Cold Bottom Hose

[mikexgough]

At the last couple of meetings I have attended I checked the bottom hose of about a dozen Bongos as they arrived at reception (just stopped engine running) some had travelled 200 plus miles.....in all cases except 2 the bottom hose was cool.......after ticking over for a few mins the hose went hot.
In the other 2 cases they had ..a..been towing a heavy van...b..really "belting" along......this was in the summer.......During their journey I suspect the hose was getting hot on hills etc ....but when cruising along the engine did not require flow through the rad to keep temps down......

I also check every Bongo that visits my home.....same result

With that observation ..........I guess that's why there is some debate over hot or warm Bottom hose ...... for me I usually expect that under normal use....warm bottom hose and under more extreme conditions the bottom hose would be hot.... which is normal for all vehicles anyway

It's a shame that any decription over bottom hose temperature is used in the known coolant change processes Factory or otherwise, if we could get some kind of dialogue of what to "feel" for then disagreements etc about bottom hose temperature would be negated ..........
The Japanese only check the bottom hose once during a coolant change, by feel, just to check that coolant is hot inside the hose... as a further "mechanical"check to a known standard temp gauge position......after that they don't bother to check it again

[widdowson2008]

FOR DISCUSSION
From heat tests (Remember - no 2 Bongos will be exactly the same but IMHO, all should follow the general graph pattern shown)
The test vehicle was driven at speeds around 50mph so no great load.
Bottom hose - green dotted line.
Temperature initially rises as engine is warming up (ATF cooler?)
When stat opens (blue dotted line), bottom hose temp rises, peaking at around 40C (which equates to around 90C at the top hose and approx 60C at the heater circuit.)

[mikeonb4c]

FOR DISCUSSION
From heat tests (Remember - no 2 Bongos will be exactly the same but IMHO, all should follow the general graph pattern shown)
The test vehicle was driven at speeds around 50mph so no great load.
Bottom hose - green dotted line.
Temperature initially rises as engine is warming up (ATF cooler?)
When stat opens (blue dotted line), bottom hose temp rises, peaking at around 40C (which equates to around 90C at the top hose and approx 60C at the heater circuit.)

Crikey Steve - that's confused the hell out of me..............you won't be surprised to hear

Why does the temp go through 4 major dips, then appear not to dip any more? I assume the readings (against time) were only started once the engine was fully up to temp and running on the open road? Which of those lines do you think most closely relates to the temperature at the thermostat? Etc.

[g8dhe]

Surely its 5 driving sessions, if not then Steve you have me confused as well!!!

[mikeonb4c]

Surely its 5 driving sessions, if not then Steve you have me confused as well!!!

That would make sense. I would rather have some commentary (qed) that attempts to explain what is happening. If these are separate driving sessions then all I can see is everything warms up until at some point the various regulator devices (thermostat, cooling fans if they kick in which they shouldn't normally at a steady 50mph in UK climate etc.) kick in to keep things steady-ish. Is there anything else I should be noticing in the data?

[widdowson2008]

FOR DISCUSSION
From heat tests (Remember - no 2 Bongos will be exactly the same but IMHO, all should follow the general graph pattern shown)
The test vehicle was driven at speeds around 50mph so no great load.
Bottom hose - green dotted line.
Temperature initially rises as engine is warming up (ATF cooler?)
When stat opens (blue dotted line), bottom hose temp rises, peaking at around 40C (which equates to around 90C at the top hose and approx 60C at the heater circuit.)

Crikey Steve - that's confused the hell out of me..............you won't be surprised to hear

Why does the temp go through 4 major dips, then appear not to dip any more? I assume the readings (against time) were only started once the engine was fully up to temp and running on the open road? Which of those lines do you think most closely relates to the temperature at the thermostat? Etc.

Sorry Mike - my fault ....and Mike, before I forget, it's the dark blue line that relates closest to the stat temp.
What you see is actually 5 different driving sessions as Geof said. The FULL graph covers many more driving sessions. This one is a 'snapshot' of a typical group.
Initially, we started the taking the test results from cold to establish the full relationship between each individual test point on the circuit.
I have posted this graph before with a greater explanation. This time, I was just trying to demonstrate that what I am saying is backed up with actual proof as opposed to 'I think this is what happens'.
If anyone is that interested, I'm quite happy to explain the whole thing again in detail, explaining what relates to what. It would probably be less of a gobfull to go through ONE driving session instead of covering the whole series.

[mikeonb4c]

Thanks Steve. I wonder why the bottom hose appears to get up to temp only once the thermstat has opened, but then seems to stay hot even when the car is on the move, even though we are told Bongos tested 'by hand' immediately after a long run, appeared to have a cold bottom hose in almost all cases? Have I mis-read the data (again!)?

[widdowson2008]

Thanks Steve. I wonder why the bottom hose appears to get up to temp only once the thermstat has opened, but then seems to stay hot even when the car is on the move, even though we are told Bongos tested 'by hand' immediately after a long run, appeared to have a cold bottom hose in almost all cases? Have I mis-read the data (again!)?

I don't think you have mis-read the data Mike.
I stress again that no 2 Bongos are likely to be exactly the same for a myriad of reasons. Just similar.
I think you might be mixing up the 'bleed' and 'normal running' scenarios.
Under NORMAL running conditions, the radiator (if it's efficient and doing its job) will reduce the coolant temperature by virtue of the through draught created by forward motion. The only way to prove this is for someone to get underneath, hands on, whilst in motion.
Personally, I have only experienced the bottom hose VERY hot to the touch on one occasion, and then only for a brief time, probably seconds.
Another very pertinent factor is that the ATF cooler resides in the bottom of the main radiator. The fluid passing through it must get hot, otherwise there would be no need for the cooler would there? Hence, the bottom hose will get warm.
Under BLEED conditions, there is no through draught so heat from the top of the rad will eventually conduct through to the bottom.

Once the system is up to working temperature (in Helens case, 89/90 in the head and 64/65 in the heater circuit), then the whole system becomes very dynamic, constantly adjusting itself to maintain ideal working temperatures for both the head and the block.
I'm trying to find a way of describing it in a simple way but aint got there yet. Not that it is complicated cos it aint. Just very fluid and constantly adjusting itself to suit current conditions.

[The Great Pretender]

Steve can you e mail or post a link so the graph can be viewed full size.

[bigdaddycain]

Personally, I have only experienced the bottom hose VERY hot to the touch on one occasion, and then only for a brief time, probably seconds.

Nice one Stevie baby! I was begining to think that the bongo's i've bled were unique! I want to win the lottery, i want to see a duck billed platipus, i want to feel a hot bongo bottom hose!

[bigdaddycain]

321 Away...that does not suprise me at all and I suspect there is nothing wrong. At the last couple of meetings I have attended I checked the bottom hose of about a dozen Bongos as they arrived at reception (just stopped engine running) some had travelled 200 plus miles.....in all cases except 2 the bottom hose was cool.......after ticking over for a few mins the hose went hot.
In the other 2 cases they had ..a..been towing a heavy van...b..really "belting" along......this was in the summer.......During their journey I suspect the hose was getting hot on hills etc ....but when cruising along the engine did not require flow through the rad to keep temps down......

I also check every Bongo that visits my home.....same result

Ok.... Just in case you revisit this thread Haydn, Isn't what you written in the above quoted post by yourself pretty much exactly what i've mentioned recently in this whole very ongoing bleeding/bottom hose temp debate? I seemed to cop for a fair amount of for casually mentioning something along the lines of "I'm not saying it DOESN'T, but i've never felt a bottom hose on a bongo get HOT" If you appreciate for a moment that part of the way i bleed a bongo involves a "few runs round the block" (rather than get visits from the council for revving the knackers off the engine at my house). And the vehicle certainly isn't driven far/long enough for any residual trapped air to damage anything. I stand by my continual viewpoint that a bongo can't be 100% bled on the spot in one session. (based on my experience). I prefer to allow the vehicle to cool naturally with the expansion cap removed (natural bleeding) after i've shifted as much air as i can initially.

[widdowson2008]

Steve can you e mail or post a link so the graph can be viewed full size.

You have an email

I screened off a single cycle to make the graph clearer. Bit better but not brilliant - sorry.
Before the eagle eyed chirp in with 'Can't be right because the heater return is hotter than heater supply', I'll explain. The readings for this graph were taken during the summer months - ie heater blowers not in use so no heat being taken out of the circuit. The temp rise is because the expansion tank and turbo circuits (Both HOT) feed into the heater circuit as it returns to the stat.
Also
Cant explain why S3 is greater than S5.
S3 is head coolant temperature, S5 is actual head temp
(just reporting the facts maaaam)

At data point 66, there is a blip in all the graph lines. The vehicle was stationary at this point (Helen shopping ), and everything does what you would expect.

Said it before but worth repeating - Notice that the system basically 'levels off' (stat in hunting mode - constantly adjusting itself) when operating temperatures are reached (head circa 90C, block circa 64C). To me, this indicates all is well and everything working as it should. (probably get my head blown off for that)

[mikexgough]

321 Away...that does not suprise me at all and I suspect there is nothing wrong. At the last couple of meetings I have attended I checked the bottom hose of about a dozen Bongos as they arrived at reception (just stopped engine running) some had travelled 200 plus miles.....in all cases except 2 the bottom hose was cool.......after ticking over for a few mins the hose went hot.
In the other 2 cases they had ..a..been towing a heavy van...b..really "belting" along......this was in the summer.......During their journey I suspect the hose was getting hot on hills etc ....but when cruising along the engine did not require flow through the rad to keep temps down......

I also check every Bongo that visits my home.....same result

Ok.... Just in case you revisit this thread Haydn, Isn't what you written in the above quoted post by yourself pretty much exactly what i've mentioned recently in this whole very ongoing bleeding/bottom hose temp debate? I seemed to cop for a fair amount of for casually mentioning something along the lines of "I'm not saying it DOESN'T, but i've never felt a bottom hose on a bongo get HOT" If you appreciate for a moment that part of the way i bleed a bongo involves a "few runs round the block" (rather than get visits from the council for revving the knackers off the engine at my house). And the vehicle certainly isn't driven far/long enough for any residual trapped air to damage anything. I stand by my continual viewpoint that a bongo can't be 100% bled on the spot in one session. (based on my experience). I prefer to allow the vehicle to cool naturally with the expansion cap removed (natural bleeding) after i've shifted as much air as i can initially.

I guess the graph and comments all agree that the Bottom hose gets warm in Normal running but gets hot in Extreme conditions (which in normal running the bongo hardy ever gets too) and just before fans do their job.....then back to warm again after fan deployment.....

I suppose the next item to rear up it's head is ........ when you bleed do you need the fans to run to ensure a full bleed.........?
Over to you guys,my comment to that debate is..... and I know this as gospel from my Jap pals is........the Japs don't run the engine until the fans kick in on coolant changes....

Ste. I know of Bongo with a Ranger head and no tee port that was filled and bled the "old Skool" way rather than the easy bleed port/screw way all cars now employ.....took about an hour for that Bongo to be done and it was run around the block like your description. I do agree with you too about the council "noise police" it is easy to complain to these guys now and if your coolant changing at home then you do have to be considerate with your neighbours these days......

[helen&tony]

Hi
Regarding Steve's graphs: This was just a sneak look at a very small part of the work Steve has put in on preparing the document on the cooling system. To single it out for microscopic examination at the moment , might be taking the issue in a simplistic fashion...like trying to judge a sandwich by tasting a crumb on the plate.
The original testing took place over a course of quite a few months, and involves sheet after sheet of data.
All the sensors were tried, tested and synchronised to ensure that the sensors were accurate to within a degree of each other, over a range of temperatures before installation. This involved trialling different types of sensor supplied by Haydn, by way of evaluation only. Different gauges were sourced elsewhere, and a mixture of analogue and digital used as comparison....Once installation was satisfactory, testing began....with results for ambient temperature, starting temperature of all water circuits, and tested in relation to time, distance , operating stability, road conditions (e.g. Uphill/ downhill/ town driving, etc.) speed related, turbo boost, and different sampling techniques used in relation to incremental readings. Once the "Opening Sequence" or warmup to temperature on the original Mazda gauge was established as reliable as clockwork, then this was put aside temporarily to gauge actual running. Eventually, two methods were used :...one where all readings were taken at 2 Km intervals, and another when any change on any instrument was seen.
The readings proved constant and accurate ( I have done a lot of laboratory work ), and we chose here as a test region, as the climate would give the cooling system more of a workout, due to 30 -40 centigrade heat in summer, and low winter temperatures. The system worked entirely as predicted, and all events were logged , such as scavenger fan operation!....Yes...park up for 10 minutes in 40C. heat, come back, and ALL fans work...and cut out VERY predictably . The engine fans work according to A/c operation, as the working temperatures for main fan operation were never reached....Stat works as expected, and towards late autumn, the bottom hose doesn't register a reading ....stat has no need to operate, as ALL cooling takes place in the upper radiator.
Once Steve had the data, then charts were made , graphs printed up, and any query thoroughly investigated
The point is...wait until the final document is revealed, as it has taken an immense amount of effort from Steve....who really is the co-ordinator of the cooling project!!!
Cheers
Helen

[mikexgough]

Helen/Steve.... this is good work and confirms to me what I have always suggested over various threads regarding the cooling system and now there is documentary evidence to support my thoughts..... and knowledge gained from Japan. well done to all concerned.