As the colder months approach, starting your Mercedes Sprinter diesel engine can become a challenge. For owners of older Mercedes diesel vehicles, especially those running on alternative fuels like WVO, a block heater isn’t just a convenience – it’s often a necessity. If you’re experiencing hard starts in cold weather, or if your existing block heater is failing, this guide is for you. We’ll walk you through an alternative, easier-to-install block heater solution that bypasses the common headaches associated with the factory location.
The factory-installed block heaters on older Mercedes diesels, if equipped, are notoriously difficult to access and replace. Years of exposure to the elements can seize the factory plug or heater in place, making removal a risky and labor-intensive process. Traditional methods often involve extreme heat and force, increasing the risk of cracking the engine block – a repair no Mercedes owner wants to face. Labor costs for replacing a factory location heater can also be surprisingly high due to these difficulties.
Instead of wrestling with the potentially seized factory location, we’ll demonstrate how to install a lower radiator hose block heater kit. This method offers a simpler installation process, reduces the risk of engine damage, and can even be more efficient at heating the entire cooling system. By heating the coolant in the lower radiator hose, we leverage the hose’s insulating properties to direct heat into the engine block more effectively. This approach harnesses convection currents within the cooling system to distribute warmth efficiently, preheating your engine for easier starts and reduced wear in cold weather.
This DIY installation is not only more straightforward but also more budget-friendly than tackling the factory heater location. We will be using the DieselGiant lower radiator hose heater kit for this pictorial guide, showcasing how easy it is to bring warmth to your Mercedes diesel on chilly mornings. For this demonstration, we’re using a classic ’79 300D – a testament to the longevity and enduring appeal of Mercedes diesel engineering. Remember to perform this installation on a cold engine for safety.
Safety First:
Before we begin, always prioritize safety. Recycle all used fluids responsibly at designated recycling centers. Avoid spills and splashes of fluids. Whenever working on, around, or under your vehicle, wear safety glasses and ensure the car is securely supported with wheel chocks and approved jack stands.
First, relieve pressure from the cooling system by removing the radiator cap. If you have a turbo diesel model, the cap will be located on the expansion tank, typically found on the passenger side fender well.
Inspect your radiator cap. A good cap, like the one shown, will have rubber seals that are soft and free of cracks or damage. It’s a good practice to replace your radiator cap every time you perform a coolant flush (every two years) to maintain optimal cooling system pressure and performance.
Drain the existing coolant from the radiator. Locate the plastic drain plug at the bottom of the radiator, usually on the driver’s side. This plug typically has a slot designed for a large slotted screwdriver.
As you can see, draining the coolant is a good opportunity to replace old, potentially green antifreeze with a high-quality Mercedes-Benz approved coolant. Regular coolant changes are crucial for preventing corrosion and maintaining the health of your cooling system.
Exercise caution when handling the plastic drain plug. Over-tightening or applying excessive force can cause it to break. Check the rubber seal on the plug for any signs of damage or wear. If the seal is questionable, it’s wise to replace the entire plug assembly to prevent leaks.
This is the DieselGiant lower radiator hose block heater kit as it is shipped. These kits are assembled to provide a straightforward and effective solution for preheating your Mercedes diesel engine.
Now, disconnect the old lower radiator hose. Start by loosening the clamp and detaching the hose from the thermostat housing inlet. Repeat this process at the lower radiator connection point.
Once removed, inspect the old hose. As you can see, significant gunk and sediment buildup is common in older cooling systems. This reinforces the importance of regular coolant flushes and system maintenance.
Here’s a side-by-side comparison of the old lower radiator hose and the new block heater hose assembly. The new hose is pre-fitted with the block heater element, simplifying the installation process.
Take this opportunity to clean any accumulated gunk or corrosion from the thermostat housing inlet and the radiator connection point. A clean surface ensures a good seal for the new hose and clamps.
Using a soft wire brush, thoroughly clean the surfaces until they are smooth and free of debris, as shown. This step is crucial for preventing leaks and ensuring proper cooling system function.
Perform a trial fit of the new block heater hose. You might need to slightly loosen the clamps around the heating element to orient it in a position that prevents rubbing against the radiator or other components. Once you’re satisfied with the fit, remove the hose again to tighten the middle clamps securely.
Install the new block heater hose, ensuring it is properly seated at both connections. Route the electrical cord for the heater to a convenient location at the front of the car for easy access.
Finally, refill the cooling system with the appropriate Mercedes-Benz coolant and carefully check for any leaks at all hose connections.
Important Usage Notes:
Caution: This block heater generates significant heat. It is crucial to run your engine for at least two full days before plugging in the block heater for the first time. This allows the cooling system to be completely purged of air. Air pockets around the heating element can cause it to overheat and burn out prematurely. Your cooling system must be completely full and free of air for the heater to function correctly. Do not attempt to test the block heater by plugging it in before ensuring the system is full of coolant, as this will also cause element burnout.
Under normal cold weather conditions, you will typically only need to plug in the block heater for approximately 3-4 hours prior to starting your vehicle to achieve effective preheating. Leaving the heater plugged in overnight is generally not necessary and can reduce the lifespan of the heating element.
Choosing this lower radiator hose block heater installation method offers a significantly easier and more user-friendly approach to ensuring your Mercedes Sprinter or older diesel starts reliably in cold weather, providing excellent results without the risks and hassles of the traditional factory location.
