“Introduce an operator to machinery and anything can happen”
Patrick ‘Cal’ Callaby, Workshop Manager at Celtic Manor Resort
weather clothing etc. and puts it behind the seat, not realising (perhaps) that he is preventing air being sucked through the radiator. Sometimes this type of blockage can be more accidental than the above but plastic rubbish bags are often stored there to be used on the operators rounds, since these are light and flimsy they are easily sucked up against the radiator or screen and very effectively block off air flow.
Leaks
Leaks on the outside can have a variety of causes, and I won’t labour the point with long explanations. Rubbing and chafing are common causes of hose failure; also oil contamination can weaken the rubber compound causing it to burst under pressure. Regular inspection of hoses is essential if failures are to be prevented. Things to look for are the above rubbing and chafing, signs of perishing and cracking, swelling behind the hose clips and hose clips in poor condition. Core plugs (occasionally) pop out or
rust from the inside (if water has been used instead of antifreeze mix).
Fan and/or water pump not turning
Keeping with our “simple” system, we will assume that the pump and fan are driven by the same belt (but this is not always the case). So, it necessarily follows that a belt failure will cause overheating because there is no flow of air through the radiator fins and the pump is not circulating water through the engine, another double whammy. Pump bearings fail - nothing lasts
forever - and, usually, coolant will leak past the seal.
Alternator bearings fail and seize and a belt could burn out.
There is no secret to preventing these things from happening; thoroughly inspecting and servicing is the key to preventative maintenance.
Summary
Blockages inside the radiator - can be prevented by using the correct antifreeze mixture.
Coolant additives that temporarily
repair leaks will settle in the bottom tank and premature blocking will occur, so leaks must be addressed by a specialist repairer of radiators and these additives should be viewed as a “get you out of jail” measure. Blockages outside the radiator - radiator fins must be blown out with compressed air and a long nozzle air gun before starting a work period. Initially, blow chaff out the opposite way to which it was sucked in then vice- versa, get right up in the corners of the radiator and alternate from one side of the radiator to the other until no more dust, pollen or chaff comes out. Start the engine and run at full throttle, wait for dust to clear, then start your cleaning of the radiator again, you will be surprised at how much more you will blow out.
Do NOT use water to clean the fins, it is much less effective and most of the debris will be left behind, this will then dry out, solidify around the fins and be impossible to remove without taking out the radiator and (carefully) cleaning with a fan spray on a pressure washer. Instruct operators not to place bags and/or clothing in front of radiators. This also applies to other equipment or materials that may prevent air flow. Leaks can be prevented with a
thorough inspection of hoses and hose clips. Radiators occasionally get holed accidentally, and there is no guard against this, but radiator condition should be included in the inspection routine as should the core plugs (where possible).
Thermostat in closed possition
Look for staining by antifreeze on the engine block and radiator that may lead to a more serious leak. Water pumps often have a tell tale hole drilled in the bottom of the seal housing - look for staining at this point, as it could be that a seal or bearing failure is
imminent. Fan
and/or water
pump not turning - check condition of the fan belt all the way round, remove if necessary and replace if in doubt, it could save time and money later. The alternator bearings may fail without warning. Again there is no guard against this but, if it should happen and the belt survives, you must replace it when changing the alternator, the heat will have made the belt very brittle and it will fail soon, very soon. The Thermostat - there is no inspection routine for the thermostat, it either works or it doesn’t. However, if the engine should overheat shortly after start up and there is sufficient coolant in the system, then take out the thermostat, the chances are it will be closed after removal because of the time it takes.
Place the thermostat in a container and pour hot water over it - it should open! Leave it until the water cools and it should close again. This is a fairly cheap part so, if you are in any doubt about its operation, fit a new one.
General
Drain the system every two years and fill with fresh coolant mixture. Each October I have the antifreeze
checked and adjusted for strength against freezing using a hydrometer. If you have machinery parked outside during the winter (as we do) then please don’t think you have “got away with it” because it didn’t freeze overnight. Such is the cooling efficiency of the system that the radiator could freeze while it is being used. Remember that cold air flows across the radiator fins and tubes and may well freeze a weak mixture in the radiator and very effectively block it causing the engine to overheat. Thoroughly inspecting the condition of the cooling system could save you a lot of downtime and much money, it is time well invested.
“Such is the cooling efficiency of the system that the radiator could freeze while it is being used”
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