Bongo Fury

Posted: **Sat Feb 13, 2010 8:32 am**

BongoMTBer wrote:My bottom hose didn't get hot hot hot either just a bit warm. I guess this because the ambient temperature was so low, the rad was particularly effective.

I doesn't get hot, just Luke warm....... if it was hot the radiator wouldn't be working correctly......

and as you say .......you can tell when the Thermostat opens as there is an immediate drop in your expansion tank level at that point....as an visual indicator that the 'stat has opened.........
I was writing up my bleeding method last night for another member and what you have said is a very good way to get over the .....what happens at what point scenario...hope you don't mind me pinching that observation for my document.

Posted: **Sat Feb 13, 2010 9:50 am**

mikexgough wrote: hope you don't mind me pinching that observation for my document.

Of course I dont

Posted: **Sat Feb 13, 2010 11:24 am**

...

and as you say .......you can tell when the Thermostat opens as there is an immediate drop in your expansion tank level at that point....as an visual indicator that the 'stat has opened.........

Mike..Is the above quote ...observed "just" during the bleeding ? or. Do you mean all the time.

A thing to remember is ..most of us cannot see the level in the tank co's they are so "stained"

Posted: **Sat Feb 13, 2010 12:27 pm**

haydn callow wrote:...

and as you say .......you can tell when the Thermostat opens as there is an immediate drop in your expansion tank level at that point....as an visual indicator that the 'stat has opened.........

Mike..Is the above quote ...observed "just" during the bleeding ? or. Do you mean all the time.

A thing to remember is ..most of us cannot see the level in the tank co's they are so "stained"

you only have that experience during the Bleeding process of course as the level is "equalised" and set at a level when the bleed hose is sealed up again and no loss/drop in coolant level can occur............
I always (and advise everyone to do this) look into the tank at the fill point in whatever car cooling system I check/work on...... who would be a numpty to rely or trust on the view through any translucent vessel?........

Take a look at the bottles on VAG and PSA group cars with their purple "lifetime" coolant.........the purple coolant discolours the tanks as they age with a blueish hue.......
I saw a 5 year old Skoda the other day.....this had been using the earlier VAG G12 Red coolant and had been changed for a Generic G12+ Red coolant, it's expansion bottle had a pink hue to it...

With a Bongo the Expansion tanks are now getting old and are made of a polypropylene type material so they will not be easy to see through....if at all.....even without any previous boiling up issues.....as they would have had many hot/cold cycles in their lifetimes..........

This one belongs to the Japanese Bongo Spanner.....the legendary Masabee

Posted: **Sat Feb 13, 2010 11:00 pm**

mikexgough wrote:
BongoMTBer wrote:My bottom hose didn't get hot hot hot either just a bit warm. I guess this because the ambient temperature was so low, the rad was particularly effective.
I doesn't get hot, just Luke warm....... if it was hot the radiator wouldn't be working correctly......

and as you say .......you can tell when the Thermostat opens as there is an immediate drop in your expansion tank level at that point....as an visual indicator that the 'stat has opened.........
I was writing up my bleeding method last night for another member and what you have said is a very good way to get over the .....what happens at what point scenario...hope you don't mind me pinching that observation for my document.

Surely while it is stationary, the radiator isn't really working is it? The coolant is just flowing through it, no air flow to cool it unless you reach fan kick in point?

Posted: **Sun Feb 14, 2010 11:05 am**

missfixit70 wrote:
mikexgough wrote:
BongoMTBer wrote:My bottom hose didn't get hot hot hot either just a bit warm. I guess this because the ambient temperature was so low, the rad was particularly effective.
I doesn't get hot, just Luke warm....... if it was hot the radiator wouldn't be working correctly......

and as you say .......you can tell when the Thermostat opens as there is an immediate drop in your expansion tank level at that point....as an visual indicator that the 'stat has opened.........
I was writing up my bleeding method last night for another member and what you have said is a very good way to get over the .....what happens at what point scenario...hope you don't mind me pinching that observation for my document.
Surely while it is stationary, the radiator isn't really working is it? The coolant is just flowing through it, no air flow to cool it unless you reach fan kick in point?

Even stationary the Radiator would have some degree of effectiveness.... probably more effective at certain times than belting along at 70 mph.... due to little if any air flow.....all I was indicating is that the coolant at the bottom hose would be cooler than the top hose and f it wasn't then the radiator wouldn't be doing it's job effectively..... and like Bongomtbr says...."My bottom hose didn't get hot hot hot either just a bit warm" which is what you expect from a free flowing system.....

Posted: **Sun Feb 14, 2010 11:24 am**

I don't think the radiator does very much at all unless you are either
a....moving forward (creating airflow)
b....the fans are on.(creating airflow)

Posted: **Sun Feb 14, 2010 11:46 am**

Natural convection cooling can still be quite powerful, though well short of either a fan or being on the move. On the other hand, if the engine is only ticking over (not doing much work, not generating much heat)

I suppose one way of getting a rough idea is whether rad fans keep coming on when sitting in a traffic jam. Interestingly, I don't think I've heard mine doing that. Not sure what all that says

Posted: **Sun Feb 14, 2010 12:21 pm**

The basics of a radiator are thus........ As the engine heats up and reaches a certain temperature, the thermostat opens to allow the flow of coolant and water. The water/coolant combination is held in the radiator. As it comes into the engine, it is sent around the cylinders to pick up the heat from the friction and burning fuel. The coolant is then sent back into the radiator where it goes into small chambers that are all throughout the radiator.

The surface area of the radiator alone is enough to cool down the coolant.

However, a fan between the engine and radiator helps to cool it down even more. Further cooling is done through the grill of the moving car as the air from outside the car blows onto the radiator.

Once the coolant has made the trip through the radiator it's ready to go back to the engine and pick up more heat.

Posted: **Tue Feb 16, 2010 1:27 am**

haydn callow wrote:I don't think the radiator does very much at all unless you are either
a....moving forward (creating airflow)
b....the fans are on.(creating airflow)

You'd be surprised at just how effective the rad actually is Haydn... Even when stationary! As Mikexgough rightly highlights above, the rad (even when stationary), is a tremendous heat sink... If it's channels are clear and unobstructed, then it works really well, doing it's job effectively, that job being cooling the hot coolant, and storing it till the stat comes into play. Cold always "beats" heat...Once cooling starts, it escalates,the coolant cools the channels in the rad, the rad then further cools the coolant, then so on, and so forth...

Posted: **Tue Feb 16, 2010 1:56 am**

haydn callow wrote:I've done quite a few now and as long as I fill to about 1cm over the FULL line when I've finished bleeding (to allow for the normal contraction of the coolant as it cools) I have never had to top up the next day or any other day for that matter. This tells me that all the air must be purged during the bleeding process. If you have to top up ..you either have a leak or some air must have been left in and it has worked it's way out....

And this is where confusion sets in regarding the system... The bongo cannot be 100% bled via any method. The natural "overnight" cooling is what bleeds the last "dregs" of air from the system. Are you aware of the actual mass of air/coolant in relative terms when you factor in the the variation from hot and cold? Are you aware of how the density of the same relative substance alters when even a few degrees separate those two identical substances? Have you ever actually wondered why icebergs float above the very same substance on which they float? Temperature change affects the density/weight/mass, that is scientific fact.

The air that is trapped has a different ratio of cooling to the surrounding (similar temp) coolant,as the system cools (post engine shutdown) the trapped air (in the cylinder head) is marginally cooler than the surrounding coolant, as the temps drop further, the slightly cooler air makes it's way up, eventually finding it's way into the expansion tank, then as the temp drops even further, the mass of the air increases in volume,in conjunction with the slight contraction of the actual coolant (if mixed to the correct ratio, 50/50 mix is wrong if the coolant manufacturers instructions advise otherwise) This is why the expansion tank needs to be topped up following the bleeding of the bongo,coolant has contracted (to a varying degree depending on the ratio of anti-freeze to the water, look at the element of "heat expansion" characteristics of plain water,to the heat expansion characteristics with the correct ratio of coolant) The amount of coolant contraction when cold is minimal, compared to the displacement (and altered mass via temp variation) of cooled air.

Posted: **Tue Feb 16, 2010 2:02 am**

I accept that when the stat first opens, the hot coolant flowing into a cold stationary rad will be cooled quite effectively initially, but once the rad has taken the heat from the hot coolant & heated up itself, that cooling effect will actually start to decrease (exponentially?), as the temperature differential will be less.
Yes there is some cooling due to convection, but as the cooling effect decreases after that initial surge, the coolant going into the engine will get slightly warmer, thus raising the temp within the stat as it mixes with the already hot coolant circulating around the heaters, this will cause the stat to open a bit more (which also shuts in the recirc) thus forcing more hot coolant through the rad, thus asking a stationary rad to "dump" more heat, which it can't, therefore the coolant exiting the rad will gradually be getting hotter as this cycle continues until the stat is fully open with the recirc shut in, after which the rad fans kick in. Bear in mind if you're bleeding it you're usually revving the engine to try & raise the temp. If this wasn't the case - you'd never be able to bleed it as the temperature would never rise

It is my belief that if you haven't got the bottom hose starting to feel hot, you haven't been at it long enough & the stat hasn't fully opened & closed off the recirc.
After a good run with the engine run up to normal running temp, park up, leave the engine running for 5 to 10 minutes & feel the bottom hose, I reckon it should get hot enough that it's uncomfortable to hold it too long. If it's not I reckon your stat isn't opening fully, or the top disc on the stat possibly isn't sealing off the recirc flow properly.

From this thread - http://www.igmaynard.co.uk/bongo/forum/ ... &start=105

missfixit70 wrote:Received a pm with some useful info received this morning to back up the Mazda stat info from some bongo owners that would prefer anonymity on this one, I've been trying to help out with a bit of info for the them over the last few weeks, seems they've got somewhere quite useful.
The difference in the operation of the Mazda original stat & blueprint is apparantly quite noticable, the blueprint had a lag between stat moving & top disc (engine recirc shut off) moving, on the Mazda original new part, they moved simultaneously & the action was more "positive".

We started for a change with a Bongo with a "Good Coolant System" instead of trying to fix an overheating Bongo, we tried to remove heat from an untouched for 3 years plus Bongo with no oil or water leaks, original head and water pump etc,

Bongo A

1st Attempt

Mason alarm fitted

Good readings generally.

Actions:
New Blue Print Stat
New Intermotor Temperature Sensor Switch
New Blue Coolant
Speed Flush
New Gear Box Oil used millarmatic DM

Results Observed:

Slight but definate raised temperature according to gauge (suspect sender inaccurate) by could be copy stat. Ran for two weeks, but not happy as would have expected lower general readings.
Spoke to you reference Stat Operation with regard to disc at the top of the stat shutting off hot head water return.

2nd Attempt

Drop Coolant, not reused
Fitted New Mazda Temp Sender
Fitted New Mazda Fan Switch
Fitted New Mazda Stat
New Red Coolant fitted (Carplan)

CHECK STAT TOP HOUSING CLEAN – It was gasket face clean

Results Observed:

Tremendous difference, the control temperature is achieved and maintained easily (Stat control) at a lower temperature band well away from the fan level temp, and away from the danger level.
The auto box warms better and quicker therefore performs better with less heat generated which would need to be cooled by the rad.
Engine and Gearbox now working at correct temperature levels giving smoother results.
Conclusion:

The stat is key. To us the £7.00 copy or £15.00 Mazda, it has to be genuine.
Thermostat housing needs to be very clean to seal correctly

Mason or one of Haydns gauge modifying instructions would show up this in relation to narrow working or operating temperature band and if these temps stray either up or down then the stat/housing should be checked .

Bongo B

History:

New Ranger Cylinder Head fitted 2 Years ago
New Mazda Radiator, 2 Years
New Water Pump, Unknown Brand, 2 Years Ago
New Copy Stat, 2 Years ago
New Coolant, 2 Years ago

Garage Bill = £1800

Full Silicon Hose set fitted, 18 months ago
12 months satisfactory running.

Then bought a light weight Caravan, raised temps noted via Mason Alarm to excessive levels. In the last three months over the winter period symptoms getting steadily worse to the point where anything over ½ hour high speed motorway driving temperature would steadily increase and would not decrease until fan level is reached. It would maintain levels, not cool levels. Fans where then wired manually and water wetter was used to pull down excessive temperatures.

Transfer of Knowlege from Bongo A to Bongo B

New Mazda Stat fitted
Bongos A's Original Old Mazda Temperature Sender Fitted, cleaned up.
Bongo A's Original Old Mazda Fan Switch fitted
Stat housing Top Disc Port from Head found to be dirty and deposit build up particularly at the flow from heaters across the stat edge: See Pics

Removed and Cleaned as per pics.

New Mazda Housing/Engine Gasket fitted
Red Coolant (Carplan)

Result:

Result!!!!!!!
as per Bongo A

Final Point:
One final point of note is that in "my opinion" a used lazy stat, when pan tested to boiling point only gives a low or inaccurate reading the 1st time tested. On second test it will normally be "Re-awakened" to work apparently normally and test well against a new stat. "Very confusing"!!!!!!!

Do they become Bongo Bound??????

So while I am happy that my system is running quite happily, when I next play with the coolant system, I'll be fitting a genuine Mazda stat.
Also find the last statement on testing a lazy stat interesting/worrying, sounds like from cold it needs a bit of a "kick" to get it going, not exactly ideal

That's my theory for the moment until I get a chance to disprove it or prove otherwise

As for the rad fans kicking in in traffic jams Mike, it happened to me last year in Wigan, stuck in an almighty traffic queue for about 40 minutes on the way to wheelquick with Ste. (admittedly this was before I changed the stat & did a flush etc) I know it was the rad fans, because you can hear & feel them & see the (mason modified) engine temp start dropping. I tested my scavenge fan on saturday, with the engine running, even with the seats folded up, I couldn't hear it running, the only way I knew it was, was that I could feel the air flow ( bloody good airflow too

) & I couldn't see the blades as it was spinnning. With the seats down, I just had no idea whether it was on or off without checking under the seats (if you pull the connector off the scav fan sensor with the engine running, the glow plug light should start flashing & the scav fan should be spinning).

Posted: **Tue Feb 16, 2010 2:56 am**

Regarding your above (inserted) post Kirsty... (forgive me if i'm wrong /misread it, it's been o LONG day and i'm in wind down mode) How pertinant to the comparison's would you say the difference was from using regular blue coolant, to the carplan red? Is that a variable enough factor to bring into question the actual amount of importance over using a spurious stat over a mazda original?

Doesn't the different coolants affect the variables? And do you happen to know what ratio the opposing coolants were mixed to?

Posted: **Tue Feb 16, 2010 3:07 am**

bigdaddycain wrote:Regarding your above (inserted) post Kirsty... (forgive me if i'm wrong /misread it, it's been o LONG day and i'm in wind down mode) How pertinant to the comparison's would you say the difference was from using regular blue coolant, to the carplan red? Is that a variable enough factor to bring into question the actual amount of importance over using a spurious stat over a mazda original?

Doesn't the different coolants affect the variables? And do you happen to know what ratio the opposing coolants were mixed to?

I'm no expert on different types of coolant & their relative cooling properties so I can't really comment too much, just passing on the info & results found. My thoughts would be that it wouldn't have a huge effect, certainly not to explain the difference with Bongo B, apparantly it was always a pig to bleed, but with the Mazda stat & the housing face cleaned up, it apparantly bled much easier & more decisively & then ran with a much lower control range than it had been.

Posted: **Tue Feb 16, 2010 9:28 am**

bigdaddycain wrote:
haydn callow wrote:I don't think the radiator does very much at all unless you are either
a....moving forward (creating airflow)
b....the fans are on.(creating airflow)
You'd be surprised at just how effective the rad actually is Haydn... Even when stationary! As Mikexgough rightly highlights above, the rad (even when stationary), is a tremendous heat sink... If it's channels are clear and unobstructed, then it works really well, doing it's job effectively, that job being cooling the hot coolant, and storing it till the stat comes into play. Cold always "beats" heat...Once cooling starts, it escalates,the coolant cools the channels in the rad, the rad then further cools the coolant, then so on, and so forth...

Obviously this is at it's most effective when the radiator is new/free flowing and as the temp raises it still has a convection effect but becomes more of a storage tank until the stat opens and when the system in at full operating temperature is still used as a storage tank that, dependent on whether you are stationary or traveling on the road, will cool in the appropriate manner.....convection....air flow by driving or by the engine fans......... as for the Blue/Red coolant differences.....the jury could be out on that...... until I can find the differences .....if any.... I would think that there would be little difference if any, but I'm prepared to be proved completely wrong....

Bongo Fury

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