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

[bandario]

Sorry for the thread revival.

After having just read every single thread on cooling in the forum + TM2s it would seem that 110 is quite high for most people, even for the diesels.

My new van + TM2 has hit 104 degrees C when I was intentionally thrashing it up and down hills for 10 minutes to test the new TM2 temp alarm.

It does not generally get this hot if I am on highways and just driving normally.

It has got a brand new radiator and I highly doubt the mechanic knew anything about bleeding the system so I am going to do this tomorrow morning before I start a big drive.

[dobby]

Sorry for the thread revival.

After having just read every single thread on cooling in the forum + TM2s it would seem that 110 is quite high for most people, even for the diesels.

My new van + TM2 has hit 104 degrees C when I was intentionally thrashing it up and down hills for 10 minutes to test the new TM2 temp alarm.

It does not generally get this hot if I am on highways and just driving normally.

It has got a brand new radiator and I highly doubt the mechanic knew anything about bleeding the system so I am going to do this tomorrow morning before I start a big drive.

Good idea.

I'd think about getting the stat, pump and hoses done as well with a mega flush through the system. I'm certain that investment now will save a new head later. Wish I had done that

[haydn callow]

Sorry for the thread revival.

After having just read every single thread on cooling in the forum + TM2s it would seem that 110 is quite high for most people, even for the diesels.

My new van + TM2 has hit 104 degrees C when I was intentionally thrashing it up and down hills for 10 minutes to test the new TM2 temp alarm.

It does not generally get this hot if I am on highways and just driving normally.

It has got a brand new radiator and I highly doubt the mechanic knew anything about bleeding the system so I am going to do this tomorrow morning before I start a big drive.

Where do you have the TM-2 sensor positioned ???

[widdowson2008]

Where do you have the TM-2 sensor positioned ???

Thats what I was wondering too Haydn.
For me, the TM-2 is an invaluable piece of kit. Brilliant
I've had mine in several places and the readings are vastly different. Outlet (where I have mine) is the best place for me cos it tells me exactly what the stat is doing.

[dobby]

Just re-read the previous pages on this and would agree about the TM2 location, mines at the rear of the block and typically indicates 87 to 91 in most conditions.

Still worth doing stat/pump/hoses as a precaution if the a new rad has been fitted. Preventation better than cure etc.

[widdowson2008]

Just re-read the previous pages on this and would agree about the TM2 location, mines at the rear of the block and typically indicates 87 to 91 in most conditions.

Hi Dobby
In that position (at the rear of the head) the temperature you are seeing is a coincidental simulation of the coolant temperature.
It is above the nearest waterway. Nearest component to this fixing is the rear rocker bearing, which is above the waterways.
See this http://www.igmaynard.co.uk/bongo/forum/ ... =3&t=48083 for an explanation.

[dobby]

Thanks

I remember seeing that post recently, particularly the cutaways I set the alarm at 96 in that location and all is well so far.

I must say that these posts and discussions are really useful, so thanks and credit to all involved.

[bandario]

My sensor is fitted to back of engine block as per latest instructions from the shop here in Aus.


I just did a 1000KM drive with only a few small breaks here and there;

Temperature at this location sat at an average of about 97 Celsius but did climb up to 107 for a time when I was heading up a very very long incline + again when heading over a mountain. I actually pulled up for a break half way up the mountain because I knew how much I had to go and 107 was already getting too hot for my own comfort, was very glad to have the TM2 because the normal temp gauge hadn't moved at all.

I realise there are compromises to having the sensor fitted in this location but I would prefer to be looking at worst case scenario numbers than a false sense of security from sensor closer to water pipes and away from engine etc.

I will get a full set of new hoses on there as soon as I get some other things under control but I have to say I'm still a bit worried about the readings; we are heading into our Winter here, I dread to think what temps would be like on a blazing hot summer day if they are already this high now.

I wonder what would be the "PULL THE HELL OVER" temp with the sensor mounted here? I think it will easily crack 110 in summer, surely that is close to boiling over even with antiboil coolant.

[binky]

The 'pull-over immediatly' temperature of vehicle cooling systems is not widely understood. The relationship between temperature, cooling, and vent pressure depends on; 1) what the coolant is and its flow rate, 2), the pressure design of the system, and 3) the available temperature drop which depends mainly on ambient temperature, engine load, and whether there is forced or ambient cooling.

If the radiator/expansion cap relief valve is designed for about 1.1 bar - 16 PSI then the maximum temperature at which the coolant should boil is 126 C. This gives you the 'pull-over, dummy' temperature. The coolant system thermostatic valve is not an open/closed switch, but operates over a range. (Modulates) The specified 82C or so at which it starts to open, gives no more than the tiniest flow through the bypass circuit (radiator) , but the 'stat will be fully open by 110C. The engine cooling system is designed to keep the engine coolant galleries somewhere at about 90C for maximum efficiency which it can easily do, even if ambient temperatures of 40C limit the amount of temperature drop across the radiator. Design standards for automobile engines are such that ambient temps of +50C (Dubai in Summer for instance) still allow the engine cooling system to operate.

Older systems with viscous-coupled fans do a good job of shoving ambient air past the engine block, and in those conditions, even in a British summer, the coolant might not go much above 80c. Electric fans are demand driven, providing closer temperature control but often higher coolant temperatures.

If the cooling system is in good order it can run all day at 115-120C coolant, 40-50C ambient without hoses popping, boiling or meltdown. If it's in good order.

In practice sludge forms, limiting coolant flow, rad/ex tank caps let go early loosing coolant, thermostats wilt, coolant contaminants reducing the boiling point, the anti-corrosion additives in the coolant become diluted by tap-water or distilled water top-ups, and hose clips become tired with the expansion/contraction cycles.

If the temperature at the base of the rad (it's a downflow rad on the Bongo) reaches 120C and continues to climb, I would say that that is the point to turn both sets of heater controls to hot, put the heater fans on full, and pull over. If there's no coolant loss, leave the engine running to allow the coolant circuits and fans to operate.

The rad/expansion blow-off cap is a vital part of the system, as you can see, and the only part of the system designed to loose coolant to prevent engine damage. It's worth replacing those when the cooling system is overhauled. However if the cap lets go early, before the 1.1 bar pressure is reached, the pressure reduction lowers the coolant boiling point, coolant loss occurs, and this can lead to engine damage before it's spotted. Coolant pressure loss into the engine block or from a gasket also lowers the boiling point, a viscious cycle from which there is no return.

Specifically, a peak coolant temperature of 107C under load is not a concern, assuming the cooling system is operating.

[Hippotastic]

This one of the best posts I have seen on here in two years.

Good write up by someone who knows their subject matter.

Bravo.

The 'pull-over immediatly' temperature of vehicle cooling systems is not widely understood. The relationship between temperature, cooling, and vent pressure depends on; 1) what the coolant is and its flow rate, 2), the pressure design of the system, and 3) the available temperature drop which depends mainly on ambient temperature, engine load, and whether there is forced or ambient cooling.

If the radiator/expansion cap relief valve is designed for about 1.1 bar - 16 PSI then the maximum temperature at which the coolant should boil is 126 C. This gives you the 'pull-over, dummy' temperature. The coolant system thermostatic valve is not an open/closed switch, but operates over a range. (Modulates) The specified 82C or so at which it starts to open, gives no more than the tiniest flow through the bypass circuit (radiator) , but the 'stat will be fully open by 110C. The engine cooling system is designed to keep the engine coolant galleries somewhere at about 90C for maximum efficiency which it can easily do, even if ambient temperatures of 40C limit the amount of temperature drop across the radiator. Design standards for automobile engines are such that ambient temps of +50C (Dubai in Summer for instance) still allow the engine cooling system to operate.

Older systems with viscous-coupled fans do a good job of shoving ambient air past the engine block, and in those conditions, even in a British summer, the coolant might not go much above 80c. Electric fans are demand driven, providing closer temperature control but often higher coolant temperatures.

If the cooling system is in good order it can run all day at 115-120C coolant, 40-50C ambient without hoses popping, boiling or meltdown. If it's in good order.

In practice sludge forms, limiting coolant flow, rad/ex tank caps let go early loosing coolant, thermostats wilt, coolant contaminants reducing the boiling point, the anti-corrosion additives in the coolant become diluted by tap-water or distilled water top-ups, and hose clips become tired with the expansion/contraction cycles.

If the temperature at the base of the rad (it's a downflow rad on the Bongo) reaches 120C and continues to climb, I would say that that is the point to turn both sets of heater controls to hot, put the heater fans on full, and pull over. If there's no coolant loss, leave the engine running to allow the coolant circuits and fans to operate.

The rad/expansion blow-off cap is a vital part of the system, as you can see, and the only part of the system designed to loose coolant to prevent engine damage. It's worth replacing those when the cooling system is overhauled. However if the cap lets go early, before the 1.1 bar pressure is reached, the pressure reduction lowers the coolant boiling point, coolant loss occurs, and this can lead to engine damage before it's spotted. Coolant pressure loss into the engine block or from a gasket also lowers the boiling point, a viscious cycle from which there is no return.

Specifically, a peak coolant temperature of 107C under load is not a concern, assuming the cooling system is operating.

[mikeonb4c]

This one of the best posts I have seen on here in two years.

Good write up by someone who knows their subject matter.

Bravo.

The 'pull-over immediatly' temperature of vehicle cooling systems is not widely understood. The relationship between temperature, cooling, and vent pressure depends on; 1) what the coolant is and its flow rate, 2), the pressure design of the system, and 3) the available temperature drop which depends mainly on ambient temperature, engine load, and whether there is forced or ambient cooling.

If the radiator/expansion cap relief valve is designed for about 1.1 bar - 16 PSI then the maximum temperature at which the coolant should boil is 126 C. This gives you the 'pull-over, dummy' temperature. The coolant system thermostatic valve is not an open/closed switch, but operates over a range. (Modulates) The specified 82C or so at which it starts to open, gives no more than the tiniest flow through the bypass circuit (radiator) , but the 'stat will be fully open by 110C. The engine cooling system is designed to keep the engine coolant galleries somewhere at about 90C for maximum efficiency which it can easily do, even if ambient temperatures of 40C limit the amount of temperature drop across the radiator. Design standards for automobile engines are such that ambient temps of +50C (Dubai in Summer for instance) still allow the engine cooling system to operate.

Older systems with viscous-coupled fans do a good job of shoving ambient air past the engine block, and in those conditions, even in a British summer, the coolant might not go much above 80c. Electric fans are demand driven, providing closer temperature control but often higher coolant temperatures.

If the cooling system is in good order it can run all day at 115-120C coolant, 40-50C ambient without hoses popping, boiling or meltdown. If it's in good order.

In practice sludge forms, limiting coolant flow, rad/ex tank caps let go early loosing coolant, thermostats wilt, coolant contaminants reducing the boiling point, the anti-corrosion additives in the coolant become diluted by tap-water or distilled water top-ups, and hose clips become tired with the expansion/contraction cycles.

If the temperature at the base of the rad (it's a downflow rad on the Bongo) reaches 120C and continues to climb, I would say that that is the point to turn both sets of heater controls to hot, put the heater fans on full, and pull over. If there's no coolant loss, leave the engine running to allow the coolant circuits and fans to operate.

The rad/expansion blow-off cap is a vital part of the system, as you can see, and the only part of the system designed to loose coolant to prevent engine damage. It's worth replacing those when the cooling system is overhauled. However if the cap lets go early, before the 1.1 bar pressure is reached, the pressure reduction lowers the coolant boiling point, coolant loss occurs, and this can lead to engine damage before it's spotted. Coolant pressure loss into the engine block or from a gasket also lowers the boiling point, a viscious cycle from which there is no return.

Specifically, a peak coolant temperature of 107C under load is not a concern, assuming the cooling system is operating.

I have to agree, and I think I might have noticed another earlier post by them and which hinted at their knowledge and their ability to put it across well. Great to have binky aboard, and I hope they will stay. I wonder what their professional background is.

One thing (binky if you are reading this) I'm curious about is whether we should all pay a little more attention to the sensors, relays etc. that can get tired with age. I wonder, for example, whether the electric fans on some Bongos are not coming on as promptly as they should. Is there an easy way to check? Would it make sense (if you have a proportional readout engine block temp gauge such as the TM2, for example) to fit a manual over-ride switch to the engine fans so that you have manual control over switching them on if you feel the need?

etc. etc.

[haydn callow]

My sensor is fitted to back of engine block as per latest instructions from the shop here in Aus.


I just did a 1000KM drive with only a few small breaks here and there;

Temperature at this location sat at an average of about 97 Celsius but did climb up to 107 for a time when I was heading up a very very long incline + again when heading over a mountain. I actually pulled up for a break half way up the mountain because I knew how much I had to go and 107 was already getting too hot for my own comfort, was very glad to have the TM2 because the normal temp gauge hadn't moved at all.

I realise there are compromises to having the sensor fitted in this location but I would prefer to be looking at worst case scenario numbers than a false sense of security from sensor closer to water pipes and away from engine etc.

I will get a full set of new hoses on there as soon as I get some other things under control but I have to say I'm still a bit worried about the readings; we are heading into our Winter here, I dread to think what temps would be like on a blazing hot summer day if they are already this high now.

I wonder what would be the "PULL THE HELL OVER" temp with the sensor mounted here? I think it will easily crack 110 in summer, surely that is close to boiling over even with antiboil coolant.

BINKY ...Super excellent post and no waffle. BANDERIO ... Can I ask where exactly on your engine you have mounted your sensor.....where did you get that position from and where did you get your TM-2 from ??? Engine watchdog at Brisbane or David Jones at EngineSaver Ingham ?? Is it a combined TM-2/LCA unit ??
Thanks

[TechnoTurkey]

After recently replacing my thermostat, waterpump and flushing then refilling with premium red coolant, I have dropped my normal operating temperature from 95c to 87c. I drove for over an hour afterwards in various conditions including half an hour at 70mph on the motorway and it never went over 89 once - very happy with this!

[bandario]

Sensor is mounted on the engine head, top left - at the bolt-on point advised in the new instruction manual for the bongo combo alarm (TM-2 + LCA).

This spot is accessible by removing the plate behind the centre console and choosing the bolt advised in the pictures.


I am in Australia - unit was shipped directly from Manufacturer here in QLD...about the only easy to find bongo bit around these parts


I am STILL waiting to hear back from the various online bongo parts places regarding who will ship some of these bits and pieces internationally for a decent price. Van is not doing a lot of KM at the moment but I am keen as mustard to get all of these new rubbers on + timing belt and full set of filters fitted.

I must also chase up a small diesel leak which I have not yet managed to place. It seems to occurr mostly on freezing cold mornings but no amount of lifting the seats and gazing longingly will reveal its location - I just hope when I get it up on the ramps it will come out to play...at least it is not unleaded.

Have to say I was absolutely blown away by just how low to the ground these things sit! I cannot even get my head under the inspection hole when it is sitting on flat ground...will certainly limit my offroad capability a bit.

[jaylee]

I hope you guys don't mind me throwing this n the mix....?!!

I'm thinking; say you put yer new hoses in, new stat, new rad, flush bleed... Basically concentrate on the whole coolant system..? Fit your sensors for peace of mind..

What about the auto box oil & flow to the cooling bit under the radiator?? If poorly maintained would that contribute to remaining abnormal engine temperatures... On hills??