Cracking/thud noise from under/front of the car and hesitation to go

[Arv]

Hello All:

Sometimes when I am trying to accelarate from a dead stop, I am hearing
Cracking/thud noise from under/front of the car and when this happens, the
car hesitates to go, I have to press the accel fully and then slowly starts
moving. This is intermittent problem and happens only when I am at a full
stop and trying to accelarate. I have to press the accel fully, then I hear this
cracking/thud noise coming somewhere from under the car, may be tranny or
torque converter or engine. Then the car very slowly starts moving. I have
gone under the car and checked the drive shaft, the flex discs, the shaft
bearing, the torque converter, the engine mounts to see if I see anything
loose or broken, but everything seems to be ok.

Any ideas will be greatly appreciated.

Thank you,
Arv.

 

[LNM]

Mine did it but it was a broken anti roll bar mounting, doesn't sound quite the same though. Dunno what model you have so can't really help much.

 

[Arv]

Thank you. It's a 94, C280.

 

[davidsl500]

Had a similiar sort of problem on my SL last year. It started when I had reversed a long way and then selected drive to move off. Copious amounts of accelerator only got the car creeping slowly forward (and the same in reverse - but creeping backwards of course). The noise had a certain crackling sound to it and the only way I can describe it is that is sounded as if there was some of that heavy duty plastic strapping that is used to wrap heavy parcels wrapped around a wheel somewhere and it was tightening up as i tried to pull off.

Didnt want to risk damaging anything so called for a tow truck. when he arrived 3o mins later,we put the car into neutral to see if it would push - no problem it moved easily. Started engine, selected drive and moved off with no noises or dragging. The recovery vehicle guy rang his mate who is a merc specialist and he suggested that either it was a brake disk badly binding - or it could be a sticking valve in the autobox and when i came out of reverse to select drive, both valves were open and there was a "tug of war" going on.

Car was fine for a few weeks, took it into a merc specialist to replace a noisy nearside front wheel bearing and when he handed the car back he told me that the rear disks looked as thought they had been locking on - apparently he noticed the tell tale signs on the edge of the disks, which would normally be a dark rusty brown colour and mine were much lighter and almost bright orange. Anyway he told me to keep an eye on them and 6 miles later they locked on solid again with that wierd crackling noise when i tried to pull away. Let the car cool down for 30 mins and drive away normally but 2 miles later same again.

Back to workshop for a strip down and investigation to the cause of the rear lock ups but nothing obvious found, force bled the system and its been fine ever since.

So the advice is to check the colours of your brake disks and be aware that the problem probably wont go away and will become more frequent in its occurence. You certainly dont want to be stressing your drive train by trying to power through the problem!

Next time the problem occurs put the car into neutral and see if you can push it easily - if it dont push then the brakes are locked on..

 

[Arv]

Thank you for a detailed explaination David. My brake disks are fine. The
weird thing is this has been happening on and off for may be a year. It
happens may be once or twice a month. I am going to change the tranny oil
and filter soon. Let's see if I see the same bebavior after that. Once all the
crackling is over, the car is then just fine and it picks up right away from a
dead stop. Any other thoughts?

Thank you again.

 

[Arv]

Any senior members out there who can answer this mystery?

Thank you.

 

[Arv]

Any experts out there on this issue? Thanks a lot.