One diesel engine dying does not prove anything. I'm sure you will find one dead V8/V6 gas engine GLS too. A lot depends on how the vehicle was serviced and also how it was used (abused). One engine dying (out of thousands) could also be a fluke. You cannot form such an opinion with one data point.

Unless someone replaces their GLS with a Toyota or alike, I don't see how they could avoid paying lots of money. If you buy a new GLS, its a $100k vehicle, and you need to pay serious monthly payments (which includes lots of interest). If you keep driving the old ones, you need to pay serious money for repairs to keep it on the road. You get what you pay for. GL has been the most comfortable vehicle I have ever driven. I've driven (or have been in the passenger seat of) Land Rovers, Porsches, BMWs. Lexus, Cadillacs and based on my experience/opinion, nothing comes even close to GL. YMMV.

 

OM642 is an OM642. Doesn't matter what chassis it is in. Do a search on the issues. Lots on issues on this forum too. MB is very consistent. The same issues will reveal it's just a matter of time and mileage.

 

Well, I have 7 years of personal experience with OM642 and am not talking based on forum posts. Its true that the add-on clean diesel components are somewhat flaky. But Mercedes gas engines are not exactly trouble free either. OM642 is unreliable when compared to 5.7 liter in Tundra, but not so much when compared to gas offerings in GLS. I doubt diesel's cost of ownership is much different than the cost of ownership of gas GLs. For starters, you save $1k (or more) on fuel annually. MB makes different engines and people can buy what they like based on their preferences. I like diesels. And I don't hate on gas engine GLs. They are nice too.

 

The diesel is not available in the US anymore so it is not possible to buy a new one. That option is gone. It was not reliable and had emissions issues. Not bashing the diesel, just pointing out the very high number of observed failures with timing chains, oil cooler seals, DEF tanks, and emissions related items. The money saved in fuel is quickly eaten by much higher maintenance and repair costs. The only reason to own the diesel would be for towing. Otherwise, it just doesn't make sense. As far as dependability, the OM642 is just not reliable for the vast majority of drivers in the US.

 

I've searched the forums before when I owned my 164 and 166 because I owned them (Diesels). I haven't had any "engine" problems and most of the problems I have seen here (this website) are related to the oil cooler seal when it comes to the engine. The rest are emissions. I don't see your instances of engine failure besides the one you continue to link to no matter how many years have passed since that "one" you listed.

 

That one was a few weeks old. There are others. Do a search. What typically happens is the oil cooler leaks the engine oil out and the oil level sensor is sludged so it does not trip the oil light so the engine fails due to lack of lubrication. Lots of very early timing chain failures too. Look at the 164 forum. Just about every few threads is on diesel issues.

 

Let's not mince words. Emissions systems connected to the OM642 are related on a 1:1 basis with the OM642 engine. Therefore the broad umbrella of "diesel GL" applies correctly to the OM642 and its associated emissions hardware.

The OM642 is unreliable when connected to the necessary emissions hardware, past the mid-late 2000s. I say this with confidence based on the proliferous postings on this site, and my own personal experience with another German diesel of the same era.

In "unreliable diesel" complaints are included:
- oil cooler seals
- DPF
- DEF system (tank, pumps, heaters, valves)
- EGR hardware
- NOx hardware
- turbos
- injectors

Not included, or infrequent complaints (engine hard parts):
- cylinder block
- crankshaft
- camshaft
- piston
- piston rings

There is no complaint against the compression ignition cycle, better known as diesel. It's the unreliable implementation of a compression ignition emissions system that is the focus.

Comfort should not be taken by absence of complaints on the "engine hard parts". The reliable hard parts are connected, without exception, to the unreliable emissions system.

 

Since we are referencing forum posts, here is a thread that discusses issues with GL450/550 engines: https://mbworld.org/forums/gl-class-...450-gl550.html
BlownV8, you seem to have contributed to this thread and discussed the issues with your gas GL there. FYI, my GL350 has not had any of the issues that you listed for your GL450.

I agree that the clean diesel components (added hurriedly to make GL get certified in CA) are flaky. However, its not the doom and gloom that some here are portraying.

 

In 7 years of diesel ownership, I have had 2 of the issues you listed: engine oil cooler leak and DEF tank heater failure. Maybe I am lucky, or maybe this list is not realistic.

 

Yeah, nothing to see here. Just did a quick search on this forum.

Seized Bluetec.
https://mbworld.org/forums/diesel-fo...ne-seized.html

54,600 miles and timing chain needed replacement.
https://mbworld.org/forums/diesel-fo...0-blutech.html

Blown diesel.
https://mbworld.org/forums/m-class-w...es-diesel.html

Blown diesel
https://mbworld.org/forums/m-class-w...e-seizure.html

https://mbworld.org/forums/diesel-fo...e-bluetec.html

Blown diesel
https://mbworld.org/forums/diesel-fo...out-mbusa.html

https://mbworld.org/forums/diesel-fo...etec-saga.html

Blown diesel
https://mbworld.org/forums/gl-class-...000-miles.html

Blown diesel
https://mbworld.org/forums/m-class-w...need-help.html

Blown diesel
https://mbworld.org/forums/e-class-w...iles-help.html

https://mbworld.org/forums/m-class-w...e-startup.html

Blown diesel
https://mbworld.org/forums/gl-class-...e-crashed.html

 

2008-2019, less than 1 per year so far across all om642s on this board. Did you read the reason's behind these failures?

Now search for oil cooler leaks and DEF tank issues..

 

Don't have to do a search for the other issues. There are many DEF failures, oil cooler leaks, timing chain failures, and turbo seal failures. Interesting way of looking at the stats and the comment of only one failure per year. Had to chuckle a bit. Diesel was already a very low production vehicle compared to the gassers. Now, take the few owners on this forum compared to the total number sold, and look at the number of failures. Search the internet and it expands the number and frequency of failures across the years. OM642 is a problematic engine for most owners with some very expensive issues that can and do lead to catastrophic engine failure.

Try to find used engines for the OM642. It's really tough to find one that was out of a working vehicle. When you do, they are often very expensive. That's because a used working engine is very rare.

With that said, the early V8 engines in the GL 450 suffered from balance shaft issues that will ultimately destroy the engine. MB used a supplier with poor quality metal and the sprocket teeth start to wear. It can be repaired but it is cheaper to put a used engine in place. In fact, my GL with 250k miles is in the early stages of the balance shaft issue. Problem is the car is worth about the same as the engine replacement cost so it will probably be replaced with a new vehicle. It's a shame because it has been rock solid performer for the 12 years I've owned it and the least expensive MB that I've had and I currently have 4 MB's. The engines should have been recalled and the balance shafts replaced but MB chose not to do so.

The M156 AMG engine is also problematic so not just picking on diesels here. The gas engines are definitely more reliable than the diesels but have their own issues too. If MB didn't build such fun, safe, and great looking/driving cars, I would be in another brand.

I originally ordered a GL320 so not a diesel hater. It just didn't arrive on time and had to go with a 450 due to timing of selling my CL600 and the diesel being 2.months late in production. Drove the 450 and fell in love with the power delivery over the 320 so I decided it wasn't worth renting a car for 2 months. I drive quite a bit so the diesel made sense for me due to the MPG's. It all worked out and I feel I dodged a bullet looking at the number and frequency of engine issues.

 

Once again, please read why the engines are failing.

The reasons to not buy a Bluetec are DEF issues and Oil Cooler leaks. They happen at a much higher rate than an engine failure due to the reasons people describe in their OM642 failure posts.

 

It also seems like we have seen FAR more problems with X164 OM642 diesels than X166 OM642 motors at the same milage points. (Ditto for ALL X166 models in regard to Airmatic issues compared to X164.)

Either X166 owners are really lucky, or MB made some across-the-board continuous improvements along the way. They are certainly not perfect, but I was honestly expecting more folks posting with X166 issues by now.

(I'll refrain from posting random links to blown MB gas motors, including ones not even installed in the X166. )

 

This is something similar to what I read in the mid 2000's about ABC in the 2005 cars vs pre 2005 cars. All the 2005 and later owners said the same about their ABC - that their ABC would somehow be more reliable. They were wrong. I've had pre and post and the problems are all the same. It's all time and mileage. Again, MB is very consistent and they fail accordingly. There are starting to be more Airmatic strut failures on the X166. Again, time and or mileage. There is no doubt I will replace the air struts on my X166 like I had to on my 164.

Yeah, there are failures in the gas engines too as I pointed out in my post. The diesels just seem to fail at a much higher rate than gas engines and have much higher maintenance costs vs the gas engines. The turbo gas engines will be less reliable than their NA counterparts. Just the way it goes. More heat, power, and stress equals more failure.

Back to the point of this thread. Yes, sell your diesel unless you are ready to change the oil every 4 to 5k miles and do an emissions bypass or spend a bunch of money on the DEF, emissions, timing chains, and the regular maintenance items. Diesel particulates are known carcinogens so, for everyone's health, don't bypass your emissions. Again, not the only problematic MB engine as pointed out above so not just picking on the diesel.

 

They due make incremental improvements. We have a 2012 GL350 (last year of X164). Many of the problems of early X164s are gone in 2011/2012 model years (heated seats, rear hatch, etc).

Anyways, this thread is going nowhere. In my experience, diesel engines have slightly higher maintenance cost and are slightly more unreliable due to clean diesel components.. They do also offer many benefits. Much better MPG (translates to $1k savings annually), low end torque that allows you to pull large campers/boats at low (relaxed) RPM, range between re-fueling specially when towing, etc. IMO, they are not the ticking bombs that some are portraying them to be. You can find as many gas engine issues on this forum. A current thread talks about oil leak on a GL450. Anyway, if someone is not comfortable with diesels, they are many great gas options as well.

 

If you want to stay in the MB family, then get a used GL550. We have had pretty good luck so far with our 2015. Only been in the shop 3x, all in the same year. It is a very comfortable and fast car. Will we keep it after the extended warranty is up, probably not. Those 3 trips to the dealer would likely set us back $10k post warranty. 1/10th the value of the car (new) at a shot to a dealer is steep. Now, if the car is only worth $25k in four more years, then the decision to trade it in early is prudent.

Now, if you want to leave the MB family, I can recommend the Land Cruiser. Not as fast, or comfortable and gets lousy gas mileage like the GL550. But, no issues to date, very few issues on the forums as well. I take it off road and do mean things to it and it doesn't complain.