Coolant Change

[Reebs]

Coolant Change

Hi . New to Bongo Fury . Just bought a N reg Bongo 3 Months ago and have decided to try a coolant change for the first time
After removing the engine air bleed plug, expansion tank cap and rad cap to assist drainage i've drained the coolant system by removing the lower N/S big coolant pipe to the lower side of the radiator and let the system drain.
In refilling the system from the radiator and expansion tank she's only taken on bout 5 litres of coolant in a 50/50 mix as stated in the factsheet. However the factsheet also say's its normal capacity is 13 Litres. Haven't started engine yet and will prob wait for feedback before trying it but she's all set up to bleed the air using the see-saw method and the funnel fills ok when lowered. It seems that the system is already full ????
I'm thinking that i've not fully bled the system initially.... All tech help gladly recieved.
Thanks . Reebs

[francophile1947]

Welcome to the madhouse
Have a read of this thread http://www.igmaynard.co.uk/bongo/forum/ ... =3&t=29471 - local help is often available.
If your Bongo is newly imported, it will probably have the original Japanese antifreeze which is not compatible with ours (it can congeal and block the system ) - you really must flush all the old stuff out before re-filling.
The reason you have so much coolant left in is the rear heater radiator and the long hoses. It needs more than just disconnecting the bottom hose to drain the system.

[missfixit70]

What you've done is empty it, not bleed it, the bleeding is the process of removing the air
Best to flush it all through properly, probably loads stuck in the rear heater pipework under the drivers side cill, undo one of those, empty it out & flush the whole system through with a hose if you can, to get any old stuff out, I'd recommend using a chemical flush too to make sure (follow the instructions of the product, but bear in mind the thermostat hasn't opened fully until the hose coming out of the bottom of the rad on the passenger side gets hot) , then flush through with fresh again & empty before refilling. It's a good idea to replace the thermostat with a genuine mazda one while you're at it, not expensive & it's the crucial control element in the cooling system.
Also not a good idea to mix incompatible coolants if you're not sure what was in there before.
It's very hard to get all the coolant out, that's why it's best to flush with fresh water until you know it's clean, then add your concentrate, then top up with fresh before bleeding IMO.

Welcome to the forum BTW

[mikeonb4c]

There are drain plugs (v easy to undo) for the main engine cooling radiator, and for the rear heater. Personally (prepares to be shouted at) I don't bother draining the heater as its too much hassle and I'm confident ( ) my system is in good condition and so I'm happy just to use the same type of antifreeze (ethylene glycol - std. cheap stuff) and accept a little dilution of old with new. I found that despite draining roughly 11 litres from the system, a lot less than that goes back in UNTIL the system is warmed and the thermostat open. Then, the thermostat opens, the system starts to vent any trapped air into the header tank, and more 50/50 needs adding. I also let a certain amount of coolant come out of the bleed pipe and into a waste bucket even if it is free of bubbles (I find a don't get many of those on mine) on the theory that doing so will help ensure the new 50/50 has made its way through the rear heater and pipes. and old stuff has been flushed out.

I await lots of 'yea but no but' for my unorthodox and lazy ways.

PS - who said I was quicker than Kirsty at replying - they're havin a larf in't they?

[missfixit70]

definitely not a good idea to intentionally leave old stuff in there IMO, get it flushed it doesn't take long

[Bob]

Welcome aboard Reebs. There is a Fact Sheet in the Members' area, which is excellent.

Remember to let the engine cool down after using chemical flushing agent, before you hose out with clean water.

[Reebs]

Thanks all for your quick replies. think I'll go grab a bit more antifreeze and start again flushing it thru this time too.
The coolant was last changed when she had her new cylinder head and gasket done 2 yrs ago. Also had new rad and thermostat fitted too. ( Know previous owner )
Thought things were smelling a bit warm after long journeys so thought best to give her a coolant change and make sure no air lock as a precaution.
Again. thanks for the guidance. I'm off to the shoppee

Cheers Reebs

[mikeonb4c]

definitely not a good idea to intentionally leave old stuff in there IMO, get it flushed it doesn't take long

Kirsty's right of course. But I'm afraid I've always treated my Bongo as one big experiement in risk management. I suspect - provided that the system is healthy - that it doesn't make a critical difference, and I don't get much time at weekends etc. for doing all the various jobs that fall to an ageing dad.

BTW - how accessible is the rear heater drain plug etc. - does the engine cover tray have to come off?

[missfixit70]

There isn't a rear hater drain plug, but the hoses & connections are just under the cill, don't even have to jack it to to get to them.
I prefer preventative maintenance to risk management Never was much of a gambler.

[mikeonb4c]

There isn't a rear hater drain plug, but the hoses & connections are just under the cill, don't even have to jack it to to get to them.
I prefer preventative maintenance to risk management Never was much of a gambler.

Sorry - should have been clearer. The Workshop manual appears to suggest there is another drain plug other than the radiator one. It gives a diagram of the local plumbing but you are left to crawl around underneath trying to identify its exact location. Rather ominously, it says 'Remove the under cover' as part of the instruction notes, suggesting you can't access it without doing this. This and the fact we know the area that may not drain from the rad. plug is the rear heater area, led me to assign it as the drain plug for the rear heater. Its also what decided me that life was too short!

Have you ever identified this drain plug? From the diagram, it looks like a cap held on by some kind of sprung clip (the type used for retaining radiator hoses).

[missfixit70]

That's on the metal pipe between the top hose & the hose to the rad on the drivers side I think, nowhere near the rear heater, should be accesible without removing the rear cover I think, I never use it, I just disconnect hoses so I can flush through thoroughly.
13-104T on here - http://www.lushprojects.com/bongopartsm ... mgno=.html

[mikeonb4c]

That's on the metal pipe between the top hose & the hose to the rad on the drivers side I think, nowhere near the rear heater, should be accesible without removing the rear cover I think, I never use it, I just disconnect hoses so I can flush through thoroughly.
13-104T on here - http://www.lushprojects.com/bongopartsm ... mgno=.html

Ah! Thanks. Must have a look sometime as I've not spotted it yet.

[mikexgough]

[missfixit70]

That's the kiddy Before anyone gets confused, the big hose & pipe underneath is the intercooler pipework going up to the air inlet manifold.

[johnny7]

Just a thought, after draining would it be worth filling up using hot water? I have done this in the past to help rebuilt engines with initial starting, perhaps it would speed up bleed time a bit.