride.

[pletevl]

Mine started doing this 2 days ago in the boiling hot weather we're having here.
Driving home one evening it sounded like something was lose and knocking against the body, it doesn't change with speed.
Slowing right down on a bumpy bit of road I could hear creaking, speeding up it sounds like knocking.
I can only think it's the anti roll bar bushes.
Pete

[petey]

Thanks for the help all , booked into garage tomorrow morning , see what they come up with ! Still love to know why it only happens when warm ?

[petey]

Now im lost. New front links fitted. Still makeing the same noise. I cant pin point the noise to the front of the car , just from under it ! As said a knocking , creaking sound. Does anyone have any other ideas ?

[pletevl]

Front anti roll bar bushes.

[Kennyeth]

Now im lost. New front links fitted. Still makeing the same noise. I cant pin point the noise to the front of the car , just from under it ! As said a knocking , creaking sound. Does anyone have any other ideas ?

My favorite answer, Lower Engine Mount.
Maybe, could be perhaps. The creaking made me think of that as that`s what mine did when the mount had perished.
Ken.

[petey]

Thanks , These were checked and i was told fine. I think its something to do with motion and weight / balance transfer more than pot holes in our roads ! Seems to happen more on bends , stop and go traffic and parking. Not wheals or breaks.

[petey]

Thanks ken , An engine mounting could also be an answer. Would this creak n knock whilst coasting at 2 mph ? Need to pin point the noise , it could be rear.

[pletevl]

No but the anti roll bar bushes do creak and knock when coasting really slow

[neilb740]

Thanks , These were checked and i was told fine. I think its something to do with motion and weight / balance transfer more than pot holes in our roads ! Seems to happen more on bends , stop and go traffic and parking. Not wheals or breaks.

I had a similar thing, a knocking from under the car mostly on bends, worse when accelerating out of bends.

an exhaust rubber had failed and the exhaust had shifted on the remaining ones causing it to knock against the underside of the car. Cornering made the exhaust shift sideways slightly and made it worse.

I dont suppose your noise could be the same thing could it?
Try shaking/bouncing the exhaust gently and see if you can replicate the noise.

[Dragrad]

Thread moved to appropriate forum. Re-direct left in old. ;)

[Kennyeth]

Thanks ken , An engine mounting could also be an answer. Would this creak n knock whilst coasting at 2 mph ? Need to pin point the noise , it could be rear.

I don`t think so, would be noticed more on pressing clutch pedal down.
Ken.

[DMGRS]

Smaller knocks are very hard to find on the 75 - took me a while to find mine (was the front drop links in the end).
Some good suggestions in the thread so far. :)

[petey]

Thanks to all for the great advice so far. Exhaust checked , new drop links , susspension checked . Wondering if garage were wrong and anti roll bar bushs should be changed and check the lower engine mounts. If its not rubber items it might be something mechanical.
Looks like i better take the work shop manuel to work for some lunch time reading !
Thanks again.

[petey]

Well hopefully the knocking saga is sorted . MOT picked up perished rear sub frame mounts , both sides . This is worth noteing as i was sure it was comeing from the front end ! This Just shows how a sound can fool you .
No idea why it was more noticed in hot weather but proberly something to do with metal expanding when hot . Have to try it next week on the work comute to find out for sure but has to be that. will let you all know next week . Yay another mot done with no advisories .

[David Lawrence]

Mine is a track rod end. After a long hard run with plenty of braking the track rod end gets quite warm and then it shows some play which dissappears when it all goes cold again. It also only does it in certain positions, so unless you can land on exactly the right position you cant find any play at all.

Try jacking both sides up so you can turn the wheels from lock to lock then try looking for play with the wheels turned a few degrees at a time and see if anything shows up.

[pletevl]

Mine doesn't do it anymoe because of the cooler weather, no doubt it will be back next summer.

[petey]

Hi again all , as said will keep you all updated on the Knocking / creaking noise. Yep still doing it ! Not as bad in the cool weather , fine on fast roads , just around town when slow.
The mot should have picked this up , but on a plus side its not something major yet ! How meny rubbers can you change !

[roverbarmy]

Have you checked over and above the wheel arch liners as there could be something loose in the void?
Mike

[Elliott]

Hi had a read through and was thinking it may be the shock absorber/damper/strut itself, when the oil is cold everything ok, but after driving a while the oil in the shock gets really hot and you may be getting some free-play movement in the shock on initial damping which would sound like a knock. Just an idea and you would only tell if shock was hot.