Bongo Fury

yes he knew. Atleast he told me he knew where the bleed pipe was?? is there more? he has been a mechanic for 40years. i would assume that he knows his stuff.

thats because i havent placed one yet.

Sounds though he did a good job...having said that....loads of garage people think they can bleed any car....the Bongo is not quite so simple and you would be suprised how many Bongo's overheat soon after a garage has worked on the cooling system.
The big secret is to make sure the bottom hose gets hot which means the thermostat has opened.....this can take 40mins or more of revving at 2500 for a couple of mins and ideling for a couple of mins (keep repeating this cycle till the stat opens) If the stat has not opened and everything seems well ..there could be air trapped in the bottom hose which will be released on a good hard run with damaging results.

haydn callow wrote:Sounds though he did a good job...having said that....loads of garage people think they can bleed any car....the Bongo is not quite so simple and you would be suprised how many Bongo's overheat soon after a garage has worked on the cooling system.
The big secret is to make sure the bottom hose gets hot which means the thermostat has opened.....this can take 40mins or more of revving at 2500 for a couple of mins and ideling for a couple of mins (keep repeating this cycle till the stat opens) If the stat has not opened and everything seems well ..there could be air trapped in the bottom hose which will be released on a good hard run with damaging results.

From memory, if the Mazda workshop manual method is to be believed, it really shouldn't take 40 mins of running, although it does take a prescribed sequence of running at tickover, then 2500rpm, then tickover etc.

I suppose that to date I have bled around a dozen differant Bongos....None have taken less than 30 mins for the bottom hose to get hot (stat open)......have taken as long as 50 mins......depends on many factors....condition of cooling system/coolant etc

haydn callow wrote:I suppose that to date I have bled around a dozen differant Bongos....None have taken less than 30 mins for the bottom hose to get hot (stat open)......have taken as long as 50 mins......depends on many factors....condition of cooling system/coolant etc

Maybe you need to tell Mazda

Have to say I followed their rules and got a perfect result 1st time - can't remember if they insisted bottom hose be hot but don't recall it. But maybe one of the features of ageing Bongos with impaired cooling systems is that they don't bleed in textbook fashion. Its all very strange

Mike....the bottom hose MUST be allowed to get hot and the stat open......There may or may not be air in the bottom hose. If there isn't air down there, then perhaps you might get away with not opening the stat....hell of a risk though...At least half of the Bongo's I have bled have erupted loads of air as soon as the bottom hose went HOT.
Stat opens...air expelled.
Also no Bongo which I have done to date has required a 'settling down top up period'
if you need to top up the following day then air must have been left in the system.

haydn callow wrote:Mike....the bottom hose MUST be allowed to get hot and the stat open......There may or may not be air in the bottom hose. If there isn't air down there, then perhaps you might get away with not opening the stat....hell of a risk though...At least half of the Bongo's I have bled have erupted loads of air as soon as the bottom hose went HOT.
Stat opens...air expelled.
Also no Bongo which I have done to date has required a 'settling down top up period'
if you need to top up the following day then air must have been left in the system.

Heres what the workshop manual says (inter alia):

Once you have drained the system and tightened the radiator drain plug

10. Set the air bleed hose downward as shown in the diagram [hooked over steering wheel]
11. Set down a container for draining coolant
12. Remove the [radiator] filler cap
13. Fill the coolant to the upper surface of the radiator
14. Attach the filler cap
15. Fill the coolant to the radiator reservoir tank flange surface

Caution
* Remove the reservoir tank cap to bleed air
* A/C Switch should be turned off

16.Start the engine and idle for approximately 10 minutes to warm up

Caution
If any of the following phenomena occurs, stop the engine to lower the water temperature as filling is incomplete. After water temperature is lowered, repeat steps from (15)
(1) Water temperature rises too high
(2) Cooling fan operates
(3) Steam comes out constantly from the air bleed hose

17. Perform the following operations after the engine is warmed up
(1) Keep the engine running at 2500rpm for 6 minutes

Warning
When checking the lower radiator hose (radiator side), be aware of burns or getting caught in the cooling fan.
(2) Check the lower radiator hose (radiator side) is warm. If it is cold, keep the engine running at 2500rpm for 3 minutes, then check again if the radiator hose is warm.
(3) Fill with coolant up to the radiator reservoir tank flange surface

Warning
When attaching the air bleed hose plug, the air bleed hose should be facing upwards as it could cause a burn if it leaks on you
(4) Attach the air bleed hose plug as shown in the diagram
(5) Attach the reservoir tank cap
(6) Keep the engine running at 25000rpm for 5 minutes
(7) Keep the engine idling for 3 minutes
(8) Keep the engine running at 25000rpm for 5 seconds then return to idling status. Repeat this 4 to 5 times.

18. Stop the engine and check the coolant level after coolant temperature has lowered.

So there you have it, chapter and (dodgily translated) verse. It seems to fit with what Haydn has been doing. The only things that perhaps need consideration are:

* if it is taking a very long time to get the bottom how warm (warm should do I think as all you need is confirmation the stat has opened and coolant is flowing fully around the full system - many owners have said their bottom hose never gets hot) then (if it were mine) I'd be asking myself why that is. The stat needs to be open not just to ensure air in the bottom hose is flushed out, but that coolant (and entrapped air) throughout the whole system is forced into circulation so that coolant and entrapped air whizz past the bleed pipe exit, where air will escape more readily than liquid.

* It seems sensible (and the manual recommends it) to re-check the header tank level when the engine is cold so that the coolant level can be set exactly to the marks when cold (the level does rise from hold to hot due to expansion I think). Also, I imagine it is possible (though the manual doesn't say this so maybe not) that any residual air bubbles (not significant of themselves in terms of adequate system bleeding) could eventually purge through to the header tank as the highest point. If that happened, the indication would be a small drop in coolant level there, which again, it might be best to top up to the proper mark so you know you have left levels as they should be.

I thought I'd type this up as its been raining and I couldn't house paint. Its stopped now so I can, but I hope the above may be useful to those about to attempt bleeding. If I've got any of it wrong, maybe someone could correct and comment.

PS - I had fitted a new thermostat to mine at the same time as replacing the coolant. It was noticeable that my Bongo reached operating temp with the new stat after 5 mins on the road whereas previously it had taken 10 minutes. So if the bottom hose is proving slow to warm then it may well be the stat is tired. Of course you'd rather know that before refilling so if in doubt I'd consider a new stat as part of the job. Not expensive and - on the 2WD at least - not too hard to fit. 4WD a bit harder due to propshaft in the way but I know some have managed it without undoing the propshaft.