2014 GL450, almost 75K.



Short: Car wouldn't start after driving around on a hot day, lots of start/stop, finally started and wouldn't go over 2k RPMs, CEL came on finally with P0238 and P0339. Called mercedes, part was going to take two weeks to get in. Rockauto had it to me in 3 days. Now I cannot find the sensor. I cannot find instructions in WIS for M278.928 (i'm not an expert, but I can find the instructions on the v6 gls). Does our engine even have it? Mercedes gave me the part info based on the vin?



Long:



Car was running rough and had a misfire on cylinders 3 and 6. I thought it was spark plugs and replaced those again. Didn't go away. Took it in to an independent as I hadn't liked my experience with the dealer and independent was highly referred. 3.5 months and over $13,000 later I have rebuilt heads as he said valve guides were bad on those cylinders, new fuel pump and 3 injectors, 2 new coil packs, new engine mounts, one of the turbo pipes, timing guides/serviceable parts, all sorts of fluids and filters. It was an engine out so I asked him to do everything reasonable to make sure the care was reliable as I wasn't expecting an engine out at 72k miles.



I've had a lot of trouble with this repair. I wasn't driving it as it got hotter because the A/c didn't work in the heat (wasn't filled correctly or has a big leak, seems to be holding what I put in). I fixed the a/c and drove it and after several start stops it failed, then went into limp mode. Let it sit for an hour and it started up and drove the 40 miles home with no lights. All codes/experience seems to point to Crank position sensor versus cams/timing.



I've torn into it following the v6 instructions and i'm too the part where I drop the exhaust. I'm still not even seeing the sensor and after double checking the instructions realized I had the v6 and cannot find v8 ones.



Any help would be appreciated. I'm trying to get it in running shape so I can resolve the issues remaining after his "repairs": Both rear struts are magically leaking after he dropped gas tank, AC needs to be evac'd and done properly or leaks fixed, losing about 1 liter of oil every 1000 miles (it has never burned oil).

 

Crankshaft position sensor at 16 minutes.

 

Thank you!

This is where I thought it was from viewing other engines on ebay/wis. I just cannot find my way to it. There are coolant lines, brake lines/vaccum lines etc. The v6 says to remove the cat to get to it so that is what I guess i'm doing next! I'll post any updates on tricks I figure out.

So Far I've removed the Cowl, cross braces, windshield whipers, and plastics along the firewall. Still not enough to get in and find the right sensor.

 

Finally confident it was there I went from underneath. Took about 3 hours which is way less time than I spent tearing apart the top!

Driver's side cat comes off, then you can reach in and do it by feel. Both body pans, drivers side trans mount and resonator mount came off to get the cat out. Worst part is the clips for the o2 sensors and one of the two reverse torx bolts for the cat. Once cat is down you can reach in and feel the clip, pop it off. It was a torx t25 i believe. I could not get a torque wrench back in for the 8 Nm so I just gave it a GoodnTight.

Everything I found online said go from the top, but the way the intake and head stick out past the block, plus with hoses/lines in the way, i could not get a feel from the top. Bottom was simple and straight forward.

I'll post an organized write up and a couple pics I tried to take later. Thanks again.

 

Why new fuel pump and coil packs? Just wondering

 

Losing oil is an interesting thing. Oil smell from the exhaust?

 

Your story sounds like mine except you are further down the rabbit hole. I have random misfires first it was one cylinder, then two, then 4 and of course then all 8. Replaced all plugs, all coils and all injectors. Then all 4 cam position sensors and the HP fuel pumps. Now I have new codes O2 sensor and turbo charger pressure to high. What was the final conclusion on the source of your problem? Why did you come to that conclusion? Did you find others that had similar issue with their M278 engine?

Regards,
Don


Short: Car wouldn't start after driving around on a hot day, lots of start/stop, finally started and wouldn't go over 2k RPMs, CEL came on finally with P0238 and P0339. Called mercedes, part was going to take two weeks to get in. Rockauto had it to me in 3 days. Now I cannot find the sensor. I cannot find instructions in WIS for M278.928 (i'm not an expert, but I can find the instructions on the v6 gls). Does our engine even have it? Mercedes gave me the part info based on the vin?



Long:



Car was running rough and had a misfire on cylinders 3 and 6. I thought it was spark plugs and replaced those again. Didn't go away. Took it in to an independent as I hadn't liked my experience with the dealer and independent was highly referred. 3.5 months and over $13,000 later I have rebuilt heads as he said valve guides were bad on those cylinders, new fuel pump and 3 injectors, 2 new coil packs, new engine mounts, one of the turbo pipes, timing guides/serviceable parts, all sorts of fluids and filters. It was an engine out so I asked him to do everything reasonable to make sure the care was reliable as I wasn't expecting an engine out at 72k miles.



I've had a lot of trouble with this repair. I wasn't driving it as it got hotter because the A/c didn't work in the heat (wasn't filled correctly or has a big leak, seems to be holding what I put in). I fixed the a/c and drove it and after several start stops it failed, then went into limp mode. Let it sit for an hour and it started up and drove the 40 miles home with no lights. All codes/experience seems to point to Crank position sensor versus cams/timing.



I've torn into it following the v6 instructions and i'm too the part where I drop the exhaust. I'm still not even seeing the sensor and after double checking the instructions realized I had the v6 and cannot find v8 ones.



Any help would be appreciated. I'm trying to get it in running shape so I can resolve the issues remaining after his "repairs": Both rear struts are magically leaking after he dropped gas tank, AC needs to be evac'd and done properly or leaks fixed, losing about 1 liter of oil every 1000 miles (it has never burned oil).[/QUOTE]