Coolant keeps the engine’s temperature in check. If the level’s too low, the engine can overheat and mess up parts. In cold weather, coolant might also freeze, which clogs or cracks the cooling system. Lots of equipment users ask: “How much coolant do I need?”Below, we’ll break down what coolant does, how much to add, and how to check the level.
What Does The Coolant Do?
Before measuring out fluid, we first need to understand its purpose. The liquid circulating through your engine, often called antifreeze or engine coolant, acts as the lifeblood of your machine’s temperature regulation system. Its job goes far beyond just “keeping things cool.” For powerful off-road equipment working under immense strain, this fluid serves two critical, non-negotiable roles.
Prevents Overheating
The engine generates a lot of heat when it is running. What the coolant does is it takes this heat away. It absorbs heat from the engine block and cylinder head and then flows to the radiator, releasing the heat into the air. Without this cycle, engine temperatures can quickly soar, and parts can burn out, warp, or even simply jam.
Prevents Freezing
Cold weather? Pure water in the cooling system freezes solid. Water expands a lot when it turns to ice. That expansion can crack the engine block or burst the radiator, repairs that cost a ton and take forever. Ethylene or propylene glycol in coolant drops the freezing point big time. These additives also bump up the boiling point, so the system can run hotter without boiling over.
How Much Coolant Is Needed?
This question sits at the core of your concern. The most accurate answer hinges on your specific machine. Passenger cars have small, consistent coolant capacities. Off-road machinery, though, varies wildly in this regard. A compact utility tractor’s cooling system might hold 5-6 quarts (around 1.5 gallons). A large mining haul truck, by contrast, could require over 100 gallons. So, how do we know the right capacity for your machine?
Consult the Operator’s Manual
Your machine’s manufacturer specifies the exact total cooling system capacity. Check the index for “Coolant,” “Specifications,” or “Fluid Capacities.”The manual will tell you the precise volume needed for a full system drain and refill. Trust this document above all other sources.
Differentiate Between Topping Off and a Full Flush
This routine maintenance task only requires a quart or two of coolant. You’ll add small amounts to bring the reservoir level from “LOW” to “FULL.”
For draining and replacing old, contaminated fluid, reference the total system capacity in your manual. Buy slightly more than the stated volume — this accounts for minor spills and leaves extra for future top-offs.For example, if your mid-size excavator’s manual lists 8 gallons as total capacity:
- Purchase 8 gallons of pre-mixed 50/50 coolant, or
- Buy 4 gallons of concentrate to mix yourself.
The Critical 50/50 Mixture
Most coolants come in two types: concentrate or pre-mixed 50/50. If you go with concentrate, mix it with distilled water first before putting it in the cooling system. Straight concentrate doesn’t transfer heat as well as the 50/50 mix — it could even cause engine trouble. Make sure to use distilled water, not tap water. Tap water has minerals that build up as scale and cause corrosion in the radiator and engine pipes.
The Risk of Overfilling
Overfilling isn’t as catastrophic as low coolant, but it’s wasteful and messy. Engine heat causes the coolant to expand. Without space to expand, excess fluid flows out of the overflow tube and onto the ground. This wastes expensive coolant and can hide potential leaks. Stick to the “FULL” or “MAX” line on the reservoir. Persistent loss might not signal a leak. It could indicate another problem, like a failing head gasket that lets combustion gases over-pressurize the cooling system.
Signs Your Coolant Needs Attention
Heavy equipment engines run hot under tough conditions. The cooling system works non-stop to move coolant through the radiator and hoses, pulling heat away from the engine. When that system fails, things can go wrong fast. Watch for these warning signs:
- Rising Temperature Gauge: This sign is the most obvious. If your machine’s temperature gauge creeps higher than normal during operation — especially under load — the cooling system is struggling. Don’t ignore it. Shut down the equipment safely and investigate right away.
- Visible Puddles: If there’s bright green, red, pink, or blue fluid under your machine, that’s an external leak. Check around the radiator, water pump, and all the hoses connecting the system.
- Constantly Low Coolant Level: Frequent top-offs for the coolant reservoir point to a leak. The leak could be external (visible) or internal (hidden from view).
- Floating Debris or Sludge: Open the radiator cap only when the engine is completely cool. Look inside for rusty particles, dirt, or thick sludge. Contaminated coolant loses its protective properties. It needs attention.
- Milky or Oily Coolant: This is a huge red flag! Coolant that looks like a chocolate milkshake means engine oil is mixing in. That usually points to major internal issues, like a blown head gasket or faulty oil cooler. Muddy or milkshake, it’s a warning of a critical engine problem. Get it diagnosed right away to avoid total failure.
- Sweet Smell: Engine coolant has a distinct sweet smell. If you catch that scent around your machine after running it, coolant’s probably leaking. It burns off on the hot engine as it drips out.
How to Check The Coolant Level?
Checking coolant is simple but vital. Follow these steps for safe, accurate results:
- Ensure a Cool Engine & Level Ground: Never open a radiator cap on a hot engine. Hot steam and fluid can spray out, causing severe burns. Park the machine on level ground to get an exact reading. Wait until the engine feels cool to the touch.
- Locate the Coolant Reservoir & Radiator: Open the engine bay and look for two key components: The radiator, a large, finned heat exchanger, usually at the front of the engine. The coolant reservoir (also called overflow or expansion tank) is often a plastic tank connected to the radiator by a small hose. Some heavy equipment uses a metal tank instead. Check your operator’s manual for diagrams showing their exact positions.
- Inspect the Level & Condition: The reservoir has “FULL” and “LOW” marks. Some say “MAX” and “MIN” instead. When the engine’s cold, the coolant should sit right between those two lines.If it’s below “LOW,” top it off. Also, take a look at the coolant’s color. It should be bright and clear. If it’s rusty brown, totally colorless, or has oil floating in it, the system needs a full flush and fresh fluid.
How to Fill Your Coolant?
Topping off coolant is straightforward if the fluid is low but still in good condition. Follow these steps:
Use the Correct Coolant Type
Cooling systems use three main types: IAT (Inorganic Acid Technology), OAT (Organic Acid Technology), or HOAT (Hybrid Organic Acid Technology). Mixing the wrong kinds makes the coolant turn to gel. Just check your owner’s manual to find exactly what coolant your machine needs.
Add to the Reservoir
Make sure the engine is cold first. Slowly unscrew the coolant reservoir cap. Pour in the correct pre-mixed 50/50 coolant. Stop when the level reaches the “FULL” or “MAX” line; never overfill.
Secure the Cap Tightly
Replace the reservoir cap and tighten it firmly. A loose cap stops the system from building proper pressure. This lowers the coolant’s boiling point and reduces cooling efficiency.
Note for Full Drain Refills
If you just did a full system drain:
- Fill the radiator first, then top off the reservoir.
- Run the engine briefly with the heater on high.
- This circulates the fluid and “burps” air pockets out of the system.
- Re-check the coolant level after this process.
When to Change Your Coolant？
Topping off works for routine maintenance, but all coolant needs complete replacement eventually. Corrosion inhibitors and other additives in the fluid break down over time. Heavy equipment requires large volumes, and environmental disposal rules apply. So, a full coolant flush is often best handled by a qualified service technician.
The manufacturer’s recommended service interval is your primary guide for full changes. This interval is measured in operating hours or years, whichever comes first. For heavy machinery, a common interval is every 2,000 hours or 2 years. Long-life coolants can extend this to 5,000 hours or more. Your operator’s manual remains the definitive source for exact timing.
Replace coolant right away if you spot heavy contamination. Signs include rust, sludge, or oil in the fluid. Drain the old coolant, flush the system with clean water to remove sediment. Then refill with fresh 50/50 coolant mix.
Shop for Quality Parts
Keeping your machine’s coolant in check isn’t hard. Just check the level regularly, keep an eye on its condition, and use exactly the type and amount the operator’s manual says. If you need to replace worn parts for maintenance, like coolant hoses, water pumps, or internal engine parts, head to FridayParts. We’ve got high-quality, tough parts at great prices. Our vast inventory fits many heavy equipment brands, with wide compatibility to get you back to work quickly.
