Coolant replacement and flush

bluedog333 · Oct 15, 2015

This weekend's job is to replace the coolant, coolant pipes and flush the system. I've got a tiny amount of oil lingering in the coolant from where the oil cooler exploded a while back, so I want to to a thorough job.
Any tips for a 100% flush, I know about the thermostat, but what are the other nooks and crannies I need to know about? Cheers all!

Flossie · Oct 15, 2015

You could remove the rad to flush it maybe and use that as an excuse to remove and flush the intercooler.
There is a drain bolt on the block for the coolent system too, lots of crap/ water remains in the block if you don't remove that. Many , maybe all, are brass bolts so use a quality tool or you'll round it off.

MeatCleaverX86 · Oct 15, 2015

This guy says it all really even include parts numbers if your is a 300tdi

discomania · Oct 15, 2015

bluedog333 said:
This weekend's job is to replace the coolant, coolant pipes and flush the system. I've got a tiny amount of oil lingering in the coolant from where the oil cooler exploded a while back, so I want to to a thorough job.
Any tips for a 100% flush, I know about the thermostat, but what are the other nooks and crannies I need to know about? Cheers all!

Get a hose in and flush and reflush over and over. Oil in the cooling system is bad as it creates a film or oil spots on the water galleries, this then creates hot spots and poor cooling as the water is not directly in contact with the metal. Hot spots are worst as it can lead to increased heat in a localised area which can cause all sorts of issues due to expansion and contraction.

A drop or two of dish soap into the flushing water will help to strip it out - also adding a drop of soap to the fresh water and coolant will reduce the surface tension and help to keep the system running well. I have always had a drop of Fairy in my coolant. When I top up I also add a new drop.

lynall · Oct 15, 2015

Dishwasher tab, washing machine powder, kettle descaler all do a good job, run them with plain water then flush thoroughly before adding anti freeze.

bluedog333 · Oct 15, 2015

Cheers for the replies guys. Thanks for the video Richard.

Roody262 · Oct 17, 2015

Stick a wet vac on one of the hoses and suck it out. Hose one end, vac the other, should shift some build up.

I'm a plumber and often wondered about running central heating cleaner through the cooling system, might damage seals or gaskets though.

Coolant replacement and flush

bluedog333

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Flossie

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MeatCleaverX86

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discomania

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lynall

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bluedog333

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Roody262

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