Thread: Flushing coolant

I just drop old coolant and replace, unless it's an old vehicle with suspect history, the need to flush completely is minimal, others may disagree..

Undo the bottom rad hose and the drain plug on the block, below the inlet/exhaust manifold.
This will get most of the coolant out.
There will be a small amount left in the heater core.
You may as well check the plastic 3 way ejector thingy as it clogs fairly easily.


Don't forget to recheck the clamps in a week or so as the rubber compresses and you get another turn on the clamps.

Re above- automatically thought 300TDI,
may not be the same for your engine.

With a pressure flush gun.

Flush in the reverse direction of flow using the old hoses.

Dry the expansion tank add some 5mm bluemental and shake it, empty and flush.

If your going to do the plugs and replace the p hastlet and water pump.

Set up a bucket with a bilge pump and a hose o. It to feeda sodium bicarbonate mix into the head via the heater outlet . On the front of the engine use the bottom radiator hose as a loop hose with the thermostat removed. Use the expansion tank eturn hose from the radiator hose to flow the mixout of the engine up into the bucket.

Keep the bucket full and above the engine and use the black drain to blow compressed air into the block to agitate everything.

Change the water regularly and once you get clean mix running around swap out your plugs.

It also helps to use an acid wash before you do your abrasive flush.

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Yes, sorry 300tdi. Anyone go down the route of running engine till thermostat is open then run engine and take heater return hose off and put a garden hose in the header tank and turn hose in header tank on, then just let the engine idle until water runs clean. this is what I'm thinking of doing tomorrow.
Cheers ted

Originally Posted by ted44

Yes, sorry 300tdi. Anyone go down the route of running engine till thermostat is open then run engine and take heater return hose off and put a garden hose in the header tank and turn hose in header tank on, then just let the engine idle until water runs clean. this is what I'm thinking of doing tomorrow.
Cheers ted

no point in doing that,,, the thermostat will close up quickly and you wont get enough agitation in the block to clean anything. if you were going to do that you'd be just as well off taking the hose off of the pipe on the top front of the engine that runs to the radiator and stuffing the hose in that.

Don't forget the engine block drain plug.