coolant flow - (follow up to cooling diagram)

[dandywarhol]

Next project - how about dissecting and graphicing (?) a viscous coupling Steve???

[widdowson2008]

Next project - how about dissecting and graphicing (?) a viscous coupling Steve???

What's one of them? Have you got a sample for me to chop?

[dave_aber]

Bearing in mind that the viscous fluid solidifies when in shear, it would be an interesting thing to try to saw through!

[haydn callow]

How about fitting a thermostat on the outlet from the head?

If anyone wants to try that I have a in hose stat

[Ron Miel]

So, as I said 5 pages back (is it really that far) 'I think the subject line, 'COOLANT FLOW' is exhausted.' for me anyway. Can't think of owt else to bother you folk about on this one......

Merciless lot aren't we? Next post from that one being "Next project..." - although that defo also means we can't get enough of you Steve.

Once again, brilliant, give that man an MBE

Anyway, have a cuppa, take a good deep breath, then carefully consider your next move. The world of Bongos is surely too small for you. Perhaps just head over to Derby, to cut up R-R Trent 900s from Quantas Airbuses, to work out how to make them a bit more reliable? Nice number for Haydn in partnership with you, as well - sensors on Quantas stewardesses checking when they overheat, low whisky alarms in flight deck drinks cabinets, passenger cooling alarms to check for dead ones on long flights....the scope is endless.

[mister munkey]

Once again, brilliant, give that man an MBE

Master of Bongo Entomology!!

Entomology (from Greek ἔντομος, entomos0, "that which is cut in pieces or engraved/segmented",

[Ron Miel]

Once again, brilliant, give that man an MBE

Master of Bongo Entomology!!

Entomology (from Greek ἔντομος, entomos0, "that which is cut in pieces or engraved/segmented",

Yep, that'll do nicely

[mikexgough]

A properly maintained cooling system, free from silt and crud works perfectly well when bled the Factory way - thousands of Bongos are proving that, including my old one which is still going strong with day to day use.....................................

I agree with Dandy.........Factory bleed....well flushed system .......good hoses and pipes.....correct coolant ratios etc ..............no worries...

BUT remember as vehicle owners in the UK many of us have got complacent and many don't even check their fluids,lights tyres etc between services and MOT and expect the garages to fix it annually....... Time to lose that attitude methinks.....

As I always say....... Better to do Preventative Maintainance than Reactive Maintanance......and we also need to remember a Vehicle is a Privilige not a right....

[Ron Miel]

A properly maintained cooling system, free from silt and crud works perfectly well when bled the Factory way - thousands of Bongos are proving that, including my old one which is still going strong with day to day use.....................................

I agree with Dandy.........Factory bleed....well flushed system .......good hoses and pipes.....correct coolant ratios etc ..............no worries...

BUT remember as vehicle owners in the UK many of us have got complacent and many don't even check their fluids,lights tyres etc between services and MOT and expect the garages to fix it annually....... Time to lose that attitude methinks.....

As I always say....... Better to do Preventative Maintainance than Reactive Maintanance......and we also need to remember a Vehicle is a Privilige not a right....

(all three paragraphs)

[The Great Pretender]

in my opinion the head can get taken out in different ways,as you stated it could be catasrophic loss,but the usuall way is a slight prolonged loss.usually related to the number of cycles the engine has made.the motor warms up leaks under pressure,pressure drops,cools,and as the system cools it sucks in a little air.this can be from a bad clip,or holed pipe.etc
this air then accumilates and either blocks flow,or goes to the head.
depending on the amount of air,the motor continues toward meltdown.

Agree, now as most of the cooling system pipework is below the engine where will air end up? Most probably in the engine and as air rises it will end up in the head, it has to. As the air slowly displaces the coolant there is less and less coolant to dissipate the heat so the head gets hotter, the air expands pressurising the system but only as far as the system pressure.


the leaks are usually started by overpressure of the system,via a stat fault,this pressure raises the load on the entire system,and finds the weakest spot in the loop,if your hoses are good it may pop the rad.if your rad is good then it may make the pump leak.
the key to it all is the stat.

Now this is where we part company Agree a faulty stat would cause problems.....................here it comes............ ..........But an otherwise effective cooling system should show signs of a problem as there is a very effective secondary flow system.

i will get my coat.im off to the shed

The pressure cap has overall control of the system and as the head is in direct communication with it without restriction the head will only ever see the same maximum pressure.

I think the only bit that hasn't been covered but very important is the pressure cap, much misunderstood. A cutaway cad pic would be very informative to the not very technical..........

A stat on the outlet Dandy................... .............You ready for WW4?.................

[widdowson2008]

The pressure cap has overall control of the system ....
I think the only bit that hasn't been covered but very important is the pressure cap, much misunderstood. A cutaway cad pic would be very informative to the not very technical..........

Life can be annoying . Just when you think a job is finished, up springs summat to prove otherwise, and this is that SUMMAT
I trawled and found this site many moons ago - it's excellent for finding out how stuff works (any stuff). Its where I got the idea of the animations from in the first place.
This animation shows a pressure cap on the main radiator, but the principle is still the same I think.
Click on the OVERHEAT button.
If not good enough for TGP, then I will need a cap to take to bits.
http://auto.howstuffworks.com/cooling-system7.htm

[mikexgough]

in my opinion the head can get taken out in different ways,as you stated it could be catasrophic loss,but the usuall way is a slight prolonged loss.usually related to the number of cycles the engine has made.the motor warms up leaks under pressure,pressure drops,cools,and as the system cools it sucks in a little air.this can be from a bad clip,or holed pipe.etc
this air then accumilates and either blocks flow,or goes to the head.
depending on the amount of air,the motor continues toward meltdown.

Agree, now as most of the cooling system pipework is below the engine where will air end up? Most probably in the engine and as air rises it will end up in the head, it has to. As the air slowly displaces the coolant there is less and less coolant to dissipate the heat so the head gets hotter, the air expands pressurising the system but only as far as the system pressure.


the leaks are usually started by overpressure of the system,via a stat fault,this pressure raises the load on the entire system,and finds the weakest spot in the loop,if your hoses are good it may pop the rad.if your rad is good then it may make the pump leak.
the key to it all is the stat.

Now this is where we part company Agree a faulty stat would cause problems.....................here it comes............ ..........But an otherwise effective cooling system should show signs of a problem as there is a very effective secondary flow system.

i will get my coat.im off to the shed

The pressure cap has overall control of the system and as the head is in direct communication with it without restriction the head will only ever see the same maximum pressure.

I think the only bit that hasn't been covered but very important is the pressure cap, much misunderstood. A cutaway cad pic would be very informative to the not very technical..........

A stat on the outlet Dandy................... .............You ready for WW4?.................

The main issue for Japanese owners .........other than odd radiator splits and odd hose/pipe leaks is......... Header tank pressure cap................ many just fit the standard 1.1 bar and some up the game to a 1.3 bar....... as for Thermostats ......they change with the coolant....

[Ron Miel]

>
>
Agree, now as most of the cooling system pipework is below the engine where will air end up? Most probably in the engine and as air rises it will end up in the head, it has to. As the air slowly displaces the coolant there is less and less coolant to dissipate the heat so the head gets hotter, the air expands pressurising the system but only as far as the system pressure.
>
>

Simplification helps get first principles over but doesn't this only take account of two of the dynamic processes involved?

As well as any gradual coolant leaking causing this build up of air in the head and its pressurisation by combustion heat, progressive entraining of that air into coolant flowing by it will also gradually carry it off to the expansion tank, where the tank's inbuilt coolant vortexing/de-gassing compartments will separate it out from the coolant - causing an equal air build up and drop in coolant level in the ex tank but away from combustion processes.

In other words, although the topmost inner part of the head is a sealed high point where air will initially tend to collect, that doesn't mean that's then a static condition. That's what the second high revving stage (ex tank pressure cap re-fitted/system sealed) of the bleeding process is about. It works by entraining any small amounts of still trapped air anywhere in the system (including heaters, although probably less effectively due to the lesser air/coolant interface there) into coolant flow, to be carried away for de-gassing. Note that if there's still enough air trapped anywhere to cause a complete blockage, no amount of water pump pressure will clear it, so there will be no coolant flow and the de-gas process will not work. Hence the importance of carrying out earlier refill stages (cold fill, and bleed tube venting) very carefully first.

That overall de-gas process will only remove head-trapped air up to its system designed rate though, so in a more leaky engine a point will arrive where air collects in the head roof too fast to be carried away before causing progressive head overheating/weakening. Hence the need to keep all coolant connections as airtight as possible, to deal with even the smallest of detected leaks immediately (or stop driving), and to replace spongy hoses (they don't have to burst to slowly leak), etc. It also means that observed slow reductions of coolant level at the expansion tank should never be allowed to continue, and the cause(s) must quickly be found and rectified.

[widdowson2008]

Many thanks TGP for bringing up the expansion tank cap, which got totally overlooked.

I took mine off the Bongo and measured/studied the individual components which go to make up the cap and there are 8. Yes EIGHT bits
Drawing bits like this causes me to think about each individual part, and WHY it is there. (there is always a reason)

The cap is not for just bunging up a hole. Its a bit more sophisticated than that.

I'LL BE BACK. (mitt pic)

[dandywarhol]

Remember the cap's also got a vacuum valve in it to prevent collapsing the hoses when the coolant temp. drops Steve

A stat on the outlet Dandy................... .............You ready for WW4?.................

I think we've learned in the past that life is just one big opinion