I have been losing quite a bit of oil recently. My M157 has 150K miles. In between the last interval oil change, I must have put in an extra 4 or 5 quarts. I just changed the oil at 150k miles. Today, at 151200, the add "one-quart oil" warning came on. I did happen to notice that when I was on the freeway and floored it, there was a puff of smoke in my rearview mirror. There seems to be zero smoke from the exhaust during idling or just driving around town.

I pulled the plugs before this last oil change and after it had lost a few quarts of oil and the plugs looked at just about a perfect burn with zero oil residue. There is no oil on the ground or on the lower air deflector/oil catch. I am wondering if the turbos are diverting oil into the exhaust somehow. I'm not an expert on turbos and I was wondering if one of you turbo gurus can help me figure this out.

 

Compression check and borescope looking for scored cylinder walls. Use the search feature, this is deeply and widely discussed.

 

I didn't mention but I did use a borescope since I removed all the plugs. the walls look fine. I didnt see the need to do a compression check but Ill search the topic.

 

Hey Chasis, can you narrow down what I'm searching for? Oil loss, low compression, turbo leaks, or blue smoke. I've been searching and I get about 5000 threads that I would need to read through so any help would be appreciated.

 

Some threads are below. Scoring affects M157 and M278.

Blue smoke means oil is going in the combustion chamber, possibly into the exhaust via the turbo. Sounds obvious but sometimes the obvious is overlooked.

If you have good compression and no scoring bad valve guides are also a candidate.

If you have misfire, check for oil in the engine harness first. It's unlikely in your case because you haven't reported misfire, but easy to check. Open the connectors for 4xcam position sensors and 4xcam magnets. Oil in the harness affects M274, M276, M278 and M157.

Turbo oil leaks are not uncommon but there don't seem to be current threads running on that topic that I have seen.

https://mbworld.org/forums/g-class-w...ne-repair.html

https://mbworld.org/forums/gl-class-...re-solved.html

https://mbworld.org/forums/gl-class-...n-wires-6.html

https://mbworld.org/forums/s-class-w...red-walls.html

 

Thanks, chassis. I'm going to read over these tonight. I've been a garage mechanic for over 40 years so I know my way around engines than most but I just have not worked much with turbos.

 

OK chassis, I just quickly glanced at the threads that you posted and none of them seem to fit my issues. in between my last oil change on my M157, I lost 5 quarts somewhere and most likely out the tailpipe. My compression seems to be fine as there have never been any misfires. Can compression below and not have constant misfire? yes, but it will still have sporadic misfires and that is not my case. I have been around engines all my life and reading the plugs tells a lot and one thing you will know about it is if you are leaking oil into the cylinder whether it be through the rings or from the valve guides. I did have blue smoke out the tail pipe when I floored it so I'm assuming it was through the turbos and as I mentioned, nothing at idle or farting around town. I just want to know if anyone has had any experience with these bi turbos and any known leaks or defects that would make me tracking it down easier.

I searched for my issues on the search bar and so far, I didn't really see anyone with anything similar to my issue at any of the Benz websites. This is kind of a reminder for me of when I had my transfer case issue. It is now a widely known issue for the x164 but when my transfer case went out, no one had ever done a write-up on it or expressed their same issues except one person who put a video of the same problem I had. I search for months and finally pulled my transfer case out and reported my finding. After that, next thing you know, everyone else had the same issue and the transfer case prices almost doubled overnight. I hope this isn't the same sort of problem with my oil loss because if it is the turbos, it would seem that I would have to pull the motor out just like I did on my GL450 when I replace that motor due to leaky valve guides. Thank god I have a lift.

sorry for being long-winded. If someone knows something about these turbos, please point me in the right direction. I have already read a bit about them but again, I am no expert on turbos. (8-71's are a different story)

 

There are a few threads that mention turbo-related oil consumption, but none that I have found so far with a detailed diagnosis and/or solution. Below is one.

https://mbworld.org/forums/gl-class-...umption-2.html

While thinking about how to diagnose turbo oil consumption, I would rule out all other potential causes. XENTRY can do a simulated compression test by measuring engine rpm variation. An indy shop can do this for you if they have XENTRY. Otherwise do an old fashioned compression and leakdown test to rule out bad compression. To me this is an obvious test do perform.

Do you have fuel smell in the cam cover when the oil fill cap is removed? Thinking about rings and blowby.

 

Hey Chassis, no fuel smell at all. The tailpipes also don't seem to have any soot so I do not know which bank might be burning. I do have a leak-down tester but I will take it to my cousin's shop to check the compression via XENTRY first to see if we can narrow it down. I want to track this down sooner then later as I know burnt oil from the motor will slowly degrade the cats and they are not cheap here in CA. I know this as I had to do it for my X164 when I had that valve guide leak.

 

I had read that last thread you posted quite a while ago and funny that some mention that adding oil every 1500 miles is acceptable. To me, it is not and I know something is amiss. I did have to add 1 quart between every oil change but this last time around, it shot up to adding 5 quarts. The motor still runs smooth and strong but adding that much oil to me is a problem. I will try to update if I find out what the issue is.

Thanks chassis

 

Was this ever solved?

 

I think I had found the issue. I believe it is the turbo oil feed line. Funny thing is that for the amount of oil I had to replace, I never had an oil drip on the ground. It must have been all absorbed in the engine catch pan. I only replaced it last week so the verdict is still out. The only way I think I had figured it out is that there was just a slight bit of oil on the lower crimp of the hose. There was never a visible active leak.

 

having same problem..but can't see no oil leaks..I do drive hard..

 

Please post back if no oil is needed within 7k of oil change

 

I drove just over 150 miles this past weekend. Oil stayed full. I'm positive that the oil feeder line was my issue. When I would drive to Sacramento which is only 90 miles, I would have to put in a quart of oil.
I'm grateful that it was not my turbos that I initially suspected.

 

Any more updates on your situation? I have the exact symptoms as you originally posted. I definitely have timing cover leaking at the moment but for how I have had to top off the oil lately it is concerning and I don't think there could be that much oil leaking from the covers to have to top off like that. My splash shield is covered in oil residue from timing covers and possibly the oil feed lines as you mentioned. Do you have a pic of the crimped area that was leaking on yours? I plan on inspecting a little later today when the weather warms up. Is it obvious it is leaking?

I looked inside when I did my plugs and everything appears fine and the car pulls hard as usual. The Xentry version I had could do a compression test but the hard drive crashed and my updated Xentry version does not do the compression test. I confirmed with my tech buddy and it looks like MB got rid of that compression test in later versions.

 

I had 2 leaks that were resolved. It didn't come from the timing cover though it looked like there was a possibility that it was coming from there. The front of my engine behind the pulleys was soaked in oil. The oil leak I had was coming from the oil thermostat. I circled it in the picture. It was just a worn o ring. You can get it done yourself as I did and if i remember correct.y, you need to remove the fan and serpentine belt. The oil thermostat cap is held in with small clips that you have to move towards the center and you can turn the cap. You can see it in the picture if you look really closely at it. It's where the notches are. I used a long set of needle nose to turn the cap and a small screwdriver to get the clips free. Be careful to hold onto the part as there is a spring that will shoot the thermostat and its cap out. Hopefully, this is where your leak is because if it is on the oil filter housing seal, just about the entire front of the motor has to be removed. This was not fun as I have done it. If you do have to remove the oil filter housing assembly, make sure you buy the two plastic oil cooler lines because THEY WILL BREAK!

The other leak was coming from the turbo oil cooler line. It's just the thin steel braided line on the driver's side. It's pretty visible. I was able to see an oil accumulation on the bottom crimp of the braided line to the hard line.

 

Oh, btw, Oil consumption is resolved. I'm back to only 1 qt between oil changes.