Radiator filling

[simon.williams]

Hi, bit of a beginners question but its hard to tell in this cold weather, is there a technique to getting the radiator filled and all airlocks out? The top hose and thermostat being above the radiator and all. My bottom hose always seems cool so I suspect thermostat may not be opening, or I have an airlock. No idea if water pump failure is common, its spinning freely.

Thanks for any tips!

[johnnydog]

I've never had any issues with airlocks filling a replacement radiator or replacing the coolant. Once flushed through thoroughly and clean water is coming out with a top to bottom and a backward flush, then any remaining water in the galleries should be clear / clean. If you intend using a mix of 33% or 50%, add the appropriate capacity of undiluted coolant, and then top up with water (I use pure water from the tap as we live in a soft water area - a hard water area would be best with deionised water). After flushing if you just add diluted coolant of your chosen rate of dilution, then it will be diluted further with the clean water already in the system from flushing.
I run it for a few minutes without the radiator cap until it starts warming up, then replace the cap and get it up to temperature, keeping an eye on the level from start up adding more pure water to keep the correct level. I never have experienced any airlock, but I don't suppose 'burping' the top hose would do any harm. When it's cooled down (say overnight) recheck the level.
The water pump should spin freely, but one in good order should have a slight resistance. A totally free spinning water pump is likely to be on its way out.
Incidentally, make sure your water pump is installed the correct way round - there is usually a drain hole on the 'snout' near the mounting bolts - this should be fitted at the bottom to allow for any condensation or moisture that gets passed through seals to drain out. If it is at the top any collected moisture can't escape and can cause the pulley to seize especially if laid up for a period.
It's an easy job to change the thermostat if in any doubt. I would use a 82 degree thermostat personally.

[simon.williams]

Thanks Johnny.