E550 severe vibration and fan noise upon startup
Thread Starter
Newbie
Joined: Oct 2021
Posts: 13
Likes: 3
2009 E550
E550 severe vibration and fan noise upon startup
Upon starting my 09 E550 in warm weather (perfectly fine under ~80F ambient temp) my radiator fan spins up to maximum speed and shakes my car with a violent vibration. The vibration perfectly correlates with the fan speed, and stops once the fan spins down to normal rpm, which takes about 15 seconds. Engine temperature is perfectly fine at all times. After this vibration stops, the engine proceeds to idle very rough and seemingly misfires, but drives perfect. Taking it out for a WOT run fixes the rough idle issue, but it will start again on another startup in warm weather. Engine mounts, trans mount, spark plugs, pulleys / tensioner / belt, water pump, and filters / oil have been recently replaced.
I also have a ticking at 2-3k rpm when driving, not sure if it's related.
I also have a ticking at 2-3k rpm when driving, not sure if it's related.
Last edited by AetherSprite; Apr 13, 2023 at 10:49 PM.
Out Of Control!!
Joined: Apr 2019
Posts: 11,921
Likes: 6,775
From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
Well maintained...
The crazy fan in spring weather only & misfires together make for an unsual combination (bumper Temp sensor?).
Pls go ahead and scan the DLC for faults to see if we can draw correlations.
Pls go ahead and scan the DLC for faults to see if we can draw correlations.
Thread Starter
Newbie
Joined: Oct 2021
Posts: 13
Likes: 3
2009 E550
It's certainly a strange issue, especially with the fact that flooring it seems to fix the rough idle. I should have mentioned that I have scanned for codes multiple times and have never found anything. Never gotten a CEL. I'll take a look at my temp sensor, though I think the rough idle is a separate issue.
Out Of Control!!
Joined: Apr 2019
Posts: 11,921
Likes: 6,775
From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
NO Code 👍
It's certainly a strange issue, especially with the fact that flooring it seems to fix the rough idle.
I should have mentioned that I have scanned for codes multiple times and have never found anything. Never gotten a CEL.
I'll take a look at my temp sensor, though I think the rough idle is a separate issue.
I should have mentioned that I have scanned for codes multiple times and have never found anything. Never gotten a CEL.
I'll take a look at my temp sensor, though I think the rough idle is a separate issue.
Have a look at your LT FUEL TRIMS... what are they: Lean/rich?
Last edited by CaliBenzDriver; Apr 14, 2023 at 09:30 PM.
Thread Starter
Newbie
Joined: Oct 2021
Posts: 13
Likes: 3
2009 E550
Out Of Control!!
Joined: Apr 2019
Posts: 11,921
Likes: 6,775
From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
Computer homework ...
The engine FT are computed by the engine ECU for each bank based on the upstream Lambda/ O2 sensors.
They are only useful to diagnose base idle rpm, not driving around open throttle A/F mixture.
++++
There's a chance your fan spining upon starting is normal and caused by residual heat. The fan vibrations may be due to bad bearings.
Check for abnormal rotor freeplay.
🤞
Last edited by CaliBenzDriver; Apr 15, 2023 at 04:37 PM.
