Intermittent knock/rattle.

[volvo always]

I have a 1989 240 GLT automatic estate and I get a slight knocking/tapping noise from it would seem from under the car. Always from pulling away or pulling away up an incline. The strange thing is it doesn't seem to do it when wet. More so when drier and colder.
I took it into the mechanic and they drove it and they could hear the knock noise. It sounds like something is loose.
They put it up on the ramp and checked the bushes visually, by raising the front off the ramp and couldn't feel/ see any play in the wheel bearings or bushes. The rear bushes on the car also looked good. The only thing which was a bit loose was the prop, but the centre bearing was complete and in good condition.
Would it have anything to do with the prop or the front anti roll bar?

Any ideas?

Thanks James

[Clifford Pope]

The prop would be a good cause to eliminate if nothing else. It can knock when tight, paradoxically, instead of loose, if one of the joints is stiff. This might loosen up a bit if wet. If one is seizing it throws the prop out of balance and makes the rubber bit thrash about.

If you drop the centre bearing cross member support, then you can
twist and waggle the centre sliding joint to see if it has play, and check that each universal joint will move freely in all directions.

[classicswede]

Bushes are certainly a common cause for knocking.

As said a dry joint on the prop can cause a knocking type vibration. Worn UJ's tend to just give a single knock as you start to pull away and again as you slow down.

The other thing that can do it is worn/broken engine and gearbox mounts

[volvo always]

Originally Posted by classicswede

Bushes are certainly a common cause for knocking.

As said a dry joint on the prop can cause a knocking type vibration. Worn UJ's tend to just give a single knock as you start to pull away and again as you slow down.

The other thing that can do it is worn/broken engine and gearbox mounts

Thanks everyone

The droplinks and ball joints are all new in the last 3 years and genuine Volvo.

Prop possibly then. The noise is always on pulling away and never on slowing down. In fact driving once on the move totally silent.

Around 10 months ago I was getting a severe knocking/ banging from under the car and the auto gear lever vibrating and clunking badly. Called the breakdown guy who diagnosed the prop centre bearing was knackered and a used prop was fitted by the recovery company's garage. They said it was fixed after having the car 9 days, but wasn't to my dismay on pulling away and they as a gesture of good will recovered the car to a Derby Volvo specialist who diagnosed the tail housing bearing was very worn and leaking atf. They replaced the worn tail housing bearing and after it was still knocking, Replaced the engine mounts to rule them out which are 10 months old now and genuine Volvo. As it was still knocking/ banging etc they then replaced the gearbox cross member, and fitted a used 140 gearbox mounting and adjusted it all to clear the tunnel. This fixed the severe knocking and atf leak.
These symptoms were severe knocking/ banging from around the transmission tunnel and the car wasn't drievable as extreme vibration etc.

Thanks James

[Clifford Pope]

I've sometimes had problems with the gearlever carrier knocking on the tunnel.
Once it still did it even with all new mountings, so I modified the mounting bracket by elongating the hole into a slot to get some adjustment from side to side.

[ekonomik]

Originally Posted by classicswede

Bushes are certainly a common cause for knocking.

As said a dry joint on the prop can cause a knocking type vibration. Worn UJ's tend to just give a single knock as you start to pull away and again as you slow down.

The other thing that can do it is worn/broken engine and gearbox mounts

Thankyou for that info about the different knocks. And it's just what my mechanic said too. RE: the U.J. knock. (So I'm not mad or over sensitive about my cars' noises!)

[volvo for ever]

they were bad for rear axle bushes and rear tie bar bushes wear/worn also both fron wishbone bushe rear (grenn bushes used to give clonks )but visual inspection also using lever should check for play


regards