Possible oil leak in a Mercedes 2013 E350 CDI, maybe due to oil cooler seals.

[MundeDas]

Hello

I just bought an E350cdi coupe registered in January 2013. 81,000 miles.

There are some oil stains on my driveway that seem to be increasing in number.

Upon inspection, I found oil behind the air filter batwings, a little amount under the turbo seals, and oil streaks on the silver heat shield at the rear of the engine. Photos included

Do these seem to be signs of oil cooler seal failure?

Thank you in advance

[MundeDas]

[BizarreBleak]

If you see oil leaks beneath, it is quite likely that the oil cooler seals are the cause. The oil cooler is located at the bottom centre of the V-shaped engine. The misting and leaks in the photos are not connected to the oil cooler, but the intake components in the V-shaped area need to be removed to access the cooler. It is advisable to remove the undertray and inspect from below to identify the source of the oil leak. After purchasing the oil cooler, new gaskets and seals for the intake components, the parts cost will be about £3-400. If someone else is doing the work, anticipate a total charge somewhat beyond £1,000. It is advisable to clean the manifolds while they are removed, despite being a filthy task. Avoid going to a big dealer since the cost will be quite high.

[BizarreBleak]

Now you understand the reason why the prior owner sold it.

[Darthilli]

The green o-ring is for the turbo intake pipe. The leak is not caused by oil cooler seals; it originates from under the automobile. It is inexpensive to fix this issue by doing it yourself or by seeking help from an independent professional.

Replace the black o-ring at the other end of the pipe and all the orange seals on the turbo as well. Inexpensive.

[AmericaMonster]

In addition, a 2013 automobile is included, and it is quite likely to feature the purple oil seals.

Ensure that the PCV pipe on the left is properly positioned. It may also need renewal. The engines release oil mist from the crankshaft via the Positive Crankcase Ventilation (PCV) system into the turbo, causing oil to eventually leak from the turbo seal. The swirlflap motor is located just underneath these drips.

Removing the batwing will allow you to thoroughly inspect all the items listed above including those specified by Darthilli.

[MundeDas]

I will remove the undertrays to investigate the source of the oil leak. I recently watched a YouTube video where an individual discussed experiencing a leak from the turbo seal and pcv seal in their c350 cdi. This leakage caused oil to drip down the back of the engine onto the floor. After replacing these seals, the oil stains on the floor disappeared, indicating that the issue was not related to the oil cooler seals.

Thank you for the useful advise on expenses.

[MundeDas]

Thank to everybody. I believe I will do this task first since it seems pretty simple, and I want to assess my progress.

I will update you on my progress in the next days.

Thank you

[Darthilli]

Apologies, that is a pipe coming out from the intercooler, not one going in.

If you search for OM642 'green o-ring' on Google, you should get results and instructions. Replacing the o-ring may be challenging without causing damage, thus it is advisable to purchase many o-rings. Also, remember to replace the black o-ring on the other end. All the orange ones covered with oil.

Enjoy the research!

[MundeDas]

Yes, I understood your message and appreciate the advice on refitting the pipe.

[MundeDas]

Today, I successfully replaced all of these seals including the 2 o-rings. The lowest bolt on the resonator proved difficult to remove, but the rest of the procedure was straightforward. I will monitor for any more oil leakage in the coming days to see whether the issue has been resolved. If not, it will probably be the oil cooler seals. Hopefully, everything is OK now.  Thank you everyone

[Darthilli]

Excellent work! The bolt on the bottom resonator is carefully concealed and requires a flexible and extensible wrench to access.

[MundeDas]

The challenge was finding the correct extension and wrench, requiring a significant amount of creativity. Everything is resolved now, fortunately. 👍

[RosaStyle]

Can you suggest a versatile and adjustable wrench?