CLS 500 - M113 and its oil leaks

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cdf40

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Nov 18, 2013
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2006 CLS 500
Hi everyone.

I am chasing down an oil leak in my 2006 CLS 500 (that is 5.0, not the 5.5 one) and figured I could you use some advice and perhaps help others in the same strange situation...

Short summary - recently purchased a great looking CLS with 100k miles on the clock. Shortly after that, I went on a wedding trip with my wife and we discovered it has quite a bit of taste for oil. This taste equaled to 4 liters of oil for a journey of about 4k miles. When I got it in a workshop the usual leaks for that engine showed up - rear crankshaft main seal, valve covers, and the breather. That was all fixed.

That was all well until I noticed again the smell of burnt oil coming from under the front doors after a drive. Oil level was also still decreasing. Went back to the workshop and this time he had another conclusion - head gasket. Now I know this is not common for those engines unless severely overheated, but performance wise the car runs and feels great. I've seen occasionally blue smoke when on a hill but that quickly goes away and under heavy acceleration, there is zero smoke of any color.

Now, oil is gathering on the top of the engine block (in the middle between the two sides of the "V") and this did lead my mechanic to the conclusion it's leaking from the head gasket.
Could that be the case or am I missing anything else that might bring oil there?
Also, a blown head gasket should indicate severe damage and yet all of the miles so far were flawless. Shouldn't it feel somehow if the engine has such level of wear?

Here are some pics.
Any ideas are warmly appreciated.

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I don't know these particular engines very well but thats a lot of oil to be losing from a head gasket. Many cars will run for a long time with no issues with HG faults, depending on what the fault is.

With this level of oil loss I'd be cleaning it up completely and then running the car with the engine cover off and watching to see if you can see it weeping from anywhere. It shouldn't take long for a weep to show itself if its losing that much oil.

Any oil in the water? water in oil? Pressure in expansion tank when cold? My last HG failure resulted in no symptoms other than pressure in the water pipes when cold.
 
"When I got it in a workshop the usual leaks for that engine showed up - rear crankshaft main seal, valve covers, and the breather. That was all fixed"

What is the breather?
is this the small breather cover sitting on each side of the engine on top of both valve covers?
 
Indeed it is. All M113s develop a seep there sooner or later.
 
I've got the same problem could please let me know what was the issue in your case.
 
FWIW, as well as the usual valve covers and split breather pipework, mine leaked like a sieve from the oil/water cooler, top front of the engine next to the oil filter. Easily spotted - oil residue over the front of the engine, power steering pump etc.
Ian
PS. I should add that it's an easy fix - two cheap seals and 30 minutes wok.
 
FWIW, as well as the usual valve covers and split breather pipework, mine leaked like a sieve from the oil/water cooler, top front of the engine next to the oil filter. Easily spotted - oil residue over the front of the engine, power steering pump etc.
Ian
PS. I should add that it's an easy fix - two cheap seals and 30 minutes wok.
Yes, the cooler seals, and the oil filter housing are both becoming more common on these (as well as M272/3 and M112s)
 
 
Next time you do an oil change, buy gasket softener Omega917, if your leaks are not too severe!
It will keep your gasket soft and moist preventing leaks from rear main seal.
I have used this product for many years and my mechanic swears by this product, he told me every year when doing an oil service I also should use Omega product .
He saved me money by not having to replace rear main seal, this part is a weak part and mostly affects cars who are only season driven.
 

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