Grinding/whining noise in N and P from transmission: Can it be the starter? - PeachParts Mercedes-Benz Forum

werminghausen · #1 09-04-2010, 07:51 AM

Here was the problem noise again last night (it didn't come up for over a year)
Can is driving normal, shifting fine...but then when I was on my driveway and wanted to put the lever in P shifting through N/R/P it mad this noise but only in N and P.
I shifted back into R - no noise- shifted again back into N- noise- then D- no noise.

I had this problem before (I posted it). I thought I had something bad inside the transmission, exchanged the filter and fluid...but never found out what it was.

As the metallic whining sound is exactly like when you have a running engine and turn the starter key....the question:

Can it be that the ignition/key is not retracting and the starter wants to engage in N and P?

vstech · #2 09-04-2010, 08:46 AM

hmm. that'd be wierd. not impossible, but wierd.
simple test, start the car, put it in park, then unhook the small wire on the starter junction block. If the noise continues, it's not the starter.

vstech · #3 09-04-2010, 08:48 AM

also, if that was the case, you would not have to turn the key to start the car, simply puting the key in the glow position would crank it up. I doubt that is the case.
it could be the starter is not disengaging, and you hear it grinding. it could also be a broken flywheel, or a loose flywheel bolt. I'd get the car up on a good lift, and listen to it in different positions of the shifter.

Oracle12345 · #4 09-04-2010, 08:52 AM

t it sounds like you have an internal problem within the transmission, ie plantary gearset even though none of the gears are being applied. take the pain off and see if you have metal particles in the pan

werminghausen · #5 09-04-2010, 12:55 PM

Th weird thing is that this grinding noise in N and P comes only once and then it is gone. This morning I started the car and nothing - runs fine.
Hard to test this situation if it is unpredictable.

I am 98% sure it is the starter... because
1) it is exactly the same noise as if you have the engine running and turn the key in order to start ( I remember when you I was in a hurry in traffic with a stick transmission and i though I killed the engine at a slope in stop and go and turned the key but the engine still cranking- this is precisely the noise I am talking about...
If you have never driven a stick then this situation might have not occurred to you.
2) it happens in N and P and that is when the starter is working- remember it doesn't in the gears.

and

Quote:

Originally Posted by vstech

also, if that was the case, you would not have to turn the key to start the car, simply puting the key in the glow position would crank it up. I doubt that is the case.
it could be the starter is not disengaging, and you hear it grinding. it could also be a broken flywheel, or a loose flywheel bolt. I'd get the car up on a good lift, and listen to it in different positions of the shifter.

werminghausen · #6 09-04-2010, 01:00 PM

I disagree.
What should make this noise in the trans? Only in N and P?
I had this issue 1.5 years ago, was convinced it is the trans and did anything: changed oil - no metal parts in there at all - I changed fluid and filters and teh noise was gone.
But now it came back.
The sound is exactly the one you know from a starter that want to start a running engine: the gear of the starter is grinding at the flywheel because it can't engage- that it the noise I hear.

Quote:

Originally Posted by Oracle12345

t it sounds like you have an internal problem within the transmission, ie plantary gearset even though none of the gears are being applied. take the pain off and see if you have metal particles in the pan

werminghausen · #7 09-04-2010, 01:03 PM

here is the thread from 1.5 years ago about the N and P noise if someone is interested.
I thought it is the trans but now I think otherwise.

300SDL: loud grinding transmission 722.321, noise in P and N position

4x4_Welder · #8 09-04-2010, 01:44 PM

Maybe your key switch is hanging in the "start" position?

werminghausen · #9 09-04-2010, 03:40 PM

Kind of...

Well never had problems with starting the engine. So this part is normal....even at the day when the noise occurred.
My explanation is that the switch is working normal most of the time but onec in a while...so every year it probably doesn't go back a full step, enough to release the magnet but then it must go back to the start position but won't do anything because starter it is locked in gear... but will turn on in N and P.
Does this sound like an explanation?

Please answer... also those who know about the ignition switch functions.
Martin

Quote:

Originally Posted by 4x4_Welder

Maybe your key switch is hanging in the "start" position?

vstech · #10 09-04-2010, 08:32 PM

well, like I said, you could disconnect the start wire from the junction block, and see if it stops the noise. or you could rig a switch to the cabin, to that wire, so it will only start when your switch is on, it'd double as a lockout for thiefs...

werminghausen · #11 09-06-2010, 07:47 PM

I love the lock out for thieves.
As a test tool for the noise I believe it won't work because I needed to wait probably for a long time that the situation occurs.
I am very sure it is the problem with the ignition key/tumbler.
As turning the key for start also sometimes is tough I fear that I need a new tumbler/cylinder
If the tumbler is sometimes stuck into start position would I need to exchange the tumbler/and cylinder?

Quote:

Originally Posted by vstech

well, like I said, you could disconnect the start wire from the junction block, and see if it stops the noise. or you could rig a switch to the cabin, to that wire, so it will only start when your switch is on, it'd double as a lockout for thiefs...

vstech · #12 09-06-2010, 08:45 PM

hmmm. I'd bet on the switch itself if it's sticking or engaging the starter. if it's difficult to turn it can be the tumbler, or the steering lock, so the less expensive option to try is the tumbler, plus it comes with a spare key, but it's not a for sure fix.

werminghausen · #13 09-08-2010, 09:07 AM

I had the 'condition' last night and figured out after starting that clearly the key didn't return to position 2 how it should. It made the noise and I could turn it back to position 2 and all was fine.
So this is the culprit 100% now.
I am contacting MB how to get a VIN coded tumbler.
Martin

Quote:

Originally Posted by vstech

hmmm. I'd bet on the switch itself if it's sticking or engaging the starter. if it's difficult to turn it can be the tumbler, or the steering lock, so the less expensive option to try is the tumbler, plus it comes with a spare key, but it's not a for sure fix.

vstech · #14 09-08-2010, 09:18 AM

Hmmm, if the key is hanging up on the return to 2 spot, I think it's more likely the switch itself, as the tumbler has little to do with the return to position. with the key in, the tumbler is just a metal cylinder. all the spring action would be in the switch.

winmutt · #15 09-08-2010, 02:58 PM

Yup. The switch on the back is almost certainly the culprit.