just some info we were given today at work about overheating problems.
the diesel engine
WHAT PROBLEMS DO THEESE ENGINES EXPERIENCE.
the cylinder heads crack between the precombustion chambers and between the exhaust and inlet valves.
frequently blown head gaskets.
WHEN ARE THEESE PROBLEMS LIKELY TO OCCUR.
they may occur when the vehicle is pulling a heavy load or performing hard 4wd work and using a turbo.
or it can simply happen at any time after the engine has reached an age where its operating in a marginal enviroment.in other words its just coping.in this situation high ambient air temperature can be enough to create any of the problems described above.
WHAT CAUSES THE PROBLEM.
there are a number of causes.with each engine type having all or some of theese problems.the fact that we find most disturbing is that theese problems continue to happen from model to model.current model engines are generally not an improvement.
BADLY DESIGNED WATER JACKETS.
the coolinjg sytem is desiigned to transfer heat from the engine to the radiator so that the heat can disipate.often the coolant is trapped in areas around exhaust ports or pre combustion chambers and is not able to circulate due to poor water jacket design.in theese cases the coolant boils and turns to steam.
WATER PUMP FLOW PRESSURE.
often water pumps are unable to continually maintain appropriate water pressure in the cooling system while operating.for example whilst driving the vehicle at 85 kph the pump pressure may be 12 psi.however a small increase in speed to say 97kph may result in the pump pressure dropping to zero.this inturupted pressure will vary with eacch vehicle and depend on the operating load,rpm and air temp.
on theese ocasions the pump pressure drops and the water remaining in the pump housing will cavitate and turn to froth and steam.and there is no water movement to help disapate heat.in other words the coolant above the exhaust ports can not flush away the heat while it is not moving.therefore the water boils and turns to steam.this isolated boiling is known as nucleate boiling.this steam displaces more coolant,placing more pressure on the cooling system,causing temprature to rapidly increase,blowing hoses gaskets and cracking cylinder heads.
COOLANT BOILS OR VAPOURISES IN THE BODY OF THE WATER PUMP.
when the pressure inside the pump falls bellow the vapour pressure of the coolant,vapourisation or cavitation will occur.every body knows that water reaches boiling at lower temperatures when it is boiled at higher altitude(lower air pressure).
BADLY DESIGNED PUMP IMPELLERS.
since the mid 90s the design and construction of water pump impellers has been dominated by the pressed steel unit that looks like the blades of a food prosser.theese impellers aerate the coolant and create inadequate coolant flow.
THE PUMP BY-PASS SYSTEM IS OFTEN CORRUPT.
there is insufficiant coolant passing through the pump when the thermostat is shut.this contributes to cavitation and water pump pressure problems.
GASKETS THAT RESTRICT DOMINENT FLOW.
much to our surprise we are discovering engines that have head gaskets that have been designed incorectly.this applies to both OE and aftermarket gaskets were designed this way. However at this stage we warn you to be vigilant when fitting a gasket. If you have any doubt please call 1800 ....... We do have gaskets in stock for some of these models, that have been upgraded to solve these issues.