Mysterious oil leak - 2005 C6 LS2 engine

the-pipe-bender

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Good Morning All !

For several months now I notice a slight but annoying oil leak under my C6. Nothing major but there is always a drop of oil hanging from the lowest parts of the cover plate just behind my oil pan - the oil pan itself seems dry. It seems to run down from somewhere and collect there until it drips off. (see photo below. The two spots where the fluid collects are marked in red). I just cant figure out from where it's coming from or what is leaking.

Does anyone have an idea where it could be leaking from ? Many thanks!

Screen Shot 2019-03-02 at 08.13.18.png
 

ddgermann

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Wow clean car. Impressive to say the least. Looking at your dots... is it possible you have a weeping rear engine seal and it’s migrating and collecting there?
Ya nothing anyone wants to hear. My C6 was a 13 and almost new when I sold it so I definitely haven’t seen this.
Fortunately there are some excellent C6 mechanical guys on here that likely have see this before. 😀
 
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Rruuff Day

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Nowhere's near being a mechanic but looks like a rear main seal to me too...
 

the-pipe-bender

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thanks so far. I really hope that is not the case because changing main seals is quite an operation. Also, even though the Vette is a 2005, it only has a bit over 18.000 mi on it and I would have thought main seals should survive longer than that. On the other hand, last time I had the oil changed they replaced it with 6 qts, overfilling it by half a quart. Now common sense would tell me this should not matter, especially since the manual calls for an additional quart of oil whenever racing or pushing the car hard and draining off the extra oil when returning to normal street driving. However, on the other hand there are at least a few people on the US Corvette Forum who claim that overfills may indeed have caused main seal failures on their cars. :confused:
 

Vegas1500

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Pretty sure there is a TSB regarding this. Something to do with the rear main and the block being “porous”. My 07 had it and I just lived with the few drops it left. I will see if I can find the TSB tonight.
 
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the-pipe-bender

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Pretty sure there is a TSB regarding this. Something to do with the rear main and the block being “porous”. My 07 had it and I just lived with the few drops it left. I will see if I can find the TSB tonight.
Wow, thanks a lot....I appreciate your efforts....:Hurray:
 

Vegas1500

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Sorry I can’t seem to locate it and I do t have my all data subscription anymore. I’m sure a few hours on google may help.... alos check your valve covers carefully. The back corner can leak and run down....I’ll keep looking.😀
 

the-pipe-bender

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Thanks anyway for looking. The valve covers are dry. I checked already. My engine is fairly clean so not really hard to see oil sweating through my valve covers (see photo). That is why this leak on the bottom is so annoying. :confused:IMG_20180630_112026.jpg
 

theboss

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Only other componemt that may leak in the rear of the engine in the oil pressure sensor located in the rear center on top of engine block. If the swith is dry and you are positive that the leak is engine oil then it realy look like a rear main seal. You might try a stop leak but it is not a permanent fix. Good luck and keep posting , might help some one else.

Stephane
 

Icecap

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Good Morning All !

For several months now I notice a slight but annoying oil leak under my C6. Nothing major but there is always a drop of oil hanging from the lowest parts of the cover plate just behind my oil pan - the oil pan itself seems dry. It seems to run down from somewhere and collect there until it drips off. (see photo below. The two spots where the fluid collects are marked in red). I just cant figure out from where it's coming from or what is leaking.

Does anyone have an idea where it could be leaking from ? Many thanks!

View attachment 24140
As already mentioned by someone else here these engine oil pressure sensors are known to fail and cause an oil leak. With the natural slope of the engine and given the location any oil leak there will end up dripping down in the flywheel housing area. Given the location these are difficult to access but some find it easier to remove the intake manifold. You can look in that area with a bore scope but can't see anything with the naked eye.

2456024561
 

the-pipe-bender

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thanks for these really useful pics...I havn't thought of that because I thought if the oil pressure gauge is working correctly the sensor can not be leaking. So even with a working oil pressure gauge the sensor itself could be leaking, right?
 

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