Mercedes Benz S320 auto, year 2000 - Burning oil and smoking heavily, looses power

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Sun 24 Jan 2016 04:48
Mercedes Benz S320 auto, year 2000 - Burning oil and smoking heavily, looses power - Bert2215

Hi, I have a mercedes s320, automatic, year 2000 with 110500 miles on the clock. It is a great car but recently failed on me. It looses power under high eceleration (ie, going up hills) It smokes heavily and is burning oil at a high rate. I have done a "basic" presure test of the cylinders to see if it is loosing presure and if the o rings are worn. There is sufficent pressure. The spark plugs were clogged with black residue which I presume was from the burning oil. I replaced them. I have read on the internet something about an oil pressure relief valve that can get blocked and cause some of these symptoms but I am not sure at the moment. Any help, advise or knowledge would be greatly appreciated.

Thanks Bert2215

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Sun 24 Jan 2016 09:39
Mercedes Benz S320 auto, year 2000 - Burning oil and smoking heavily, looses power - craig-pd130

Did you do the compression test across all 6 cylinders? If you did, and they were all within 10% of each other, then the cylinder bores, piston rings and valve clearances (and valve seats) are probably OK.

What were the readings? I would think you should see 130psi or more.

If the comp test was OK, it would point the finger at either a failed valve guide oil seal, or the pressure relief valve you mentioned. However a failed valve guide seal probably would not give that much smoke.

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Sun 24 Jan 2016 11:07
Mercedes Benz S320 auto, year 2000 - Burning oil and smoking heavily, looses power - Bert2215

Thank you for your speedy reply. I didnt take down the readings and cannot remember. I will do another test and check for variences between the cylinders and the pressure amount.

It was smoking heavily, I could not see the lane behind me it was so bad. You mention the valve guide oil seal would not make a large amount of smoke, however could the pressure relief valve cause a large amount?

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Sun 24 Jan 2016 10:54
Mercedes Benz S320 auto, year 2000 - Burning oil and smoking heavily, looses power - hardway

Buy your self a "Cylinder leak down tester"

round £40 on Ebay.

Now this tool that will fit any combustion engine is fairly easy to use and EXTREMLY accurate,

It will determine if the is any leaks from rings/gasket/valves/valve guides or ANY other place.

As long as you have a compressor,

even a little one you fit the tool into the plug hole with cyl at TDC and charge it to 100 psi and the second gauge reads the holding pressure.

So 100n in say holding atany less than near 100 say 70 and all you have to do is listen for where the air is coming out from.

Intake?then an intake valve is suspect,same with exhaust ETC.

Practically idiot proof.

So much so I don't even remember where my compression gauge is it's been so long since I used it!

Do yourself a favour and buy this tool.

All that said it does sound like the pressure relief valve is faulty.

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Sun 24 Jan 2016 11:10
Mercedes Benz S320 auto, year 2000 - Burning oil and smoking heavily, looses power - Bert2215

Thanks, Ill search ebay now

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Sun 24 Jan 2016 11:17
Mercedes Benz S320 auto, year 2000 - Burning oil and smoking heavily, looses power - elekie&a/c doctor

I think I would be checking the crankcase breathing system before parting up with any cash .Check the pipework and breathers on top of the cam box covers.Are you saying all 12 plugs were fouled,or just a few cylinders?

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Sun 24 Jan 2016 11:57
Mercedes Benz S320 auto, year 2000 - Burning oil and smoking heavily, looses power - Bert2215

Just a few, I think 3

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