I had some free time and all the necessary pics, so I put this little DIY together. Hope it's useful to someone.
REPLACING THE MAIN WATER PUMP ON A MKIV 12v VR6
The following outlines the procedure for replacing the main water pump on a MKIV 12v VR6 engine. It is common on high-mileage VR6 engines for the bearing in the pump to fail, resulting in a loud grinding/scratching noise when the engine is running and eventually, a significant coolant leak (the bearing acts as a seal in the pump). Contrary to what the Bentley Manual says, the engine must be raised slightly to replace the pump (it actually neglects to mention anything about having to raise the engine ). The steps below will describe how to prep the engine for raising, how to raise the engine and how to remove/replace the water pump.
The procedure below was based on a '99.5 MKIV Jetta GLS 12v VR6 and should be valid for all MKIV 12v VR6 cars regardless of model and year. The steps for raising the engine to access the water pump will be slightly different on other 12v VR6 cars (MKIII, Corrado, custom swaps), however the steps for actually removing and replacing the water pump should be the same. The procedure may also differ slightly on the MKIV 24v VR6 engine, although the steps below should also be very helpful for replacing the main water pump on that engine.
Please do these procedures at your own risk and be ready to make small adjustments while doing them. Also, please be observant while removing parts so that they go back together correctly.
The procedure below is fairly involved and potentially dangerous and extreme care should be taken while performing it. Depending on how mechanically inclined you are, it should take somewhere between 2 and 4 hours to perform. We had little idea about what to do when we started this procedure (other than researching the procedure for a MKIII 12v VR6) and it took us 4.5 hours to perform, including a lunch and beer break.
I purchased a replacement water pump (VW# 021-121-004-A) at Impex for $48.50 (recently raised to $56). The unit is manufactured by Hepu, has a metal impeller (significantly better than the plastic impeller which is used on some versions of the water pump) and comes with a new o-ring. There is also a Graf version available for roughly the same price. I'm not sure what material the impeller is made of on the Graf unit. Just in case my water pump pulley was damaged from running the engine with a water pump with a bad bearing, I purchased a new pulley (VW# 021-121-031-A) from Impex for $12. I reused the existing bolts when I performed the below procedure. If you want to purchase new bolts (not a bad idea since they sometimes strip when being removed), the VW part#s are N-905-442-01 for the pulley bolts (need 3) and N-902-218-03 for the pump mounting bolts (also need 3). They can be purchased at Impex for $0.62 and $0.95 each, respectively.
For those who want to replace engine/tranny mount bolts that are removed (some are stretch bolts), the part#s are as follows:
- passenger's side engine mount-to-body bolts - VW# N-905-969-02 (need 2)
- pendulum mount-to-tranny bolt, front - VW# N-102-466-03 (need 1)
- pendulum mount-to-tranny bolt, rear - VW# N-905-970-01 (need 1)
- driver's side mount-to-tranny bolts - VW# N-102-096-03 (need 2)
The tools/parts needed to perform the procedures are:
1) two jacks (can probably be done with one, but is easier with two - the procedure in this DIY assumes two jacks will be used)
2) two pieces of wood - I recommend a one foot long piece of 2x6 (only one piece of wood is needed if only one jack is used)
3) small flathead screwdriver (to help undo hose clips and harness connectors)
4) large flathead screwdriver or small pry bar
5) T25 and T30 Torx sockets or drivers
6) medium Phillips screwdriver
7) socket wrench with 10mm, 13mm, 16mm and 18mm sockets
8) 6mm hex socket or wrench
9) long socket extension - 6" or so is fine
10) M8x**x1.25 pitch bolt, where ** is the length in mm (available at Home Depot, Lowe's or other hardware stores). I have not specified a length since it varies depending on the model-year car you have.
Special thanks go to Eric (BCDS2003T), James (James 93SLC) and Shashi (DJ-SBK) for their help with the procedure.
Let me know if you have any questions.
As always, do this procedure at your own risk. I am not responsible for any mistakes in the below procedure or those that you make while performing it.
Modified by VgRt6 at 11:05 PM 4-2-2006