What Is the Best Coolant Reservoir Tank Replacement for 2013-2018 Ram 6.7 Cummins?

A 2013-2018 Ram 2500 or 3500 6.7L Cummins with a cloudy, cracked, leaking, or hard-to-read factory plastic coolant reservoir needs a real diagnosis first, then a stronger direct-fit aluminum replacement if the tank is actually the weak point.

Key Takeaways

• Replace the factory tank when you see yellowed plastic, seam seepage, coolant odor, hairline cracks, or repeated low-coolant warnings after level checks.
• Check the pressure cap, coolant type, hoses, sensor, and system pressure before blaming the reservoir alone.
• Ram/Mopar service information references a 21 psi / 145 kPa coolant pressure cap and OAT coolant conforming to MS.90032 for this diesel platform.
• A TIG-welded aluminum tank is a reliability mod, not a horsepower mod.
• This SPELAB tank is built as a direct bolt-on replacement for 2013-2018 Ram 2500/3500 6.7L Cummins trucks and reuses the factory cap and level sensor.

Should You Replace the OEM Plastic Coolant Reservoir Tank?

Replace the OEM plastic reservoir if the tank is brittle, cloudy, seeping at the bottom seam, stained with dried coolant, or triggering low-coolant warnings after you have already verified the actual coolant level.

Ram heavy-duty trucks are built to work, but the plastic tank lives in a rough spot under the hood. When a 6.7L Cummins is pulling a loaded gooseneck down a long grade and the factory VGT exhaust brake is working hard, under-hood heat goes up fast. The passenger-side reservoir area sees repeated heat soak, vibration, and pressure cycling. Years of that abuse can cook the factory plastic until the seams and mounting areas start looking tired.

Use the Coolant Tank Kit for 2013-2018 Dodge Ram 2500/3500 6.7L Cummins when you want a bolt-on reliability fix for an aging plastic part. Do not use it as a bandage for a deeper cooling-system problem. A bad cap, wrong coolant mix, leaking hose, failing water pump, dirty sensor, or combustion gas entering the cooling system can still cause problems after a new tank is installed.

What Usually Makes the Factory Plastic Tank Fail?

The factory tank usually fails from a mix of plastic aging, heat cycling, vibration, pressure stress, and neglected cooling-system parts around it.

Start with the pressure cap. Ram/Mopar diesel service information lists a 21 psi / 145 kPa coolant pressure cap for this platform. A cap that is dirty, incorrect, weak, or sticking can make diagnosis ugly because the system may not hold or release pressure the way it should. That does not mean every cracked tank is caused by the cap, but it does mean the cap deserves a look before you throw parts at the truck.

Check the coolant chemistry next. If the system already shows sludge, scale, or casting-sand contamination, compare Diesel Coolant Filter Kits before assuming the reservoir is the only weak point. The factory guidance calls for OAT coolant conforming to MS.90032 and warns against mixing in HOAT, “globally compatible” coolant, alcohol-based coolant, straight water, or random rust inhibitors. Wrong coolant does not magically split a tank overnight, but it can reduce corrosion protection and create cooling-system deposits that make the whole system harder to trust.

Watch the warning light on rough roads. On ranch tracks, washboard roads, muddy jobsites, and uneven access roads, coolant can slosh around the reservoir. If the level is already close to the sensor threshold, that movement can set off a ghost “Low Coolant” warning even when the truck is not pouring coolant on the ground. A tank with internal baffling helps calm fluid movement around the sensor area.

Aluminum vs OEM Plastic Coolant Tank: What Actually Changes?

An aluminum coolant tank gives the truck a more rigid, heat-resistant reservoir body while keeping the service layout close to stock.

Plastic makes sense for factory cost and weight. It does not age gracefully forever under diesel-truck heat. Aluminum makes more sense when the truck is older, towing often, parked outside, hauling payload, or getting kept for the long haul. For owners comparing tank options across diesel platforms, the Aluminum Coolant Reservoir Tanks category is the closest match.

SPELAB uses aluminum construction, TIG-welded seams, a powder-coated black or red finish, and a direct bolt-on layout. The supplied product data does not claim 5052 aluminum, robotic welding, or internal anodizing, so those claims should not be written into the article unless the factory confirms them.

Will This Tank Fit a 2013-2018 Ram 2500/3500 6.7 Cummins?

This tank fits 2013-2018 Ram 2500 and Ram 3500 trucks equipped with the 6.7L Cummins diesel engine. If the truck is being planned as a larger reliability build, the 2013-2018 6.7L Cummins Diesel collection keeps the platform-specific parts in one place.

Fitment needs to be boring. That is a good thing. The tank mounts in the OEM reservoir location behind the passenger-side battery, reuses the factory cap and level sensor, and does not require cutting or fabrication when installed on the correct truck.

Will the Factory Cap, Sensor, and Warning System Still Work?

The SPELAB tank is designed to reuse the factory coolant cap and coolant level sensor, while internal baffling helps reduce coolant slosh near the sensor during rough-road use.

This matters more than most product pages admit. A universal tank can look tough but still turn into a wiring and sensor headache. Keeping the OEM cap and sensor setup lets the truck keep its familiar service routine and dash warning logic.

Internal baffling is not magic. It will not fix a bad sensor, damaged wiring, actual low coolant, or a system leak. It does help stabilize fluid movement inside the reservoir when the truck is bouncing through jobsite ruts, ranch roads, rough gravel, or off-road access trails.

What Should You Diagnose Before Installing a New Tank?

Diagnose the cap, coolant type, hoses, sensor, wiring, and system pressure before installing a new reservoir, especially if the truck keeps losing coolant after top-offs.

1. Let the truck cool completely. Never open the pressure cap on a hot system.
2. Inspect the pressure cap. Look for a damaged seal, wrong cap, dirt, corrosion, or signs that it is not venting correctly.
3. Check coolant type. Use OAT coolant that matches the factory specification and avoid mixing coolant chemistries.
4. Inspect the tank seams. Look around the bottom seam, corners, sensor port, hose nipples, and mounting points.
5. Look at hose clamps and nearby fittings. A reservoir may get blamed for a leak that starts at a clamp, hose end, or the Upper Coolant Pipe for 2010-2024 6.7L Dodge Ram 2500HD/3500HD path; this is also where understanding coolant pipe vs coolant hose helps with the diagnosis.
6. Verify the level sensor. A dirty sensor, loose connector, or harness issue can trigger warnings even when the tank is not split.
7. Pressure-test if the problem keeps coming back. Fast pressure buildup, rock-hard upper radiator hoses within 5 minutes of a cold startup, or coolant boiling out repeatedly points directly to combustion gas entry, not just a blown head gasket rumor. Use a block tester kit (combustion leak detector) or a cooling system pressure pump before blaming the reservoir tank.

Use the tank upgrade after the diagnosis points to aged plastic or weak reservoir construction. A good part installed on an undiagnosed cooling system still leaves the real problem hiding under the hood.

How Hard Is the Installation?

Installation is a direct bolt-on job that usually takes about 1 hour for an experienced DIY owner or shop tech on a correct-fit truck.

Remove the stock tank only after the engine is cold. If you are comparing DIY labor against shop labor for related hose service, review radiator hose replacement cost before ordering parts. Transfer the factory cap and level sensor as required, mount the aluminum tank in the OEM location, reconnect the hoses and fittings, refill or top off the correct coolant, bleed the system as needed, and check for leaks after the first full heat cycle.

The kit includes the aluminum coolant tank, mounting brackets, hardware kit, and hose or fittings where applicable. For owners replacing more than the reservoir, SPELAB Coolant Tubes are the related cooling-pipe category. Lay everything out before starting, because missing hardware is easier to catch on the bench than halfway through the job.

Who Should Upgrade to an Aluminum Coolant Tank?

Upgrade if your Ram is high-mileage, tows often, hauls payload, sees hot weather, runs rough roads, or already shows reservoir aging around the plastic seams and sensor area.

A work truck that loses coolant is not just annoying. It can lose a day on the jobsite, cook a tow trip, or leave you watching the temperature gauge instead of the road. That is why this mod makes the most sense for owners who plan to keep the truck working.

Wait if the factory tank is clear, dry, structurally sound, and the truck only sees light use. Good maintenance means fixing the weak point you actually have, not buying every shiny part in the engine bay.

Final Recommendation

Choose the SPELAB aluminum coolant tank when diagnosis shows the factory plastic reservoir is aging, leaking, hard to read, or no longer trustworthy on a 2013-2018 Ram 2500/3500 6.7L Cummins.

The best use case is a truck that still works: towing, hauling, long-distance driving, jobsite duty, ranch roads, hot climates, or high-mileage ownership. The value is not horsepower. The value is replacing a tired plastic reservoir with a more rigid TIG-welded aluminum unit that keeps OEM cap and level-sensor function.

FAQ

Q: Why does the factory coolant reservoir fail on a Ram 6.7 Cummins?

A: The factory plastic reservoir (degas tank) ages and degrades from intense under-hood thermal cycles, turbo radiant heat, and pressure stress. Furthermore, the stock hollow plastic tank lacks internal baffle plates, allowing fluid to violently slosh on washboard roads, which triggers chronic false 'Low Coolant' dashboard warnings.

Q: Should I check the pressure cap before replacing the tank?

A: Yes. Ram/Mopar service information references a 21 psi / 145 kPa cap for this diesel platform. A damaged, wrong, dirty, weak, or sticking cap can make cooling-system diagnosis worse.

Q: What coolant should a 2013-2018 Ram 6.7 Cummins use?

A: Factory guidance calls for OAT coolant conforming to MS.90032. Avoid mixing HOAT, “globally compatible” coolant, alcohol-based coolant, straight water, or random rust inhibitors into the system.

Q: Is an aluminum coolant tank a performance upgrade?

A: No. It is a reliability and durability upgrade. It helps replace an aging plastic reservoir, but it does not add horsepower or lower EGT by itself.

Q: Will this tank fit both Ram 2500 and Ram 3500 trucks?

A: Yes. This tank is built for 2013-2018 Ram 2500 and Ram 3500 trucks with the 6.7L Cummins diesel engine.

Q: Will the factory low-coolant sensor still work?

A: Yes. The SPELAB tank is designed to reuse the factory coolant level sensor. Internal baffling also helps reduce coolant slosh around the sensor during rough-road use.

Q: How long does installation take?

A: Installation usually takes about 1 hour on a correct-fit truck. Let the engine cool fully, reuse the factory cap and sensor as required, refill with the correct coolant, and check for leaks after the first heat cycle.