Car bought with 27,000 miles on it - full CPO.

Previously at 64MPH a whining noise could be heard when you let off the gas and coasted down hill.

So far the dealer has replaced:

Wheel Bearings in front
Entire Transmission
Front Differential

The noise went away for about a week... and now:

At exactly 54 MPH the engine/car makes this HORRIBLE high pitch whining noise.

So it's going back in for the 5th time for the same damn noise, and now an additional problem with some loud droning noise coming from the exhaust. My car now sounds like a 1996 Buick with 100k miles on it.

Any thoughts on this noise??

 

Check your PM.

 

Answered. Hoping to get to bottom of this... the noise is unbearable, and one highway I drive is 54MPH for 45mins

The exhaust noise is new and also bothering me, but that isn't as bad as that whine.

 

Interesting. We had the entire transmission replaced on our 2011 E350 and then the transfer case replaced about a month later (after it seemingly felt like it was stuck in AWD). This was about 2 months ago. Car has 53K. I guess I'll have the wheel bearings checked too as it's still a little noisy at certain speeds.

 

They also replaced the transfer (I assumed this was part of the transmission.) My appointment is for the 15th, I fear from my research that this new noise in the rear may perhaps be the differential. All said and done, if that is the case this car will have had more repairs done than the car was worth when i bought it if you had to pay for all this at a dealership. Thank God for warranties!!

 

Full cpo 25k mile e class one or two model year old is usually 7-9k more than what they are actually worth and that is before depreciation to follow, tax and interest etc. Now in your case it worked out well but my feeling is that year or two old car with 25k can easily go upto 100k miles with no problems at which point cpo runs out. 100k is usually the time when things may go wrong. So chances are you are not going to use it. But I will think about warranty when I start looking for my next car. The one I bought had a lot of noise coming from floor while moving. Thankfully I dont have to worry about it anymore since its gone now. But definetely something to think about.. Used to be 2-3k would buy some warranty but fineprint may exclude some expensive repairs.