Msnrasool

Hello Everyone,

I am new to the MBworld and to Mercedes 2014 GL450 W166, M278 engine with 108K miles . There was no record of prior transmission fluid change so I have got it done yesterday at a dealership in Twin Cities. MN. All went well with transmission (they didnt drain comberter), no issues with fluid that came out or metal shaving in the pan. I must say this was a relief. However tech pointed out water pump pully walking out. Looking at the wear pattern on pullly, It seems to me belt has been riding on same spot for long time. See attateched picture. There are no leaks and no issue with engine temprature . Dealer wanted 2300 for the job. I can do this on my own and will take me bit longer.

Is this is something that needs to be taking care right away? Does anyone has step by step procedure for that job.

Water Pump pully wear pattern/belt current path.

Thanks

Jamal

BlownV8

I can't tell much from the pic but it's not uncommon, according to many members on this site, for the MB dealers to persuade customers to do unnecessary work to pad their bottom line.

Msnrasool

Thankss, pully has walked out about 1/8 an inch, trried to show belt movement in attatched pic (within half fill yellow circle). I understand this can fail anytime but wondering how quickly it has failed for others.

I will change and will do it myself.

Jamal

rapidoxidation

Is the back edge of the belt supported by the pulley? If so, I'd be inclined to just monitor. If it is hanging over the edge, you know what you'll be doing this weekend.

Msnrasool

Belt is hanging over the edge by 1/8 of an inch. Looks like it has been running there for long time. Since I know now, I will change the pump and whatever else I break doing that. Plastic lines, touch them and they are yours.

Does Anybody have repair manual step by step instruction. I did watch youtube videos but instruction work better for.me.

Thanks.

chassis

Belt replacement is trivially easy. Check the DIY in my signature. It's for M276, but applies in principle to M278 also.

Check idler and tensioner pulleys to see if they are causing the belt to wander. "Water pulley riding out" is not posted on this site often, or ever.

I don't see that your water pump pulley has moved, from the photos.

Msnrasool

Thanks! Over the weekend, I did a 250 miles round trip to Des Moines, IA without any change in belt position on the pump pully. I will check the tentioner and idler pulley tomorrow.

If i am going to do the pump, make sense for me to replace the turbo cooler lines as well, most likely they will break during disassembly.

Jamal