A slight twist to the "bleeding method"

Technical questions and answers about the Mazda Bongo

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helen&tony
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Re: A slight twist to the "bleeding method"

Post by helen&tony » Mon Jul 06, 2015 3:44 am

Hi
No...don't use a one-way valve...part of the reason the see-saw method works so well in removing an air-bubble that can result in air lock is that you are moving a column of water in the bleed-tube one way, then the other, with the aid of the water-pump one way, and a head of water in the funnel / jug the other way, and it hopefully gives up the ghost and shifts, with the final burp of air with a push when the stat opens, along with the bit of air trapped under the stat 'till it opens. You could try a quick-release valve with the valve end permanently left on the end of the bleed hose, but it's one more thing to go wrong...I've used such systems on high-pressure gas, but they tend to be very expensive , but the tap is only about £15.00 .
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Re: A slight twist to the "bleeding method"

Post by mikeonb4c » Mon Jul 06, 2015 8:30 am

helen&tony wrote:Hi
No...don't use a one-way valve...part of the reason the see-saw method works so well in removing an air-bubble that can result in air lock is that you are moving a column of water in the bleed-tube one way, then the other, with the aid of the water-pump one way, and a head of water in the funnel / jug the other way, and it hopefully gives up the ghost and shifts, with the final burp of air with a push when the stat opens, along with the bit of air trapped under the stat 'till it opens. You could try a quick-release valve with the valve end permanently left on the end of the bleed hose, but it's one more thing to go wrong...I've used such systems on high-pressure gas, but they tend to be very expensive , but the tap is only about £15.00 .
Cheers
Helen
Aha! Maybe an explanation for why the seesaw method could be more effective than the Mazda method? Presumably needs 2 people to do it?
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Re: A slight twist to the "bleeding method"

Post by helen&tony » Mon Jul 06, 2015 9:18 am

Hi
Mike...
That's my take on shifting an air bubble...I've done it in laboratories loads of times, joggling tubing, tapping it , etc. Beggar of a job to shift sometimes , in small-bore tubing...so I guess that's why see-sawing works so well in the Bongo...PLUS the revving at 2500 RPM, shutting off , and letting it tickover also shunts the fluid...it's the equivalent of tapping a tube to shift a bubble....and , believe me, it's a lot harder in lab glassware :lol: or a hypodermic...they can be stubborn little pigs, those air bubbles :lol:
As for 2 people...perhaps with a fuel tap in as I described, it is easier for single handed work?
Cheers
Helen
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Re: A slight twist to the "bleeding method"

Post by cookan » Mon Jul 06, 2015 12:21 pm

yup..see what your saying Helen and take your point re jiggling stuff around to get the bubbles to shift. Thought revving the engine would be enough to shift that column of water..so provided you have enough of a reservoir..no need to physically move the funnel..just let it draw down..there'd be up to 4 litres it could draw down through the bleed hose in my case (not that it would take that much in) without needing to lower the funnel.

by directional valve I meant diverter valv...so turned one way it allows coolant to flow back up and down into/out of the funnel but when you're done, you switch the valve which firstly would cut off flow to the bleed hose and secondly drain the funnel/reservoir...

I should probably just do it and stop talking about doing it shouldn't I !

thanks,
Ant.
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Re: A slight twist to the "bleeding method"

Post by mikeonb4c » Mon Jul 06, 2015 12:35 pm

helen&tony wrote:Hi
Mike...
That's my take on shifting an air bubble...I've done it in laboratories loads of times, joggling tubing, tapping it , etc. Beggar of a job to shift sometimes , in small-bore tubing...so I guess that's why see-sawing works so well in the Bongo...PLUS the revving at 2500 RPM, shutting off , and letting it tickover also shunts the fluid...it's the equivalent of tapping a tube to shift a bubble....and , believe me, it's a lot harder in lab glassware :lol: or a hypodermic...they can be stubborn little pigs, those air bubbles :lol:
As for 2 people...perhaps with a fuel tap in as I described, it is easier for single handed work?
Cheers
Helen
Ha ha yes, I was a medical laboratory scientist for 4 years in my youth so am familiar with your arguments. I'm guessing the Mazda recommended method may result from it allowing the job to be done by one person rather than needing 2? That would make it more practical in a cost driven garage servicing set-up. It was also handy for me when I bled mine on my own. The Mazda method does indeed prescribe a quite specific procedure for leaving the engine at tickover for a period, then at 2500rpm, then more time at tickover, then more at 2500rpm etc, and its all clearly aimed at ensuring the thermostat is open and every effort made to ensure air bubbles will be scavenged. I think Ant could be right though about not needing a funnel as, if it were that important, Mazda might have stipulated it: it strikes me as unlikely they would have allowed garages to be put at undue risk of Bongos returned with blown heads resulting from ineffective bleeding.
Last edited by mikeonb4c on Mon Jul 06, 2015 12:38 pm, edited 1 time in total.
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Re: A slight twist to the "bleeding method"

Post by dave_aber » Mon Jul 06, 2015 12:38 pm

Neat solution Helen - I will be shamelessly copying this!

I have done the funnel see-saw method a few times now, single handed each time. The trick to doing it solo is to have a piece of skirting board or similar resting on the throttle - you can rev up the engine, let go of the plank and it stays in place due to the friction on the carpet / seat.

Any reason not to just leave the tap fitted once the bleed is complete? Add a bung to its outside port to prevent leakage if the tap fails?

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Re: A slight twist to the "bleeding method"

Post by mikeonb4c » Mon Jul 06, 2015 12:41 pm

dave_aber wrote:Neat solution Helen - I will be shamelessly copying this!

I have done the funnel see-saw method a few times now, single handed each time. The trick to doing it solo is to have a piece of skirting board or similar resting on the throttle - you can rev up the engine, let go of the plank and it stays in place due to the friction on the carpet / seat.

Any reason not to just leave the tap fitted once the bleed is complete? Add a bung to its outside port to prevent leakage if the tap fails?

DA
Ah - so the seesaw can be done 1 handed then :-) Something to hold the throttle at 2500rpm is needed with the Mazda method also, so it seems like either method can happily be used.
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Re: A slight twist to the "bleeding method"

Post by helen&tony » Mon Jul 06, 2015 1:43 pm

Hi
Dave...
Purely personal, but I wouldn't trust leaving the tap in...it's a ball-valve, and maybe unlikely to hold pressure?...If it was designed for a high-pressure system, I'd say yes, it's safe...I have an address of a very helpful company I used to buy fittings from in the UK...I was using pressures of 750PSI and temperatures of maybe minus 100C...and they were pretty fail-safe :lol: ...OR, the race shop in Silverstone circuit had quick-release fittings that were for high-pressure....they sent a couple of reps to my house to look over what I was using....BUT....VERY pricey gear!....
For remotely operating the tap, you can get motorised ball valves, but, hey, it all gets too high-tech... :lol:
Mike...
For the throttling,you could use a system like the Series 2A Landy cruise control...a wire loop in the dashboard...put your finger in and tug to set the throttle :lol: Kool invention...I've used it when stuck in mud....put it in low box 1st, get out, stand on rear bumper handle, and jump up and down...and when said landy moves, walk round and get in whilst it's driving along! :lol:
Cheers
Helen
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Re: A slight twist to the "bleeding method"

Post by haydn callow » Mon Jul 06, 2015 1:52 pm

mikeonb4c wrote:
helen&tony wrote:Hi
Mike...
That's my take on shifting an air bubble...I've done it in laboratories loads of times, joggling tubing, tapping it , etc. Beggar of a job to shift sometimes , in small-bore tubing...so I guess that's why see-sawing works so well in the Bongo...PLUS the revving at 2500 RPM, shutting off , and letting it tickover also shunts the fluid...it's the equivalent of tapping a tube to shift a bubble....and , believe me, it's a lot harder in lab glassware :lol: or a hypodermic...they can be stubborn little pigs, those air bubbles :lol:
As for 2 people...perhaps with a fuel tap in as I described, it is easier for single handed work?
Cheers
Helen
Ha ha yes, I was a medical laboratory scientist for 4 years in my youth so am familiar with your arguments. I'm guessing the Mazda recommended method may result from it allowing the job to be done by one person rather than needing 2? That would make it more practical in a cost driven garage servicing set-up. It was also handy for me when I bled mine on my own. The Mazda method does indeed prescribe a quite specific procedure for leaving the engine at tickover for a period, then at 2500rpm, then more time at tickover, then more at 2500rpm etc, and its all clearly aimed at ensuring the thermostat is open and every effort made to ensure air bubbles will be scavenged. I think Ant could be right though about not needing a funnel as, if it were that important, Mazda might have stipulated it: it strikes me as unlikely they would have allowed garages to be put at undue risk of Bongos returned with blown heads resulting from ineffective bleeding.
I would guess that Mazdz and their dealers use a vacuum device to fill/bleed the system
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Re: A slight twist to the "bleeding method"

Post by mikeonb4c » Mon Jul 06, 2015 1:52 pm

helen&tony wrote: For the throttling,you could use a system like the Series 2A Landy cruise control...a wire loop in the dashboard...put your finger in and tug to set the throttle :lol: Kool invention...I've used it when stuck in mud....put it in low box 1st, get out, stand on rear bumper handle, and jump up and down...and when said landy moves, walk round and get in whilst it's driving along! :lol:
Cheers
Helen
Already got that one covered with a throttle lock cruise control that doubles v well as a tickover/rpm adjuster when required ;-)
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Re: A slight twist to the "bleeding method"

Post by mikeonb4c » Mon Jul 06, 2015 1:56 pm

haydn callow wrote:
mikeonb4c wrote:
helen&tony wrote:Hi
Mike...
That's my take on shifting an air bubble...I've done it in laboratories loads of times, joggling tubing, tapping it , etc. Beggar of a job to shift sometimes , in small-bore tubing...so I guess that's why see-sawing works so well in the Bongo...PLUS the revving at 2500 RPM, shutting off , and letting it tickover also shunts the fluid...it's the equivalent of tapping a tube to shift a bubble....and , believe me, it's a lot harder in lab glassware :lol: or a hypodermic...they can be stubborn little pigs, those air bubbles :lol:
As for 2 people...perhaps with a fuel tap in as I described, it is easier for single handed work?
Cheers
Helen
Ha ha yes, I was a medical laboratory scientist for 4 years in my youth so am familiar with your arguments. I'm guessing the Mazda recommended method may result from it allowing the job to be done by one person rather than needing 2? That would make it more practical in a cost driven garage servicing set-up. It was also handy for me when I bled mine on my own. The Mazda method does indeed prescribe a quite specific procedure for leaving the engine at tickover for a period, then at 2500rpm, then more time at tickover, then more at 2500rpm etc, and its all clearly aimed at ensuring the thermostat is open and every effort made to ensure air bubbles will be scavenged. I think Ant could be right though about not needing a funnel as, if it were that important, Mazda might have stipulated it: it strikes me as unlikely they would have allowed garages to be put at undue risk of Bongos returned with blown heads resulting from ineffective bleeding.
I would guess that Mazda and their dealers use a vacuum device to fill/bleed the system
Hmmm, I wonder. How many Bongos (in the UK) have ever been handled by Mazda dealers. When I contacted my local one (Mazda Warrington) some years back the mechanics didn't even know what they were (though the spares department certainly do know by now). I think it is (as you say) just a guess what happens outside of the workshop manual (which I assume is a Mazda authorised book?). The manual makes no reference to vacuum bleeding and you'd think it might, if it were anticipated that garages might opt for that.
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Re: A slight twist to the "bleeding method"

Post by helen&tony » Mon Jul 06, 2015 3:42 pm

Hi
Ant...
You'd be surprised I've had nearly un-shiftable air-locks in tubing that couldn't be shocked by merely moving fluid in a manner such as throttling / de-throttling....they just move forward and backward , and are VERY stubborn...I've rebuilt laboratory equipment to get rid of an air-lock....a LOT of work, so moving the funnel / jug is just that last bit that "broke the camel's back, so to speak.
Haydn...
Absolutely, they use workshop compressors ....high output ones!, because the vacuum fillers are pretty efficient if you have MORE THAN 12 CFM FREE AIR DELIVERY...most compressors people use at home are like a damp squib in comparison....and compressors are mostly rated in DISPLACEMENT , which basically means cylinder capacity, and not delivered air...By co-incidence, I'm looking at an 18-20 CFM compressor on Wednesday!...you can't get much more on single phase, and all the 3-phase installations in the barn are disconnected!
If it's any good, here's a video clip of the jug...I'm merely demonstrating it cold, using an old bleed hose for effect, but it shows the idea better than words!....excuse my bumbling in the clip... :lol:

http://smg.photobucket.com/user/solstic ... rt=6&o=171

With the tap , you could pop it on the floor, or a handy chair, and pop round to top up when the LCA goes off!
Cheers
Helen
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Re: A slight twist to the "bleeding method"

Post by helen&tony » Mon Jul 06, 2015 3:55 pm

mikeonb4c wrote:
helen&tony wrote: For the throttling,you could use a system like the Series 2A Landy cruise control...a wire loop in the dashboard...put your finger in and tug to set the throttle :lol: Kool invention...I've used it when stuck in mud....put it in low box 1st, get out, stand on rear bumper handle, and jump up and down...and when said landy moves, walk round and get in whilst it's driving along! :lol:
Cheers
Helen
Already got that one covered with a throttle lock cruise control that doubles v well as a tickover/rpm adjuster when required ;-)

Hi Mike...
Do show details...PLEASE... :lol:
I like simple ideas like that...I keep meaning to do the tickover when the air-con's on!
Cheers
Helen
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Re: A slight twist to the "bleeding method"

Post by mikeonb4c » Mon Jul 06, 2015 4:10 pm

helen&tony wrote: Absolutely, they use workshop compressors ....high output ones!......
Yea but no but. I'm sure they do but how many UK Bongo owners use, or are likely to use, Mazda main dealers (and their labour charges) to do a Bongo coolant change. So it may be academic what Mazda main dealers do, which is sad really as I should imagine vacuum refilling, done properly, could be more effective than any other method at shifting stubborn air bubbles. It could also take a lot less time so that in theory and even with main dealer charges, it could be cheaper than either the workshop or the see-saw method. Mind you, whether the main dealer would pass the labour cost saving back to the customer is another matter! :roll:

P.S. - throttle lock cruise control: Well, its an unusual and inexpensive cable operated device that was already fitted when I bought the Bongo. I advised the insurers and they are happy about it being fitted. But it isn't a true cruise control. It comprises a little black box fitted with a release button and a thin rod/lock lever that you flick over to lock and that can also be turned to finely adjust the throttle position setting (though you need to gently depress the throttle in order to reduce friction pressure before the lever will turn easily). It also has a solenoid release linked to the footbrake but I find this inadequate at any but the lightest throttle settings as it lacks sufficient power to overcome the spring tension from the throttle otherwise. The unit is mounted on the centre console behind the handbrake and exactly where my left hand rests, so I can (and do!) operate the button probably quicker than I can get my foot on the brake pedal. I generally only use it when I want to rest my throttle foot on long runs but over the years it has become as instinctive a control for me to use as any other. And it has the great side benefit of being usable as a means of raising the tickover/rpm whenever that might be useful to do. I think it was made and marketed by some people called Eagle, but don't quote me on that. Famous old BF member and mpg experimenter Torchwood reckoned that a constant throttle setting device was the best for optimal fuel consumption. I'm very used though to being a human CC controller and fine tuning the throttle lock as I go up and down inclines (for anything more I release it and go manual).
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Re: A slight twist to the "bleeding method"

Post by helen&tony » Mon Jul 06, 2015 4:21 pm

Hi
Mike...
I'll look out for something like that....I've only ever used cruise control on the Jag...I have cruise control on the Jeep...never use it!...I don't like them....OOOooohhh I'll get shouted at now!!!
:lol: :lol: :lol: :lol:
Cheers
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