Strange noise

[glenn989]

Hi all,

Not sure where to put this one as it could be anything but I have a strange and unpleasant graunching noise when accelerating from a standstill. It is coming from the front somewhere but so hard to pin point where.

It seems to be worse uphill or the more enthusiastic the pull away is. When excelerating hard from say 20 mph I do not get the noise

It also coincided with having the car back after the following work was carried out;

Rear springs and dampers
Rear discs and pads
Rear subframe mounts
Front springs and ball joints
Gearbox mount

The dampers are adjustable and I was sent home with them on zero - this broke an exhaust olive and caused a leak at the manifold. Not sure if it could also have caused this noise though

Anyone experienced anything similar?

Glenn

[ptjs1]

Glenn,

Just a thought.:

Although it might sound slightly contradictory with you having just had the gearbox mount replaced, the symptoms you've described have some resonance with similar cases I've seen of a very worn gearbox mount. A very soft worn mount can cause the front of the engine to lift under acceleration from rest and the fan touches the top of the fan shroud causing a brief graunching noise.

I don't know if you had ALL the components of the mount replaced including the foam-type bush that degrades and the springs. But it could be that the bush still has worn parts or its fitting has exacerbated this problem.

Perhaps have a look at the underside of the top of the fan shroud and see if there are scratch marks which might indicate this is happening. If so, you really need to address it quickly and also replace the fan. If the fan is already weakened by touching the shroud and a blade lets go, it can punch its way through the bonnet and cause a lot of damage!

There again, it could be something completely different....!

Good luck

Paul

[glenn989]

Thank you Paul, that is useful

I will have a look in the morning and also get thorough details of what was changed

[steve_m]

Front shock absorber top mounts may have worn; that causes funny noises.

[glenn989]

I just had a look at the fan and I can see small chunks out the fan (pic attached)

Looks like that is the culprit then, thank you for the replies. That’s been driving me mad!

[AndyF]

Hi Glenn

Just seen your post - one additional point, linked to the replacment/repair of the gearbox mount. Are you happy that the gearbox output flange fixings to the prop shaft are fully tight (and possibly even the flange itself?)? I ask, as on my 6.0 V12 with the 4 speed GM box, Dave Marks had to sort this issue out when he refurbished the gearbox mount. He was expecting it to be an issue - it seems that many have this.

Mine used to make a bit of noise when in reverse (like a straight cut gearbox tooth meshing noise) - but this has all but disappeared with the flange fixed and the mount repaired.

Worth a look? Or contact David directly and ask?

Stay safe.

AF

[glenn989]

Thanks for the input Andy

She goes back to the garage that did the work on the 16th and I will pass that on to them

Hope I come back with a resolution!


Glenn