How "HOT" does it have to get ???

[haydn callow]

How HOT does it have to get ??? before the Bongo gauge moves ??
I have recently repositioned the sensor of my TM-2 temp gauge to one of the threaded holes on the exaust side of the cylinder head via the passenger seat.
Driving to the Brookerswood Bash this morning towing our small Eriba Caravan the Bongo gauge settled at it's normal 11o'clock position when the TM-2 was reading 45c.....at one point on the journey we were pulling up a steep hill and the TM-2 reached 123C......the Bongo gauge was still happy at 11 o'clock......123C is getting close to meltdown....We all thought the Bongo gauge was useless....now I know it is...

[Ron Miel]

How HOT does it have to get ??? before the Bongo gauge moves ??
I have recently repositioned the sensor of my TM-2 temp gauge to one of the threaded holes on the exaust side of the cylinder head via the passenger seat.
Driving to the Brookerswood Bash this morning towing our small Eriba Caravan the Bongo gauge settled at it's normal 11o'clock position when the TM-2 was reading 45c.....at one point on the journey we were pulling up a steep hill and the TM-2 reached 123C......the Bongo gauge was still happy at 11 o'clock......123C is getting close to meltdown....We all thought the Bongo gauge was useless....now I know it is...

I confirm - our Bongo gauge reaches stays at the 11 o'clock position when the TM-2 hits about 45C, and still hasn't shifted at 83C on the TM-2, the hottest we yet ran at.

Our V6 normally runs at somewhere in the mid 70s C, when moving along, and gets up into the low 80s C in any traffic crawl. Will be interested to see how well the cooling system does/does not keep it regulated within those ranges, when (if) the summer gets here - our first Bongo summer

[mikeonb4c]

But aren't these observations all a bit unscientific. How do we know what temperature at various points in the engine/exhaust system equates to the engine core 'going critical'? Taking it to the extreme, if you attached the temp. sensor to the exhaust manifold, you'd wonder from the temp. readout why the oil was'nt boiling, never mind the coolant.

Or have I missed something (probably, knowing me ). But I must admit, trying to work out exactly what the Bongo temp. gauge (and other cars too no doubt) is there to do does remain bit of a mystery.

[David Edwards]

Hmm or does it mean the fans are doing a damn good job, I often wonder mind how it seems to stay perfectly at 11 o clock.

[haydn callow]

It stays at 11 o'clock co's it's so heavily damped and so useless. The 123C is a fact , no matter what the fans are doing.
Without the caravan the highest it ever goes is abour 108C. Any one towing a big van must be getting near crictal.
I belive my cooling system is working well and as it should.

[mikeonb4c]

It stays at 11 o'clock co's it's so heavily damped and so useless. The 123C is a fact , no matter what the fans are doing.
Without the caravan the highest it ever goes is abour 108C. Any one towing a big van must be getting near crictal.
I belive my cooling system is working well and as it should.

Sounds to me like a good argument for fitting a Mason Alarm to undamp the temp. gauge.

I'd still counsel wariness in attempting to interpret engine block surface temperature as being a meaningful indicator of core temperature, or of having some reliable link to it. After all, the job of the coolant channels is to carry away heat from the block, whether it has arrived from the core (detonations in the chambers) or from conduction from some other hot spot (e.g. exhaust manifold location which, with your TM2 sensor mountings on the exhaust side, seems a distinctly possibility). I don't think it can be assumed that 123C measured by the TM2 sensor indicates the engine may be near meltdown.

Or have I missed something (probably knowing me )

[scanner]

It stays at 11 o'clock co's it's so heavily damped and so useless. The 123C is a fact , no matter what the fans are doing.
Without the caravan the highest it ever goes is abour 108C. Any one towing a big van must be getting near crictal.
I belive my cooling system is working well and as it should.

Sounds to me like a good argument for fitting a Mason Alarm to undamp the temp. gauge.

I'd still counsel wariness in attempting to interpret engine block surface temperature as being a meaningful indicator of core temperature, or of having some reliable link to it. After all, the job of the coolant channels is to carry away heat from the block, whether it has arrived from the core (detonations in the chambers) or from conduction from some other hot spot (e.g. exhaust manifold location which, with your TM2 sensor mountings on the exhaust side, seems a distinctly possibility). I don't think it can be assumed that 123C measured by the TM2 sensor indicates the engine may be near meltdown.

Or have I missed something (probably knowing me )

I'm not doubting the point Hadyn is making, but to get a meaningful comparison the reading point for Hadyn's meter needs to be as close as possible to the point at which the standard gauge's sensor is located to eliminate any discrepancy.

Is it possible to fix the TM-2 sensor to the standard sensor in any way?

[mikeonb4c]

It stays at 11 o'clock co's it's so heavily damped and so useless. The 123C is a fact , no matter what the fans are doing.
Without the caravan the highest it ever goes is abour 108C. Any one towing a big van must be getting near crictal.
I belive my cooling system is working well and as it should.

Sounds to me like a good argument for fitting a Mason Alarm to undamp the temp. gauge.

I'd still counsel wariness in attempting to interpret engine block surface temperature as being a meaningful indicator of core temperature, or of having some reliable link to it. After all, the job of the coolant channels is to carry away heat from the block, whether it has arrived from the core (detonations in the chambers) or from conduction from some other hot spot (e.g. exhaust manifold location which, with your TM2 sensor mountings on the exhaust side, seems a distinctly possibility). I don't think it can be assumed that 123C measured by the TM2 sensor indicates the engine may be near meltdown.

Or have I missed something (probably knowing me )

I'm not doubting the point Hadyn is making, but to get a meaningful comparison the reading point for Hadyn's meter needs to be as close as possible to the point at which the standard gauge's sensor is located to eliminate any discrepancy.

Is it possible to fix the TM-2 sensor to the standard sensor in any way?

Well put Scanner - that seems the logical thing to do. Sounds suspiciously like wot the Mason Alarm does, by using the original temp. gauge sensor. I'm beginning to think the Mason is the best option (cheap too) for taking the engine's pulse, as long as you've no coolant loss so that the temp probe is not immersed and mis-reads. Interpreting the engine block surfce temp. seems a trickier proposition altogether, although I think it is still a very interesting exercise.

[francophile1947]

That's interesting Haydn
When I was testing your prototype Coolant Alarm add on, I had a 110C switch and a 90C switch - they were also bolted into the spare holes on the exhaust side of the head, but neither triggered the alarm. The 90C one did drive me mad when I stopped for a coffee or a pee though - all the heat rose to the head, whilst the engine was stopped, and it took about 10 minutes for the switch to cool down enough to reset itself

[helen&tony]

HiHaydn
That's very hot I had mine in that same place, and, like you never got more than upper 90's 110....other members have had the same readings there, but 128 is abnormal. I have had the Bongo towing a very over-laden van, plus the whole rear of the car behind the middle seats ( which were pretty well forward) laden almost to the top of the windows. I drove from the midlands, all the way to and from the Chunnel, through most of Europe and eventually into Greece via Italy, and into Bulgaria....The temp . gauge sat still, but I know the radiator must have been hot, as the Bongo was down to second gear and struggling through the hills and mountains, to the extent that I often had to stop for a couple of hours to cool the transmission, which cools through the bottom of the rad. The Bongo does not like long periods of towing (in excess of 4-5 hours)...most days, this extended my driving time to 12- 14 hours daily. Having given it this much of a test, I would concur......the standard gauge is just a decoration, and serves no function whatsoever, except as a talking point for us coolant-mad Bongoists, one of which I count myself , having TM2....low coolant , high coolant alarm, plus one of your heat sensors. I am also fitting a water temp. gauge in one of the coolant hoses soon.....just for interest!
Cheers
Helen

[mikeonb4c]

I am also fitting a water temp. gauge in one of the coolant hoses soon.....just for interest!
Cheers
Helen

But Helen, you already have one of sorts don't you It just needs undamping with a Mason Alarm if I understand correctly

Interesting to hear your observation on the 4-5 hours towing heavy loads limit as I recall someone posting some time back claiming that their Bongo towed a caravan up and down Alpine passes all day with no complaint. Maybe it depends on the ambient temperature. But it's on hearing things like this I start wondering about scavenger fan and radiator fan over-ride switches all over again

[teenmal]

Hi Guys,
Mazda and other Japanese car manufacturers doctored temperature gauges by fitting a Zener diode.
By removing the Zener and a resistor,and fitting 2No resistors the gauge will work as it should.

Cost of resistors about £1.00.

Malc..

[francophile1947]

Hi Guys,
Mazda and other Japanese car manufacturers doctored temperature gauges by fitting a Zener diode.
By removing the Zener and a resistor,and fitting 2No resistors the gauge will work as it should.

Cost of resistors about £1.00.

Malc..

Sounds like you may have a few jobs at the Bash in Stourport

[scanner]

Hi Guys,
Mazda and other Japanese car manufacturers doctored temperature gauges by fitting a Zener diode.
By removing the Zener and a resistor,and fitting 2No resistors the gauge will work as it should.

Cost of resistors about £1.00.

Malc..

It's all very well knowing that - but it's know HOW to do that that matters.

[mikexgough]

Sounds like a "How To" coming up..........