Hello,

There is a big problem with our S class. The car is S320 2007.

We were on a trip and before it the car was serviced. After about 1000 miles in Germany the oil light came on. No oil in the car!

Since then the car consumes all of its oil after about 1000 miles. There is not oil leak, no engine light.

There was no issue with power, the car drove great even after the first time the oil was used, however after the second time it started getting into limp mode once up to motorway speeds.

Nothing comes up on diagnostic machines, including STAR. Official Mercedes dealer were very helpful to offer engine swap for £15 000.

What should I do from here to search for the problem ?


Thank you in advance for any help.

 

how many miles on the car? do you have the electronic oil level sensor or old fashioned dipstick? did the dealer do a compression check?

 

The car is 160000 miles. It is with standard dipstick. Compression test will be done, however the engine runs fine and car has normal power, until it goes into limp mode.

​​​​​What might be the reason if compression is fine?
Turbo?

 

ugh.. is it a diesel with the om642 motor?

i would start with checking the pcv functionality.

next i would check oil cooler for leaks. a lot of the oil coolers leak, but never on the ground- instead they drip onto exhaust where they properly burn. when standing still - especially if you just went up an incline, do you detect a burnt oil smell?

next have them check turbo shaft for play... alternatively they can start the car without the intake tubing and observe turbo impeller if it spills oil when engine is revved up and let go...

right about here i would check compression.

lastly i would suspect valve guide seals and if all checks out - oil piston rings.

btw, limp mode always leaves traces/ codes. it is a software event and it has the corresponding audit trail.

 

There isn't burning smell of oil while driving

The computer showed couple things which can cause limp mode, however nothing suggested the reason for such excessive use of oil, so they could not be sure.

Thank you for th the suggestions. Hopefully I will find it!