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Thread: Cooling system flushing

  1. #1
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    Cooling system flushing

    Hi,
    I have an excavator that has a serious amount of rust in the bottom tank of the radiator which I have found whilst it was out to be repaired. The engine block has a bit of rusty water coming from the drains plugs but isn't too bad. There's no oil or sludge just rust

    I have flushed the radiator numerous times and is a lot better. Apart from keeping on flushing the system with clean water what else can I do ?

    Thanks

  2. #2
    Senior Member Footsfitter's Avatar
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    Re: Cooling system flushing

    Quote Originally Posted by Right-arm fast View Post
    Hi,
    I have an excavator that has a serious amount of rust in the bottom tank of the radiator which I have found whilst it was out to be repaired. The engine block has a bit of rusty water coming from the drains plugs but isn't too bad. There's no oil or sludge just rust

    I have flushed the radiator numerous times and is a lot better. Apart from keeping on flushing the system with clean water what else can I do ?

    Thanks
    Sometimes its worth trying to reverse flush an engine. If the rad is still out, remove the thermostat and connect up something with a decent flow to the bottom hose connection into the engine, a small water pump or a sprayer at low speed (depending on its pump size) Your aiming more for flow than pressure, plus stopping and starting the flow abruptly may help as does somehow introducing air to the flow as bubbles will loosen stuff up inside (the Air-con flushing kit we have does this once you get it connected up and flowing correctly- the hoses jump/jerk about like made and loads of crap comes out!). Another way to get air in there is to fill, flush and drain, repeatedly- also it can help to connect up to other coolant inlets/outlets around the engine and try them.

    Also, if it has water-to-oil cooler(s) then remove these and inspect the small core tubes the coolant runs through, you'd be surprised at the debris and crud they collect over the years restricting the coolant flow quite easily.
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  3. #3
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    Re: Cooling system flushing

    Quote Originally Posted by Footsfitter View Post
    Sometimes its worth trying to reverse flush an engine. If the rad is still out, remove the thermostat and connect up something with a decent flow to the bottom hose connection into the engine, a small water pump or a sprayer at low speed (depending on its pump size) Your aiming more for flow than pressure, plus stopping and starting the flow abruptly may help as does somehow introducing air to the flow as bubbles will loosen stuff up inside (the Air-con flushing kit we have does this once you get it connected up and flowing correctly- the hoses jump/jerk about like made and loads of crap comes out!). Another way to get air in there is to fill, flush and drain, repeatedly- also it can help to connect up to other coolant inlets/outlets around the engine and try them.

    Also, if it has water-to-oil cooler(s) then remove these and inspect the small core tubes the coolant runs through, you'd be surprised at the debris and crud they collect over the years restricting the coolant flow quite easily.
    Thanks Footsfitter. I flushed the rad using loads of water and an airline in through the bottom hose connection which fetched a lot of material out of the bottom tank.
    The machine is back up and running now, have go it up to temp and pulled the bottom hose off about 4 times, and the water has come out pretty clear. We have got a drain to put across a field shortly and so I have left off the under guard and was going to do these flushes at the end of the day on a daily basis. The oil cooler is a separate radiator altogether in front of the main engine radiator. To back flush the engine block I would connect the supply to go in through the top hose connection on the block after taking out the thermostat?

    Cheers

  4. #4
    Senior Member Footsfitter's Avatar
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    Re: Cooling system flushing

    Quote Originally Posted by Right-arm fast View Post
    To back flush the engine block I would connect the supply to go in through the top hose connection on the block after taking out the thermostat?

    Cheers
    Yes, that would be a reverse flow. The difficulty is often that the flow of water at the rear of the water jacket around the rear cylinders is poor when flushing. When pulling wet liners out of the old CAT engines it was an eye-opener to see how high up the sludge could go on very old systems that hadn't been apart for ages!

    Generally with todays better anti-corrosion coolant mixes corrosion seems less of a problem, but like where oil jugs are left in the open, watering cans or containers can often have a load of bits from a dusty environment and often just gets thrown in along with the water/antifreeze/coolant
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