So I purchased a black 2011 GL550 with black interior with the factory TV entertainment system. The body and interior are in excellent condition.
The guy was about to trade it in for a new one, so I was able to purchase it from him for $4000.

It runs great but has a few issues that he was very open about but at $4k, that gives me a lot of wiggle room to deal with the issues. I will do most of the work myself.

First thing I want to do is change all of the fluid:

- Both differentials: Are you guys using Mobile1 75W90 for LSD? I hear its .5 quarts per diff.
- Transaxle: What fluid are you guys using and how much is needed?
- Oil: I'll run full synthetic using Mann filters.
- Power steering fluid: Do you guys just use the turkey baster method? Which fluid do you prefer? I've noticed the power steering whines while turning wheel.
- Brake fluid: I'll power bleed these to get out all of the fluid and put in new fluid.
- Transmission fluid & filter: I will have the dealer do that. From what I understand, this should only be done by the dealer and should cost about $300?

Mechanical things-to-do:

- Rear shocks are gone. It bounces all over the place like there are no shocks on it. Although it fares better when I switch it from Comfort to Sport mode. I will order some new Arnot rear shocks with ADS today.
- Replace valve cover gaskets. I've notice puffs of smoke coming from the rear of engine near the firewall that smells of burning oil.
- Replace serpentine belt.

Things I've noticed:

- When making sharp turns (mainly right turns) I feel a slight resistance/shutter. It reminds me of what was happening to my AWD Honda CRV. I resolved that issue by simply replacing the differential fluid and adding a bottle of LS additive. I hoping thats all this needs.

- If I accelerate slowly sometimes I feel like I'm driving on a cobble stone road. Last for about a second or two then its fine.

- During moments of acceleration (sometimes when driving straight but mostly when accelerating while turning) It feels like I'm driving on a cobblestone road. A passenger may not notice it but as the driver I do. It only last for a second or two.
- The transmission seamlessly changes gears and I don't hear any noises.
- The engine runs very smooth.
- Power Steering: does whine while turning steering wheel.

 

Tonight I changed the:
- front & rear differential fluid and I was happy to see the fluid that came out was still honey translucent color. There were no metal shavings or gritty feel to the sludge on the drain plug.

- Transaxle fluid was equally in good shape.

- I also suctioned the power steering fluid out of the reservoir and added new fluid.

After changing the power steering fluid the whine dramatically reduced, Still slightly there but much better.

After changing the differential fluids it appears to be doing much better although it could just be in my head.

Everything under the car looked to be in great shape with the exception of the transmission pan, it was very rusty. Looks like I will have the dealer install a new one when I have them replace the transmission fluid and filter. Anyone knows approximately what that may run for them to install a new transmission pan, drain & fill fluid and install filter?

 

Yes. Please check on of my threads for replacement of the tranny pan. I attached my receipt in that thread.

 

Dont replace the valve cover gasket as there is none. It is just a form a gasket thingy. You can buy from MB parts dept. it is probably the rear cam plug that is leaking. Easy fix.

 

I'm order this transmission pan kit pl;us 3 extra liters of fluid for the flush for $260 and I'll have a local Mercedes indy shop doe the work for $180.

https://www.fcpeuro.com/products/mer...n-001989680310

 

Thanks a million, I just ordered the plugs.

 

Really. Check my receipt. It wasn't that much I think.


Reasonable price though

 

The main fcp euro kits are what you should buy.

The plug kit and oil separator one is important.

The belt and idlerpulkey tensioner one is probably a good one.
The fcp euro 8 cylinder tune up kit too as well as their maintained service kit one wirh the spark plugs.

 

You're talking about this one correct?

https://www.fcpeuro.com/products/mer...es-2720100631k

 

Yes sirree

 

Also I see thgt they have the sway end link kit.

This is a must for front and rear. Lemforder or mb genuine only.

 

Congrats on the the GL!! To follow up on the engine smell, I also recommend using FCP Euro for the crankcase vent valve and rear cam plugs. Some folks have had problems with aftermarket ones sold on Amazon and other places. I had this same problem and I had a leaking crankcase vent valve and cam plug. Fixed the leak/smell.

Good luck!

 

In a separate thread I talk about my challenges with Dorman brand plugs. I solved it by sealing them with good high temp silicone (Permatex black). I recommend this regardless of the brand of plug, because even the OEM ones leak.

 

Update:

So after returning from a week long vacation I'm finally able to resume working on the GL550.

Yesterday I replaced the rear shocks and I was happy to see it partially resolved another issue that I didn't think was even remotely related to them. The issue was sometimes when I accelerated or accelerated while making right hand turns the car would shutter from the rear for a second or two....almost likely driving over those speed strips when approaching pay tolls (not the sound, just the feel). The issue isn't 100% gone but it doesn't happen anymore when accelerating straight and is barely noticeable when accelerating from a right or left hand turn.

I also replaced the three plugs and oil separator and the happy to report the leak has stopped but I did notice this morning that the engine started stumbling at idle every few revolutions that coincided with an odd noise coming from the same location where I just installed the oil separator. I'll have to investigate that further tonight. *** UPDATE on this: About an hour after writing this post I took a quick ride to the gas station to video record the issue but it was gone. The issue appears to of resolved it self.

I'll be doing the spark plugs next.

 

So the engine miss actually is still happening.

This morning I sprayed the MAF with CRC MAF cleaner going off the assumption that dirt may of fallen onto the MAF sensor while removing the the air box. Unfortunately that didn't resolve the issue.

It's not a consistent miss and it only started after replacing the Oil separator and 3 plugs. No CEL as of yet. It only happens at idle but runs amazing great while driving. When it happens the RPM's fluctuate between 5K to 8K.

Here is the Youtube video of the noise:

 

So I finally go the CEL. I never thought I would be happy to get the CEL light on.

I only have a generic reader but those codes are P0172 (Bank 1 too rich) & P0175 (Bank 2 too rich).

Given that it;s running too rich, I believe I can rule out a vacuum leak.

I did remove and reinstalled the Oil Separator I put on the other day to make sure it was seated properly. I did notice that (before installing the bolts) it rocks left and right, creating a 1/8' gap on the opposite side as it rocked. It doesn't rock up/down, only left/right. I put the Oil Separator on a flat surface to make sure it wasn't warped, but it was flat. I reinstalled it and tightened it down really good. After starting it, it appeared to run better but the symptoms returned after driving it.

Secondary Air...possible?
MAF......possible.

I think it would be smart to have an Indy shop do a real diagnostic on it to determine what is really causing the issue.

 

Following for updates as I'm in the process of getting all the plugs for a tune up.

I'll definitely check out fcp euro for the whole kit. I have a 2010 550.

 

Update: This update is regarding the surging at idle issue I'm experiencing after changing the Oil Separator and three plugs.

I don't believe changing those parts are in any way related to the issue. I believe the dust that was knocked loose during the removal installation of the air intake box may of damaged the MAF sensor. So I took the MAF sensor off the day before yesterday (easy peasy) and sprayed it down real good with some CRC Mass Air Flow cleaner. After reinstalling the MAF it initially ran worse but leveled out after a short drive. The surge is still there but a ton better than what it was. So I do believe the MAF sensor was damaged from the dust, so I ordered a new one and some new air filters that will arrive today. I'll keep you posted on the results.

Yesterday I decided to replace the spark plugs with Denso Iridiums. This was probably the easiest tune-up I've ever done on an eight cylinder car. It took less than 30 minutes to replace all spark plugs.
The old spark plugs were Autolite Iridiums and looked almost brand new. I'm assuming the previous owner had recently replaced them. I installed new plugs with anti-seize on the threads and dielectric grease in the boots. The engine is purring like a kitten.

My next task is to resolve the random shutter on acceleration / shutter on acceleration from sharp turn.
Possible culprits:
- intake manifold flap ( https://www.ebay.com/itm/Metal-Intak...IAAOSwyJFcpcb0 although I don't think so because I would assume the RPM's would fluctuate when it happens if the flaps were operating improperly)
- Transfer case (I don't think so because if the chain was stretched I would assume it would be more of a jumping kind of fell rather than a shudder. Plus what I'm experiencing doesn't always happen and doesn't exist during the first few minutes of driving after the car is cold. A stretched chain would have issues no matter when you drove the car.k)
- differential (I don't think so but possible)
- transmission (I don't think so because the transmission changes gears flawlessly)
- fuel delivery to keep up with demand (I don't think so because the RPM's would fluctuate if the fuel was reduced when the engine required more.
- flex disks and shaft bearing
- motor mount

 

Update: I picked up a used MAF sensor from the salvage yard for $30 and installed it. I'm happy to report that the issue is gone.

Besides for the shutter I was also getting the rotten egg/sulfur smell from the exhaust due to the unspent fuel being dumped into the catalytic converter as a result of the engine running too rich. The rotten egg smell is gone now.

 

Not to be Negative Nellie, but a new MAF sensor is about $60-$70. Given how fragile they are, I wouldn't put a used one in.

It would be interesting to find who manufactures for MB / Bosch. Knowing how little goes in to those things, they should not cost more than about $25 new.

 

Normally I would agree with you and would of purchased a Bosch one from FCP Euro for $85 (I wouldn't consider buying an Ebay version), but I didn't have patience to wait for it to arrive via shipping so I grabbed one from the salvage yard. Also I wasn't 100% sure that was the issue so I didn't want to buy a brand new part only to find out my current part was perfectly fine.

The way I look at it is, I was able to resolve my issue for $30 and if it goes bad in the future I will purchase a new one, but for now I can use that $50 savings on other parts

 

Over the weekend I found out I have remote start. I noticed a yellow warning sticker in the door about the remote starter from the company Smartkey Starter so I went to their website to see how to use the remote starter, pushed the red panic button on my remote and the car started right up.

Niiiicccceee

 

You'll likely be fine. I don't know what goes wrong with those things, but my sense is they typically last around 10 years.

 

So I didn't clear the codes after replacing the MAF sensor because i wanted to let the cars system confirm that everything was ok. So today while driving the CEL light went out, plus there was another positive unexpected result as well. The random shutter on acceleration or while accelerating after a turn has gone away after changing the MAF sensor. Also it is so much quicker on acceleration than before. I always felt as though something was holding it back, so now I know.

I'm curious to see how my fuel mileage might improve.

Now I can get back on track with replacing the transmission oil pan, filter & fluid.

 

So this past weekend I replaced the Flex disc. It's not a hard job at all. It took me about two hours due to my own issues but honestly it can be down in an hour. no special tools and no lift needed.

Although it's hard to tell from the pictures, there were a few cracks on the rubber that was very apparent while stretching the disc to remove it.




Make sure the rear wheels are off the ground before you begin. The driveshaft can't be rotated by hand to access all of the bolts if the rear tites are on the ground, even with the tranny in neutral.





Not many tools are needed. 18MM socket, 18mm wrench, T55 socket, 8mm socket, 10mm socket






After removing the 6 bolts I was met with the surprise of a rod that went through the disc. In an X164 YouTube video I watch in preparation for replacing the flex disc, there was no rod in his video. I'm assuming the GL450 doesn't have the rod but the GL550 does......don't know but mine did. So I had to figure out how to get additional play in the driveshaft to remove the disc. The wetness you see in the picture is just PB Blast.



You need to remove the heatshield and the two large bolts holding up the axle shaft to get additional play in the driveshaft to be able to remove the flex disc.




I used a pickle fork to release the flex desc from the differential side and axle side. those little round metal sleeves in the flex disc are compression sleeves that lock into the axle shaft holes once pressed in, as a result they are extremely difficult to separate.




Here is a better shot of the rod that will prevent you from removing the flex disc. There is only about 3/8' move rod sticking inside, so the trick is just to stick something between both to force it out, using a flat metal instrument as leverage.



Don't attempt to remove the shaft from this end to give you the extra play......just trust me.




This is how it looked after I was able to get the rod out, which then allowed me to remove the flex disc. Now you just have to install the new flex disc in reverse.