You have to remove the timing belt to get access to the water pump which is why this article is rated 3. Other than that it's very easy, just remove 3 bolts and the pump will come out.
Caution - do not use green prestone type coolant. Use VW G12/G12+ or compatible coolant. During this change you will drain most of the coolant. Some will stay in various parts so you only need 3 liters/1 gallon of coolant and an equal amount of distilled water.
I suggest a metal impeller water pump since it's rare for the metal water pump to have shaft separation. This is more likely on the plastic impeller water pumps. Since replacement of the water pump requires timing belt removal, a metal pump should be more reliable.
related links: 1000q: Mk5 Jetta full coolant system flush
Remove the timing belt. Refer to 1000q: BRM timing belt part 1- removal for detailed instructions.
Remove the lower radiator hose. There's a spring clamp holding it on. This
will drain the radiator. The service manual shows a drain valve but you may
not have one. When removing
coolant hoses, first twist them to break the seal. This will make it much
easier to pull off.
Optional: remove one of the coolant hoses on the oil filter housing. Twist the hose with pliers before trying to pull it off. This will break the seal so you can pull it off easily. Be careful to not tear the hoses.
Removing one of the hoses will drain most of the coolant out of the engine
block instead of it coming out of the water pump spot. Apply
compressed air to the coolant reservoir. This will blow out most of the
old coolant. This will drain almost all the coolant out of the
system. Refer to 1000q: coolant flush if
you want to further drain the coolant but unless it's contaminated, do not use a
water flush, just drain and refill.
Remove the 3x 10mm bolts holding the water pump.
If it's stuck, use a block of wood to gently tap it out, alternating
on the top and bottom until the water pump is loose. Do not hit it hard or
use a screwdriver at the base to pry it out because this may damage the metal
surfaces. Then just pull it out. Some coolant will come
splashing out so have paper towels and a catch pan below the pump to catch any coolant. Make sure the old o-ring is removed!
Visually inspect the pump and water pump cavity to make sure there's nothing left behind like broken vanes! In one case, someone found a defect in the block which was causing a slow leak. They fixed it with RTV, here is the post.
To install the water pump, first clean the sealing area with a soft scrubber or paper towel. Do not use anything which could scratch the metal.
Use some coolant to lubricate the o-ring to avoid twisting/pinching and press the new pump in place. Do not use any liquid gasket maker.
Torque the 3 bolts to 11 ft lbs.
***CAUTION: If it were my car, I would slightly overtighten the bolts to 15 ft-lbs and use medium locktite on the water pump bolts. This is because a few people have reported the water pump bolts backing out on this engine. In one case, the bolt backed out and shredded the timing belt. The offical torque spec has been 11 ft-lbs for a long time but going slightly higher and using locktite should prevent this rare failure.
For timing belt installation on the BRM engine, see BRM engine timing belt part 2 - installation. It's in the resources forum so please join our community for free and upgrade your account to premium to view for only $2.
Are there broken pictures or do you have more questions on how to replace the water pump on a 2005.5-2006 Jetta TDI engine? Please post in the myturbodiesel.com forums
To bleed air out of the system, see 1000q: coolant flush.