Sunday, Feb 15, 2015 at 21:48
Gone Bush is on the money - but it's the lower hose that sucks flat, not the top hose.
If you haven't been maintaining your coolant quality with exceptional care, then the tubes in the radiator core become partly-plugged with a buildup of gunk.
As the water pump sucks from the bottom of the radiator and pumps the coolant through
the block and head and into the top tank, the core flow blockage is where the problems start.
It's almost impossible to have a flow blockage through
the block and head, as the coolant passages there are huge (compared to radiator tubes).
Bottom radiator hoses should be stiffly reinforced or contain a spring, to prevent flattening under high water pump flow levels.
If you find there is no spring and you desire to install one, make sure you select a stainless steel spring, to combat corrosion.
Bottom line is, if the tubes are partly congested, a trip to the radiator repair
shop is the order of the day, to have the tubes cleaned out.
If the tubes are blocked exceptionally badly, the radiator crowd will have to unsolder the top tank and physically clean the tubes.
Usually an acid-bath dip, followed by a pressure flush will clean them out.
Cooling systems should only be filled with the manufacturers recommended coolant - or coolant additive plus pure water.
In the case of Toyotas, the proper Toyota coolant additive added in the ratio of about 40% additive to 60% pure distilled water, or clean rainwater (NOT tap water!) - and then changed out every 3 years - will ensure your cooling system stays in excellent condition.
The genuine Toyota coolant additive isn't cheap, but you have to look on it as cheap insurance.
Always carry a supply of premixed coolant for any top-up, and never add just plain water to a low cooling system.
Cheers, Ron.
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