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DIY - Replacing the C5 Water Pump

111K views 120 replies 42 participants last post by  Maniacmechanic1 
#1 · (Edited)
Well folks, you get to benefit from another situation I found myself in. The day before I was supposed to drive to Arkansas from Kentucky, my water pump decides to reveal to me that it was leaking. I had been smelling antifreeze but it wasn't leaving any drops on the floor. Well, that finally changed at the most inopportune time.

Some info on how to check for a leaking water pump. First of all, if you smell antifreeze, you have a leak. Period. You may not see it, see coolant on the ground or be able to locate it but trust me, you have a leak. I think I have managed to have a leak in every possible common location:

  • The "T" connector located on the surge tank (it usually cracks).
  • The upper hose connector at the top of the radiator. It develops a hairline crack. There's a TSB that has you polish it out and not replace the radiator. I replaced my radiator instead because it had over 100,000 miles on it.
  • The water pump.

Here's the deal with detecting a water pump leak on the C5. The fluid will not drop to the floor directly under the water pump unless you have a really heavy leak. It will land on the belt or belt pulley and sling to one side of the car (most likely the driver's side because of the direction that the belt travels). I didn't know that as I kept checking dead center of the engine on the garage floor. My leak was extremely small up until the point that I actually found it. Hey, I'm old school and my previous experience taught me to check dead center of the engine on the garage floor. Now I know better. :lookinup:

This turned out to be a rather easy repair compared to some that I have done. I would easily recommend a shade tree mechanic take this on as long as you have one very important tool: hose clamp pliers. Don't even attempt this repair without them as there are quite a few hose clamps that you have to remove. Those things will take you forever to remove with a pair of pliers. Don't waste your time, buy a nice pair of hose clamp pliers with the extension cable. You'll thank me later. You'll see them in the pictures below.

With all that said, let's get to the repair!

Tools needed:
  • Hose Clamp Pliers
  • 3/8" 10mm Socket and Ratchet
  • 3/8" 15mm Socket
  • Flat Head Screwdriver
  • Dielectric Grease or Vaseline
  • Radiator Hose or White Lithium Grease
  • Safety Glasses
  • Another socket for the thermostat bolts but I forgot what size it was! :lookinup:
  • These instructions! :thumbsup:

This repair should only be done when the engine is cool or cold.


Step 1: Remove the air cleaner intake duct. This is actually done as a unit. You don't have to remove the entire thing as I did, you can just remove the air bridge but for me, it was quicker just to remove the whole thing since I know how. Here it is removed:



To do this, pop up the pins that hold the air bridge onto the radiator shroud.



Unplug the mass airflow (MAF) sensor connector. Once you get it unplugged and the harness is disconnected from the clip that holds the harness down, move it toward the back of the engine out of your way.







Remove the air filter in order to make the next step simpler. As you can see, I'm a firm believer in the K&N filter.



This next part is kind of tricky the first time you do it. The air cleaner intake duct is held onto the front frame cross-member by 2 rubber grommets. The air box just pushes on and pulls off. The first time you do it is like pulling teeth because you really have to give it a tug. It gets easier to do once you've done it before. See pictures below.





You will also need to unplug the Secondary Air Injection (AIR) hose. The bottom part of that hose simply pulls apart from the top part if you twist it back and forth.



Last of all, loosen the screw that holds the air bridge onto the throttle body.



Once you get all this stuff disconnected, separated and unplugged, the air cleaner intake just simply lifts out of the engine bay. Put it to the side.


Step 2: The first thing you need to do here is look at how the accessory belt is routed. Take pictures of it from various angles so that you will have something to look at when it comes time to put it back on. That's what I do before disassembling anything.

Remove the accessory belt from the accessory tensioner pulley and allow it to drop toward the bottom of the engine. There is no need to remove it all the way so don't make more work by doing so. To remove it, use the 15mm socket and rotate the pulley clockwise (toward the driver's side), until you can slip the belt off the tensioner.





Step 3: Drain the cooling system. In order to do this, you will need to raise the car. for those who don't have a lift, here's the way I do it.

A) Drive the front of the car up on some 2X12's.



B) Using a low profile jack that I got from Harbor Freight, I center a 2X4 on the jack plate and run it under the front of the car.







Once in place and lifted, I support the car with jack stands.



I follow the same exact procedure for the rear of the car, making it slightly higher for draining purposes.

Warning: Pay special attention to the front jacks as you raise the rear. They could topple over if you get to extreme with your lift height!!!



Now I have all kinds of room to work under the car. :D



Remove the overflow tank cap and get your safety glasses on. Remember, safety first! :thumbsup:





The actual draining of the system is pretty easy. You simply loosen the drain cock (hey, I didn't name it... that's what it's called) and you will see the fluid begin to flow. You will turn it counter-clockwise. Do not completely remove the drain cock, just loosen it until the antifreeze starts flowing real good. Now go have Dagwood Pizza and your favorite drink because it will take the fluid a little bit to completely drain.. :D





Once all of the coolant has drained, close the drain cock and lower the car. You can reuse your old coolant if you want to but if it wasn't changed recently, I don't know why you would. Don't be a cheap azz, buy some new fluid for your baby. Don't get the 50/50 stuff because you're paying for water, which is free (however, if you don't have access to distilled water, buy the 50/50 stuff). Other than that, buy the full strength stuff and dilute it with distilled water. You can use A 50/50 mixture of clean, drinkable water but use only GM Goodwrench® DEX-COOL® or Havoline® DEX-COOL® silicate-free coolant. It takes approximately 11.9 liters (12.6 quarts) to refill the cooling system.
 
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#93 ·
Several issues when I did mine

I'm only half way thru this job and it's turned into a real pain. Let it be known...I read over the steps several times to become completely familiar with the process. I also printed them out and placed them nearby for quick referral
1. The first thing that hit me was my drain plug. It's designed to use a ratchet inserted into the center of the plug and then you turn it. No coolant would flow until I used a screw driver to pop the plug out and then I got flow. Two hours trying to figure this out.
2. As soon as I removed the inlet and outlet hoses from the pump, coolant gushed out all over the passenger side of the engine bay and down to the floor. I quickly put the outlet hose back and looked over the instructions for something I must have missed. Nope! Obviously, there was a great deal of coolant in the engine that did NOT drain from the radiator. This clearly suggests there's a step missing in the how-to-do-it. Perhaps after draining the radiator, you run the engine to push the coolant out of the engine back to the radiator. I'm guessing maybe you need to do this a couple of times?
3. After wiping up the coolant on the floor, I'm ready to remove the water pump. Oh no! The only way I could gain access to the three pump bolts on the driver's side is to remove the bracket that holds the power steering reservoir to the alternator. This was not easy and took another hour and half.
So now the pump is finally off and the fun of installing the new one begins. Perhaps tomorrow.
:WTF:surprised:huh:
 
#94 ·
You are definitely doing it wrong.


... 1. The first thing that hit me was my drain plug. It's designed to use a ratchet inserted into the center of the plug and then you turn it. No coolant would flow until I used a screw driver to pop the plug out and then I got flow. Two hours trying to figure this out.
Can't help you with the drain cock. Sounds like Shade Tree Thomas got there before you did and changed something. Every C5 radiator I have seen has a drain cock like mine. Even my El Camino has the same drain cock.

2. As soon as I removed the inlet and outlet hoses from the pump, coolant gushed out all over the passenger side of the engine bay and down to the floor. I quickly put the outlet hose back and looked over the instructions for something I must have missed. Nope! Obviously, there was a great deal of coolant in the engine that did NOT drain from the radiator. This clearly suggests there's a step missing in the how-to-do-it. Perhaps after draining the radiator, you run the engine to push the coolant out of the engine back to the radiator. I'm guessing maybe you need to do this a couple of times?
That would be a good way to mess up your engine. It sounds like you didn't allow the car to drain completely. Although not necessary, you could have either lowered the front end or raised the rear end to get any remaining fluid out of the block. That simple.

3. After wiping up the coolant on the floor, I'm ready to remove the water pump. Oh no! The only way I could gain access to the three pump bolts on the driver's side is to remove the bracket that holds the power steering reservoir to the alternator. This was not easy and took another hour and half.
Now you're really trying to screw the pooch! That is TOTALLY NOT NECESSARY! As a matter of fact, I'm going to include in this post the instructions from the GM service manual, which is the exact same one that they use at EVERY GM dealership. Now show me where the power steering bracket needs to be removed? :huh:
 

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#95 ·
The radiator you have is a newer design and has not been hacked up by anyone...

Also running the motor after you have drained the radiator is a good idea. Just running it for 30 seconds will be enough to pump the water in the pump and block into the radiator. Also running with out any coolant will not hurt anything so long as you don't do it to long....

If a motor is cool running it at idle with no coolant for 2-3 min won't hurt anything....
 
#96 ·
The radiator you have is a newer design and has not been hacked up by anyone...
You have a picture of this "newer" design? Every C5 stock radiator I have seen is pretty much exactly the same.

Also running the motor after you have drained the radiator is a good idea. Just running it for 30 seconds will be enough to pump the water in the pump and block into the radiator. Also running with out any coolant will not hurt anything so long as you don't do it to long....
Which is totally unnecessary. If you give the coolant time to drain, you won't have to risk damage to your motor. Notice that the GM engineers who DESIGNED the car do NOT call for that procedure. :lookinup:

If a motor is cool running it at idle with no coolant for 2-3 min won't hurt anything....
Two to three minutes? Famous last words. I wouldn't take that advice.
 
#97 ·
I purchased the car new, from a dealer. I've never had the radiator replaced nor had anything done to the cooling system at all. The only "garage" work I've had done was installation of a racing cam and replacement of the clutch. Perhaps the cam mechanic is responsible for this non-standard drain plug. FWIW, the one I removed is pretty chewed up after all my efforts to figure out how to get the coolant to flow, so it's been replaced with the type with a tab that you simply twist.
 
#104 ·
My radiator is the newer design with the 1/4 inch insert as well. I have had it open at least a half dozen times. Its not a hack it new design. GM made it so because of just the reason mayday said. The tabs will fail after time and because of techs turning them to far thinking they screw out when in fact it unlocks and pulls out slightly.

As far as running the engine, you can run it for longer than a few minutes without water, but I would only do that if I knew I was replacing the water pump anyway as the coolant also lubricates the water pump bearings. That is the only issue along with overheating that will arise from running the engine with no water.

That said, I wouldn't run the engine, I would remove the radiator hose and finish draining the fluid if it was going to be an issue.

Now as to the banning, would he have been banned if this was anybody elses thread that disagreed with him? :rolleyes:

I doth protest that the banneth wand has been used to freely.
:down:
 
#105 ·
My radiator is the newer design with the 1/4 inch insert as well. I have had it open at least a half dozen times. Its not a hack it new design. GM made it so because of just the reason mayday said. The tabs will fail after time and because of techs turning them to far thinking they screw out when in fact it unlocks and pulls out slightly.
Isn't that the same thing that I said? People doing it wrong so it had to be redesigned instead of telling people to do it right?


I doth protest that the banneth wand has been used to freely.
:down:
He was warned first. If you get warned and still want to be an ass, you get the pink slip. When you mess with the bull, you get the horns. By the way, you meant "too freely".
 
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#107 ·
Thank god for this thread. I tackeled this job and thanks to this thread it was simple. While I was there I finally installed my vararam, cleaned out my radiator and changed my oil. One thing I did do because with one attempt I knew it was gonna me a motha f'er. I silicone the gaskets to the water pump. I just did it on the case of water pump to the gasket where gasket over hangs the pump. not getting it in between the gasket n waterpump. I let it dry over nite, It took about 5 minutes to install it. I did try and find those hose pump pliers locally but no one had them. Once I did job I didn't even lose a second to dealing with the clams. My basic pliers worked flawlessly. I guess it all depend on where your hose clamps are placed if the tabs are easy to get to, Mine were simple. I never could have had such a smooth and easy install.
 
#108 ·
Welcome to DC Killertiller. :buhbye:

Make sure that you go back and edit your profile to include the YEAR of your C5, in case you need some help with something else. The year makes a difference with some repairs. I have plenty more repairs like this one documented here on this forum for the C5. You will find that most of the common issues that this car experiences are not that hard to fix at all. :cheers:
 
#110 ·
It looks a lot more daunting than it actually is because I took a lot of pictures but the pictures include multiple angles for some steps. This ensures that I am crystal clear with each instruction.
 
#120 ·
Search for photobucket picture problems. It's all over the net. PB started charging $399 a year to release the pic for web hosting. Basically the "owner" can see them but no one else
 
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