Replacing the water pump on the 2008 Astra

So, quite some time ago, I mentioned that the water pump ("coolant pump," technically) in my Astra needed to be replaced. It's dripping coolant from the weep hole, which indicates that the pump is nearing the end of its life. It has not been losing a lot of coolant (I've only had to put a small-ish amount of coolant into the reservoir and when the engine is cooled off, it's at the "cold" ("kalt") mark. That said, it's weeping enough that it's hitting the serpentine drivebelt and slinging coolant up on the underside of the hood, as you can readily see:

The Necessities

Since then, the ACDelco water pump has arrived (GM # 19310027; ACDelco # 252-947) from (as shown in the photo below), and I've picked up a couple of gallons of Valvoline Zerex Dex-cool to refill the coolant once I am finished with the job. I also had to make a run to Canadian Tire to purchase a T45 Torx bit, which is the size needed for the pump pulley retaining bolts (interestingly, this is the first time since we bought the car new in 2008 that I have needed a Torx bit larger than T30 for working on it). The retaining bolts that mount the pump to the pump housing are E12 ("E" = external Torx), which I already had and have used before.
Oh, I also bought a giant bag of heavyweight absorbent pads (like Pig Mats) to help me contain the coolant mess, since I am not planning to drain the coolant before removing the pump; I'm just going to pull the pump and let the coolant pour out. So, I will put my pan under the car and cover the A/C pump with the absorbent pads. Anyway, all of this is to say that I am ready to tackle this job.
I was planning to do this job today (15-October), but when I got up this morning it was windy and raining. The rain has since stopped, but it's still quite windy, and my car is right beneath a maple tree that is shedding its beautifully colored leaves. I could probably keep debris out of the water pump housing, so maybe I will change my mind and do the job anyway. Or, maybe the wind will die down enough. Or maybe I will do the job tomorrow afternoon. Nevertheless, in classic Eric O. style, I've made a plan, and when the right time comes, I will work the plan (I just hope the "right time" is not on the shoulder of the 403 during rush hour--and rush hour lasts all day, incidentally).

The Plan

This plan is based on the Haynes manual for my car (Haynes manuals rock!) and a few videos I have watched on YouTube, of course.
  1. Disconnect the negative battery terminal (I have to unplug the mass airflow sensor for the next step, so it is a good idea to disconnect the battery).
  2. Remove the airbox to gain access to the water pump. This requires unplugging the MAF sensor, loosening one worm clamp, disconnecting an air intake duct, and removing one retaining screw. Then the box lifts out of the front right (= passenger side) of the engine bay.
  3. Loosen the three pump pulley bolts (these are the T45 bolts mentioned above) while the serpentine drivebelt is still on (it will keep the pulley from spinning while loosening the bolts).
  4. Using a 14mm wrench (if I remember correctly), lock on to the projection on the belt tensioner and turn it counterclockwise to slacken the belt. Slip the belt off of the water pump pulley and remove it (mark it before removing so it can be put back on in the same direction).
  5. Finish removing the fasteners that hold the pulley on the pump, and remove the pulley.
  6. Remove the plastic splash guard from underneath the car (two retaining screws) so that the coolant that drains from the water pump housing can pass through to the pan.
  7. Place catch pan under the car, as well as a few absorbent pads as needed).
  8. Cover the air conditioning pump with absorbent pads.
  9. Remove the five retaining bolts that hold the pump in its housing, and remove the pump from the housing.
  10. After coolant stops draining, clean the mating surface on the pump housing (use a lightly abrasive scouring pad and/or plastic razor blade as needed; I don't recommend using a metal razor blade or carbide scraper because you do NOT want to gouge the aluminum housing or you'll create more and worse leaks).
  11. Install the new gasket that came with the new pump on the pump.
  12. Place the new pump (with gasket) into the housing and replace the 5 retaining bolts. Tighten these bolts in a star pattern to 15 lb ft. (these specs are found in the Haynes manual).
  13. Place the pump pulley on the pump and install its retaining bolts to "snug" (slightly more than finger tight). EDIT: Put 1 drop of BLUE Loctite on each of these bolts.
  14. Replace the serpentine drivebelt.
  15. Tighten the pulley bolts to 15 lb ft. (these specs are found in the Haynes manual).
  16. Refill the coolant reservoir.
  17. Reinstall the air box and ducts, taking special care to reconnect the MAF sensor wiring harness.
  18. Start the car and let it warm up to running temperature. Once the thermostat opens, add more coolant as needed.
  19. After running the car for a while and the coolant level no longer drops, let the car cool off and make sure that the coolant level is at the "cold" ("kalt") mark.
  20. Take the car on a test drive to make sure everything works as it should.
I think that's all of the steps. I'm not sure yet if I will record the repair or not. Once I'm into a job like this, I tend not to stop until the job is complete. Maybe I will conscript my daughter to run the camera or pay (= bribe) her to do it with coffee.🙂