How to Change the Coolant Reservoir on a 2004 Chevy Blazer

Updated on January 18, 2019
Chevy Blazer 4.3 Coolant Reservoir
Chevy Blazer 4.3 Coolant Reservoir


In this how-to, we are going to be changing out the coolant reservoir on a 2004 Chevy Blazer. The procedure may vary on 2.2l engines and engines 1997 and older, but the process should be similar.

Required Tools

This is a very simple and easy job, so you only need a few tools.

  • Ratchet
  • 10mm socket
  • 10mm deep socket

Chevy Blazer 4.3 Computer Bolt Location
Chevy Blazer 4.3 Computer Bolt Location

The computer unit is held on with three 10mm bolts, which are easily accessible. Remove these three bolts to release the computer unit from the coolant reservoir and you can move it out of the way.

Note: You do not need to unplug the computer unit to do this repair, but if you are replacing the computer unit, there are two small bolts holding on each plug. Removing these bolts (the bolts won't separate from the plug unit) will allow you to pry the plugs from the computer unit.

Chevy Blazer 4.3 Coolant Reservoir Bolt Location
Chevy Blazer 4.3 Coolant Reservoir Bolt Location

The coolant reservoir is held on with three 10mm nuts, and removing these will let you take the reservoir out of the vehicle.

Note: There are three studs attached to the inner fender wall, and because they are so long, you will most likely need a deep 10mm socket to remove the nuts.

Chevy Blazer 4.3 Coolant Reservoir Radiator Hose
Chevy Blazer 4.3 Coolant Reservoir Radiator Hose

Don't forget to remove the hose from the radiator and switch it over to the new reservoir if it didn't come with one (mine didn't). It should just pull off easily, but if it's stuck, try twisting it while gently pulling on it.

Chevy Blazer 4.3 Coolant Reservoir
Chevy Blazer 4.3 Coolant Reservoir

Here's a side-by-side comparison of the old and new reservoirs. You can see how dirty the old one was, and that was after I cleaned it up as best as I could. You can't see it, but the inside was much worse.

New Chevy Blazer 4.3 Coolant Reservoir
New Chevy Blazer 4.3 Coolant Reservoir


Make sure you pour coolant up to the ADD line before you finish.

This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.


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    • WheelScene profile image


      2 years ago from U.S.A.

      Awesome article, thanks for sharing all the great photos to follow along with!


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