coolant flow - (follow up to cooling diagram)

[widdowson2008]

Ok - enough festivity for one year - back to business.
I prepared this diagram showing the relative heights of the cooling system components just in case some clever person may spot something relevant.

I also have some interesting thoughts to share on the stat flow.

[widdowson2008]

Yet more ............. FLOW diagrams this time!!!!!
Stat CLOSED
Stat @ 2.6mm lift
Stat @ 5mm lift - FULLY OPEN
Stat @ 8.5mm lift

These diagrams suggest that the ONLY flow which has an immediate effect on the wax cylinder (and hence stat lift) is that from the heater circuit.
Flows from cylinder head and radiator both seem to pass through the engine BEFORE seeing the wax.

Any thoughts out there??????

[missfixit70]

Ok - enough festivity for one year - back to business.
I prepared this diagram showing the relative heights of the cooling system components just in case some clever person may spot something relevant.

I also have some interesting thoughts to share on the stat flow.

Should rear heater not lower Steve? it is below the rear floor level, I can't make out which is which on that diagram, eyes getting old but they both seem too high to be the rear heater.

[missfixit70]

Yet more ............. FLOW diagrams this time!!!!!

Stat @ 5mm lift - FULLY OPEN


These diagrams suggest that the ONLY flow which has an immediate effect on the wax cylinder (and hence stat lift) is that from the heater circuit.
Flows from cylinder head and radiator both seem to pass through the engine BEFORE seeing the wax.

Any thoughts out there??????

I think it's a valid theory, BUT maybe slightly simplistic in its view of the flow? Doesn't the actual structure of the stat interrupt the flow & create a turbulence which will have an effect of mixing the coolant within the stat housing around the wax cylinder? Also you show the flow going through with nothing in the "dead spaces" but they will contain coolant which will surely be affected by the flow going through, creating "eddies" - ( not this kind of Eddy before Mike or Jaylee start
)

that will mix the coolant too? The speed of the flow is also relative to the speed of the waterpump which is relative to the engine speed.
Just a few thoughts to chuck into the ring
Fantastic work BTW Steve, not easy to stick your neck on the block with something like this, credit to you , you need to change your forum name to "Pitbull" methinks

[widdowson2008]

Ok - enough festivity for one year - back to business.
I prepared this diagram showing the relative heights of the cooling system components just in case some clever person may spot something relevant.

I also have some interesting thoughts to share on the stat flow.

Should rear heater not lower Steve? it is below the rear floor level, I can't make out which is which on that diagram, eyes getting old but they both seem too high to be the rear heater.

If you take a closer look Kirsty, the levels on the diagram are to the pipework and NOT the heaters. This is because I could actually SEE the pipes, and therefore take a physical dimension. The heaters on the other hand - not a clue where these are - wouldn't recognise one if I fell over it. I was rather hoping someone else would tell me.
Rear heater is the one shown on the far left.

[missfixit70]

In that case it's way too high, as I said, it's just below the level of the floor pan, if you look under the bongo on the drivers side between the front & rear wheels you'll see a lower section of floor like the level of the side door step, the heater sits between that & the rear floor level. the pipework comes up from underneath, just about the level of the bottom of the cill at the lowest point.
The front heater matrix is is under the dash where the ducting comes through from the bonnet in the middle, about the level of the top of the rad I'd say.

[widdowson2008]

Meant to reply to this much earlier but things got in the way.
Yet again, Kirsty is right and I have amended this diagram to comply. I have also added some flow arrows.

[widdowson2008]

Another question .
There have been a few posts lately refering to 'lazy stats'. Can someone define a 'lazy stat'?

[mikeonb4c]

Another question .
There have been a few posts lately refering to 'lazy stats'. Can someone define a 'lazy stat'?

If I've used the term (which I think I may have - the relevance of it came up in that article about Rover cooling system problems) it'll be to describe a stat. that is slow to express a critical change in temperature by responding with mechanical action. I've no idea what might cause it (increased frictional resistance of some sort maybe?), but it's effect is too put it out of phase with the demands of the system for greater or lesser flow at the moment it is needed. Again, this all came out of the Rover article and I wouldn't know just how critical that might be on a bog std Bongo engine - you'd think designers would be at pains to avoid that kind of susceptability

[widdowson2008]

Another question .
There have been a few posts lately refering to 'lazy stats'. Can someone define a 'lazy stat'?

......... I've no idea what might cause it (increased frictional resistance of some sort maybe?), ........

Mechanically speaking, your thinking is my first port of call.
Another possibility (relating to the initial stat lift) is gunge in the stat seating area which has a slight taper at the seat. (Sticky valve)
Yet another very real possibility is loss of the wax compound through the stem area of the valve. There is a specific amount of wax in a new stat, so if any is lost through leakage, the stat WILL behave in a sluggish manner - NO DOUBT ABOUT IT - SIMPLE HYDRAULICS.
All these things would affect the stat movement.
I would expect the original Mazda stat will be manufactured to a much higher specification than some of the replacements you can get, so when mine needs changing I will go for the real thing. May cost a bit more but I think the expense is well worth it - the alternative scenarios don't bear thinking about.

[mikeonb4c]

Another question .
There have been a few posts lately refering to 'lazy stats'. Can someone define a 'lazy stat'?

......... I've no idea what might cause it (increased frictional resistance of some sort maybe?), ........

Mechanically speaking, your thinking is my first port of call.
Another possibility (relating to the initial stat lift) is gunge in the stat seating area which has a slight taper at the seat. (Sticky valve)
Yet another very real possibility is loss of the wax compound through the stem area of the valve. There is a specific amount of wax in a new stat, so if any is lost through leakage, the stat WILL behave in a sluggish manner - NO DOUBT ABOUT IT - SIMPLE HYDRAULICS.
All these things would affect the stat movement.
I would expect the original Mazda stat will be manufactured to a much higher specification than some of the replacements you can get, so when mine needs changing I will go for the real thing. May cost a bit more but I think the expense is well worth it - the alternative scenarios don't bear thinking about.

I had wondered about loss of wax but not knowing the construction/design I hesitated to say. It has to be strong candidate as otherwise, hydraulic expansion and contraction are pretty effective at overcoming frictional forces.

Yes, this business of cheap alternative products is v. worrying. I would like to think though that those with reputations to consider (and likely to get regular feedback from business-to-business clients) would know which of the pattern parts were OK and which were not. So companies/motor factors supplying local garages ought to be a reliable source for parts. But I worry that the fierce economic pressures could cause anything to buckle and bend these days My local motor factors have shut down

[missfixit70]

Received a pm with some useful info received this morning Steve 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

[mikexgough]

You can buy the Thermostats from the supplier Mazda use for O.E parts too.......and in the UK.

I have done this kind of thing before with Citroen's....... They use mainly Valeo/Beru/Bendix parts for O.E and you can buy the self same parts a good deal cheaper BUT at O.E quality and standards...... Same parts but not in Citroen packaging.....

The Bongo Thermostat is made by Tama Enterprises.... http://www.tama-e.co.jp/en/products.html#00 and there is a supplier in the UK of the said thermostats....... O.E quality and £££'s cheaper... Take a look at the Bottom Bypass link on their site

For me a Mazda/Tama Thermostat is way to go...... but you pays your money....

[widdowson2008]

Need to tread carefully here.
Is it possible to find out exactly which Blueprint thermostat was used in these tests?
Reason for asking is that on the one Ian supplied to me (ADM59208), there is definitely no lag between stat moving & top disc - physically impossiblity. This suggests that the Blueprint stat used in the tests might not be an ADM59208.
I checked on the Blueprint website and there are a number of stats which appear to be the same but are slightly different. Is it possible to check which one was used Kirsty?
Whatever your reply, when mine needs changing I'm afraid I would rather get an original Mazda stat than a Blueprint, simply for peace of mind. There are too many variables in the Bongo cooling system without introducing more. The stat needs to be precisely to the original spec to eliminate it as a possible problem area. I stress that this is my personal opinion and not an attempt to rubbish the Blueprint in any way.

[missfixit70]

Info requested Steve I figure for the sake of a few pounds difference in price for such a critical component & control band, go for the proper job.