pandanoid

Test drove an '09 C63 with 25000 miles on it and I am in love with it but the only thing that is keeping me away from pulling the trigger is the brake pedal feel. Cold start all the way to parking the vehicle back at the dealership I felt a pulsation whenever the vehicle was at a full stop. Is this normal or is something horribly wrong?

I will most-likely test-drive the '10 C63 with 30000 miles just to see how the brake pedal feeling differs.

CarHopper

Full stop? Not the brakes. That'd the the 6.2L engine saying "slam it... *****."

AMGonFire

Pulsation while applying brakes is warped rotors. Foot on brake pedal while stopped feeling pulsation no idea any misfires

pandanoid

Oh I see, I came from an Audi S4 with the 4.2 so it is a much smaller V8. I just wasn't sure if the salesmen was being honest when he said the engine is big enough where I could feel the vibrations through the brake pedal. I thought it was BS since I don't know all too much about cars haha.

pandanoid

They replaced all spark plugs when it went into the dealership before going onto the lot for showing.

CarHopper

As long as there are no CELs and the car otherwise drives fine my money is just on the fact you aren't used to such a large engine. I had an RS4 at the same time as my C63 and it was night and day at stop lights.

The C just wants to go. Although, if anything, I'd say that it could be a sign of wearing engine mounts but I doubt it at that mileage.

Drive the 10, see if you feel the same thing.

pandanoid

Will do. Thank you for the input guys. Muchly appreciated.

DivzB

I have recently been getting the same thing on mine, its a 12 plate with 47k. It is slightly worrying as I've never noticed it before.

If the car is at a stand still with foot on the brake pedal you can feel a knocking every second or two through the pedal. Is that what your getting?

I have read on here that it could be due to the oil level being too high, but checked that and its fine.

This morning was the worst its been, and warranty has just ran out last month.

pandanoid

Yes, that is the feeling I am getting. I stood outside of the car to see if I could hear any noise that repeated the knocking/pulse on the brake pedal.

pandanoid

Buddy got back to me saying that if your revs are not smooth in neutral, coil packs may be an issue. At idle, it should be a mount.

pandanoid

Update: The C63 just had two front brake pads replaced 20km prior to my test drive. Could this be a reason to the pulse/knock on the brake pedal at full stop?

CarHopper

No. At a full stop nothing will be happening with the brakes, they've already done your job and you're stopped. If it happened while you were slowing down that's a different story.

If there is no CEL then it is probably nothing. However, it can be a sign of coil packs on their way out or engine mounts. No matter what it has nothing to do with the brakes.

pandanoid

Pulled the trigger and picking her up in two days!

t4orce

I've had my car for 1.5 years and it has had a pulsing brake pedal all that time. It feels worse when the car is cold. It has a stealership service and they have said nothing about it so I have reasonably assumed that its fine. Mine's a 2011 with about 45K kms.

ENV²

Mine does this. Feels like misfires but no codes. I guess its normal for large DOHC motor.

bullitt69

Any updates? I can feel the brake pedal pulse when stopped in gear on traffic lights. (feels as if the engine is misfiring)

chrisridebike8

1) this is a big ole V8. It moves a little. 2) could be the motor mounts wearing a little. When they go, you will definitely know. Don't worry about it now.

McMood

Hey guys, new on here and glad I'm not alone with this break pedal pulse. Same issue, knocking / pulsing when holding breaks in drive. Greatly reduced when in neutral but still there and very intermittent. Under warranty for another year and dealer has no clue whats causing it. They replaced the intake manifold gasket thinking thats what was causing it but its still there. Revs are steady when the pulsing occurs and car otherwise fine so dealer not worried but i really want to figure out whats causing it so that a potential expensive repair isn't round the corner after warranty runs out. Anyone had a successful diagnosis of this problem?? it gets quite loud every once in a while and can feel the pulsing through whole car then disappears for days. Help!!!

BLKROKT

I think the solution was: Get a Prius

arrowskartax9

Engine Mounts. Mine did this, had them replaced and all good.

McMood

Thanks for feedback, will get dealer to take a look at them!

bullitt69

I had both engine mounts as well as the tranny mount replaced yesterday - the brake pedal pulse is still there. It didn't change a damn thing

Patel

Least you got all new mounts! Lol

-Patel

350SL

Disconnect the hose from your vacuum booster and plug it off. See if it does he same thing? Your pedal will go hard but you are eliminating a vacuum leak and the vacuum pulse from the engine. If everyone has this same issue maybe MB did not spec the correct size diaphragm booster for the system. If it were a hydrovac system the pulse would be normal from the pump. But with vacuum it should always be steady. Also something to check. After you put it in park. Shut engine off. You should have three brake applications of the pedal before t goes hard.

McMood

Still no luck...dealer checked the mounts, all ok. Still no clue where its coming from and can never get it to be bad when its at the dealer. seems to be very intermittent. Have been trying to see if anything triggers it but its completely random!! Driving me nuts. You still facing same problem??