VR6 main water pump

[MartiniOlive]

Not long ago, my main water pump bearing failed and this caused the water pump pulley to go out of alignment and as a result the serpentine belt broke off. On taking the pump out, I found out that the impeller is made out of plastic and when the bearing failed, it hit the side of its housing inside the block and broke up. Sending pieces of plastic into the cooling system. I fished the bigger pieces out and tried back flushing the engine to get the smaller bits but can only get about half of them. Gave up and put it all back and it seems to be OK so far.

The new pump has a metal impeller but I don't think that's the main problem. My opinion is that the water pump is poorly designed. The bearing should never be allowed to fail like this and allow the pulley/impeller to get out of alignment. The worst I've experienced in the MKI (and other cars) is a leaky pump or a noisy bearing.

I've read that a similar water pump is also used in 1.8T but with worst consequences. The water pump is driven by the timing belt and when it fails, the cams and the crank can get out of alignment with the worst case senario of piston and valves making contact. One hopes that VW have redesigned the pump in the MKV.

[imported_brackie]

I agree. There's no excuse for poor design in a car with the breeding of a VR6. Plastic water pump impeller! :roll: I wouldn't sweat about not having removed the smaller bits of plastic from an old Golf or Passat cooling system as the tubes in the radiator are of a large diameter, but I don't know about the VR6. I used to install a plastic cone-shaped filter in the top hose of any car that I had worked on and had used silicone on cooling system gaskets. It was available from the RAC and it caught a scary amount of silicone and Al oxide lumps coursing around the cooling system. If you can still get them it should be worth the $4.

[Bug_racer]

Im yet to see a water pump lock up on a 1.8t or any mk4 4 cylinder (they are all the same design ) Most VR6 water pumps last over 100k km , most 4 cylinder mk4 units dont make it to 120000km when timing belt is due

[aprr32]

I change more water pumps on 1.8 and 2l Golf4/NB than you would believe. That plastic impellor is the most stupid design I have ever seen.Most seem to fail at the 80 to 90 thou mark or are just about to let go at the belt change. I guess the make it to the end of the warranty if thats what counts VW.

[Bug_racer]

Earliest water pump I changed was at 23k km and the car was just over a year old . The S3 / TT motors are the best ones , they dont crack the impellors as easy . Must be due to the electric water pump ?