Re: Draining / Flushing coolant

In message , AstraVanMan writes

I don't think it would do any harm but it wouldn't get anything out of the heater matrix. I disconnected the LT to the coil and cranked it over on the starter but it didn't make a difference.

I'd be flushing it through (I'd do the rad separately as well, but also flush the engine - I was going to do it via where the thermostat bolts onto the engine), but if I did that, how would I know how much water was left in the coolant channels (water jacket) around the engine/rad??

Basically, if I did that, and the coolant system had a capacity of 6 litres, but it would only take 4 litres, and those 4 litres were 50% antifreeze 50% water, then obviously the solution would be weakened. Any suggestions on how to completely drain it so that that wouldn't happen?

Peter

Ah, cheers, that's very useful. So will the amount of coolant left in the heater matrix (and left hanging around in the pipes leading in and out of it) be a fairly insignificant amount compared to the total cooling system capacity? Any idea of roughly what percentage?

Peter

Your total capacity will be between 6-10 litres. The matrix will hold 0.3-1 litre.

BTW, what I usually do is disconnect both top+bottom rad hoses, and connect a garden hose to the top hose while it's connected to the engine (make your own adapter from bits of hose, pipe, jubilee clips, fairy bottles, chickens, whatever). I then flush 'til it comes out clear.

Then, I connect the top hose back to the rad, and disconnect it from the engine, and flush the rad in the same way.

I do this because most of the cars I do it on have crudded up coolant systems. If your coolant looks clean, and has been changed regularly, then don't worry about it. Just remove the bottom hose 'til it all drains out, reconnect it, and refill.

What I do is as follows:

Drain as much of the coolant as possible then tighten drain plug (or bottom hose). Fill up until overflowing with fresh water. Run the engine for a minute or two (don't bother waiting for it to warm up fully). Drain again Insert hosepipe into top-hose stub on rad and flush until clear water emerges. Put everything back together. Fill half of the stated coolant capactiy with neat antifreeze, then top up to line with water. Start engine and top up with plain water if necessary. Drive until warmed up, then check level again. Top up with plain water if necessary.

The above procedure ensures that most of the old antifreeze is removed from the heater and radiator.

The Dervboy

It might make a difference in that the water can't be rusty, although their are some steel parts in the system, but there was no corrosion inside the waterjacket either - I changed the water pump at the same time. I think modern anti-freeze with corrosion inhibitors are the main reason.

Make sure the heater is set on 'hot' so the flow control valve is open to drain the heater. Just taking the bottom hose off may not fully drain the block. You need to locate and open all drain points. To flush heater disconnect hose at bulkhead and put a water hose on it.

Supposed to use soft or distilled water to refill with, so if you live in a hard water area you need to buy some.

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