Cooling system heat test results

[widdowson2008]

Follow on from
http://www.igmaynard.co.uk/bongo/forum/ ... &start=240

The test Bongo
The cooling system has been refurbished as near as possible to the original spec. apart from the gauges added for tests.
New main radiator, all new hoses, new Mazda thermostat, heater matrix (2nd hand), rear heater motor (2nd hand)
Also, during refurbishment, the cooling system has been drained and re-filled 5 times.
The object of this excercise is to find out which section of the cooling system is in control and at what stage (temperatures) control is passed on to the next part of the system.
We had a problem from the start because Bulgaria, where the system is being tested, has strict speed restrictions so 'gunning' the engine to raise temperatures is not an option. To overcome this, the next stage of data collection will be powering up hills which should get temperatures a little more elevated. If that fails to get results, then plan 'B' kicks in - FILL THE BONGO WITH FAT LADIES and repeat the hill climb.

The results of the first set of data are shown on the graph below. This data was collected running at speeds up to 90 kph (56mph) and max engine speed of 3000 rpm. Bongo not even broken into a sweat and thermostat remaining closed. The upper radiator appears to have the control of the cooling system at this stage.
One thing that has come as a bit of a surprise (to me at least) is that the heater supply is LOWER in temperature than the heater return. I expected it to be the other way round.

graph amended - ambient added

Roll on the FAT LADY TESTS

More to follow when available.

[Doone]

Nice graph Helen and Steve... BTW, if there's a shortage of fat ladies you can also use fat men.

[missfixit70]

Does the fact that the rad bottom connection temp rises not show that the stat is opening? That's what I use as my indicator.
Is the anomaly of the heater returns being warmer than heater outlet down to where the temps are being measured?

[widdowson2008]

Nice graph Helen and Steve... BTW, if there's a shortage of fat ladies you can also use fat men.

Sorry but no - fat blokes tend argue too much and would cause the tester to loose her temper and we don't want that do we?. - gotta be fat ladies out for a run in the hills.

[widdowson2008]

Does the fact that the rad bottom connection temp rises not show that the stat is opening? That's what I use as my indicator.
Is the anomaly of the heater returns being warmer than heater outlet down to where the temps are being measured?

Thats what I thought at first but the bottom hose temperature doesn't get much above ambient and I suspect it's getting that heat from the ATF cooler.
The heater supply/return sensor points are as close as possible to the block. I think perhaps the return is getting its heat from the flow back from the expansion tank. May be wrong (probably am) - This is why the fat lady/up hill test is important cos it will definitely pass control to the thermostat.

[missfixit70]

I agree with the returns from the header/top of rad as the factor in increasing returns temp, but shouldn't the bottom rad temp should be getting cooler than ambient due to airflow rather than warmer? & there are spikes, it looks to me like it roughly follows heater return temps, which is what controls the stat? the gearbox won't cause that IMO, I think that indicates stat opening myself. Could be wrong, but just saying what I see

[widdowson2008]

I agree with the returns from the header/top of rad as the factor in increasing returns temp, but shouldn't the bottom rad temp should be getting cooler than ambient due to airflow rather than warmer? & there are spikes, it looks to me like it roughly follows heater return temps, which is what controls the stat? the gearbox won't cause that IMO, I think that indicates stat opening myself. Could be wrong, but just saying what I see

Bottom hose removes heat from the ATF, that's why the cooler is positioned at the bottom of the rad isn't it? So where is this heat going to manifest itself? Bottom hose I would have thought.

To be honest, what you are saying were my first thoughts but I am trying to talk myself out of it and the reason is:
- our current understanding that the heater return controls the stat opening, but that gets blown out of the water big style because the heater return test data NEVER gets above 67C (stat opens at 82C)

Not argueing with you at all - just trying to make sense of the numbers.

[francophile1947]

you can also use fat men.

Stop talking about me behind my back

[helen&tony]

Hi
Heating of transmission had always been a thought...on the way here, towing a caravan through various Alpine areas, and some very heavy slogging, total all-up weight maybe nearing 4 tonnes, there seemed to be a drive problem due to transmission overheating. After cooling the Bongo for several hours, transmission worked fully again. This happened repeatedly, and was less apparent in cold, but I guess that i was lucky not to cook the transmission.
On reflection, and after replacing the radiator, i imagine that the old radiator was providing insufficient cooling at the lower part, and I suspect this to be due to the weight, rather than the sludging effect, as it ran perfectly at all other times, so...I am currently trying to source a reasonable temperature gauge to check transmission temperatures, and co-ordinating the results with coolant temperature.
Cheers
Helen

[helen&tony]

Hi
Oh...BTW I AM a Phat Lady ....noo...I'll load the Bongo up with ""Stuff" and tackle the hills....some of them around 8- 10 Km, and rather steep.
Cheers
Helen

[widdowson2008]

you can also use fat men.

Stop talking about me behind my back

'Twere Doone.........Not me guv ..........honest

[widdowson2008]

Graphs are always a bugger to interpret, especially if all the data isn't added. I omitted what is probably the single, most important info - the temperature that the stat opens/closes - but that has now been rectified (see below).
2 lines (at 82 and 96) have been added that indicate the stat starting to open/fully open temperatures. What these highlight is that the cylinder head temperature seems to stabilise around midpoint (89), so when Kirsty said she thought the stat WAS in fact opening, I think she may be right.
It will be interesting to see if this remains the case when the Bongo is asked to work a bit harder. (Fat ladies and hills)
Need to think about this a bit longer.

[missfixit70]

I agree with the returns from the header/top of rad as the factor in increasing returns temp, but shouldn't the bottom rad temp should be getting cooler than ambient due to airflow rather than warmer? & there are spikes, it looks to me like it roughly follows heater return temps, which is what controls the stat? the gearbox won't cause that IMO, I think that indicates stat opening myself. Could be wrong, but just saying what I see

Bottom hose removes heat from the ATF, that's why the cooler is positioned at the bottom of the rad isn't it? So where is this heat going to manifest itself? Bottom hose I would have thought.

To be honest, what you are saying were my first thoughts but I am trying to talk myself out of it and the reason is:
- our current understanding that the heater return controls the stat opening, but that gets blown out of the water big style because the heater return test data NEVER gets above 67C (stat opens at 82C)

Not argueing with you at all - just trying to make sense of the numbers.

The heater return IS a control factor in the stat opening, it is part of the flow, along with the recirc flow & the returns from the top of the rad via the header tank. Without the heater returns the stat would be in a different control state, it would appear that the returns act to moderate the stat temp rather than increase it at the lower end, be interesting to see those results for high load with stat fully open & up to fan switching on point.

On the graph, don't you mean stat open & the stat fully open (closing off recirc?) That seems to agree with how I was seeing it

[widdowson2008]

..................] gets above 67C (stat opens at 82C)
The heater return IS a control factor in the stat opening, it is part of the flow, along with the recirc flow & the returns from the top of the rad via the header tank. Without the heater returns the stat would be in a different control state, it would appear that the returns act to moderate the stat temp rather than increase it at the lower end, be interesting to see those results for high load with stat fully open & up to fan switching on point.

On the graph, don't you mean stat open & the stat fully open (closing off recirc?) That seems to agree with how I was seeing it

I agree totally - the heater return IS a control factor, but not in the way I expected. It's not the head heating the heater circuit - more like the heater circuit keeping the head temperature stable at 90'ish.
Know more when Stig-H has been for a burn-up.

Terminology got to be just right for Kirsty (picky bugger ) so I changed the wording on the graph. Used the wording from manual - 'Stat fully closed' and 'Stat full lift' (bypass closed) - see below

[B*Witched Blingo]

Nice graph Helen and Steve... BTW, if there's a shortage of fat ladies you can also use fat men.

Here, Here.