Duramax Water Pump Change

[Sammconn]

Well don’t seem to see a DIY on this so here we go.

Had a buddy text me that I was leaking “a lot” of antifreeze.
This was late on a Friday night. I went and relieved the pressure and thought I’ll look at it in the morning.
My pump was a lot late. 510xxx kms. About 315xxx miles.
Had to use his pressure tester in the morning as there was no noticeable leak.

Tools needed:
Screwdrivers. Flat Phillips
Wrenches. 10,12,13,14
Sockets. 10,12,13,14,36
Torque wrench
Breaker bar, ratchets and extensions.
Deadblow, 18” crescent, BFH
Antifreeze collection means

[Sammconn]

Being in need of a cooling stack flush I opted to pull it to add a bit of work room.




Stripped off the grill, lights, light buckets.
Nate did a write up on his stack cleaning DIY.

Fan clutch came out (this pic is going back in. It is right hand threads) and that miserable fan shroud as well.

Inter cooker and trans lines off.

Oh. There it is. The front of the engine.

[Sammconn]

Next up a bit of google foo and you tube to see what I was up against.

Turns out not too bad. Especially with all the room I just made to work.

Next up pull the belt off.
Then fan pulley. (It’s a speedy bit. 600 bones)

Then off with the harmonic balancer.
This was where my heart skipped.
It’s 36mm 12 point. Turns out that’s what I had for the front axle nuts! Problem solved.
I do not have my flywheel lock set yet (at my sons down south) so had to improvise. Big hammer no go, small Milwaukee no go, big Milwaukee did the trick.

With all that crap gone you can finally access all of the front water pump mount bolts. The two on the oil cooler line you still can’t see but are there to get at.
They’re in there somewhere.


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[Sammconn]

Off with the mounting bolts and oil cooler nuts and off comes the pump and housing.



And here we have the assembly.


Pump removed.


New for the other motor sinister tig welded water pump.

And into the housing with new o-ring. Torque 18 ft/lbs


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[Sammconn]

I somehow totally missed the thermostat pipe so I’ll add in a post for it.

It is sealed with o-rings top and bottom.
You need to be careful installing it.

You need to be careful installing it.

You need to be careful....

Yeah three times I leaked.
It is not fun and on attempt final it held pressure.
I also used the pressure tester before I totally topped up with a leak again.


Being the fan had to come off a second time cause I was stupid, this thing stayed out.
It may go back in when I do the motor swap but not sure just yet.


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[Sammconn]

Installation is simple reverse of removal.


Top up bleed etc all the antifreeze.
Go for a good drive and get the coolant moving.
Likely need a top up.
And good to go.


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[Sammconn]

Now. To be honest after fighting the good fight with this.
I think I’d take the stack every time.
There is just so little room to work otherwise.

Now Ken may disagree, and if it was for hire I may as well.

Knowing the tricks and path now it’s probably a 3-4 hour job with rads left in.
Add a couple hours to pull and reinstall stack.

[Flyin6]

Oh you are so right about that T-stat pipe. I fought with that...and with the stack in there, making me have to a second wrist to get my hand in the right position.

Concur on removal of the stack for the novice...Just do it

And

Thank you, sir, for sharing and showing us why people like Ken are so necessary to fix the things we don't want to mess with!

[KensAuto]

That pipe is the worst! You can lube it, silicone, dielectric, wheel grease, or oil and it doesn't change a thing! I've had them seal the first time and just 2 weeks ago took 3 tries... employee 1st, me 2nd and 3rd, even using a flat plastic pick on the top one to keep from cutting it.

I think pulling the stack is best if it needs cleaned but we leave it in to make money.