HMMWV Repairs: Cheap HMMWV Heater Core Replacement

HMMWV Repairs: Cheap HMMWV Heater Core Replacement Josejuan was in the passenger seat of the Project HMMWV Battlewagon and gave a surprised yelp when warm engine coolant dripped on his feet […]

HMMWV Repairs: Cheap HMMWV Heater Core Replacement

Josejuan was in the passenger seat of the Project HMMWV Battlewagon and gave a surprised yelp when warm engine coolant dripped on his feet the first time I turned left after turning on the heater. While waiting on the new heater core I shut the valve so the heater shouldn’t get coolant flow. The valve had been stuck part way open.

Diagnosis – dead heater core

Looks to me like the heater core is shot, as it appears to be seeping.


Where to buy HMMWV heater core

I hit the interwebs in search of a heater core that would cross-reference to the HMMWV M998 or M1038 heater core.

I found that the heater core from a 65-67 Mustang (link) is nearly the identical dimensions and a suitable replacement. Even better, I found it on Amazon for $24 shipped!

The new heater core has short coolant pipes instead of the 12″ long metal pipes on the HMMWV heater core. So, I ordered 6 feet of 5/8″ heater hose to span the gap and connect the new heater core to the HMMWV and stainless steel hose clamps to secure the hoses.

Alternative – used HMMWV heater core

As luck would have it, just before finding the cheap, NEW heater core from Amazon, I ordered a used heater core from an eBay seller .

How to replace HMMWV heater core

Heater core and blower housing. Blower removed. Heater core leaks, so this is a fair condition housing for you to install your blower and heater core in. $10

Instructions are in section 10.69 of TM 9-2320-280-20-3

HMMWV manuals download page

HMMWV heater core cheap replacement - TM instructions page 1

If I can find the video I shot while changing the heater core, then I will edit and post it. For now, it is MIA.

Where to get Humvee, M35A2, M923 & military vehicle parts:

HMMWV stuff, M35A2 stuff, military vehicle stuff

More HMMWV and M35A2  articles can be found under the Humvee or M35A2 category menus above (just below the Gear Report log) or by clicking HERE for HMMWV articles or HERE for M35A2 articles.


Quarter Horse Arms - machine gun from HMMWV

Jeff shooting the Quarter Horse Arms AR15 Full Auto from the Project Humvee Battlewagon

Please leave a comment if you have suggestions on other HMMWV or M35A2 upgrades we should consider, or you have done upgrades that we can share on Gear Report.

The Project Humvee Battlewagon

Gear Report acquired a real HMMWV (High Mobility Multipurpose Wheeled Vehicle) from the US Army for use as our official field and shooting range vehicle. We have already posted about some of our upgrade projects (Project Humvee Battlewagon article links) and have a lot of really cool projects on the way. Consider subscribing so you don’t miss any of the cool reviews as we post them.

Here is our Project Intro (link) and our list of HMMWV upgrade projects.

The Deuce Utility Vehicle (D.U.V.) Project M35A2

The D.U.V. project started with a fairly standard 1968 M35a2 two and a half ton 6×6 cargo truck. Commonly known as the “Deuce-and-a-half” or “The Deuce.” We aren’t yet sure where it will stop.

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About Jeff

Jeff is the Editor in Chief of Gear Report and a National Shooting Sports Foundation Media member. He reports on the outdoor industry, reviews gear for camping, hiking, shooting, hunting, paddling, backpacking and other active pursuits. A USAF veteran, Jeff earned a MBA in Marketing and Health Services. He specializes in consultative selling and internet marketing. As the VP of BD & Marketing, Jeff provides sales and marketing leadership to MGECOM, Inc. and helps acquire new clients in need of solutions for online merchants in need of Affiliate Marketing program management. Jeff founded and manages Cress Sales & Marketing LLC, offering online sales and marketing consulting and services to online merchants and service providers.