Underheating?!

Technical questions and answers about the Mazda Bongo

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mikeonb4c
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Re: Underheating?!

Post by mikeonb4c » Fri Nov 13, 2009 9:13 pm

missfixit70 wrote:
haydn callow wrote:you said....From the radiator top...the only coolant pipe which exits the top of the radiator is a smallbore pipe that goes up to the expansion tank....this exiting coolant is NOT cooled by the rad as it dosn't pass down through it....the temp of this coolant is almost the same as the coolant entering the rad from the engine.
If you ment the rad bottom hose then you are correct..this exits the rad after being cooled on it's passage down through...


But only if the vehicle is moving (for airflow across the rad) or the fans are running & the engine is warm enough for the stat to open :wink: If the vehicle is stationary, with no airflow across the rad (ie when bleeding) this will be warm/hot.

There is no simple - "this should be cool & this should be hot or warm" it depends on what point in the control process it's at (discussed at length in the aforementioned & linked to thread :-" :wink: )
OK - I see what you are both (all) saying. You'll have to forgive me as it is very hard to find time (esp. in stolen time at work) to quickly read up a 10 page thread (though I did try and whizz through it), which I haven't followed because I groaned when I read another coolant thread was starting up. The last one wore me out. Well I'm not about to challenge the diagrams correctness, but I'd be more comfortable if Mazda rubber stamped it as well as confirming our well considered but speculative view on how the whole thing is intended to work.
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Re: Underheating?!

Post by The Great Pretender » Sat Nov 14, 2009 1:33 am

haydn callow wrote:
mikeonb4c wrote:
haydn callow wrote:Your temp gauge is useless at the best of times....
Wouldn't have said that. Its very useful for telling me when my thermostat has opened.....but that's about it :lol: :lol: :lol:

Actually, on that serious note, you should be seeing a definite 'kick-off' point as the thermostat opens (after about 5 mins running approx on a healthy one) and the temp gauge needle moves off its COLD stop to its 11 oclock position. If you aren't it strongly suggests either that there is no thermostat fitted or else that there is but it is jammed open :roll:
Mike the gauge dosn't start to move co's the stat opend....the gauge starts to move when the engine temp reaches about 50C and is at 11 o'clock by the time it gets to 60C .. it then stays at this position till it reaches around 110C then it "wips" across to hot and Bingo.

I doub't a stat could Jam open....if they go wrong they would jam shut
The stat starts to open when the temp of the stat reaches 82c and should be fully open at about 90C
When I was monitoring temp most gauges were not accurate. Using an accurate thermistor in the coolant exiting the head close to the Mazda gauge it didn't start moving at 50c. It started to move at 67-69c rising to 75-78c at 11 o clock.
I now have a digital 52mm gauge fitted and as the sender sits in a brass bulb in the coolant this shows the lower readings expressed.

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Re: Underheating?!

Post by dandywarhol » Sat Nov 14, 2009 11:28 am

Did you fit the gauge sensor in the same place as the original Mazda sensor Mel?
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Re: Underheating?!

Post by haydn callow » Sat Nov 14, 2009 11:51 am

I think I read months ago that TGP has "slipped" the sensor into the top hose where it exits the engine under the drivers seat.
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Re: Underheating?!

Post by missfixit70 » Sat Nov 14, 2009 6:52 pm

haydn callow wrote:http://www.motoradusa.com/products/fail ... index.html

Could somone go to this link and watch the VIDIO...they state ...when your vehicle overheats the "normal" thermostat WILL FAIL....Dosn't have to do this ??

And surely even their failsafe could faiy before a high enough temp is reached to trigger the lock

I'm not so sure how well this'd work on the bongo system, I reckon a lot of the overheat problems with the bongo's cooling system that are stat induced are more to do with it not opening (at all or far enough) in the first place.
It looks like the failsafe stat "extra bit" that lifts it to a position where it lifts up beyond the clips that lock it out only works at the top end of the stroke. Unless this is capable of lifting the stat all the way on it's own, it just ain't going to do what it needs to for the bongo IMO if the standard wax bulb component fails in the closed position or degrades as most seem to.
As stated elsewhere, stick a new stat in if you're not sure how old yours is, test it beforehand in a pan of water against the old one & preferably with a temp gauge/thermometer to check it's working as it should.
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Re: Underheating?!

Post by The Great Pretender » Sat Nov 14, 2009 11:39 pm

dandywarhol wrote:Did you fit the gauge sensor in the same place as the original Mazda sensor Mel?

As haydn said into the top hose so the sensor in direct contact with the coolant reading to 0.1 of a degree c. Pukka digital car temp gauge fitted in the same area getting the lower readings.
A certain MINX asked about temp readings in another thread.............recon she was trying to get me in hot water............


:shock: :lol: :wink:
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Re: Underheating?!

Post by missfixit70 » Sat Nov 14, 2009 11:45 pm

The Great Pretender wrote:
dandywarhol wrote:Did you fit the gauge sensor in the same place as the original Mazda sensor Mel?

As haydn said into the top hose so the sensor in direct contact with the coolant reading to 0.1 of a degree c. Pukka digital car temp gauge fitted in the same area getting the lower readings.
A certain MINX asked about temp readings in another thread.............recon she was trying to get me in hot water............


:shock: :lol: :wink:
You're far too paranoid Mel :wink: :lol:
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Re: Underheating?!

Post by The Great Pretender » Sat Nov 14, 2009 11:58 pm

missfixit70 wrote:
The Great Pretender wrote:
dandywarhol wrote:Did you fit the gauge sensor in the same place as the original Mazda sensor Mel?

As haydn said into the top hose so the sensor in direct contact with the coolant reading to 0.1 of a degree c. Pukka digital car temp gauge fitted in the same area getting the lower readings.
A certain MINX asked about temp readings in another thread.............recon she was trying to get me in hot water............


:shock: :lol: :wink:
You're far too paranoid Mel :wink: :lol:
:shock: who..................me? :lol:
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Re: Underheating?!

Post by mikexgough » Sun Nov 15, 2009 12:17 pm

haydn callow wrote:http://www.motoradusa.com/products/fail ... index.html

Could somone go to this link and watch the VIDIO...they state ...when your vehicle overheats the "normal" thermostat WILL FAIL....Dosn't have to do this ??

And surely even their failsafe could faiy before a high enough temp is reached to trigger the lock

They do make a compatible Failsafe Thermostat that will fit the Bongo.....opens at 180f.... 82c in rough terms.......

Not going to confuse the thread .......anyone who wants one will have to get it from the states.....and it fails open... :D in the case of an overheat problem.....wont sort the issue leading to an overheat but might protect your engine.....and my issue is how will you know ...unless the temperature gauge goes high on the reading....
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Re: Underheating?!

Post by rita » Sun Nov 15, 2009 1:26 pm

mikexgough wrote:
haydn callow wrote:http://www.motoradusa.com/products/fail ... index.html

Could somone go to this link and watch the VIDIO...they state ...when your vehicle overheats the "normal" thermostat WILL FAIL....Dosn't have to do this ??

And surely even their failsafe could faiy before a high enough temp is reached to trigger the lock

They do make a compatible Failsafe Thermostat that will fit the Bongo.....opens at 180f.... 82c in rough terms.......

Not going to confuse the thread .......anyone who wants one will have to get it from the states.....and it fails open... :D in the case of an overheat problem.....wont sort the issue leading to an overheat but might protect your engine.....and my issue is how will you know ...unless the temperature gauge goes high on the reading....
Hi,do you happen to have the part No for the stat,the number that I have is 7207-180 for a 2.5 td.
I am not 100% sure of this number.
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Re: Underheating?!

Post by Rhod » Sun Nov 15, 2009 11:10 pm

mikexgough wrote: They do make a compatible Failsafe Thermostat that will fit the Bongo.....opens at 180f.... 82c in rough terms.......

Not going to confuse the thread .......anyone who wants one will have to get it from the states.....and it fails open... :D in the case of an overheat problem.....wont sort the issue leading to an overheat but might protect your engine.....and my issue is how will you know ...unless the temperature gauge goes high on the reading....
Equally not wanting to divert the thread, but I had a couple of problems last winter with the stat sticking closed. Whether it was the very cold weather, or whether the stat partially opened, I don't know, but both times the temp rose relatively slowly. However my point is that the Mason modified gauge warned me of a problem & let me sort it (tap on the stat with a handy stick!) before it became terminal. A "failsafe" stat might or might not work, but would you be any the wiser? I fell that an accurate temperature guage is the best investment for your money - that way at least you can monitor the health of your cooling system.
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Re: Underheating?!

Post by mikexgough » Mon Nov 16, 2009 8:12 am

A warning about Fail Safe Stats..............

Extract from a U.S site........... http://www.bonnevilleforum.com/t269434/

Still might work for some, but you have to ask........Why they are not "mainstream" in the UK as they are in the U.S.....

---------------------------------------------------------------------------------------------------------------------------------------------------------
And adding onto to the thread but not wishing to divert........something learnt from the MG TF/ Lotus Elise cooling system research (Bongo works in a similar manner)....... They have fitted remote thermostats and extra piping for road vehicles to stop overheating.......and the guys who race the same cars......remove the 'stat ......some road car owners have also modified the stat by drilling holes for circulation when on "bypass"......BUT and a big BUT.......this engine gets a whole lot HOTTER than the Bongo engine.......
________________________________________________________________________________________________________________
Back to thread..........

I'm with Rhod.......the minimum needed is a Mason alarm or undamped gauge......at least you will see the engine temperature rise and although you see changes as you drive (mine varies from 55% to 70% dependent on driving conditions (which affects the parts of the cooling system in operation) it is worth having a temperature gauge will a reading other than zero or 45% (11 o'clock)
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Re: Underheating?!

Post by curlew » Tue Nov 17, 2009 11:08 pm

Update, in case this happens to anyone else.
On the mechanic's instructions, I have been driving round for the last few days. The temperature gauge rises very slowly but gets to the famed 11.00 position eventually and more or less stays there - fluctuating a bit, but generally staying there. The mechanic thinks that the suppliers have sold him the wrong thermostat with a different operating temperature to a normal Bongo one.
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Re: Underheating?!

Post by dandywarhol » Tue Nov 17, 2009 11:15 pm

curlew wrote:Update, in case this happens to anyone else.
On the mechanic's instructions, I have been driving round for the last few days. The temperature gauge rises very slowly but gets to the famed 11.00 position eventually and more or less stays there - fluctuating a bit, but generally staying there. The mechanic thinks that the suppliers have sold him the wrong thermostat with a different operating temperature to a normal Bongo one.
.............so said mechanic gets the right feckin' one then!
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Re: Underheating?!

Post by curlew » Wed Nov 18, 2009 6:06 am

Absolutely - he's ordered it and has offered to come out to us to fit it. As he bloody well should!
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