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Re: Draining / Flushing coolant

>This is a general question that could apply to any car really, though in

> >specific I'm soon to do this job on my Carlton and Fiesta van. > > > >Basically, you drain it by either removing the bottom hose from the > >radiator, or unscrewing the drain plug if there is one, but does that drain > >the cooling system in its entirety? I'm thinking stuff like the heater > >matrix, where it goes round in another big loop - does this all happily > >drain by gravity, or would it be worth turning the engine over a few times > >(and hence the water pump) to get rid of every last bit, or would this > >really not be neccessary? > > Its something I have just got on with in the past but a couple of weeks > ago I changed the coolant on my sons Polo. Its supposed to hold 5-6 > litres but I only managed to put 3 litres in when I filled it up. I had > made sure that the heater control was open and there's even a bleed > screw on the heater control valve. I did the normal stuff of squeezing > the hoses to get rid of any air. > > I was so concerned that it wasn't right that I drained it down and > filled it again. Still took only 3 litres so I guess I didn't get it all > out. Still, I ran the engine between drains so it must have pumped the > new stuff around the system and most of it must have been replaced. Its > done a few hundred miles since and its fine.

I was thinking of maybe draining as much as I could get out by gravity, and then running the engine for literally no more than about 10 seconds (i.e. nowhere near long enough for damage to happen as a result of it running without coolant). Would that work, or would there be a risk of the water pump seizing up, or anything worse?

Peter

Reply to
AstraVanMan
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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.

Reply to
Paul Giverin

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

Reply to
AstraVanMan

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

Reply to
AstraVanMan

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.

Reply to
Grunff

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

Reply to
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.

Reply to
Dave Plowman

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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Reply to
Peter Hill

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