When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
For those of you looking into a 2013 or early Model X166, besides bringing it for a pre-purchase inspection, I would recommend scanning for any engine codes or "stored" codes for Cylinder #5 misfire as you do not want to go through the hassle I went. Especially for these cars, topping off the purchase with an extended warranty consideration would be essential as many things can go wrong if the one you are buying isn't Certified Pre Owned.
Essentially, not even 2 months after purchasing our GL550, the Check engine light came on for Misfire on Cylinder 5
We took it to the dealer and dealer informed us the 70k interval maintenance had already been done so transmission fluid and more importantly, spark plugs had been changed. We had these items changed after the light came on which did not resolve the problem for me:
-Both MAP sensors: 0071530528 Manifold Absolute Pressure Sensor (As it worked for another member)
-Ignition coil
-Changed both engine air filters
-Fuel injectors (changed them 3 times at the dealer as they kept thinking this was the problem)
-Software update (at the dealer. After changing the fuel injector the 2nd time, they discovered there was somehow an "update" and went ahead and updated it)
This problem still persisted and everything checked out fine which puzzled the dealer, leading to an engine disassembly.....Engine was dropped which transmission, exhaust, and many others had to come out.
Fun stuff.....
After engine disassembly.......:
Leaking Cylinder
The circled cylinder in blue is what the technician told me was the cylinder that was leaking and the "valves", in red, specifically was the actual "seals" (either intake or exhaust - don't remember), that were leaking.
He also did a water test for me. MP4 vids don't post here so here is the link:
Since the engine is out, this might be a good time to port and polish the heads, as well as replace the valve stems. Then it would be like a brand new engine after they get it back together and will put out even more power than stock and run more efficiently. If the mechanic working on it is a car enthusiast and has experience with rebuilds, then you may be able to talk him into doing it as a side job on the weekend. Since the engine is already taken apart, it shouldn't cost all that much to do it.
Do you currently have a warranty on it? How much have the repairs run you so far?
On 6/26/2019, we finally got our car back. After engine disassembly, our extended warranty company, Endurance had been delaying the repair as long as they could. They went back and forth, sending inspector after inspector, and did not believe the heads with Cylinder #5 was leaking. They made the dealer send the head to an independent head repair shop, have them inspect it, and then return it to the dealer. Even though we had the "top-of-the-line", "bumper-to-bumper" warranty package listed on their website as "Supreme" package, to offer "peace-of-mind", they were a PITA to deal with. Calls took 30 minutes on hold to get to a "customer service" agent who had no idea what was going on. Both, my service advisor (SA), and myself had to repetitively call to follow on essentially everything. The "rental car" option actually only covers up to something like 7 days of the repair and you had to get it from, I believe the company, Enterprise, unlike CPO offers dealer loaner cars for the length of the repair. Endurance finally had no choice, but to repair the GL.
Basically, they went literally "By the book". They only paid for what was "essential" to the disassembly of the engine and reassembly and also brought their own parts in. Because only 1 of the 2 heads was bad and needed replacement, the SA strongly recommended replacing the other head too. Only the cost of parts, would have totalled to $13,593 for the full engine rebuild (Attached PDF). The extended warranty company offered to purchase their own parts from their own source(Which was half of the parts on the list for one head), and I also brought in my own parts(The other half of the parts on the parts list for the other head) which totalled to around $4000, instead of $6500 which the dealer wanted per the pdf attached.
After all the parts arrived, the dealer started engine reassembly. The engine reassembly process was also on-and-off since apparently the technician installing it "lost some parts" and also realized some parts could not be put back onto the car, like Thermostat, coolant hoses, etc. At this point, the "extra parts" needed, was billed into the invoice and SA had called Endurance to finalize the bill. Final cost of the bill at the dealer was $10119.99 and endurance only paid $7253.17 (Basically labor + very little "extra parts" they covered) when my deductible is $200....... My total cost at the dealer was $3048.65 because of the "additional parts needed". Needless to say, when the technician was test driving the car, the auxiliary battery failed, so that was included into my total. I am probably forgetting some stuff as this process was from Christmas of 2018 to end of June 2019. Both files attached.
If I were to buy another used car, definitely go with CPO and a pre-purchase inspection.
@chassis I don't think the valve stem seals are that common in the M278 since I haven't seen them around in this forum except for mine. @kombifan My SA told me Certified Pre Owned and "Redshield" are the easiest to deal with. I will check out Carmax maxcare too! Thanks
2010 Mercedes GL450; 2000 Mercedes ML55 AMG; 2016 VW GLI SEL Stick!!!
For me the biggest issues have been the techs replicating difficult issues.
Carmax maxcare has been stellar in their payments and covering nearly everything. Except glass and Wear and tear items. They even covered my led rear taillight.
This also happens to the 5.5L V8 M157 engine (GL63/ML63/CLS63/E63/S63/etc). There have been about 3-4 just at my local dealership and the cost is around $15,000 out of pocket or 100% covered under factory warranty or CPO.
It's also Cylinder #5 misfire, the issue I'm told is the factory press didn't push in the sleeve correctly and causes a leak. Not all M157 are affected, but the ones that used that press were. At least what I'm told.
Interesting this also occurred on a M278 non-hand built engine.
Glad you got this fixed and enjoy your "brand new" engine!
How much did the extra valve stems cost you for the other side? Looks like normal carbon build-up so as the other poster mentioned, possibly re-gained hp/torque and fuel economy. Hopefully the car now lasts you 300,000 miles!!
Watch your transmission - if it starts clunking or hard shifting, a few also got that and the torque converter replaced under warranty - which is another $10-$15k repair at least on the AMG.
On the used market, your car is the one to own, similar to a M156 engine that already head the head bolt issue resolved!
Does anyone know if a TSB has been issued for either the valve stem seals or transmission clunk on M278? I also have 2013 GL550 with 65K miles. No issues so far with either. My CPO warranty runs out in November.
@Chedman13 What transmission do you have on your 2014 GL63? My 2013 GL550, according to a vin decoder, has the 722.909 transmission. I've never heard of the transmission clunk on the 722.9, only the conductor plate issues where the car will shift into "neutral" and you lose speed + can't shift into any gears, even with manual shifting via paddle shifters.
My 2014 GL450 just started getting rough idling at 50K. Dealership says Cylinder #5 has low pressure. They suspect its probably a bad valve. Quoted me $17K just to replace the valve/seat. That's just ridiculous. I sure I have the same problem with a factory build error. That's just too much of a coincidence.
I had a ton of trouble with my 14 gl450. I ended up putting a new engine in there. After months of research. I think I have a pretty good handle on how to fix the issue. If you want to get the heads repaired, there are a couple shops in New Jersey that very familiar with the issue. One is a Porsche race shop that my friend uses, another is a very well regarded machine shop that has done these. Cranky old guy that has seen it all. In any case, i have a complete engine sitting at home, If you wanted to buy the heads you could get them repairs so you have a replacement part to swap. The labor was really inexpensive and everyone said it made sense to just do both at the same time.
I had a ton of trouble with my 14 gl450. I ended up putting a new engine in there. After months of research. I think I have a pretty good handle on how to fix the issue. If you want to get the heads repaired, there are a couple shops in New Jersey that very familiar with the issue. One is a Porsche race shop that my friend uses, another is a very well regarded machine shop that has done these. Cranky old guy that has seen it all. In any case, i have a complete engine sitting at home, If you wanted to buy the heads you could get them repairs so you have a replacement part to swap. The labor was really inexpensive and everyone said it made sense to just do both at the same time.
Let me know if that is helpful
Thanks for the advice. I’m in Texas and don’t have access to those shops. By the time I buy the heads, pay for shipping and repair I could probably just get new ones. But honestly I have no idea. Where did you find a new engine and what did it cost? That may be more palatable since it would be much faster turn around with the car in shop. I’ve heard these repairs could take months and I’ve been quoted $17k by MB just to fix a single cylinder valve leak. I think they know about this issue. I brought it in and they did a pressure test on Cylinder 5 and it came back at 65(norm 120ish).
I’m also pretty upset with MB that this seems to be a known issue and all of us are left with these flawed engines. I’ve never had a vehicle have this type of issue with 50k miles. I love the GL450 for its ride and space but this is ugly.
Anyone have any luck getting MB to do the replacement after warranty???
i got this exact issue and my dealer (Herb Chambers Natick in MA) do the work in about a week.
I have extended warranty with CNA and they covered everything (minus odd and ends which ended up around $500).
I'd fight MB if you are not too much over the mileage after factory warranty. This is a common issue and i am baffled its not accepted as a recall.
17k is average quote for cylinder head swap (labor plus new parts) - there is no repair for valve, engine out, pull apart, drop in new head, assemble back.
As a for head rebuild it will be about 350 for overhaul in any machine shop.
Last edited by arsupisemnet; 10-22-2019 at 11:09 PM.
I am in a process of rebuilding head with compression loss at cylinder 5, which i swapped with rebuilded ones on my M278. I am very curious what is the matter. Looks like bended valve. Will check on the valve seats and so on if that is the matter behind failure.
It’s CNA warranty. I got the platinum coverage. Sold through the dealer Herb Chambers. Cost me around 3500 for 3 years 36k miles. Covers everything except wear and tear items. Includes suspension which was a key for me.
TSB M278 engine cylinder #5, #6, #7 & #8 left bank cylinder misfire
Originally Posted by BLK GL550
Does anyone know if a TSB has been issued for either the valve stem seals or transmission clunk on M278? I also have 2013 GL550 with 65K miles. No issues so far with either. My CPO warranty runs out in November.
Yes there was a TSB on this issue dated 08/06/2015
Topic l101.30-P-061835
01.30 cylinder head
M278 engine with numbers after 2789xx 30 128000
I just had my 2015 M278 engine removed and replaced the left cylinder head @ 57K miles. Cylinder #5 misfire. 2 months left on the warranty!!!
If this happened after the warranty lapses would MBZ cover it???
After reinstall of the engine, left turbo coolant line (hot side) leaked so had to replace tubing.
The engine was power washed to clean off sprayed antifreeze. Still see steam coming from fender well/hood after hard run. Smells like burning antifreeze. Dealer says wait a few days, it might be pooled water from the power wash! We will see...
01-21-2019, 01:38 PM
2014 GL450 low cylinder pressure #5
TSB M278 engine cylinder #5, #6, #7 & #8 left bank cylinder misfire
