bleeding cooling system

[missfixit70]

I suspect some bongo's must be different Dave, i've never felt a hot bottom hose Warm yes, but i suppose the issue of temps are subjective.

If the bongo is stationary, engine running, once it gets up to temp, the inlet temp into the rad gets up to 80-90 ish degrees. No airflow across the rad, therefore minimum cooling across the rad (maximum I've seen stationary is @15 c cooling), stat starts opening, bottom hose starts warming up as flow starts inceasing, once the stat opens fully, full flow through the rad, hot coolant going in, only cooled by @15c, therefore bottom hose should be 65c+, which is HOT, quite simple really. If it ain't getting HOT, the stat isn't opening FULLY & you haven't taken it up up to temp to prove the stat works as it should.
This does not mean there is a problem, usually it just means you haven't got it up to temp, ie spent long enough at it.
This can also be shown after you've been driving & pull over, leave the engine runnning (no heaters on), & within 10 minutes the bottom hose should be HOT (unless your fan switch/control system is modified/fubar meaning the fans are permanently on) for the above reasoning.

[mikexgough]

I suspect some bongo's must be different Dave, i've never felt a hot bottom hose Warm yes, but i suppose the issue of temps are subjective.

Same here, but I suppose I compare with other makes/models in respect of bottom hose temps I have felt...... but then of course other cooling systems also have return side thermostats these days instead of outlet side types.....

[missfixit70]

Unless the system is modified, or not working as it should, how are some bongos different? Sorry, don't get it I give up, I'll leave you guys to it.

[bigdaddycain]

I'd just noticed a repeat of "bottom hose gets hot" All i'm saying is that i've never felt a bottom hose hot. Maybe i've never squeezed one when it was hot! I'm certainly not implying that it's impossible for the hose to get hot, just that i've never felt it that's all Kirsty! I'll be doing a bleed on a bongo (i suspect) in the coming weeks, i'll pay more attention to the hose temp when i'm doing it...

[stockportdave]

OK thanks to both of you. Will wait till weather gets a bit warmer as it can take ages to get up to 'open stat' temperatures at +1 deg C
Thanks again.

[haydn callow]

A hot bottom hose means just that !!!! you cannot grip it tightly for more than 5 to 10 sec's......If you can then it ain't hot yet....i.e. stat not fully open.
A hot bottom hose on a stationary bongo is just about as hot as the top hose.

[Northern Bongolow]

mike and steve,you wont notice the bottom hose getting hot,as the method you use to bleed the system doesnt rely on this happening.not saying ones right or ones wrong,its just a different method of hopefully getting to the same result.
what i will say,and i will get my hat ready,is that using the bottom hose as a tell tale enables me to tell whats going on at every stage of the bleed process. no doubt you have ways of telling whats going on and when its happening too.

[stockportdave]

"The Bleeding Chronicles of Dave"
Just some info for you all

I tried to get the temp up to +83deg, I reved the car for about 40 mins with at least 15mins at 2700 rpm. Temp = 55deg. The bottom hose felt warm, the top hotter. Right, I thought the stat must be open.Took it for a drive to shops and temp got up to 65 - popped the bonnet and felt botom hose - COLD ! As I suspeted, the bottom hose can get hot via conduction. The stat must be closed. ps just read the previous comment re temp of bottom hose - yep I agree.

I suspect that I can't get up to temp because the outside temp is about 2deg, the passenger seat is up and the air flow from underneath, past the engine and up through the hole where the seat was is cooling it ?

Kirsty - I was using the method where you put the hose in a container with some coolant, at about the same hieght as the filler tank - I now realize that if you do this the head that is created (u can see this in your video, when you have to raise the funnel) will fill the container and drain the header tank - so mystery solved.

BigdaddyCain - great tip about looping hose - I used an old washing machine water connection hose - if you saw off the end cap and leave a bit of the pipe, its just the right size fore the filler hose. Unfortunately you can't see the bubbles coming out (if your on your own that is).

Thanks for those temperatures Kirsty

[widdowson2008]

Finally do you know of a diagram that shows the bongo cooling system.

Think these are what Kirsty are refering to. If Not, let me know - I have MANY more

[mikeonb4c]

When someone reports observations that seem not to agree with the current understanding of things, the Discoverer will always wonder how this could be so, and search endlessly for an explanation. Others will label the dissenter as a heretic, pillory (or vilify) them, and cast them out.

It was the Discoverers who established that the earth moved round the sun (and not vice versa), that the earth was not flat, that there were new great lands across the sea, that the expansion of water was anomolous, that E=MCsquared, that the sound barrier could be broken, and that the Bongo was not in fact a joke, but a gem.

[steveyd]

Hi Dave,

Sorry to hear the problems are continuing- but here's one thing that may help (and apologies if already mentioned in previous post and I've missed it) - I had huge problems bleeding my Bongo once and couldnt work out what was wrong - turned out that I hadnt put the radiator cap back on... Took ages to get it to temp, water everywhere.. If following the first method in the FAQ (the one I use), just need the rad cap on and the expansion cap off and then it takes about 20-30 mins for bottom hose to get hot...

Good luck!

Steve

[stockportdave]

Thank you very much all of you. Special thanks to widdowson who provided the wonderful diagram. Every new member should get a link to this because bongo cooling problems are so common.

[ADAMD]

Following fitting a new head, I couldnt bleed mine as the fans came on too soon stopping the stat opened. Ady diognosed problem -
I had fitted non original head temp sensor (green plastic connector) gave incorrect reading.
Best way to check if stat is open is to feel bottom of stat housing, it is cold to touch when not open, not cold when open.

Thanks again Ady - all still running well.

Adam

[Northern Bongolow]

glad all is well,this part is to important to be trusted to a copy part,in my opinion.

[mikexgough]

Following fitting a new head, I couldnt bleed mine as the fans came on too soon stopping the stat opened. Ady diognosed problem -
I had fitted non original head temp sensor (green plastic connector) gave incorrect reading.
Best way to check if stat is open is to feel bottom of stat housing, it is cold to touch when not open, not cold when open.

Thanks again Ady - all still running well.

Adam

Glad your sorted...... Mazda use a Denso unit 179700 0220 - although the Intermotor is a cross reference....the Denso one is best....fitted on RX8/2 & 3 models as well as the latest Jags........strangely the Jag spares cost is cheaper than Mazda.....even cheaper from Germany...