Good Morning All, seeking your help for my 2007 ML500. The vehicle has about ~150k miles, and has always received dealer service, but the amount invested is absurd given the minimal value of the vehicle, so I'm interested in pursuing other avenues with the apperance of a recent oil comsumption issue.

1. Problem: Excessive oil consumption

• Symptoms include whiteish blue smoke on cold start
• 1 quart of oil every 200 miles
• Started to consume over the last 5,000ish miles and has gotten worse
• No soot on the back of the rear hatch, but of course the exhaust tips are dirty

Other than rings, which is what I suspect, what are some key parts that can be checked to eliminate potential cheap fixes? PCV? I assume I should look into leakdown and compression tests?
If we source a used engine, what are the most important bits to replace before installation? I'm thinking EGR/PCV, oil pan gasket, valve cover gaskets, spark plugs and coils (maybe?), RMS, what else?
Would an '06-'07 junkyard motor require any special coding after install? I suspect not, but want to be sure.

2. ML550/W164 update parts on an ML500

• Can I plug 'n play a NAV unit from a refreshed W164? Any benefit to the later headunits vs. my '07?
• What is the last year MB NAVIs used discs? If I purchase these maps, will they work on my current '07 unit?
• What interior and exterior bits can I swap from a refreshed W164 to my early W164? For example, can I swap on refresh bumpers? What about the interior? The gauge cluster binnacle looks different, but could other parts swap out?

The objective is if we found a suitable parts car to give the ML500 a cleaner, more current, look, what could be used? I understand the drivetrain is different.

 

This oil consumption could very well be that the valve seals on either or both heads are faulty.

 

I too agree that this is the likely cause. In reality, I am looking for workable pre-owned engines. I was surprised to experience this issue on a later M113. I really didn't think it was common, but the car has higher mileage now, so I suppose anything can happen.

I can imagine a valve stem seal job at the dealership/indy would not be more cost-effective than a 70-100k engine, especially if I do some work on it before it goes in.

 

Any dealer will never tell you it is the valve seals. They will try to sell you an engine.

 

Alright, All, this is a bit embarrassing, but I was quite off on the vehicle mileage. I looked today and it's 189,182! Wow! I'm not the primary driver, so I hadn't looked in a while. My mistake!

I decided to compile all of the service records, and noticed that back in late November, 2018, at 167,925 miles the dealership performed a leak down and compression check and wrote on the RO that both were within spec. Given the car has about 22k more miles, I wonder if something happened that would push the rings/valve stem seals over the edge. The records state that the first time the truck required an oil top off at the dealer was 64k miles. Moreover, the usage seems to be prevalent at a low level since then but obviously increasing in severity in the last couple of years. Given the somewhat recent leak down and compression results, can someone point me in the right direction of simple items to diag?

Valve cover gaskets have been replaced 2-3 times, the rear main seal was replaced at 144k (2014), the rack has been replaced, and last July the power steering o-ring seal was replaced yet again (3rd time). What else could be leaking and causing this level of consumption I could potentially check? I ordered Liqui Moly Motor Oil Saver for fun. We'll see if that does anything.

Any feedback is very appreciated!

EDIT: Went out to take a look at the car. I can't really notice any large external leaks. There is a little oil residue on the left valve cover gasket (right side of the engine, facing you), and one of the lines connected to either the PS or some cooler seems to be weeping a bit. That said, there is not much there, it's not really blowing back on the chassis in large amounts, and it certainly doesn't account for 1 quart every 200 miles. What do you guys think? An alternative hypothesis, is there an oil level sensor that could be going bad?



Noticed some oil around the edges of this valve cover and some very light moisture on two spots on the exhaust manifold.


What are these lines and where do they go? The top line has some weeping that starts here.


And deposits here, but there is no pool of liquid on the garage floor.


Here is another angle. There seems to be a little blow-by on the subframe that likely happens when the vehicle is traveling at speed. Behind this point, there is no oil residue on the chassis.

 

Please update you profile to include the year, model and where you live.

 

I updated.

 

Parts and locations are determined by by sitting in the car, hence you have a leak at the left valve cover.

The valve cover gaskets get tired after 13 yrs.

I have no idea what that hose/cable is. Remove the under eng. cover and see where it goes to.

By the way, what model do you have, ML500 or ML550

 

Good to know! I was wondering about that, and both valve covers have been replaced at least 2x already, but the mileage is high. This leak does not worry me that much. Doesn't seem to be significant yet.

It's a 2007 ML500.

I will be able to get the truck on a set of rhino ramps this weekend and have a look underneath.

 

All, an update. I put the truck up on rhino ramps and took a closer look at the oil leak. Still not sure what these lines go to. Also, it seems that the leak is coming from somewhere else and potentially dripping down on these lines and collecting at the bottom of the pan. Would anyone agree with that?




One of the lines goes into this, and the other goes towards the back of the engine but is almost hidden by the body/header. Again, not really sure if they're the source of the leak or are just collecting oil that's leaking from something at a higher point on the front cover. I will look for a an engine diagram to see where everything is (power steering pump, alternator, etc).


I put two 300ml Liqui Moly Motor Oil Saver cans in the oil. I also ordered all of the parts to redo the left valve cover gasket and breather. Everything should be here this week. I did valve covers on my W208 CLK55, and anticipate that it should be pretty straightforward on the ML. I am interested to see if fixing all of the leaks will impact oil consumption. The valve cover is is leaking enough to actively burn off oil on the exhaust manifold; the other oil leak pools on the garage floor after a couple of days. Maybe it's losing enough oil to add up to a quart within 200-300 miles. Won't know until it's fixed!

Open to any feedback!

 

Update: I serviced the left valve cover gasket and breather. Will post pics of the process soon. A week later, the cover is no longer pissing oil on the exhaust manifold, so that's a success.

I still have not diagnosed where the other leak is coming from. I did purchase a pinhole camera, so I may remove a few spark plugs and get a look at each of the combustion chambers to look for bore scoring while trying to find the source of the leak. Seems like a fun exercise.