Coolant- Opposite to usual problem

[missfixit70]

[mikeonb4c]

Coolant change using that method is basically the "Hosepipe method" Mike KK - Kawasaki Kid

Wow. Are we really suggesting then that you can

1) Take 12 litre (or whatever system capacity is) of fresh 50/50
2) Warmed the engine properly so thermostart is open etc. (best done by some real driving as they never warm up when stationary - why?)
3) Being v. careful in removal of the cap from the pressurised and hot header tank
4) Open up engine bay and uncork bleed pipe (being v careful not to scald yourself, hence why remove header tank first to depressurise system)
5) Place bleed tank in bucket (or just drain to ground)
6) With mate ready to pour in replacement 50/50 coolant mix, start engine and, as old coolant exits the bleed pipe, just top up the header tank with new coolant.
7) Cork bleed pipe when supply of new coolant almost gone
'8) Use last of the new 50/50 mix to make sure header tank is settled at correct level.

And then the $64 question - why haven't Mazda suggested it as a viable method.

But it sounds like a potentially worry free way of ensuring that a Bongo that had no airlocks before coolant change is very unlikely to have them after coolant change.

Discuss?

PS - discovered you can't do a list on here with an item numbered '8)' in it as you get - ha ha!

[bigdaddycain]

The anti-freeze doesn't HAVE to be pre mixed mike, it can be added neat, (around 5 litres, 6 litres if you really must have a 50/50 mix), all the mixing takes place naturally as the coolant circulates the system.

But, yes, your understanding is correct, coolant can be replaced that way. Airlocks occur due to pipes,rad, pump, etc being depleted of said coolant, replaced with air, then it's the removal of that air that causes the problems.

If the air isn't introduced in the first place, it doesn't NEED to be bled!

The only trick to it is not allowing the level in the expansion tank to drop below minimum whilst replacing the fluid.

[missfixit70]

Don't know about the method you've just described Mike, as with the engine running, you'd have the cooolant exiting the bleed hose quite soon after starting, but, by flushing through thoroughly with a hose with the engine running & bleed pipe open, balancing the level in the header tank so as not to introduce air, then adding neat coolant with the engine off, as described in this thread, then yes

[bigdaddycain]

And then the $64 question - why haven't Mazda suggested it as a viable method.

Ooh, controversial Michael!

Some are of the opinion that there was a spot of scare-mongering going on in japan upon the launch of the bongo, rumour has it that a deliberately complicated bleed procedure was insisted upon for various reasons,one of which is a void warranty if anybody other than a ford/mazda dealer carried out the bi-annual coolant change (another stipulation of the warranty ).

Some would argue that a simpler yet equally effective method would be frowned upon by the main dealers,as it would effectively mean that they wouldn't receive their £120 for the coolant change/bleed procedure.

[bigdaddycain]

Don't know about the method you've just described Mike, as with the engine running, you'd have the cooolant exiting the bleed hose quite soon after starting, but, by flushing through thoroughly with a hose with the engine running & bleed pipe open, balancing the level in the header tank so as not to introduce air, then adding neat coolant with the engine off, as described in this thread, then yes

I missed that, yes mike, with engine running.

[haydn callow]

Coolant change using that method is basically the "Hosepipe method" Mike KK - Kawasaki Kid

Wow. Are we really suggesting then that you can

2) Warmed the engine properly so thermostart is open etc. (best done by some real driving as they never warm up when stationary - why?)

You will get the engine up to running temp quicker by going for a run. However you probably won't get the stat open unless you stop and idle.(heatsoak). If you then start pouring coolant in without the engine running and at high temp the stat will soon close and the rad and bottom will not receive coolant.
This worries me !!

[bigdaddycain]

If you then start pouring coolant in without the engine running and at high temp the stat will soon close and the rad and bottom will not receive coolant.
This worries me !!

If the stat is open, with the engine running, cold coolant can be added via the expansion tank, for the purpose of replacing 5 or so litres of coolant to strengthen the mix. This would not cause the stat to close, as the cold coolant would by the time its reached the stat have heated as it's mixed with the other hot coolant. The 82 deg stat opens and closes very slowly, i'd be surprized if it had chance to close fully before the whole procedure was completed.

[missfixit70]

Coolant change using that method is basically the "Hosepipe method" Mike KK - Kawasaki Kid

Wow. Are we really suggesting then that you can

2) Warmed the engine properly so thermostart is open etc. (best done by some real driving as they never warm up when stationary - why?)

You will get the engine up to running temp quicker by going for a run. However you probably won't get the stat open unless you stop and idle.(heatsoak). If you then start pouring coolant in without the engine running and at high temp the stat will soon close and the rad and bottom will not receive coolant.
This worries me !!

But then once you run the engine again, the stat opens (if it closed) & the coolant mixes.

[haydn callow]

You would have to make sure that happened....It can be quite a long process....I can somtimes drive all day and not reach 82 c at the stat...
I 'm not trying to knock this method...don't get me wrong.....If the peep doing the change is aware of exactly what needs to be done,,then fine...But if not, and lets say the rad was left half full of water overnight at this time of year !!!!

[missfixit70]

Fair point Haydn, it just struck me as being the simplest option by not introducing air again in the first place.
What a civilised coolant thread

[daveblueozzie]

You would have to make sure that happened....It can be quite a long process....I can somtimes drive all day and not reach 82 c at the stat...
I 'm not trying to knock this method...don't get me wrong.....If the peep doing the change is aware of exactly what needs to be done,,then fine...But if not, and lets say the rad was left half full of water overnight at this time of year !!!!

at least he would have some coolant in the rad, at the moment he just has plain water.
once youve finished adding enough coolant, there is nothing stopping you taking it for a good run and a bit of hard driving to open the stat and mix the coolant properly.knowing youve not introduced air into the system (as long as you carefully fill and empty at the same time)

[haydn callow]

Yes...in this particular case....I was thinking of all the others that may have a go and perhaps not understand all the possible implications of getting it wrong

[mikeonb4c]

I'm with Haydn on this one. I would love there to be a simple, angst free way of doing the job (though its debatable how relaxing it might end up being (not) with the need for my assistant to get it right at header tank end etc. so level didn't drop too low.

But its Haydns point about thermstats closing that worries me as this is a thought I had quite independantly and his thinking it too etc.

I think there is a lot of stuff in the official bleeding procedure that (whatever political reasons in contains) is intended to ensure the coolant and the system are both nice and hot. Introducing cold coolant mix carries a risk of shutting off part of the circuit from being purged of old stuff.

OK, so modify the method and say new 50/50 mix must be heated to near boiling before pouring it in. Ha ha - I think not

[daveblueozzie]

I would love there to be a simple, angst free way of doing the job (though its debatable how relaxing it might end up being (not) with the need for my assistant to get it right at header tank end etc. so level didn't drop too low.

Good communication between the filler and the person on the bleed pipe is essential, but as long as the person filling the expansion tank keeps it brim full all the time,(OR AT LEAST NOT LETTING IT DROP BELOW THE LOW WATER MARK) then no air is introduced.(as long as no air is in the system in the first place)
When me and BDC have done this, i always tell him im running low on coolant filling the tank ,and then he stops the bleed till i refill.
There is quite a bit of leeway between brim full ,and the low marker on the expansion tank.
Its not the Mazda way but it works. MR MUNKEY,KAWASAKI KID, BDC AND ME can vouch for this method.
As for the stat i can understand Haydns concern, but as long as you give it a good run and a bit of hard driving after you have put the coolant in, it will open the stat and then mix the coolant ,i suppose just pottering about and not forcing the engine may not open the stat as quickly. so dont potter about, give it a bit of welly.