Bongo Fury

For the first time I've watched all 3 episodes of how to bleed a Bongo cooling system. Surely a lot of faffing about folks???

Maybe I've been lucky but having bled overhauled Bongo cooling systems countless times using the tried and tested Factory method, I can't see the need for all the see-sawing and running the engine until the coolant is constantly boiling (just look at the amount of steam being produced - and how much coolant has to be added to replenish the vapour.

The Mazda Factory method simply states to ensure the bleed pipe is higher than the expansion/degassing tank and to hold a bucket below the pipe. The pipe is made especially long enough to place it on a steering wheel spoke to ensure it is high enough. Revving the engine for around 5/10 minutes (depending on ambient temperature) til the lower hose is hot and the 'stat is open and instantly the trapped air shoots out of the bleeder hose into the bucket - as long as you ensure the expansion tank level doesn't drop (as Haydn correctly states) it's a one person job, over and done quickly and efficiently without having to let the coolant boil for ages.

Sitting back to be shot down in flames......................

When I changed the thermostat on my 2.5 diesel I ran it up to temperature (stat open) and made sure all the air was out. I didn't know "any better" it has been fine for almost 2 years. I was thinking when I have to do it again, a 32mm tube resting in a bucket so it is kept high up, after the stat opens and the air clears lower the bleed hose and fit the cap when water comes out (quickly as it is very hot)
Will try this next time.

Cheers

John

[quote="dandywarhol"]For the first time I've watched all 3 episodes of how to bleed a Bongo cooling system. Surely a lot of faffing about folks???

Maybe I've been lucky but having bled overhauled Bongo cooling systems countless times

The Mazda Factory method simply states to ensure the bleed pipe is higher than the expansion/degassing tank and to hold a bucket below the pipe.

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I was in the 'trade' 40years and flushing the cooling system was something that happened during the the 1970's pushed by various manufactures to sell work..... I also own a Rover des' 75, had it over 10 years now not once have I had to mess around with the cooling system its done 79,800 miles and still got the original exhaust...(just)... I think all this paranoia regarding the cooling systems on bongo's is a inherant problem with the 2.5 diesel engine that stems from a poor engine design after all, I ask this question do bongo 2.0 litre engines have a history of coolant associated engine problems as most of the posts regarding this subject usually refer to diesel engine vehicles
sorry about the rant, no intention to upset the diesel brigade!

Not shooting you down in flames dandy - I got more respect for you than that, but......
The see-sawing motion, even with engine switched off, DOES get air out of the system. How do I know? I can see it happening. And again, with the engine running, air can be seen to be expelled.
I also believe that the factory method would also do the same thing, PROVIDING that the system is in good working order and all pipes and fittings, especially the heaters, are clean and clear of any debris, allowing an unimpeded coolant flow. I suspect that for the majority of Bongos a clean system will not be the case, the main culprit being the front (and possibly the rear) heater matrices.

This is a pic of a Bongo front matrix with the end tank chopped off. It can be seen that the coolant tubes themselves are quite small, but to make matters worse, there is a wavy piece of nylon running through each tube which further restrict the flow. (take a close look at the pic).



Air WILL be present in the heaters after a refill and anything that helps remove it has got to be the way to go. See-sawing causes coolant to flow through the pipework, even with the engine switched off. It may not be the factory method, but most Bongo systems are not in factory condition and may need a little help.

It also needs to be remembered that most Bongo owners do not have the experience (or confidence) that certain members have to do the bleeding.

As far as the videos are concerned, yes, they could be improved by explaining what each stage is actually doing, but for me (and I suspect many others who are not in the know), they were produced to help folk through this important process VISUALLY, and the authors should be applauded .

Nice cut through the matrix Steve - the wavy bits are turbulators which assist in directing the coolant to the walls of the matrix tubes and assists in heat transfer.

I'm hearing your point about old Bongos cooling systems not being perfect but the one's I bled were just as old. I'm also guessing that the waterpump will give better circulation (when the 'stat opens) than the pressure differences by see-sawing..................

It dosn't matter how you bleed the thing as long as it is bled.
I have done at least 2 dozen differant bongos ... on my own (most of them)....using the "see saw" method......it always takes around 35/40 mins (30 mins to get the stat open which I assume must happen whatever method you use) .... it works for me and I have never had to top up next day.

I only ever saw the factory method used once and the bleed pipe "flicked" off the Steering wheel spraying hot coolant all over the interior and the operator...

Horses for courses.

dandywarhol wrote:Nice cut through the matrix Steve - the wavy bits are turbulators which assist in directing the coolant to the walls of the matrix tubes and assists in heat transfer.

I'm hearing your point about old Bongos cooling systems not being perfect but the one's I bled were just as old. I'm also guessing that the waterpump will give better circulation (when the 'stat opens) than the pressure differences by see-sawing..................

Turbulators? - wondered what they were called . Incidentally, the matrix cut was done by Helen (Bulgaria).
I don't think age of the system is as important as its condition. In your case (knowing and having confidence in what you're doing), I would think bleeding is a doddle to you, but Joe average aint got your experience. AND you probably keep your system squeaky clean.
Pump/circulation? Constant delivery pump isn't it? (centrifugal). I would have thought the flow remains pretty constant at a given engine speed, the difference (when the 'stat opens) is that the main flow is through the radiator as opposed to the heater circuit.

Hi,I cant imagine Mazda bleeding the system other than vacuum,otherwise it would probably take longer to bleed the cooling system than actually making the vehicle.

I can also imagine an army of wee Japanese guys at the end of the production line,up to their eyes in Bongos,and up to their knees in antifreeze.

teenmal wrote:Hi,I cant imagine Mazda bleeding the system other than vacuum,otherwise it would probably take longer to bleed the cooling system than actually making the vehicle.

I can also imagine an army of wee Japanese guys at the end of the production line,up to their eyes in Bongos,and up to their knees in antifreeze.

I suspect that the filling/bleeding at Mazda will all be done by some techno machine don't you think.

ive waited a couple of days before commenting, just to see if this went the usual way and ended up as a forum fight it seems safe to come out now so here goes.
in answer to your question alan, it is a faf, and no doubt, but in my opinion it justifies to some extent the faf.

firstly ive got to declare for those that dont know, it was my mrs who filmed them, and my bongo was used in the filming.
this idea really came out of discusions with myself, kirsty, haydn, and ian that such a vid would be useful and would be made available to all on here.
when i first start bongoing i had no access to a manual or the members area factsheets so was working totally blind, it turned out that myself and others were all doing the same/similar sort of bleed thing so a plan to standardise things was hatched. the films were then shot in a rush at the end of the bongo bash a few years ago.
at no time was this said to be the only way to bleed a bongo. but i feel this method has numerous advantages to other methods that i have seen, but the number of others i have seen is nil .
all the bongo specialist must have a way, or their way, but obviously for commercial reasons they are not going to say how they do it, nor would i ask.
but just to put a little spin on that, at last years bash a bongonaught came chatting and asked for help, he said he had been the first uk owner of a p reg bongo, he had taken it into a bongo specialist for maintenance work, weeks later the head cracked, they then fitted a new head, 7 months later the head cracked again, they fell out he took it to another bongo specialist and had a head fitted, that cracked within a year, and to the second dealers credit he has since replaced this last one free of charge. the point of the story is that during all this the owner who was at his wits end knew there was a problem but no one could find it. he has now had trouble free bongoing for the last 6 months due to doing some basic leak checks, replacing a few components and (proper) bleeding of the system.
i have since found out which bleed method they both use, and one is the vac method, and one is nearer the method in the manual. had they used the vid method the problem would have shown itself in the bleed.
as steve comments earlier the method in the manual would no doubt work on a newish system, or a well maintained airtight system, but the question for me is how do i know if its right or not, especially if its not my bongo, or dont know its history, all very important if i am to get paid and gaurentee the work as a garage must do, the answer is drive it .
in the vid method key things can be seen to happen at certain times, and should they not happen then things can be stopped and answers sought before the damage is made worse. with enough experience the timings and steps become clearer. having seen 6 busted head bongo's and how they bleed or dont, the tell tale signs are even more obvious to spot, although on a thermal opening crack this can still be difficult to diagnose in the field without sniff tests etc.
the vid method can be used to get flow temps of certain parts of the circuit/s, heater/s operation,stat operation,waterpump efficiency,fan switching point/temps.
as i said above everyone seems to have their own way of bleeding a bongo but as no one wants to film them, or tell me how they do it, (with the exception of simon jones) so in the absence of knowledge from elsewhere i will stick with what is known to work.
i really would be grateful if someone could work this through and film another easier method so come on peeps get filming.
it's 18 months now since these vids were made, and our knowledge of the coolant system has come a long way, this is certainly due to the efforts of the forum members who have taken an interest, be it big or small, all the contributions are neccessary and are to be applauded. if these films were to be remade things would be done slightly differently but the core points would i feel remain the same.

edit----- has anyone bled one yet using the bleed/vent on the first steel pipe out of the head towards the rad, i would put a lushy link to it if i knew how , the little nipple thing, or as i suspect, the fill point in the factory.
regards ady.

Northern Bongolow wrote:

edit----- has anyone bled one yet using the bleed/vent on the first steel pipe out of the head towards the rad, i would put a lushy link to it if i knew how , the little nipple thing, or as i suspect, the fill point in the factory.
regards ady.

Do you mean this one Ady? (13-104T and 15-538)
If so, I believe that this is simply a drain point for the steel pipe from head to rad (top). You need to open this when doing a complete coolant drain-off. Don't know about it being a 'FILL' point though. Off to have a think about it.

edit: First thoughts are that as this IS probably the lowest point on the system, when the system has been completely drained off and refilled, there will very likely be trapped air in this section of piping (at the head end).
Filling point? Would get a bit messy don't you think? but hey, what do I know.
Just first 'off the cuff' thoughts

thanks for that steve, yes thats the part i am on about .

It wasn't meant to be a contentious post Ady, I was just curious as to why the see-saw was required. I presume it's to create a little pressure during the downward "stroke" to purge any trapped air out. My thoughts are that the combination of pump pressure and the stat opening will create more coolant movement in the system than see-sawing and as air is lighter than coolant it will automatically rise to the highest point - i.e. the bleeder pipe.

As you and Hayden say, whatever suits the individual.

I also thought if I was a newcomer about to buy a Bongo and researched the 'net, I'd be put off by the well intended videos.

would fitting an automatic air vent(ie from a boiler) to bleed tube work for bleeding??

chipvan wrote:would fitting an automatic air vent(ie from a boiler) to bleed tube work for bleeding??

Recently fitted a self bleeding valve to the radiator in my loft and was wondering the same thing....

However, not keen to use my Bongo as a guinea pig to prove the theory