Bleeding the System
No, we’re not talking about the almost inescapable scrapes and cuts you’ll get on your fingers and hands during the engine installation process. We’re talking about the car’s cooling system. When you drop the old engine out of the car, the cooling system is going to drain as well. More will escape during the installation process – there’s no escaping this. You’ll have to refill the cooling system once the new engine is in place. However, if you don’t bleed it, you might cause it to overheat and that’s always a bad thing, commonplace among cheap engines for sale and preexisting condition.
Failure to Bleed
Bleeding the cooling system is a two-step process. You’ll do the first step when you install the cooling system components and add coolant to the system. The second step comes when you’re ready to run the engine, not before. As a note, some older engines can be bled using the initial step only, but most newer cars require two steps for the job to be done correctly.
Once you’ve installed all the cooling system components (after making sure each is known to be good and has no excessive wear and tear or damage that might compromise the system), open the bleeder valve on the upper radiator hose stub. Once the valve is open, fill the system with coolant until it comes out the bleeder valve. This forces air out of the system. Close the bleeder valve now. *Note: Not all vehicles have a bleeder valve, and the steps to bleeding air from the system vary considerably from one vehicle to another. Generally, you’ll need to make sure that the heater is on full hot.
When you’re ready to run the engine (and not before – make sure you’ve completed every step necessary for safe engine operation), take the next step. This is easiest with a specialized cooling system funnel so you can add coolant while watching the level in the funnel, but it can be done without one if necessary.Make sure the coolant reservoir and the radiator are full, and then crank the engine with the heater set to full hot. If you’re using a funnel system, the funnel should be in place now – add coolant to the funnel, enough to fill at least the neck and the very bottom of the funnel. If you’re not, leave the radiator cap off. Run the engine until the cooling fans cycle twice and the thermostat opens (you’ll see the coolant level drop when this happens).You’ll see air bubbles rising from the fluid. This is normal (and the entire point of doing this). Tap or shake the upper radiator hose to release additional pockets of air. As the air is purged from the cooling system, the level of coolant will drop. Top it off. Once the cooling fan/fans have cycled twice and the coolant is full, turn off the engine, tighten the radiator cap and let it cool. After it’s cooled for several hours (or overnight if possible), check the coolant level in the radiator and the reservoir; top off if needed. *Note: The process above is messy, and you will get coolant on the radiator and hoses. Make sure you clean the engine properly (and safely) before finally handing the car off to the customer.
