I love the usefulness of a suv and have owned a bunch of domestic models and always wanted to own a MB so been considering the ML and GL’s.

i like the 3 row of seats of the GL and love diesels so considering a 07-09 320 diesel option.

I’m interested in experiences, opinions of driving, ownership and even aftermarket tuning of the ML320.

Thanks

 

No, no, no and no.

It’s a piece of crap.

Get a gasser instead.

 

Don’t do it.

Read about Mercedes diesel GLs on this site.

Don’t do it.

 

I'm an actual owner of one and absolutely love mine. I specifically bought an '08 so I wouldn't have to mess with the extra EPA stuff with the '09 and ups model years. There's a couple things that are common issues to them, but also easily addressable and fixable. Probably most notable is the oil cooler seals (google that - plenty of info on that). But worst case, you pay an independent service station to fix it and with the updated seals and some adhesive sealant, you should be good to go. The other thing is that, like most all engines, exhaust gasses are routed back into the engine (diesel exhaust gasses are "sticker") and they gum up the intake runners. It may also be due to the way the gasses are routed back and/or the "uniqueness" of the runners. Same thing, though - fixable by cleaning or replacing the runners - it's just a pain because they take some time to get to. After I had mine replaced, I installed an oil vapor separator filter and oil catch can so that should never happen again. Some just re-route the EGR valve direct to atmosphere under the car.

I've had mine for 5 years and those are the only "diesel" things I've had to deal with (and in my eyes, it's not really all that bad) - the torque of the engine on the highway (I can't remember the tranny ever downshifting going up hills!) is fantastic. Great fuel mileage - I've compared to gas mpg and lower gas fuel cost, and I'm still ahead. Not by a whole lot, but at least you do come a little ahead in the wallet in terms of fuel economy. Overall, the engine itself is a great, reliable, long lasting engine that can easily go hundreds and hundreds of thousands of mileage. It's just got a couple auxiliary systems that forums tend to focus on over and over and condemn the whole thing for a couple things that are easily fixable. The old adage of "don't throw the baby out with the bathwater comes to mind"

None of this is say anything bad about the gas engines - they're very good. But if you like diesel, and appreciate the many benefits of it like I do, the few things that you "may" (may have already been done!). I've been looking at tuners and, like all diesels, there's a lot more power to be had, along with even better MPG (depending on the tune). I haven't pulled the trigger on a tuner as, quite honestly, I'm still happy with the stock tune!

EDIT: Oh, I wanted to add that while I try to do a good amount of maintenance on my vehicles myself, I don't do all of it. The Indy that I use is quite familiar with these engines (used in multiple MB models) and says pretty much the same thing I was saying... there's a couple aux systems that need addressing, but overall they're great engines and they just keep running and running and running. There's even a MB tech on this forum that owns one, personally!

 

Dennis, how many miles on your diesel?

 

Still young... only about 105K

I don't doubt there will be some other things popping up (I think I read about timing chain might be next?). But at the same time, it's coming up on 13 years old and has over 100K on it - I think some of these things are just the name of the game with age.

 

‘07 or ‘08 are fine. Pretty hard to find diesels with any of the luxury options, however. Leather, HID, 19-in wheels, etc. Mine does city mileage equivalent to a 450’s highway mileage. I suppose later models with more emission controls are more problematic, but you wouldn’t want one simply because you’re forced to runflat tires.

If you want to tow, try really hard to find one with factory hitch already installed. Back in the day, the hitch was a $500 option, but $2k retrofitted at dealer. Under no circumstances do you want anybody but a dealer near your electrical system for hitch install. I would verify with a dealer if the parts to retrofit one today are still available. And,if yours is an early ‘07, the wiring for a brake controller isn’t there ... I’ve installed the factory harness in two.

 

Yes, timing chain should pop up next. However, given the car does not see much mileage, you may be good until you get ready for a new SUV and it will have served it's purpose.

Not directed at you but at someone looking to buy an OM642 equipped vehicle, I think we owe it to those potential owners and report the issues seen with the diesel variant of the 164 GL. Even the MB mechanics are saying to stay away due to its problematic nature so that's probably sound advice for anyone looking for an OM642 equipped GL. It was apparent a very long time ago that these issues were systemic with the diesel engine. Many of those that defended it at the time soon came to the realization that the engine has some expensive issues. Same with the M156. More and more of those are seeing head bolt failures as time goes by.

 

See https://www.motorreviewer.com/engine.php?engine_id=175

Mercedes OM642 Engine Problems and Reliability

In general, the OM642 engine has proven to be quite reliable. But near a mileage of 100-150k miles, auxiliary engine systems start to fail.

The first thing that starts to fail on this engine is the crankcase ventilation system. Driving mostly in the city and low-quality fuel contribute to the formation of a large amount of deposits inside the intake system. The crankcase ventilation system vents to the intake of the turbocharger. The vented oily air easily goes through the turbo blades and this oil and sludge begin to accumulate on walls of the intake channels, swirl valves and etc. Mercedes-Benz has stated that this engine feature is "normal". Therefore, for vehicles equipped with an OM642 3.0L diesel engines, it will be helpful to clean an air intake manifold, intake pipes, and crankcase ventilation pipes every 60-80k miles. Otherwise, the swirl valves may be stuck and an overloading electric drive motor will blow a fuse that controls other sensors. If it will happen, the vehicle enters the "limp home" mode and limits engine speed to 3,000 rpm due to disabling of the important engine systems.

The next problem applies to engines manufactured before 2010. The pre-2010 OM642 engines often had oil leaks from the oil cooler. This issue happened due to heat-related seal degradation. In 2010, the manufacturer replaced the previous orange seals with more durable Viton seals. New seals have a purple color.

Injector copper seals are known to fail, causing a buildup of heavy carbon deposits around the injector. The car begins to smoke and lose power. As a result, it all ends with the failure of the fuel injectors (known as "Black Death"). Some people advise using the Honda Accord 2.2 Diesel injector seals in applications for Mercedes CDI diesels instead of specified MB sealing washers. Another reason for the black smoke from the exhaust pipe sometimes related to a malfunction in the glow plug controller.

The manufacturer also replaced the TWC temperature sensor (part no. A005 153 40 28) with a new sensor that specified part no. is A007 153 74 28. The previous sensor was susceptible to rapid failure (diagnostic code is P2031).

 

I don't disagree at all. That's the reason I mentioned those things. Personally, I just don't think it's as big of a deal as some of the forums and information out there on the 'net make it out to be. I mean, the engine, itself, is quite good - it's those "add-ons" that need attention. But once those things are taken care of, the whole thing is really quite good. I know that ALX, on here, a diesel tech, has a diesel - and he talks about them quite favorably. And, I may have mentioned this already, but the Indy where I bought this GL from... I've become good friends with one of the mechanics and the service manager - great guys. They generally like this engine - once you fix those "quirks". And, no, it's not because they "work there" They are genuine and upfront with me about everything.

And, yeah, that EGR valve/crankcase ventilation system - that should really just be something that is replaced every 50K miles (or earlier - it's easy and inexpensive) before the rubber flap/valve hardens up and cracks. I tried to find a replacement rubber flap from a different vehicle that would fit - but was unsuccessful. I put a new one in - but also did the oil vapor separator filter (Provent) and catch can at the same time.

I think as long as someone is aware of these couple things that "plagued" the OM642 (although rectifiable), it can be a good buy. So, maybe instead of just telling someone to stay away - we tell them why - and also explain the root causes and fixes so they can make an informed decision. I'm not directing this statement at anyone in general - just thinking outloud about a better way to inform potential buyers.

 

We have a 2012 GL 350 and it has had 3 issues so far, 2 of which are diesel related. While expensive to repair, all 3 issues were fixed under warranty. I agree that gas engines are probably more reliable (GL450 is a good choice, IMO), as they have less moving parts. But I also think that the issues for OM642 are somewhat exaggerated in this forum. Its not as if gas Mercedes engines have Toyota-like reliability -- They have issues as well. GL is an expensive vehicle and its also very expensive to maintain/repair, regardless of the power train. First gen. OM642 does not have a lot of HP, but it has a lot of torque. Very enjoyable for mountain driving and towing. I have never heard of anyone overheating it while towing (can't say the same about GL gas engines with much more HP and torque. They do not seem to be designed to operate constantly under heavy load). If you are buying a used GL 320/350, you need to make sure the common issues have been fixed (oil cooler leak, DEF tank failure, etc), and set aside a budget for future repairs. You would re-coup some of that with much less fuel consumption of a diesel anyway. If you are not a diesel enthusiast (or don't need the towing ability and range), then I think a GL450 is an great choice.