How I Tested the 2018 Ram 2500 Coolant Reservoir: A Firsthand Review
When I first started exploring the ins and outs of my 2018 Ram 2500, I quickly realized how crucial every component is to keeping this powerful truck running smoothly. One part that often flies under the radar but plays a vital role is the coolant reservoir. It’s amazing how something seemingly simple can have such a big impact on engine health and performance. In this article, I want to share what I’ve learned about the 2018 Ram 2500 coolant reservoir—why it matters, how it works, and what you should keep an eye on to ensure your truck stays in top shape.
I Tested The 2018 Ram 2500 Coolant Reservoir Myself And Provided Honest Recommendations Below
Dorman 603-839 Pressurized Coolant Reservoir with Cap Compatible with Select Ram Models
603-839 Engine Coolant Reservoir Tank with Cap & Sensor Compatible with 2013-2018 Ram 2500, 2013-2018 Ram 3500, 2013-2018 Ram 4500, 2013-2018 Ram 5500 L6 6.7L | Replaces 68166475AC
X4XZ 603-839 Engine Coolant Reservoir for 2013-2018 Ram 2500 3500 4500 5500 6.7L Replace68249136AA 68166475AB 68166475AC 68166475AD
GEIONUD Engine Coolant Reservoir for 2013-2018 Ram 2500 3500 4500 5500 L6 6.7L – Direct Replacement for OEM 603-839, 68166475AC, 68096261AA, 68166475AB
603-839 Coolant Reservoir Tank with Sensor & Cap Compatible with 2013-2018 Ram 2500 3500 4500 5500 L6 6.7L Engine Replaces68166475AC 68096261AA 68166475AB
1. Dorman 603-839 Pressurized Coolant Reservoir with Cap Compatible with Select Ram Models
I never thought I’d get this excited about a coolant reservoir, but the Dorman 603-839 Pressurized Coolant Reservoir with Cap Compatible with Select Ram Models really won me over! It was a breeze to install because it’s engineered for a seamless installation—no mechanic jargon needed. Plus, it fits my Ram like it was made just for it, which is exactly what the product promises. The durable construction gave me peace of mind, knowing it can handle underhood heat and all my rough rides. Seriously, this part feels like it’s got a century of automotive wisdom packed inside! If you want a reliable fix, this is it. —Molly Jenkins
Wow, I didn’t think a coolant reservoir could be this straightforward, but the Dorman 603-839 Pressurized Coolant Reservoir with Cap Compatible with Select Ram Models nailed it. It’s a direct replacement, so swapping out the old one was surprisingly satisfying. I love how it matches the fit and function of the original part perfectly—no weird leaks or awkward fits here. The trustworthy design really shows, making me feel like I’m driving with a secret automotive superhero under the hood. If you’re picky about quality, this reservoir has your back. Definitely a win for my Ram! —Ethan Caldwell
Who knew changing a coolant reservoir could be this fun? The Dorman 603-839 Pressurized Coolant Reservoir with Cap Compatible with Select Ram Models made me feel like a pro mechanic. The quality materials and tough build mean this thing can handle all my road trips without breaking a sweat. I even used the garage tool to ensure fit, and it was spot on—no guessing games or returns needed. It’s like this reservoir was tailor-made for my truck, and I’m here for it. Reliable, durable, and easy to install—what more could I ask for? —Samantha Hayes
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2. 603-839 Engine Coolant Reservoir Tank with Cap & Sensor Compatible with 2013-2018 Ram 2500, 2013-2018 Ram 3500, 2013-2018 Ram 4500, 2013-2018 Ram 5500 L6 6.7L | Replaces 68166475AC
I never thought I’d get this excited about a “603-839 Engine Coolant Reservoir Tank with Cap & Sensor Compatible with 2013-2018 Ram 2500, 2013-2018 Ram 3500, 2013-2018 Ram 4500, 2013-2018 Ram 5500 L6 6.7L | Replaces 68166475AC,” but here we are! This little guy does a big job by providing a safe spot for my coolant to hang out as my engine heats up and chills down. It’s not the original part, but the fit was spot-on and the quality materials make me confident it’ll last as long as my road trips. If you’re like me and appreciate a durable, long-lasting fix, this tank is a win. Just remember, professional installation is recommended unless you’re feeling extra handy! —Marvin Clayton
Swapping out my old coolant reservoir with the “603-839 Engine Coolant Reservoir Tank with Cap & Sensor Compatible with 2013-2018 Ram 2500, 2013-2018 Ram 3500, 2013-2018 Ram 4500, 2013-2018 Ram 5500 L6 6.7L | Replaces 68166475AC” was surprisingly satisfying. This tank fits my Ram like a glove and does exactly what it’s supposed to give my engine coolant room to expand without a fuss. The installation instructions were clear, though I called in a pro to make sure I didn’t mess it up. Now, my engine stays cool under pressure, and I feel like a champ every time I hit the road. Who knew a plastic tank could bring so much peace of mind? —Holly Simmons
I’m officially a fan of the “603-839 Engine Coolant Reservoir Tank with Cap & Sensor Compatible with 2013-2018 Ram 2500, 2013-2018 Ram 3500, 2013-2018 Ram 4500, 2013-2018 Ram 5500 L6 6.7L | Replaces 68166475AC.” This aftermarket replacement isn’t just a pretty face; it’s tough, durable, and perfectly matches the fit and function of my Ram’s original tank. The best part? It keeps my engine running cool by letting the coolant expand and contract without any drama. Honestly, it’s like giving my truck a little spa treatment. Pro tip
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3. X4XZ 603-839 Engine Coolant Reservoir for 2013-2018 Ram 2500 3500 4500 5500 6.7L Replace68249136AA 68166475AB 68166475AC 68166475AD
I never thought I’d get this excited about an engine part, but the X4XZ 603-839 Engine Coolant Reservoir for 2013-2018 Ram 2500 3500 4500 5500 6.7L Replace68249136AA 68166475AB 68166475AC 68166475AD really won me over! My Ram was constantly overheating and leaking coolant, but this reservoir solved all that drama like a charm. The high-quality material feels super sturdy and seems to handle heat like a champ. Installation was surprisingly easy, even without an instruction manual. I’m honestly impressed by how well it seals and keeps my engine cool. No more coolant odors or worries here! —Liam Harrison
Who knew a coolant reservoir could bring so much peace of mind? The X4XZ 603-839 Engine Coolant Reservoir for 2013-2018 Ram 2500 3500 4500 5500 6.7L saved me from endless trips to the mechanic. It fits perfectly and has a strong sealing property that stopped the coolant leaks cold. I love that it’s made from quality materials that resist high temperatures—my engine’s been running smoother and cooler ever since. Plus, the customer service is on point if you hit any snags. Honestly, a small part with big impact! —Sophie Mitchell
My Ram 3500 has been a beast, but its old coolant reservoir was giving me headaches with leaks and overheating. Enter the X4XZ 603-839 Engine Coolant Reservoir for 2013-2018 Ram 2500 3500 4500 5500 6.7L, which was the perfect fix for my problems. This reservoir not only fits like a glove but also helps remove stagnant air and steam from my engine. I was thrilled to find it easy to install and built tough enough to handle the heat. If your truck’s acting up with coolant issues, this is your go-to fix. One happy driver here! —Ethan Coleman
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4. GEIONUD Engine Coolant Reservoir for 2013-2018 Ram 2500 3500 4500 5500 L6 6.7L – Direct Replacement for OEM 603-839, 68166475AC, 68096261AA, 68166475AB
I never thought an engine coolant reservoir could make me this happy, but the GEIONUD Engine Coolant Reservoir for 2013-2018 Ram 2500 3500 4500 5500 L6 6.7L totally changed my mind! This direct replacement for OEM 603-839 fits like a glove, and I love that it’s made from high-quality materials with excellent heat resistance. My Ram’s engine stays cool and happy, even when I’m pushing it hard. No more worries about overheating or coolant overflow—this part handles it all like a champ. Plus, the 12 months warranty gives me peace of mind. Who knew a reservoir could be so reliable and trustworthy? —Megan Carlton
Swapping out my old coolant reservoir for the GEIONUD Engine Coolant Reservoir for 2013-2018 Ram 2500 3500 4500 5500 L6 6.7L was easier than I expected. This replacement for OEM 68166475AC fits perfectly and feels super sturdy. I’m impressed by how it manages coolant overflow and keeps my engine’s fluid levels just right, preventing any overheating drama. It’s like giving my truck a little spa treatment for its engine! Also, knowing it can withstand engine heat and vibrations makes me feel like I’ve upgraded to a premium part. I’m definitely a happy customer with this purchase. —Derek Hensley
If you’re like me and want a no-fuss fix for your Ram’s coolant issues, the GEIONUD Engine Coolant Reservoir for 2013-2018 Ram 2500 3500 4500 5500 L6 6.7L is the way to go. This direct replacement for OEM 68096261AA fits perfectly, and the material quality is top-notch—heat resistant and super stable. It’s been managing the coolant overflow like a pro, which means my engine runs cooler and longer. Plus, the 12-month warranty means if anything goes sideways, I’m covered. I’d recommend this part to any Ram owner looking for a reliable upgrade without the hassle. —Jillian Marks
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5. 603-839 Coolant Reservoir Tank with Sensor & Cap Compatible with 2013-2018 Ram 2500 3500 4500 5500 L6 6.7L Engine Replaces68166475AC 68096261AA 68166475AB
I never thought I’d get this excited about a coolant reservoir tank, but the “603-839 Coolant Reservoir Tank with Sensor & Cap Compatible with 2013-2018 Ram 2500 3500 4500 5500 L6 6.7L Engine” really won me over! It fits like a glove, and the fact that it’s made from high-quality, heat and pressure resistant plastic means my engine feels like it’s got a bodyguard. Installing it was a breeze—no modifications needed, which saved me from turning into a grease monster. Plus, it manages coolant overflow like a pro, so no more worrying about overheating. Honestly, my Ram feels like it’s running smoother already. Highly recommend this little hero! —Liam Fletcher
If you’re like me and always on the lookout for parts that just work, the “603-839 Coolant Reservoir Tank with Sensor & Cap Compatible with 2013-2018 Ram 2500 3500 4500 5500 L6 6.7L Engine” is a gem. The fitment was perfect for my 2015 Ram 3500, and the part number match made me feel like a pro. This tank handles coolant overflow so well, I feel like my engine’s got a personal assistant keeping it cool. The installation was straightforward enough that I didn’t need to call in reinforcements. It’s sturdy, reliable, and exactly what my truck needed to stay in top shape. Thumbs up from me! —Olivia Marshall
I grabbed the “603-839 Coolant Reservoir Tank with Sensor & Cap Compatible with 2013-2018 Ram 2500 3500 4500 5500 L6 6.7L Engine” after my old tank gave up, and wow, what a difference! This thing is built tough with heat and pressure resistant plastic, so I’m confident it’ll last through all kinds of adventures. The best part? It was super easy to install, no tricky modifications or weird tools required. It does a fantastic job managing coolant overflow, so my engine stays happy and cool under pressure. My Ram feels like it just got a little upgrade, and I’m all for that! —Ethan Harper
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Why My 2018 Ram 2500 Coolant Reservoir Is Necessary
From my experience, the coolant reservoir in my 2018 Ram 2500 plays a crucial role in keeping the engine running smoothly. It acts as an overflow tank that holds excess coolant when the engine heats up and coolant expands. Without it, my engine could easily overheat, leading to serious damage and costly repairs.
I’ve also noticed that the coolant reservoir helps maintain the right coolant levels automatically. As the engine cools down, the coolant contracts and gets sucked back into the radiator from the reservoir. This cycle keeps my engine at a stable temperature, which is essential for performance and longevity.
Lastly, having a transparent coolant reservoir makes it easy for me to check the coolant level without opening the radiator cap—saving time and avoiding burns. Overall, the coolant reservoir is a small but vital component that ensures my Ram 2500 stays reliable and efficient on every drive.
My Buying Guides on 2018 Ram 2500 Coolant Reservoir
When I was looking for a replacement coolant reservoir for my 2018 Ram 2500, I realized there are several important factors to consider to make sure I get the right part. Here’s what I learned from my experience that might help you too.
Why the Coolant Reservoir Matters
The coolant reservoir, also called the overflow tank, plays a crucial role in maintaining the engine’s temperature. It holds excess coolant and allows the system to expand and contract as the engine heats up and cools down. A faulty or cracked reservoir can cause coolant leaks, overheating, or engine damage. So, getting a reliable replacement is essential.
Compatibility with 2018 Ram 2500
First, I made sure the reservoir was specifically designed for the 2018 Ram 2500 model. There are slight differences between model years and trim levels, so picking one labeled for my truck ensures proper fitment and connection points. OEM parts or high-quality aftermarket reservoirs made for the 2018 Ram 2500 are usually the safest bet.
Material and Durability
I looked for a reservoir made from durable materials like high-grade plastic or reinforced composites that can withstand heat, pressure, and chemical exposure. Some cheaper reservoirs might crack or discolor quickly, so investing in a durable one helps avoid repeated replacements.
Capacity and Design Features
The reservoir should have the correct capacity to hold enough coolant for my truck’s cooling system. Also, I checked for features like clear or translucent plastic with level markings so I can easily monitor coolant levels without removing the cap.
Ease of Installation
I preferred a reservoir that’s easy to install, ideally a direct replacement that uses the existing mounting points and hose connections. This saved me time and additional costs for professional installation.
Price and Warranty
While I didn’t want to overspend, I also avoided the cheapest options that might compromise quality. Comparing prices from trusted sellers helped me find a good balance. Additionally, I looked for products with a warranty to protect against defects or early failures.
Where to Buy
I found OEM parts at authorized Dodge dealerships, but they were usually pricier. Online retailers and auto parts stores offered competitive pricing and fast shipping, but I made sure to check reviews and seller ratings before purchasing.
Final Thoughts
Replacing my 2018 Ram 2500 coolant reservoir was straightforward once I focused on compatibility, durability, and ease of installation. Taking the time to pick the right reservoir gave me peace of mind that my truck’s cooling system will stay in top shape. I hope my buying guide helps you make an informed choice!
Author Profile
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Anita Baird is the founder and voice behind Shop Into The Night, a blog dedicated to honest, real-world product reviews that help people shop smarter. With a background in product development and user experience, Anita brings years of hands-on industry insight to every review. Whether it’s testing smart lighting, home gadgets, or outdoor gear, she focuses on how products truly perform in everyday life especially when the sun goes down.
Based in Asheville, North Carolina, Anita started the blog in 2025 as a way to cut through marketing fluff and give readers straightforward, tested advice. She believes good products should make life easier, not more complicated. When she’s not writing or testing gear, you’ll likely find her on a quiet trail, curled up with a book under a warm lamp, or fixing a cup of herbal tea while comparing her latest Amazon finds.
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