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Water Pump Replacement


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Have any of you replaced the water pump on the northstar engine before? If so, would you be so kind to share some basic instructions or items of concern that I can expect when doing this work? Tried to find a basic "free" diagram on the net but no luck. Do you need to mix the coolant with a 50/50 (H2O/Dextcool). What about these tablets, are they absolutly required? Any help would be appreciated.



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First thing to do when considering changine the Northstar waer pump, is to get your hands on a Northsar water pump removal socket, you cant get it off without one, BUT you can rent one from this site for i think $20.00 or so if you go to the items for sale forum. You should always mix your coolant 50/50, and most people on this site will tell you that if you are messing around with the cooling system, always add the sealent, but make sure you add it directly to the rad hoses and not in the surge tank, there isnt enough flow through there to distribute the sealent and it gets stuck in the tank.

If you need more info , search the archives on this site, there is a lot of information on this subject,

Matt B)

A good friend will come and bail you out of jail...BUT, a true friend will be sitting next to you saying, "darn...that was fun!"


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I've done it before. Easiest water pump I've ever changed.

1) Remove the intake tube and air box.

2) Drain the cooling system. I would just unbolt the lower hose from the thermostat housing, (2) 10mm bolts, and let the system drain from there. I cover the ABS box with cling wrap, but that's probably not necessary. Slide the thermostat out when you get the hose undone.

3) Remove the (4) bolts that mount the water pump cover to the housing. At this time, you'll have to remove the shiny black water pump belt cover that bolts to the housing (and also to the intake manifold near the throttle body).

4) With a 1/4" drive ratchet, loosen the water pump belt tensioner and remove the belt.

5) With the belt removed and the water pump cover removed, you should be looking at the water pump unit. It's a small impeller unit, about the size of a child's clenched fist.

6) With the removal socket, engage the tangs on the socket with the recesses in the water pump and turn RIGHT to loosen. It gets "clocked" to the RIGHT for removal. Don't try to crank left on it like you would a bolt. If you have a hard time engaging the socket with the pump unit, try it first on the new water pump module, so you can see how it engages.

7) Install the new water pump, reverse of removal. Careful to get the o-ring seated properly. Clock LEFT to install. Make sure it's tight, but don't wail on it.

8) Be sure to purchase a new water pump cover gasket and use it. I reused my original water pump cover gasket when I did mine and after about 140,000 miles of being on the car, it finally gave up the ghost, and I had to go back in and replace it.

9) Installation is the reverse of removal. Don't over-torque any of the bolts. I can try to find the exact torque values this evening if someone doesn't post them first.

10) Fill the system with a 50/50 ratio of Dexcool to distilled (mineral-free) water. Yes, go ahead and use the sealing pellets. They're only about 3 bucks from the dealer for the package of 6. Stick (3) of them into the lower radiator hose before you bolt it back to the water pump cover. Then fill the system up. Start the car and rev the engine to 3000 rpm a few times to expell any air that may be in the system. If you fill the surge tank slowly, you shouldn't have any air. I've had the system drained twice (once when I replaced my pump, and again when I had to go back and do the gasket) and didn't have any problems with air either time.

Jason(2001 STS, White Diamond)

"When you turn your car on...does it return the favor?"

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I agree with Jadcock, very easy to change WITH the tool. You can get the tool for about $25 on ebay. You probably will not find it in the local parts store. NAPA has the same water pump as OEM (made by, I think, Airtex) for a lot less. I am thinking about $60.00. Lots of info in the archives. Good Luck.

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