Changing Coolant

[hama61]

Hello,

I am thinking of replacing the coolant of the BN4.

As I have never changed coolant before, I just wondered what is the best way and are there any tips and tricks?

Is it, for example, sufficient to drain to old coolant and have it replaced with fresh coolant, or do you have to flush the system with demi water after draining before putting in the fresh coolant?

Regards,

Harry

 

[Rob Glasgow]

If you haven’t changed the coolant in more than Three years, I would suggest the following.
1. Make sure your valve to the heater hose is open and the heater control lever is in the full hot position.
2. Remove the radiator cap and Open the petcock under the radiator and drain the existing coolant.
3. Refill the system with tap water and add a bottle of radiator flush like Prestone or similar.
4. Drive the car for at least 30 minutes or longer. You can leave the flush mixture in the engine for several days if you wish, just make sure you run it at least an hour or so before the next step. Remember to have the heater level on hot so the mixture will circulate through the heater core.
5. Open the petcock and drain the flush mixture and refill with plain tap water. Run the motor for 10 minutes again with the heater lever on hot. Drain again and repeat step 5 one more time.
6. Drain the system and refill with 50% antifreeze and 50% water. I use distilled water but some say just use tap.
That should do it for 3 to 5 years.

 

[Bob_Spidell]

All 6-cyl Big Healeys, AFAIK, have a block drain (#14), located under the exhaust manifold (unfortunately). It's good for a quart or more but, again unfortunately, if it hasn't been 'exercised' in a long time there's a good chance the handle will snap off if you try to force it to turn (straight out, IIRC, is open). Best to soak it with your favorite penetrating oil and some gentle heat and, if necessary, use pliers to turn (better to scratch the brass a little than break the handle off). Same for the radiator drain and the heater valve.

External Engine 100-6, 3000

External Engine 100-6, 3000

mossmotors.com

 

[Healey Nut]

All 6-cyl Big Healeys, AFAIK, have a block drain (#14), located under the exhaust manifold (unfortunately). It's good for a quart or more but, again unfortunately, if it hasn't been 'exercised' in a long time there's a good chance the handle will snap off if you try to force it to turn (straight out, IIRC, is open). Best to soak it with your favorite penetrating oil and some gentle heat and, if necessary, use pliers to turn (better to scratch the brass a little than break the handle off). Same for the radiator drain and the heater valve.

External Engine 100-6, 3000

External Engine 100-6, 3000

mossmotors.com

Or just remove the drain tap in its entirety from the block and let it drain . A shop vac (with dry bag removed) can also assist with sucking out pockets of coolant stuck in the system .

 

[John Turney]

I agree with just removing the block drain. There is a way to loosen the valve plug so it will turn, but it's just easier to remove the valve. The coolant passages in the block may be loaded with rusty crud, so poking a wire into the drain valve hole should get some flow going.

 

[hama61]

Good day,

Thanks for the anwers so far

The coolant has been changed more than 3 years ago.

For a start i will soak the described valves with penetrating oil the next days.
So if i understand correctly filling up the whole system with 100 percent coolent ( not diluted coolant ) as mentioned below is not desired.

Coolant Antifreeze Type G11 Concentrate is based on mono-ethylene glycol and contains additives to protect against limescale, corrosion, foaming, and other common performance-affecting issues.

This automotive coolant is suitable for diesel and gasoline engines and is engineered to protect all open and closed cooling systems against overheating and freezing.

regards

Harry