M6csi
04-23-2008, 02:05 AM
Just had an unfortunate experience with a non-oem water pump which I bought and installed today. Having never replace an M6 water pump, I had no clue as to who manufactured the oem unit so the Bosch part looked pretty enticing as compared to other lesser name aftermarket parts manufactures.
The unit in question in a Bosch water pump labeled as an 87 and 88 M5/M6 replacement with the Bmw part number. I bought it from an online parts retailer at about $40 compared to the $200 Bmw unit. The Bosch and the original Bmw water pump look identical with no discernible differences. I was kind of weary though when I checked the box, to my amazement, this Bosch part was made in China and not from Germany.
The installation process went in effortlessly with no fanfare. I also installed a new radiator with all new cooling system hoses and a full coolant system flush through the engine block drain. At this point, I was almost done so I poured in new coolant and proceeded to mount the pulley for the fan clutch, to my horror, the four mounting holes on the pully did not lined up with the holes on the water pump flange. After being dumbfounded for a short while, I discovered the mounting holes on the Bosch unit are symmetrically lined up on a square or X pattern whereas the oem Bmw unit is configured in a more non symmetrical rectangular layout.
My car was needed to run an errand for a friend so not finishing up on the car was not an option. I did managed to mount two bolts on the pulley and the water pump, two on the opposite end of the X layout. Hopefully, this will hold up and not backfire on me before I replace this crappy unit with a Bmw unit or a Graf pump.
Another design flaw is the big stub bolt on the water pump flange is shallower than the Bmw unit and does not allow the fan clutch mounting nut to be fully tightened. Right now, the nut while securely fastened but it is resting fully on the pump flange but I'm not too comfortable with this setup on a longterm basis.
Boy, do I dread tackling this water pump replacement again as the M6 radiator does not have a drain petcock thereby even a partial draining of the coolant is a messy process.
So, it does not pay to buy cheap parts. Even though the part was made in China, I do blame Bosch fully that they do not have better quality control on their products. I have learned my lesson.
The unit in question in a Bosch water pump labeled as an 87 and 88 M5/M6 replacement with the Bmw part number. I bought it from an online parts retailer at about $40 compared to the $200 Bmw unit. The Bosch and the original Bmw water pump look identical with no discernible differences. I was kind of weary though when I checked the box, to my amazement, this Bosch part was made in China and not from Germany.
The installation process went in effortlessly with no fanfare. I also installed a new radiator with all new cooling system hoses and a full coolant system flush through the engine block drain. At this point, I was almost done so I poured in new coolant and proceeded to mount the pulley for the fan clutch, to my horror, the four mounting holes on the pully did not lined up with the holes on the water pump flange. After being dumbfounded for a short while, I discovered the mounting holes on the Bosch unit are symmetrically lined up on a square or X pattern whereas the oem Bmw unit is configured in a more non symmetrical rectangular layout.
My car was needed to run an errand for a friend so not finishing up on the car was not an option. I did managed to mount two bolts on the pulley and the water pump, two on the opposite end of the X layout. Hopefully, this will hold up and not backfire on me before I replace this crappy unit with a Bmw unit or a Graf pump.
Another design flaw is the big stub bolt on the water pump flange is shallower than the Bmw unit and does not allow the fan clutch mounting nut to be fully tightened. Right now, the nut while securely fastened but it is resting fully on the pump flange but I'm not too comfortable with this setup on a longterm basis.
Boy, do I dread tackling this water pump replacement again as the M6 radiator does not have a drain petcock thereby even a partial draining of the coolant is a messy process.
So, it does not pay to buy cheap parts. Even though the part was made in China, I do blame Bosch fully that they do not have better quality control on their products. I have learned my lesson.