[lenster]

To the guy whose cruise control bracket is in the way of getting a socket on the forward thermostat housing bolt...remove the 10 mm bracket bolt going into the firewall and then the bracket can be pushed an inch over to get your deep well in there.
The stud will unscrew with the nut so don't keep ratcheting thinking the nut will come out in the socket, (in other words don't let the stud drop down where you can't find it, (I lost the t-Stat housing hose clamp like that).

 

[gordo999]

Good article.

I recently replaced the water pump in a 2001 Safari and I could have used your article.

I removed the fan nut by striking it straight down with a heavy, tapered marlin pin with a fairly blunt end. At least, I placed the tip of the marlin pin on the nut and tapped it's large end firmly with a claw hammer. I was aware of the force used but reasoned that it was attached to the old water pump and would likely cause no damage.

Tapered steel has the property of transmitting taps on the large end to compressed impact on the small end. Anyway, a couple of hits loosened the nut enough for it to turn with a small pipe wrench.

Be sure to turn the nut the right way!!

Before placing the water pump on the engine block, I cleaned and inspected the engine block water port faces to be sure they were free of contaminants, then applied some gasket cement to them. I coated the water pump port openings and gaskets with gasket cement and applied the gaskets, aligning the gasket holes with the water pump bolt holes. Then I inserted the bolts, holding them in place while I aligned the pump bolts with the threaded block holes.

Once I had the 4 bolts started, which is not that easy, I slid the pump forward on the bolts till it made contact with the block. It's important to do this carefully so as not to knock grime off the block and get it between the gasket and the block ports.

It might not be a bad idea to remove the alternator as well, to get better access to the water pump bolts.

Then I tightened the bolts one at a time till just before they were snug. After that it was a matter of tightening them diagonally till they were tight enough.

 

[Whiskeyrebel]

Zombie thread bump! I did this last Wednedsay with the help of this thread. Thanks everyone for the tips.

Autozone has the flat wrench set for $25. They said it's returnable for a full refund.

One tip I'll add for using it, which was demonstrated to me by my brother-in-law. He is an autoshop teacher and former dealership mechanic:
If you can't get the larger spanner to grip across the four bolt heads, put the serpentine belt back on, use only the smaller wrench, and tap the end of the wrench handle with a mallet to get the large clutch nut to start turning. This worked like a charm and saved me hours of struggling with lining up the bolt heads.

Another tip was to thread the four pump bolts through the gasket holes and start each bolt with only a turn or two, then walk the bolts in one at a time with only a half turn to a turn per bolt. Sort of like walking a wheel onto the studs with lug nuts. Then when the four bolts are seated, torque each bolt only partway and go around adding a bit of torque to each. This is to prevent wrinkling or misaligning the gaskets.

He also cautioned me to use the gaskets dry without RTV. I was skeptical about this but FelPro's website confirms that their gaskets are designed to be used without sealant or compound.

The one thing that did go wrong was when I installed the new bypass hose, I somehow started a hairline crack at one of the clamps. What did I most likely do wrong in installing it that caused it? Could this be caused by trying to nudge it into place without spreading it enough?

 

[AstroWill]

He also cautioned me to use the gaskets dry without RTV. I was skeptical about this but FelPro's website confirms that their gaskets are designed to be used without sealant or compound.

Dry is definitely the recommended way.

 

[gordo999]

He also cautioned me to use the gaskets dry without RTV. I was skeptical about this but FelPro's website confirms that their gaskets are designed to be used without sealant or compound.

If you read the fine print on the gasket manufacturer's claims they likely specify absolutely flat surfaces on the water pump and block faces and with corrosion and possible warpage, that is not likely to be the case with an older block.

I used a thin coating of high temperature RTV on both sides of gasket to ensure imperfections in the metal were accounted for. Also, the gasket I received from the supplier had no instructions.

I think it's far more important to ensure all dirt and grime is cleared away from the mounting surfaces and that none gets knocked off to fall between the mounting surfaces. It's been over two years now since I replaced the pump. I added a fluorescent dye to the cooling system water recently and using a UV light, there are no tell tale signs anywhere of water leaks.

I was disappointed in a way because I have been trying to track a tiny leak that is possibly spraying coolant onto my fan belt, causing it to squeal. Nary a sign of the fluorescent die anywhere, not even on the fan belt. There is a tiny amount of fluorescent green at the end of a heater hose, coming from the heater control valve where the hose attaches to the block. It's the hose with the metal pipe in it.

 

[Ericglo]

Here is a pic of the Autozone rental tool. I struggled with this till I finally figured out what was going on. Loosen the four bolts to line up on the tool. Just remember to tighten them when your done or you will get a noise that you won't like.

To quote myself, I went to Autozone and they have a new tool. I wish I would have rented that one. It is free, so I don't know why I didn't get it just in case. I ended up going to Advance and their tool was slightly to large, but I was able to get a grip on the bolts. They didn't have a small enough tool for the fan clutch nut either. I was able to find a large enough adjustable wrench to fit. Frustrating when you don't have the correct tools.

 

[Ericglo]

Oh and as someone suggested I used smaller longer bolts to hold the water pump and gasket in place to get the other bolts started. Worked like a charm.

 

[SidewaysEightSix]

Quick tip as I just did the entire coolant system (rad, pump, belt hoses, tensioner, stat, flush, everything)

Use a angled wrench from the pump bolts and rest it in the tensioner. Then use a crescent wrench to tap the clutch fan off. No special tools required

 

[AWD98]

Your water pump may eventually fail. I hope it never does, but my friend's did on his 96 Astro van. We changed it last weekend along with some other stuff. It was my first time for this on an Astro, but perhaps someone else can benefit from that experience. I won't mislead you, I consider this job kind of a pain. If you're going to do it, replace your hoses and thermostat so you hopefully don't have to mess with the cooling system for a while. It is certainly do-able by many of us, and who doesn't want to have this job done for under $100 when it is needed.

I can't show you a picture of your water pump yet, because we'll need to expose it first.

You'll need your basic metric wrenches, metric sockets and socket extensions. You'll also need a GM fan clutch removal tool. The exact GM tool is J46406, I think, but don't run out and spend $150 on that. Such things are available at places like Advance Auto Parts-they would have rented us a tool kit for this, but they were out so we had to use a Ford Fan Clutch removal wrench set, exactly like this one at the top of the following web site-we found it for $22 so don't pay that price.... http://www.mytoolstore.com/kd/kdengi06.html You may be able to get by with a really large strap wrench and a huge cresent wrench, but we couldn't get that to work.

Before you start this, disconnect the battery!

Water Pump

1. Make sure the engine and coolant are cool. Place a large basin under the van and open the radiator stopcock found at the bottom of the radiator, facing the interior of the van on the passenger side-make sure that the coolant goes into the basin. You may wish to use pliers on the spring for the lower radiator hose and remove it at this point too at this point.

2. Now remove your air intake as per this procedure: Air Intake Removal How-To (2003 Astro)

3. Next remove the upper fan housing as per this procedure: Fan Housing Removal How-To (2003 Astro)
3a: Remove the serpentene belt as shown here: Serpentine Belt Removal/Replacement How-To (2003 Astro)

4. The fan clutch removal tool that I used consisted of a large really thin wrench and an even bigger, but just as thin, crows foot wrench. Because of the tight space we simply could not get good photos of the tool in use. To use the tool, first put something with a half inch drive on the crows foot wrench and slip the crows foot wrench over the four small bolts on the fan/water pump pulley. You may need to align the bolts so that they are all flat side facing the sides of the crows foot wrench-sorry for not writing down bolt sizes, I think they're either 10 or 13 mm bolts. Use the box end of a wrench for that task if you need to do it. Now slip the open end wrench on the large nut between the fan and the pulley, hold the crows foot wrench in place and turn the nut between the fan and pulley counterclockwise (from the drivers side to the passenger side). This may be require considerable effort... Here's a photo of the nut I was talking about and the four bolts on the pulley:

5. Now remove the pulley from the water pump. Because the pulley spins, I found it easiest to zip them off with a 3/8" drive impact wrench. If that's not an option for you, try to hold it in place with a large strap wrench and remove the bolts (10mm socket if I remember correctly, could have been 12):

Okay, there's your water pump.

6. If you are changing hoses-and you should be-you'll want to pull out the lower fan housing at this point. It has plastic tabs holding it at the bottom, so try not to break them as you unclip them. You'll also need to remove the lower radiator hose at the bottom of the pump-his wouldn't separate from the water pump so we just cut it with a pair of pruning sheers-the kind you cut branches with. The hose has a spring in it so have wire cutters handy if you do that... Remember to get a basin under the hose before you remove it.

7. Next pull the line off the top of the water pump as shown.

8. It's probably best if you remove the center top pulley, shown below. To remove it, simply remove the bolt in the center.

9. This will reveal another hose on the top of the water pump. Remove that hose from the water pump.

10. Now you're ready to pull of the old water pump. It's held in by four bolts on the front (15mm bolt heads if I remember right). Remove those bolts, but have a hand on the water pump to catch it for the last one.

11. Sorry, no photos of this, but you'll find old gasket left behind where the water pump bolted on. Scrape those off as best you can. Sorry, no photos here. Apply rtv to the new water pump, place the new gaskets on the water pump and apply rtv to other sides of the gaskets as well.

12. Now, bolt the new water pump back on.

13. Reinstall everything you removed. Sorry, no more photos there.

Thermostat

1. To replace the thermostat, you'll need to first pull the upper radiator hose from the thermostat housing. Here is the upper radiator hose, follow it back toward the motor.

It connects to the thermostat housing. Here is the housing with the thermostat shown inside (hose pulled)

Now pull the wiring harnesses off of the sensors that are in your way.

Next unbolt the thermostat housing cover and pull it off. Note: On the back side of it (facing the engine, you'll actually find two nuts. One attaches a ground lead to the back of the stud on the back of the thermostat. I mention it so you don't break the thing trying to pull it off.

Pull out the old thermostat.

Pop the new thermostat and bolt the cover back on. Remember to reattach the sensor wiring harnesses you just pulled and the pulley. Sorry, no more pics.

Torque Settings
Thermostat cover nuts: 18 ft/lb
Water Pump Bolts: 33 ft/lb
Water Pump/Fan Pulley Bolts: 18 ft/lb
Fan clutch nut: 41 ft/lb - I have no idea how you'd set that... :banghead:

Notes:

• You may wish to double check my torque specifications before using them for your vehicle
• Engine coolant is poisonous, generally sweet tasting, and harmful to the environment. Be careful to collect all of it and properly dispose of or recycle it. This goes doubly if you have pets
• I am only providing this procedure to tell you how I did this. In no way am I telling anyone to do this, especially if they're not comfortable with this repair. Also note, I'm a chemist not a lisenced mechanic, so as with all things, consider the source.

Amazing write up , I am about to do this thermostat myself. Just had a question what size are the bolts for the thermostat housing ?

 

[AWD98]

Amazing write up , I am about to do this thermostat myself. Just had a question what size are the bolts for the thermostat housing ?

Found the sizes, mine are 13mm and 15mm but they are very hard to get off, tight space even with removing things. could get a wrench on the 13mm bolt but too hard to remove, the other 15mm bolt similar. how did you all remove these bolts? someone please help.