[kindlethespirit]

First.....this is not related to my R129, but rather my CLS550. This specific forum is very active whereas the CLS is dead, so I'm going to ask this engine question here.

I'm currently waiting on the flatbed to take my 13 CLS550 back to the selling MB dealer. I've only had this car for 30 days. Currently on hot start the engine will knock, sounds like lifter noise, for about 5 seconds. Usually the dash lights up in red stating "low oil pressure, shut off engine".

So, with only 73K miles, what goes on in MB engines that could be causing upper end noise like this? I know that the M278 and M113 engine is different as far as NA vs FI, but the basics of engines are similar.

 

[robm.UK]

You are right to be concerned.

I quote member brandwooddixon from UK Mercedes Owner Club forum here

“I've got one of these in my CL.

I think that I can say that I've had the main troubles and they are timing chain and turbocharger wastegate linkages.

The timing chain and tensioners can suffer wear and there was an MB service notice to replace the oil supply check valves on the tensioners with a redesigned type. There is a timing chain for each bank.

The turbocharger waste gates and linkages can suffer wear (in fact the tolerances for play for these on new units is shocking).
I think that both issues are exacerbated by the start-stop system (my vehicle was low mileage at 37k miles at 6 years old and had been used for a daily commute of about 15 miles a day).

I don't know about the S-class but on the CL a turbocharger replacement is a massive job - full engine out including removing most of the front suspension (cross members etc) and everything forward of the engine. MB will quote £8500 to replace a turbocharger and £600 to diagnose the problem.

So my advice, listen out for noises on start-up”.

 

[kindlethespirit]

I spoke with the dealer. They related that the shop foreman needs more time to look at the car.

I called my MB indie mechanic who related that it sounds like they know there is a serious issue with the motor and need time to figure out how to deal with this since it's going to be a dealer problem and not a MB problem.

Since the car sounds like a cold start diesel when you start the car on a hot motor and the oil pressure light is lit up red, the indie is guessing that the check valve in the oil pump is probably faulty and the upper end is being starved of oil on start up. There definitely isn't rod knock but the valve train is way louder than just minor lifter tick.

To replace an oil pump on this motor, being a 4matic, the engine has to come out.

Here's what I need an opinion on:

1. If the motor ends up having to come out of the car and an oil pump has to be put in and I assume lifters need to be replaced, should I try to get the dealer to install a quality low mileage used motor? Used motors on Ebay are going for around 6500 with 50-60K miles. Apparently a new crate motor is around $20,000.

2. Let the dealer replace the oil pump and lifters and hope that no damage was done that will affect the longevity of the motor?

3. Ask the dealership to buy the car back? I really like the car and would like to keep the car.

So, I'm looking for opinions and advice as well as any other option that would be reasonable.

Thank you.