bleeding the bongo - experts please

[andyb36]

hi all

after owning my bongo for 4 plus years - i rekon its time for a coolant change

not any coolant loss or signs of hot temperatures - in all 4 plus years

so you can feel my reluctance to change it

my bro in law mechanic - doesnt smug and laugh at the bleeding method because he states he cannot comment and doesnt want to fit a new head if it all goes wrong

his garage is a very modern hi tech fit with all sorts of gadgets

he hasnt done a bongo before but has done other vehicles with heater matrixs in the rear etc

but what they do is add a gismo that pressurises the system at up to 20 psi and then gets the coolant sucked in and out with any air

??????????????????????????????????????????????

hes been with the same garage for 24 years and works on all sorts of posh upper market stuff so i cannot doubt his knowledge and he states the same when i shown him the bleeding method video

well all you bleeders out there - give me a heads up

or the 2nd alternative is- i start extracting the coolant in the chamber and only refill the chamber with a high mix once a week to a fortnight and get fresh stuff in that way

at least it freshens the inhibiters etc

i do have a noise in that area which may indicate - water pump - manifold gasket - belts

so may have to strip and empty coolant if its the pump

but going to check all this out one cold morning - and locate the noise - it does stop once warmish and only makes the sqeelly noise when damp and cold - hence belts - gasket

but at present i need some advice or guidance

cheer guys

andy

[mikexgough]

If he has the use of a Vacuum kit to refill...... you are sorted ...

[dave_aber]

What he's talking about is a vacuum filler system.

We all (should) understand that due to the design / layout of the Bongo, there are a number of places where air can become trapped and create airlocks in the cooling system - which prevent flow, and cause areas where cooling doesn't happen and thus damage occurs.

The reason that the Bongo 'needs' bleeding is that most DIYers will not have the (expensive) equipment required to fill the system without creating these airlocks. The various bleeding methods we are use are just a way to shift the air, unlock it, and get it out of the system.

Your brother is wise to not mock the methods used by many on here - they do work, and have been proven to many times.

However, I seriously doubt that on the production line Mazda had a team at each Bongo for half an hour or so revving, funnel up, funnel down, etc. Perfectly fine for a home mechanic, who has one Bongo to do, and isn't 'on the clock'. What garages and factories do is suck the air out first, then let the coolant flow in replacing the vacuum left behind.

I have a compressor, so I bought a vacuum filler kit and used that when I changed my radiator. It worked fine. If your brother has the kit required to do it, then it's perfectly valid to use this to refill the Bongo system.

The 'you tube' method does have the advantage that you are seeing the cooling system 'working' at various stages as it warms up, and you can feel when the stat opens etc. It is well worth going through the whole warm up / cool down cycle anyway even with vac filling to test everything.

Of course, usual disclaimers apply - It's YOUR van, so it's up to YOU how you fill / bleed it.

[wonkanoby]

but do flush it out from several places before you refill

[Northern Bongolow]

please remember the system is an old girl now possibly, so i wouldnt want to over do the vac pressure.

i wouldnt use it myself, but i would say that wouldnt i . it may find leaks you never had and give you leaks when the pressure becomes positive in the system later.

your choice, but please let us know how you get on.

[mikeonb4c]

I've done mine twice now using workshop manual method, single handed, and had no trouble. I don't drain the rear heater, which may simplify things a bit risk-wise. I use ethylene glycol standard antifreeze and rely on the dilution principle.