PJmak

This is on my 2000 c280. Iill ask here and I hope its ok because I know there are some gurus here.

Changed sparkplugs and they were terrible. One wire was completely unplugged so I swapped it. Checked all wires and coils and they should be good.

Unfortunately that didnt fix the issue.

The car is fine when cold but as soon as it warms up(two minutes into driving) the car shakes pretty bad while at a stop and in drive.

Shifting into neutral is smooth. Shifting back into drive makes the rpm drop to almost 5 and the car starts shaking. As soon as I start driving the rpm goes up of course and the car is fine.

So you can imagine that I shift in and out of neutral every time Im at a stop.

I also cleaned my airflow and tried running the car without it. Doesnt seem to make any difference.


Any ideas?

cm60k

Did you diagnose the car..?, if so, any codes..??

did you check if there is any air leaks around the MAF..???, and did you check all breather hoses..????

,,ZAYED,,

PJmak

No check engine light and I havent diagnosed it.

Could a dirty throttle body be the issue?

PJmak

What are the breather hoses?

fredtga

Common issue: motor mounts.

The giveaway is the fact that when you have the engine running and in neutral, it is smooth. If you'd have a misfire or bad MAF, the engine would run rough no matter the gear is in.

KJI3jflarryfe93

si kupio jos jedna limonada s ukus w202?
valjda si bio mnogu zedan za sok od limona
sorry I couldn't help it

seriously, could you have a vaccum leak somewhere cracked rubber hoses?
look around with a flashlight

ECTurboGSX

Agreed, motor mounts. Have a buddy sit in the car and shift into neutral and drive while you have the hood popped. See the shaking? In neutral, the engine has no external load and isn't putting anything beyond its own weight on the engine mounts. Once you put it in drive, it gets loaded through the torque converter and the engine compresses the bad engine mount and you get that vibration transmitted through the vehicle.

PJmak

Ovu limunadu vec imam duze vreme haha

I replaced one of the tiny hoses in the back by the throttle body but that didnt help. The reso ofem look fine :/

PJmak

Thanks guys. I did peak at them and there were signs of leakage. I didnt know bad engine mounts could cause that much shake

I have a pair os spare c43 engine mounts. Would those work?

cm60k

There're 4>>5 breather hoses attached to the valve covers & MAF elbow housing,

sometimes they causes vibration, when they got cracked..!,,

also, check any leaks around the MAF, or check if MAF set properly, not moved while you driving..!??!

,,ZAYED,,

ECTurboGSX

What year? M112 V6 or the older straight-6? If it is M112, they might work but would have to look at EPC to know for sure.

PJmak

2000 year is a v6 M112

Would bad engine mounts make the rpms drop?

ECTurboGSX

Bad engine mounts would send engine vibrations through the chassis when the car is in drive and they would be especially bad when sitting still with the brakes applied, like at a traffic light. It may be that you have bad engine mounts and that is amplifying another problem that you have.

RPM's would only drop in the sense that you shifted from neutral to drive. I can't think of any reason that engine mounts would cause a drop in RPM beyond that. Any kind of vacuum leak, TPS, MAF, etc should throw a code and turn on the CEL. If it can tell that your gas cap isn't screwed on all the way, it should pick up pretty quickly on stuff like that.

PJmak

Ok thanks for all your input everyone.

Ill figure out if the mounts are the same.

Heres a pic of rpms while in D at a stop. If they were slightly higher the vibration would go away seems like

ECTurboGSX

Does the vibration reduce when you drive away?

vinceC

Had the same issue with our old 2000 C280. Chased everything, wires, coils, vac leaks, breather hoses, etc. because the mounts only had 60K on them. In the end it was the mounts.

The RPM you show looks correct. 5-600 is normal in D.

DRBC43AMG

Despite the rev counter pic upside down

KJI3jflarryfe93

PJMak is currently in Australia, that's why he is down under at the moment

DRBC43AMG

That figures then

PJmak

Pic showed up normal on my phone.....weird :/

Thanks for input vtw. I hope the heat comes down so I can tackle this soon. Feel free to post thtorials on how to seap those mounts out if you want

vinceC

I've done them on both our 2000 C280 and my son's 1999 C43. The C43 was easy. The C280 - not so much. The passenger side goes fairly easy. The upper bolt is a pain, but if you are a decent wrench you'll figure it out. The driver's side on the C280 is really tough. On the C43 I remove the mount on the driver's side going forward and down behind the A/C Compressor. The C280 A/C Compressor is further aft in the car, closer to the crossmember. The mount can't go that way. I had to remove the transmission cooling line from the bell housing and extract the mount to the rear.

ECTurboGSX

Marcus to the rescue. I followed his site and it was helpful. That being said, I couldn't get a torque wrench on the top side, so that was best guess. Make sure to use some high temp loctite.

http://www.fitzhughmedia.com/MBF/motormounts.html

PJmak

Thanks for your input. You could probably save me some research since yove done both cars. Are the mounts the same on both the m112 and m113?

PJmak

Thanks you sir. I read through it all.....it sounds a bit intimidaying but my brother will be helping me so I think well handle it just fine

vinceC

I don't think the C43 and C280 mounts are there same. C43 mounts are P/N 202 240 29 17. C280 mounts were P/N 202 240 34 14 and have subbed over to P/N 203 240 12 17. M-B would not have different numbers if the mounts were the same.