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Coolant Flush/New Antifreeze


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I need to replace the top and bottom hoses as well as replace antifreeze as 8 years old on my 1974 TR6. I have reviewed the website and this is my plan:

1. Get the engine hot (heater on and set to maximum) until thermostat is open, and leave for a few minutes to fully circulate.

2. Remove radiator cap, remove bottom radiator hose, and top hose and replace new hoses.

3. Remove cylinder drain plug, check water drains out, but if not "poke around" with a coat hanger/screwdriver to unblock any gunge until water flows out.

4 Flush with a garden hose, BUT FROM WHERE, AND WHICH DIRECTION?

5. Mix antifreeze (seems that 30% is favorite??, NON AOT ie Bluecol), fill radiator and start engine, keep topping up radiator and continue when thermostat opens to full circulate. When full replace radiator cap and let cool down.

6. Next day check levels warm up and top up as necessary.

What do you think, is this a good plan any other suggestions welcome please, Regards, Colin 

 

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Hi Colin,

 why not put some RadFlush in for a couple of days before the change. This will help loosen, at least, the easy stuff.

Why get it hot before draining?  

You could remove the thermostat  housing and remove the thermostat. This will give you a good entry into the head/block to get the hose in.

Flush the rad separately  from top to bottom.

 

Roger

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Hi Colin 

Im sure there will be many comments but in the process of curing my overheating when I got my '6", I power flushed from the top radiator hose in to the engine and out the block,  plus I made my own sealed system to inject the water. I had a spare water pump connector ( poor soldering)

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I also bought a Radiator flush kit and fitted a  'T" connector into the top hose to the heater matrix

https://www.ebay.co.uk/p/215085676

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Regards Phil

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Hi Colin.

I drained the system when I replaced hoses and the water pump, filled the system with tap water and radiator flush and circulated that through the system as per the instructions.  I'd also fitted a new drain tap to the radiator so used this from that point.  I then drained the system and repeated the cycle with straight tap water 3 times and then swapped to demineralised water I'd purchased from the supermarket in large 6L containers (really cheap stuff) for anther 4 flushes.  lastly I added Castrol old school green anti-freeze diluted to 50/50 with demineralised water.

The radiator had been out just prior to have some leaks sealed and so had been professionally flushed at that time.  I couldn't get to the drain plug in the block as my exhaust headers prevented access but by the time I added the final brew the water was draining completely clear so I was satisfied that I'd removed all of the original contents.

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I just flush the radiator in both directions until the flushing water  comes  out clean. I do everything cold, I wouldn't be too keen on putting cold water into a hot block.

I refill the radiator to overflowing  with 50% quality coolant and the expansion tank  about 2/3 full. Then run the engine until it reaches operating temperature with the heater full on. The radiator will expel any  air to the expansion tank. 

I then let the engine cool down and top up the expansion tank to the full level.

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Thanks for all the reply's. Taken on board all your comments, with these conclusions:

Best to remove the thermostat and do it cold. Best to flush the radiator both ways separately, best to flush the block separately which I will do. However two further questions please:

1. I live in Devon (UK), never gets that cold (-5°C) minimum, so is 30% antifreeze OK?

2. When I refit the thermostat housing gasket what do I seal it with as dont want leaks. I have a tube of Red Hermetite, but do I coat both sides of the gasket etc?

Cheers, Colin

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I like to use 50% antifreeze to enhance the coolant mixture's anti corrosion properties- as I see it anti freeze is cheap compared to the consequences of corrosion. 

Gasket coatings are a personal preference- I personally coat both sides of most gaskets with non setting sealant- I use  Permatex No 3. 

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3 hours ago, c.hydes said:

Thanks for all the reply's. Taken on board all your comments, with these conclusions:

Best to remove the thermostat and do it cold. Best to flush the radiator both ways separately, best to flush the block separately which I will do. However two further questions please:

1. I live in Devon (UK), never gets that cold (-5°C) minimum, so is 30% antifreeze OK?

2. When I refit the thermostat housing gasket what do I seal it with as dont want leaks. I have a tube of Red Hermetite, but do I coat both sides of the gasket etc?

Cheers, Colin

I regularly use Hylomar Blue both sides of paper gaskets as I hate leaks and don't trust the gaskets on their own.  Thermostat housing and water pump gaskets are both a definite for being coated in my view.  The beauty of Hylomar is that it doesn't harden so the gaskets can be removed at a later date without damage .

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