2006Merc

Hi all, I have a unique situation on my 2006 E350 4matic wagon. This all started with a loud noise coming out from under the hood when the engine is running. This noise would rise and fall with RPMs. After checking several forum threads and youtube I have replaced, first, the alternator, tensioner, Serpentine belt. No cure. Then I replaced the power steering pump and reservoir. No cure. I am now down to the water pump. The interesting thing about this car is that for some reason Mercedes decided to change the application of certain parts mid year, with that said I have purchased several parts that did not fit causing frustration when having to reorder. I ordered a new water pump and had it installed only to discover that it was the wrong pump. So after removing the new pump I reinstalled the old pump while the correct pump is on order. Now all of a sudden my radiator fan cycles on and off more than it used to and I have no hot air when the heat is on. The only electrical connectors that were touched was the radiator fan connector and the small connector at the thermostat housing. Both of those are reconnected. Any ideas will be greatly appreciated.

rapidoxidation

When you order parts, provide the seller with your car's VIN. They should be able to make sure you have the correct part for your car before selling it to you. If they can't or won't, find another seller.

To your other question: Check connections, even ones you "know" you didn't touch. It's pretty easy to knock something loose when working in tight places.

If the water pump wasn't the right one, how did you install it?

Plutoe

Do a search on MB heating systems and concentrate in the device that allows hot coolant to circulate on demand!----Don't go out and replace the complete AC\heating system---start small this time.

2006Merc

Everything lined up but the shorter bolts bottomed in the block 1/16 before contacting the housing. Also the lower idler pulley mount had a nipple on it and my original was smooth.