Oil leak location?
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Joined: Jan 2018
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C230 coupe
Oil leak location?
I noticed that there's oil drops on the bottom of the alternator bracket. It's hitting the ps hoses and rack boot, so initially thought it was a ps leak. But it's definitely engine oil. It looks like there's something behind the alternator leaking. What's in that area that might leak? C230 m271
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c240
I noticed that there's oil drops on the bottom of the alternator bracket. It's hitting the ps hoses and rack boot, so initially thought it was a ps leak. But it's definitely engine oil. It looks like there's something behind the alternator leaking. What's in that area that might leak? C230 m271
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Joined: Mar 2019
Posts: 152
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2011 C300 Sport 4matic, 2005 C240 4matic, 2003 C230K Sport, 1999 C230K Sport, 1969 220D (first car!)
I can’t help you with a specific thing to check but maybe I can suggest an approach.
Clean everything really well. Brake cleaner, degreaser, scrubbing bubbles, brushes, rags, whatever it takes to get the area really clean. Invest some time and energy into cleaning it well.
Then run it a bit and pull into a garage or dimly lit area and shine a UV light in the area. Walmart has UV flashlights for less than $10 and it will help light up the leak—oil is sorta greenish. The leak will be near the highest point on the engine showing oil.
It’s a hassle to clean everything but it’s the best way to track down leaks.
I won’t get into the best way to clean an engine—other threads can do that—but I’ve had good luck with brake cleaner on the really stubborn oil-soaked grime. Scrubbing bubbles (bathroom cleaner) followed by a water mist rinse works well on ordinary dirt and dust. You should probably avoid high pressure spray. It cleans well but you risk getting water where it shouldn’t be. Warm/hot engines will self dry much more quickly. Avoid electrical connectors, sensors and computers.
When you do the repair you, or your mechanic will be glad everything is clean.
5
Clean everything really well. Brake cleaner, degreaser, scrubbing bubbles, brushes, rags, whatever it takes to get the area really clean. Invest some time and energy into cleaning it well.
Then run it a bit and pull into a garage or dimly lit area and shine a UV light in the area. Walmart has UV flashlights for less than $10 and it will help light up the leak—oil is sorta greenish. The leak will be near the highest point on the engine showing oil.
It’s a hassle to clean everything but it’s the best way to track down leaks.
I won’t get into the best way to clean an engine—other threads can do that—but I’ve had good luck with brake cleaner on the really stubborn oil-soaked grime. Scrubbing bubbles (bathroom cleaner) followed by a water mist rinse works well on ordinary dirt and dust. You should probably avoid high pressure spray. It cleans well but you risk getting water where it shouldn’t be. Warm/hot engines will self dry much more quickly. Avoid electrical connectors, sensors and computers.
When you do the repair you, or your mechanic will be glad everything is clean.
5
Thread Starter
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Joined: Jan 2018
Posts: 109
Likes: 6
C230 coupe
Good suggestions. My issue is I can see the area behind the alternator has oil, but short of removing it I can't see the area it's leaking. The fabric tray under the pan is fine, the crank seal is fine. I may have to start disassembling things
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Joined: Jan 2018
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C230 coupe
Casting plug leak
After doing a lot of searches, this appears to be an oil gallery plug on the block. No fix but to remove the alternator to get at it. Here's better pics from someone else with the same issue:
https://mbworld.org/forums/mercedes-...-see-pics.html
https://mbworld.org/forums/mercedes-...-see-pics.html
Thread Starter
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Joined: Jan 2018
Posts: 109
Likes: 6
C230 coupe
I'll post a final on this. I removed the alternator and replaced the brass/copper washer on that plug. No idea why it started leaking; maybe someone messed with it when they did the timing chain. FWIW, the Mercedes part number for the sealing ring is N 007603 010404. I happened to have a compatible sealing washer in my miscellaneous hardware bin, so was able to fix it quickly. Autozone probably has something compatible; otherwise those are $2.70 plus shipping as of 8/15/20.
That oil gallery feeds the chain tensioner, so when you start again, it'll make a racket for a moment until everything fills up.
A few notes on removing/installing the alternator. Clearance is tight. I'd advise buying some external torx box wrenches, if you haven't already. You can also get a Gearwrench 10/12 E wrench for about $20. The other option for using your E-torx sockets is to get an adapter to use a 1/4" socket wrench with a 3/8" socket. That allows you to get in there and tighten/loosen the alternator bolts. [And also buy a swivel head 1/4" drive socket wrench.] Otherwise getting those bolts out is a pain.
A second note is to note the position of the alternator (m271 engine). Installed, the 13mm cable nut should be to the outside, and the sensing wire plug down and to the inside. You can install the alternator rotated 180, but it probably won't rotate. Check that the alternator rotates freely before you put the belt on.
That oil gallery feeds the chain tensioner, so when you start again, it'll make a racket for a moment until everything fills up.
A few notes on removing/installing the alternator. Clearance is tight. I'd advise buying some external torx box wrenches, if you haven't already. You can also get a Gearwrench 10/12 E wrench for about $20. The other option for using your E-torx sockets is to get an adapter to use a 1/4" socket wrench with a 3/8" socket. That allows you to get in there and tighten/loosen the alternator bolts. [And also buy a swivel head 1/4" drive socket wrench.] Otherwise getting those bolts out is a pain.
A second note is to note the position of the alternator (m271 engine). Installed, the 13mm cable nut should be to the outside, and the sensing wire plug down and to the inside. You can install the alternator rotated 180, but it probably won't rotate. Check that the alternator rotates freely before you put the belt on.
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