Excessive oil consumption of CLK55 AMG

[baz.purdue]

Hi all.
I need some help. I am using approx 1ltr of engine oil every 100 miles. The crankshaft seal was replaced some time ago, which didn't resolve the problem. Recently a lot of checks have been made in an attempt to find the issue. The crankshaft still has a small leak. The right rocker cover is also now leaking, now the garage believe these are caused by crankcase pressure. But when the oil cap is rested on the oil fill point it doesn't appear to have pressure there. There is a small amount of blue smoke on start up and when under hard acceleration a blue/black cloud of smoke out of the back. The garage carried out a over run test and no smoke was present. I'm at a loss. I would expect to see a lot of smoke with this amount of oil usage. But it's just not there. Where could it be going? Next item to be changed is the oil level sensor. If this were faulty and I was putting too much oil in would this cause the oil leaks and smoke on hard acceleration?? Im also going to have the garage measure how much oil is in the engine when changing the sensor, currently at an indicated 2ltrs down. What other checks can I do?
Thanks for your help

 

[kth286]

so if you let the car standing with the engine running for a couple of hours, how much oil would you collect underneath ?

 

[wireman]

For how long has this problem been going on?
How much oil is stuck to the cars underside?

Too much oil in the sump is not a good thing, all manner of damage can be done some of it expensive to repair, things like smoke and oil leaks would be expected, far too much will allow the crank shaft to hit the oil sending shock waves through the engine, making some peculiar noises and eventually causing severe damage.

If that much oil was passing into the combustion chambers I'd expect blue exhaust fumes all the time, if it was leaking I'd expect a wet underside and very slippery garage floor.

I think you are on the right track with the sensor.

 

[star]

We have seen this before on a clk, take the plugs out to check for oil deposits.

 

[WG M-B]

As above. If its excessive i would remove the top half of the inlet to see if its filling up with oil.

 

[Steve@Avantgarde]

I did an A Service on this car and replaced the spark plugs about 6 weeks ago, from what I remember there was no signs of oil deposits on the plugs or signs of ring wear that have caused the plugs to burn out/coke up.

There is no excessive oil leak that would cause this amount of consumption. Olly at PCS looked at the car a week before me and gave the same opinion. There is a leak from the crankseal and RCG's but I have seen a lot worse.

Before I got my grubby mits on it, it had been to 2 other specialists localish to me, one has replaced the crankseal already.

I think the only way to find out is to measure the engine oil over 1000 miles and see how much oil or even if it is burning any oil. It may be a fault sensor.

 

[star]

An oil leak would be hard to miss esp if its that much, so either faulty sensor or burning it. The car we saw was coking up plugs on certain cylinders every 6-8000 miles.

 

[baz.purdue]

Update

Hi all,
Thanks for all you input, today i took out a spark plug....see the attached picture. I'm going to assume that this is a bad sign, imagine these plugs have only done 2k miles.
I have noticed a cloud of smoke, but only when i put my foot down to overtake or similar. Thinking in excess of 4k revs is when it happens, but it is a single cloud, no trail of smoke....any more ideas before it finds the nearest tree to me??

 

[star]

Hi all,
Thanks for all you input, today i took out a spark plug....see the attached picture. I'm going to assume that this is a bad sign, imagine these plugs have only done 2k miles.
I have noticed a cloud of smoke, but only when i put my foot down to overtake or similar. Thinking in excess of 4k revs is when it happens, but it is a single cloud, no trail of smoke....any more ideas before it finds the nearest tree to me??

Thats not a good sign, you are burning oil and the cats are cleaning up the smoke to a point where they can't cope and then the puff of smoke. we have seen cats break up and be sucked up and prematurely wear bores/pistons.

 

[baz.purdue]

Thats not a good sign, you are burning oil and the cats are cleaning up the smoke to a point where they can't cope and then the puff of smoke. we have seen cats break up and be sucked up and prematurely wear bores/pistons.

Any idea on rectification? And costs???

 

[Steve@Avantgarde]

Or could that be down to overfilling the engine with oil due to a dodgy sensor...

I dont remember your plugs looking that bad when I replaced them a couple of months ago Baz....

Now the sensor is replaced and you know how much oil is in the engine we will find out I guess.

 

[star]

Any idea on rectification? And costs???

Depends on how far you want to go and whats worn. Pistons/rings, maybe the bores are worn???? With steve, wait and see what the level of consumption is now you've had a new sensor.

 

[WG M-B]

These symptoms are very similar to a couple of cars we have seen in the last year with the breathing gallery behind the crank seal casing is blocked.
But obviously over filled oil will do the same
I would say you have a pretty deep puddle in the inlet manifold looking at those plugs

 

[baz.purdue]

These symptoms are very similar to a couple of cars we have seen in the last year with the breathing gallery behind the crank seal casing is blocked.
But obviously over filled oil will do the same
I would say you have a pretty deep puddle in the inlet manifold looking at those plugs

So if a monkey put a new rear crankshaft seal in incorrectly that could be the cause? Would it also mean a small leak from the same seal??

 

[WG M-B]

Well I wouldn't want to accuse anyone of being a monkey. But your plugs have oil deposits on them and from my personal experience with the 112 v6 and 113 v8 engines this is uses caused by breathing issues.
The crankase seal sits in a carrier bolted to the rear of the engine block. Behind this carrier lies the main breathing exit! If this blocks then the engine will burn oil.
The classic symptom is the puff of smoke on acceleration that you described

 

[WG M-B]

And just to add. Fitting the rear main seal does not necessarily make this problem apparent to the tech. The gallery is behind the carrier not the seal.

 

[Steve@Avantgarde]

I wasnt that monkey by the way Wayne!!!

 

[WG M-B]

I wasnt that monkey by the way Wayne!!!

Im sure you wasnt Steve!!!!!!

 

[bigasotonuk]

Hi,
I have leaking rear main oil seal on my 55 engine in my C43, would my M113 V8 have the same set up, the engine was originally from a MY 2000 208 CLK.
If so would cleaning this gallery add much labour time when replacing the seal?

 

[baz.purdue]

It appears the sensor wasn't to blame...3 ltrs of oil this week, but 750 miles (mainly done at 65mph on motorway)