jensenajj

I'm in the market for a new vehicle for my wife and for our family road-tripper. I've been shopping around for MDX's, but I love the idea of a big diesel SUV. I'm a little hesitant based on my personal bias of "When this breaks, it's going to cost a mint." My wife's current vehicle has 155k on it and we've had it for over 100,000 miles and 5 years.

The one I'm looking at has 47k on it and they are asking just under $31,000. It's at a Mercedes dealership and the dealership will warranty to 100,000 miles.

Any thoughts from long term owners who have run up over 100k miles on their GLs? Is chasing the diesel prudent or does it just add maintenance costs over the long term? Any must-have or should-avoid options to look for? Thanks!

chassis

Avoid the diesel powertrain. Search this site and use Google for search terms: Bluetec, DPF, SCR, DEF, adblue.

Use some skepticism with the warranty. Ask the dealer, while looking him/her straight in the eye, if all diesel related failures would be covered by the warranty. If he/she says yes, ask him/her to point to the sentences in the warranty where this is supported. Then make your own decision.

In the same price range you can find gasoline powered MLs, GLEs and GLs, all reliable family road trippers with style and presence.

Avoid the pre-2012 3.5L gasoline V6, because it is known for balance shaft issues. Post-2012 3.5L V6 and gasoline V8s seem to be the most reliable in the medium-large SUV M-B platforms.

vivaitalia

you will find, if it's a big thing for you, the GL's 3rd row much more (relatively speaking) spacious and foot/knee friendly than the MDX's ( have 2 of those in the family and both have well exceeded 100k) ... regarding the warranty, I'm not aware of any ELW (MBUSA's Extended Limited Warranty with a 100k miles) ... MB-ELW has a two year, unlimited miles cap and it's almost identical in coverage to the original manufacturer's warranty ... everything else would be considered 3rd party, in which case understand it very well ... I'm approaching my 3rd year of a second owner of a CPO 2013 GL450 ... not sure what ima do when my ELW expires ... :-( :-( :-( ... you may want to do some math and ask the MB dealership if they would CPO the car and that you have the ability to purchase an ELW (and definitely shop here in the forum to get the best deal on ELW) ....

Bern6389

Depends on how the GL was taken care of. I lucked out with the one I purchased as it was decently taken care of. One issue that has been resolved (timing chain stretch). Owned it for about 4 months now and have over 13k miles on it, rig has 118k total now.

big things are long trips and frequent oil changes, don’t wait the full 10k miles. Monitor the dpf with a gauge.

as for maintenance cost, find a dealer with a good maintenance package. I purchased a 4yr/40k mike service plan at a very good deal.

BlownV8

Avoid the diesel like the plague. Too many issues centered around timing chains, adblue system and related emissions components, oil leaks, turbo leaks, black death, and then there are the common issues with all GL's too. Run Forrest run!

Roger1944

Que, what is "Black death"? Suggestion to anyone buying SH any make, especially MB, pay for a full gov history, currently costs $37 and you get heaps of info plus peace of mind. My very good mate has owned his own workshop and looked after my car's for 40yrs and swears by diesels like anything treat it right and follow the manual especially for service, you don't have to take it to MB for service and repairs, amazing how many parts fit other makes at the right price.

geniushanbiao

Be honest it depends on what you are expecting. If you are expecting for something like your refrigerator that you are simply using it without having to pay some care, go with the MDX. The GL definitely rides better than the MDX and has more room, but you'll need to pay some care to it.

BlownV8

Google Mercedes Black Death. As always, internet search is your friend and will give you the largest perspective from costs to opinions.

The OM642 is not your granddad's diesel. This one is plagued with very expensive issues. You can google that too or go over to the X164 forum and see what to expect when the car gets a few miles on it.

geniushanbiao

I be very honest the black death is really a small issue on OM642 and it usually won't happen until the motor reaches at lease 100k miles milestone and can be easily prevented by replacing the seals every 100k miles or so. The biggest problems with OM642 to me is actually the timing chain, as I have no way to predict when it's going to happen, although I haven't encountered it yet. Hopefully I won't be having the issue. Other problems are mostly preventable as long as you know how to properly care it.

BlownV8

Agreed, black death is not a deal breaker for the OM642 but the adblue system and tank failures, timing chain failures, and oil cooler.seal failures are.

geniushanbiao

If you compare between the available engines offered on the 166 model, each of them has some common issue due to design flaw or parts supply quality. Each engine has its own pros and cons, but overall I'd say the OM642 is probably the best among the engines offered for the 166 model. The M278 has an even bigger issue with the silitec cylinder lining and will require engine replacement if it happens. Rebuilding is even quite difficult. I remember another folk posted the rebuilding of a M278 on a GL in the forum. There's not too much we can do to prevent it from happening. The M276 is also problematic although it's already better than its predecessor M272. I used to have a 2013 C300 with the M276 and at just less than 60k miles the engine had a sudden loss of power on highway when my wife was driving it. The problem went away upon restart, and there was no trouble recorded in the computer. Dealer couldn't find anything wrong either and we couldn't reproduce the problem. Not to mention the carbon deposit problem with those DI engines.

At least the OM642 gives the best range with each fill up. Gas mileage might not be much better considering the cost of additives, and maintenance cost is at least comparable to me.

BlownV8

That's a joke right about the OM642 being the best engine? Must be a joke. Cost of keeping the diesel on the road will be way more than a comparable gasser even with a slight advantage in MPG's. There are just too many issues with the engine and the issues with the gas versions are hit or miss. The OM642 need oil cooler seals and timing chains/tensioners like clockwork. Not to mention the clogged emissions components and other emissions related issues. Don't see this engine making it back to a US GLS ever. So much for the best engine thoughts.

Here's the typical OM642 story. https://mbworld.org/forums/gl-class-...row-towel.html

geniushanbiao

I'm not joking. OM642 is not the same as the gassers. It requires some extra maintenance work like intake cleaning at every service. It's not trouble free, but with proper care it lasts wayyyy longer than the gasser. Lots of "typical" OM642 you are talking about here are due to improper care. TBH even the US dealers don't know how to care the OM642 properly. The same motor works much better in Europe than in US.

Similar story happens on VW/Audi/BMW as well. The basic skill set required to work on those German cars are much higher than others, which is also well beyond the average education level of US auto mechanics. That makes it much more difficult for those vehicles to receive proper care here. Problem resides in the human, not the machine itself.

Long story short, with proper care, OM642 is the best. However with typical care in US, gassers win.

BlownV8

The 350 requires excess maintenance and is not suitable for most US drivers unless it is in a long haul type situation or in a vehicle that runs all day every day without stopping and starting. I've got 250k+ miles on my GL450. Cheapest car I've ever had to maintain. Changed plugs, plug wires, and coil packs at 200k miles for a little over $100. Pretty much all the engine needed that was not covered under warranty. Oil and fluids are the only maintenance items I've had engine wise.

geniushanbiao

I don't think I'll have the opportunity to drive my cars to 200k+ miles because I live around Philadelphia and average driving distance is not that high.
I have a 2012 ML and a 2015 GL both with OM642 one with 96k the other with 75k. I bought both of them used. The ML was bought with 82k and the GL was bought just recently with 70k. They both received "typical" dealer service in the past according to history, but not according to the "proper care" I talked about. That's obviously not enough for both vehicles. I be honest the dealer service doesn't even include transmission fluid and filter change, which I changed both of them after purchase and found the transmission fluid dark color. The ML was obviously used for towing by the previous owner extensively as I can judge from the black differential fluid coming out of the rear diff when I replaced fluid. So far both of them are running well. The GL is leaking a little bit oil so I'm replacing the oil cooler seals now in my garage. I have this posted in the diesel forum.

It's good you got 250k+ on your GL450. But it's not a "typical" case for the 450 model. You can look around and see how many complaints about the 450 model, including a lot of non-addressable issues like this.
https://mbworld.org/forums/gl-class-...e-trouble.html
Also I don't know which engine you have in your 450. They put a detuned M278 in the 13-14 model and a charged M276 in the 15+ model. I don't know which one behaves better, but they both have issues born with them. From my observations, if you compare 450 and 350 you can't really say which one is better. Both have examples that last more than 200k miles and both have examples fail within 100k miles. You don't have to agree with me that the OM642 is better, but at least they are comparable. I haven't even mentioned the towing advantage from the diesel due to the huge torque. Although I'm not towing things very frequently, I do have RV trailer that I use for vacation so towing is a must to me. I don't have opportunity to compare the 350 and 450 on towing, but other folks who have done this all say the 350 is much better.

BlownV8

The diesel does not really have an advantage over the modern tuned bi-turbo V8 in the MB, certainly not one over the M157 in my GL, and not much of one over a tuned v6 tt. The reliability of the OM642 is abysmal and not at all comperable to the other GL engines. You have to search for problems with the other engines and in comparison to how many were produced is a fraction of the total. OM642 all suffer from the same issues. You are looking a big ticket repairs soon if you haven't already and you know what I'm talking about.

geniushanbiao

Well let's see. You can be comfortable with your own gasser while I'm satisfied with my diesel. There's no need to judge other's choice. If you like judgement then I hope you don't run into silitec problem soon as well. That will only lead to engine replacement or if you want to rebuild it, you can try to get in an iron sleeve instead of the silitec, but iron sleeve will never perform the same way as silitec. At least whatever problem that might happen on OM642 will not lead to engine replacement. At least Om642 doesn't use the nasty silitec. Rebuilding is always an option.

I work on my own cars and I know how to care the diesels properly. I agree that if you rely on dealer or indy shop the diesel will cost you more in maintenance/repair, but that's certainly not my case. I know what problem I might be facing in the future, but none of them is costly to me. I have owned a few gas MBs before and I know how they are.

Performance wise, The M157 is faster if you floor gas all the time, but with average daily drive the diesel performs better than the V8tt overall in my opinion. You can't simply compare a gas and diesel using the spec data. Most people who have driven both vehicles say the diesel feels better in daily driving although they can't tell why. I'm tired of hearing the noise of those gas engines. They sound really terrible compared to the diesel. That's part of the reason I switched to diesel.

If the diesels are really as bad as you described, then why the hell are there so many OM642 in the sprinters in both US and Europe? You can take a look a the sprinters on craigslist a lot of them are hitting 200k or even 300k miles.

vivaitalia

@BlownV8, what year is your GL? and this is the first i've come across the reference to M157 and I have no clue ... sorry ... lol ... I currently have the 2013 GL450 V8 engine ... Thanks :-)

geniushanbiao

M157 is actually a variant of the M278 tuned for AMG models. It's equipped on GL63 AMG and If you have the 2013 GL450 then you have the detuned M278. The GL550 has the regular tuned M278. The M278 on your truck can actually be tuned to 550 easily. Some people have done that. The hardwares are exactly the same.

RostamDastan

Clean diesel components are not very reliable and are costly to repair out of warranty. Its probably safer to go with a gas engine, unless you can find a diesel that has been properly maintained (verifiable by maintenance records), or if you tow a heavy trailer and need the performance. My suggestion is to get a low mileage first generation GL 450. It has a simple naturally aspirated V8 engine and should have less issues than 5.7 liter V8 in GL 550 and 3.0 liter Turbo Diesel in GL 350 (Less issues than Turbo charged gas engine in 2nd generation GL as well). Also, no disrespect to MDX, but GL and MDX are in 2 separate leagues. After driving GL, you would not want to drive MDX. Finally, keep in mind that GL is a very expensive vehicle to maintain/repair. Its super comfortable, powerful, quiet, and efficient (at least the diesel variant), but you pay a price for that.

geniushanbiao

I'd suggest you check your information before posting. I guess the "first generation GL450" you talked about with NA V8 are actually X164 and the NA V8 is the M273. We are talking about a X166 here. The early M273 engine used on X164 suffered from balance shaft problem until around 2009-2010. Also GL550 never had a 5.7L V8. On X164 chasis the GL550 has the 5.5L M273 and on X166 chasis the GL550 has the 4.7L M278 also used on 2013-2014 GL450. The one on the GL450 is a detuned version and some people tune it to 550 easily since hardward is the same.

RostamDastan

Yes, first generation GL450 had a 4.7 NA engine. I recommend that car over X166 450 with Turbo V8 engine. You are right, first gen 550 had a 5.5 liter not 5.7 liter engine. My bad.

geniushanbiao

The M273 on the 2010-2012 X164 is pretty solid, but the performance is not as good as latter models. Even the detuned M278 on X166 GL450 has much more power than the M273 on X164 GL450 (362hp/406lbft vs 335hp/339lbft), not to mention the possibility to turn the detuned M278 to a regular (429hp/516lbft). The major advantage of M273 is that it uses port injection so it doesn't have the problem of carbon buildup on DI engines, but on MB DI engines the carbon buildup is not as a big issue as those on VW/Audi though.

BlownV8

If you are going to tune the bi-turbo V8 450, go for the 550 hp tune.

geniushanbiao

One fun fact is that if you go with the 429 or 449hp tune to make the GL450 a GL550, then you'll gain a little MPG. 550hp tune is also a fun thing to do.
The OM642 can also be tuned crazily as well if you do the EGR/DPF delete, however it will make the vehicle not that environmentally friendly. In US a lot of states don't have emission inspection on diesel vehicles that makes this mod practically possible.