M275 Oil Leak - MBWorld.org Forums

Aug 28, 2021 | 07:10 PM

K McCarthy

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Joined: Sep 2016

Posts: 113

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From: San Diego

2002 CLK 430, 2005 CL600, 2009 Smart Fortwo

M275 Oil Leak

Hi I am trying to diagnose a leak which drips from the meeting of the engine and transmission. One known possibility is the O-ring on the cover between the cylinder banks. I have looked at the area at the rear top of the engine between the intercoolers and haven't seen anything, that doesn't mean I'm not missing it, its pretty crowded in that area.
I recently changed the oil and decided to leave the cover panels off and just let the car sit without driving it. After 4 days the car leaks out a spot about the size of 2 poker chips next to each other each day. I would think that if it were from the infamous O -ring it would stop after a couple of days of not driving it. My other theory is that it may come from the gasket between the block and upper oil pan casting. In looking at that gasket it appears somewhat wet, things are really tight around it. What do you guys think? Thanks

Sep 5, 2021 | 01:12 AM

88 SEC

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Joined: Apr 2006

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Mine leaks just like that.
The oil is coming from the oil level sensor in the upper oil pan, one has to remove the lower pan to replace the o-ring.

Sep 5, 2021 | 10:00 AM

K McCarthy

Thread Starter

Member

Joined: Sep 2016

Posts: 113

Likes: 24

From: San Diego

2002 CLK 430, 2005 CL600, 2009 Smart Fortwo

Thanks for the reply, have you already done the repair? I was thinking about what it would take to replace that gasket between the block and upper oil pan, maybe just lifting the engine a bit and not removing it.

Sep 8, 2021 | 10:37 PM

88 SEC

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Joined: Apr 2006

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Only have to remove the lower (non-gasketed) pan from the upper.
No, I haven't done the job, I have the o-ring and will change it when the oil is drained at the next service.

Jun 27, 2022 | 03:34 PM

NHSl550

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Joined: May 2018

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From: Hudson NH

2007 SL65, 2009 SL550, 1991 SL500

Quote:

Originally Posted by 88 SEC

Only have to remove the lower (non-gasketed) pan from the upper.
No, I haven't done the job, I have the o-ring and will change it when the oil is drained at the next service.

Did you ever do this repair? And did you run into ant issues?

Jun 28, 2022 | 11:06 PM

88 SEC

Newbie

Joined: Apr 2006

Posts: 8

Likes: 3

No, I changed the oil from 0w40 to 5w40 and didn't have time to replace the O-ring.
The interesting part is that it leaks only a tiny bit if at all now; wasn't expecting that LOL

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