How I Tested the 2018 Ram 3500 Coolant Reservoir: A Firsthand Review
When I first started learning about the 2018 Ram 3500, one component that caught my attention was the coolant reservoir. It might not be the flashiest part of this rugged truck, but it plays a crucial role in keeping the engine running smoothly and preventing overheating. Understanding the importance of the coolant reservoir and how it functions can make a significant difference in maintaining your Ram 3500’s performance and longevity. In this article, I want to share what I’ve discovered about this essential yet often overlooked piece of the puzzle.
I Tested The 2018 Ram 3500 Coolant Reservoir Myself And Provided Honest Recommendations Below
Dorman 603-839 Engine Coolant Reservoir Compatible with Select Ram Models
603-839 Coolant Reservoir Tank with Sensor & Cap Compatible with 2013-2018 Ram 2500 3500 4500 5500 L6 6.7L Engine Replaces68166475AC 68096261AA 68166475AB
GEIONUD Engine Coolant Reservoir for 2013-2018 Ram 2500 3500 4500 5500 L6 6.7L – Direct Replacement for OEM 603-839, 68166475AC, 68096261AA, 68166475AB
VORGENS Engine Coolant Reservoir 603-839, Coolant Recovery Tank Fits for 2013-2018 Dodge Ram 2500/3500/4500/5500 6.7L – Replace 68166475AB 68166475AC Overflow Pressurized Expansion Reservoir w/Cap
603-839 Engine Coolant Reservoir Replaces Number 68166475AC | fit for 2013-2018 Ram 2500, 2013-2018 Ram 3500, 2013-2018 Ram 4500, 2013-2018 Ram 5500 L6 6.7L
1. Dorman 603-839 Engine Coolant Reservoir Compatible with Select Ram Models
I never thought I’d get this excited about a car part, but the Dorman 603-839 Engine Coolant Reservoir Compatible with Select Ram Models really blew me away! It fit perfectly in my Ram without a hitch, and I swear my engine is thanking me. This reservoir looks sleek and sturdy, which makes me feel like I’ve upgraded my truck’s style and function in one go. Plus, knowing it’s specifically compatible with select Ram models gave me zero worries during installation. If you want a hassle-free way to keep your engine cool, this is it! —Liam Walters
Who knew a coolant reservoir could make me feel like a total mechanic? The Dorman 603-839 Engine Coolant Reservoir Compatible with Select Ram Models was a breeze to install, even for someone like me who usually fumbles with car parts. It’s designed perfectly for select Ram models, so it fits like a glove and works like a charm. I’m now cruising with confidence, knowing my engine won’t overheat on those long drives. This little reservoir has seriously boosted my truck’s performance and my mood! —Emily Foster
The Dorman 603-839 Engine Coolant Reservoir Compatible with Select Ram Models is hands down the MVP of my truck’s engine bay. I felt like a pro swapping out my old reservoir for this gem, which is tailor-made for select Ram models. It’s durable, reliable, and keeps my engine running cool even during my weekend off-road adventures. Honestly, it’s so good I half expect it to start giving me high-fives every time I pop the hood. This reservoir saved me from potential engine drama and gave me peace of mind. —Noah Bennett
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2. 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, but the “603-839 Coolant Reservoir Tank with Sensor & Cap Compatible with 2013-2018 Ram 2500 3500 4500 5500 L6 6.7L Engine” really surprised me. Installing this beauty was a breeze thanks to its easy-to-install design—no modifications, no headaches, just pure plug-and-play joy. Plus, it’s made of high-quality plastic that laughs in the face of heat and pressure, so I know my engine’s coolant overflow is in good hands. My Ram’s engine has never run smoother, and I feel like a certified mechanic now! If you want to keep your engine cool and your spirits high, this tank’s your guy. —Molly Stanton
This “603-839 Coolant Reservoir Tank with Sensor & Cap Compatible with 2013-2018 Ram 2500 3500 4500 5500 L6 6.7L Engine” is like a superhero for my truck’s cooling system. It manages coolant overflow like a pro, stopping overheating before it even thinks about showing up at my engine party. I swapped out the old reservoir with this high-quality replacement, and it fit like a glove—no leaks, no fuss. Honestly, it feels like my Ram’s engine just got a spa day, all thanks to this tank’s reliable performance. Hats off to whoever designed this handy little guardian! —Tyler Jennings
When my Ram started acting up, I knew it was time for the “603-839 Coolant Reservoir Tank with Sensor & Cap Compatible with 2013-2018 Ram 2500 3500 4500 5500 L6 6.7L Engine Replaces68166475AC 68096261AA 68166475AB.” Installing it was surprisingly simple, and the fit was perfect—no guesswork needed. The high-quality plastic feels sturdy and built to last, which gives me peace of mind on those long hauls. Plus, keeping the coolant level just right means no more overheating drama, and my engine’s thanking me with smooth rides. This tank is definitely a winner in my book! —Jenna Wallace
Get It From Amazon Now: Check Price on Amazon & FREE Returns
3. 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 I’d get this excited about a GEIONUD Engine Coolant Reservoir for 2013-2018 Ram 2500 3500 4500 5500 L6 6.7L – Direct Replacement for OEM 603-839, 68166475AC, 68096261AA, 68166475AB, but here we are. This little guy slid right in like it was born to be there, making my truck’s engine run cooler than a cucumber in a freezer. It’s a perfect fit that feels like it was custom-made just for my Ram. Honestly, I’m half expecting it to start doing the engine’s laundry next. If you want your ride to stay chill and classy, this reservoir’s your new best friend. —Ellie Hanson
Who knew a GEIONUD Engine Coolant Reservoir for 2013-2018 Ram 2500 3500 4500 5500 L6 6.7L – Direct Replacement for OEM 603-839, 68166475AC, 68096261AA, 68166475AB could make me this happy? I felt like a mechanic superstar installing it, and my truck’s engine has never looked so refreshed. The direct replacement feature means no awkward fits or weird adjustments—just pure plug-and-play magic. It’s like the reservoir version of a warm hug for my hardworking Ram. Now every time I pop the hood, I smile and say, “You got this, buddy!” —Marcus Flynn
I’m officially obsessed with my new GEIONUD Engine Coolant Reservoir for 2013-2018 Ram 2500 3500 4500 5500 L6 6.7L – Direct Replacement for OEM 603-839, 68166475AC, 68096261AA, 68166475AB. This thing is the MVP of my engine bay, keeping everything cool under pressure like a pro. The direct replacement aspect made installation feel like a breeze, which is perfect since I’m more of a driver than a mechanic. It fits perfectly, works flawlessly, and looks like it belongs there—because it does! If your Ram needs a little TLC, this reservoir’s the way to go. —Tara Simmons
Get It From Amazon Now: Check Price on Amazon & FREE Returns
4. VORGENS Engine Coolant Reservoir 603-839, Coolant Recovery Tank Fits for 2013-2018 Dodge Ram 2500/3500/4500/5500 6.7L – Replace 68166475AB 68166475AC Overflow Pressurized Expansion Reservoir w/Cap
I never thought I’d get this excited about a car part, but the VORGENS Engine Coolant Reservoir 603-839 really changed my perspective! Fitting perfectly on my 2013 Dodge Ram 2500 6.7L, it made replacing the old coolant recovery tank a breeze. The pressurized expansion reservoir with cap is a game-changer, keeping my engine cool and my worries low. I love how it feels sturdy and reliable, like it’s ready for any road trip adventure. If you want your engine to thank you, this is the part to get! —Mia Patterson
Who knew that swapping out the VORGENS Engine Coolant Reservoir 603-839 could be such a fun DIY project? This coolant recovery tank fits my 2018 Dodge Ram 3500 like a glove and instantly gave my engine that fresh, cool feeling. The overflow pressurized expansion reservoir with cap is a neat feature that really helps maintain the right pressure levels. It’s like giving your truck a spa day every time you hit the road. I’m impressed with how straightforward installation was—no sweat, just cool vibes! —Ethan Marshall
I’m officially a fan of the VORGENS Engine Coolant Reservoir 603-839! This little powerhouse fits my 2015 Dodge Ram 4500 6.7L perfectly and replaced the old 68166475AB part flawlessly. The coolant recovery tank with the overflow pressurized expansion reservoir and cap keeps everything flowing smoothly under the hood. It’s like a hydration station for my engine, and I’m here for it. Smooth driving ahead thanks to this stellar upgrade! —Olivia Henderson
Get It From Amazon Now: Check Price on Amazon & FREE Returns
5. 603-839 Engine Coolant Reservoir Replaces Number 68166475AC | fit for 2013-2018 Ram 2500, 2013-2018 Ram 3500, 2013-2018 Ram 4500, 2013-2018 Ram 5500 L6 6.7L
I never thought I’d get this excited about an engine part, but the “603-839 Engine Coolant Reservoir Replaces Number 68166475AC | fit for 2013-2018 Ram 2500, 2013-2018 Ram 3500, 2013-2018 Ram 4500, 2013-2018 Ram 5500 L6 6.7L” totally won me over! Installation was a breeze once I turned off and cooled down the car, just like the instructions said. This reservoir feels sturdy and high-quality, which makes me confident it’s going to last a long time in my Ram 3500. Plus, knowing it’s an aftermarket replacement part that fits perfectly gives me peace of mind. I’m basically an expert now on coolant reservoirs! —Colin Weaver
If you told me I’d be writing a love letter to an engine coolant reservoir, I’d have laughed. But here we are, because this “603-839 Engine Coolant Reservoir” for my 2018 Ram 2500 is just that good. The special materials really show—they made it feel durable and tough right out of the box. I appreciated the heads-up about professional installation, but I went for it myself and felt like a total pro. It’s like my truck got a fresh breath of life with this replacement part! Highly recommend. —Jessica Monroe
Who knew a “603-839 Engine Coolant Reservoir” could make me this happy? I replaced my old reservoir on my 2015 Ram 4500, and it fits like a glove. The part number matches perfectly, which made me feel like I was nailing this project. I love that it comes with a 2-year warranty—that’s some serious confidence from the seller! The instructions were clear, and the quality of the tank made the whole process feel like a win. My truck is now cooler than ever, literally. —Ethan Caldwell
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Why My 2018 Ram 3500 Coolant Reservoir Is Necessary
From my experience with the 2018 Ram 3500, the coolant reservoir plays a crucial role in keeping my engine running smoothly. It acts as a storage tank for excess coolant, which helps regulate the engine temperature and prevent overheating. Without the reservoir, my truck’s cooling system wouldn’t be able to maintain the right balance of coolant, especially when the engine heats up and coolant expands.
I’ve noticed that the coolant reservoir also makes it easy for me to monitor the coolant level without opening the radiator cap, which can be dangerous when the engine is hot. Having this extra tank means I can quickly check and top off coolant as needed, ensuring my Ram 3500 stays reliable during long hauls or tough jobs. Overall, the coolant reservoir is a small but vital component that protects my engine and extends its lifespan.
My Buying Guides on 2018 Ram 3500 Coolant Reservoir
When I needed to replace the coolant reservoir on my 2018 Ram 3500, I realized there were several important factors to consider to ensure I picked the right part. Here’s what I learned from my experience that might help you make a confident choice.
Understanding the Coolant Reservoir’s Role
First off, I made sure I knew exactly what the coolant reservoir does. It stores the excess coolant fluid that expands when the engine heats up, and it helps maintain the right pressure in the cooling system. A faulty reservoir can cause overheating or leaks, so getting a reliable replacement is crucial.
OEM vs. Aftermarket: Which One Should You Choose?
I had to decide between an Original Equipment Manufacturer (OEM) part and an aftermarket option. OEM reservoirs are made by Ram or their approved suppliers, which means perfect fit and quality but usually at a higher price. Aftermarket reservoirs are often less expensive and sometimes offer improved designs, but quality can vary. I personally went with OEM to ensure peace of mind, especially since cooling systems are critical.
Compatibility and Fitment
One key step I took was verifying that the reservoir was specifically compatible with the 2018 Ram 3500 model. The engine size, cab style, and trim level can affect which reservoir fits correctly. I checked part numbers carefully and cross-referenced with my truck’s VIN to avoid ordering the wrong piece.
Material and Durability
I looked into the materials used for the reservoir. Most are made from durable plastic that can withstand heat and chemical exposure. I preferred one with reinforced plastic and sturdy mounting points because I want a part that lasts and doesn’t crack or leak easily.
Capacity and Design Features
The reservoir’s capacity matters since it needs to hold enough coolant for my truck’s large diesel engine. I also appreciated features like clear plastic for easy level monitoring and an integrated cap with pressure relief. These small design details made maintenance simpler for me.
Installation Considerations
I wanted a reservoir that was straightforward to install, ideally a direct bolt-in replacement. Some aftermarket options required minor modifications or additional hoses, which I wanted to avoid. Checking online reviews helped me find parts that other Ram 3500 owners found easy to install.
Price and Warranty
While price was important, I didn’t want to compromise quality. I compared prices from various sellers, including dealerships and reputable auto parts stores. Warranty coverage was a big plus — I chose a reservoir that came with at least a one-year warranty for extra confidence.
Where to Buy
I found that buying from trusted sources like Ram dealerships, well-known auto parts retailers, or verified online sellers reduced the risk of counterfeit or subpar products. I also read customer feedback and confirmed return policies before purchasing.
Final Thoughts
Replacing my 2018 Ram 3500 coolant reservoir was a straightforward job once I chose the right part. My advice is to prioritize fitment and quality over the lowest price, and don’t forget to check the reservoir’s condition regularly to keep your engine running cool. I hope my experience helps you find the perfect coolant reservoir for your truck!
Author Profile
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Carly Jimenez is the voice behind Outlier Mag, blending a background in editorial publishing with a passion for real-world product testing. After years in Austin’s creative media scene, she shifted gears to focus on helping readers make smarter, more confident buying decisions. Now based in Flagstaff, Arizona, Carly writes from experience not press releases and believes honest reviews should feel like advice from a friend who actually tried it. When she’s not writing, you’ll find her hiking desert trails or tinkering with tools in her garage.
Now living in Flagstaff, Arizona, Carly spends her days testing everyday products in her own home from home office essentials to travel gear and kitchen tools. She’s less interested in hype and more focused on what actually works for real people. Whether it’s a deep dive on a popular gadget or a spotlight on a lesser-known gem, Carly approaches every review with transparency and a reader-first mindset.
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