Scavenger fan sensor test

[mikeonb4c]

Sounds odd that to me Dave as I'd have thought you needed to leave the original setup working so the fan could be switched by the sensor setup. You would then take another feed direct from the battery and run that via a suitable rated ON/OFF switch to the fans so that you supply power direct at any time if you wished, over-riding the sensor controlled circuit. That's what I did with my scavenger fan set up. A refinement would be to use a relay to avoid high current through the ON/OFF switch. Mine gets a bit hot (though it is supposed to be adequately rated) and I may fit a relay if I get a Round Tuit.

[dandywarhol]

I don't really understand what this manual overide switching is all about - and you're interfering with an ECU circuit to boot. I've only heard my scavenger fan come on a couple of times or so - once in the UK on a v. hot day...........and as you say Mike, it's when virtually stationary in traffic that it senses it to come on.

The manual states the fan will come on when:

The engine bay temp. is below minus 27 deg C and the coolant is over 90 deg or when the engine bay temp is over 180 deg C. These figures for automatic vehicles.

I can only take from the 1st one that for some reason the radiator cooling fans sensor won't work if the engine bay is too cold and the coolant is hot. It seems to be an intricate piece of kit - I'd say my all means test it's operation but avoid messing about overiding it cos "the ECU says "NO"!

Thanks to Little Britain for bastardising a sketch

[mikeonb4c]

I don't really understand what this manual overide switching is all about - and you're interfering with an ECU circuit to boot. I've only heard my scavenger fan come on a couple of times or so - once in the UK on a v. hot day...........and as you say Mike, it's when virtually stationary in traffic that it senses it to come on.

The manual states the fan will come on when:

The engine bay temp. is below minus 27 deg C and the coolant is over 90 deg or when the engine bay temp is over 180 deg C. These figures for automatic vehicles.

I can only take from the 1st one that for some reason the radiator cooling fans sensor won't work if the engine bay is too cold and the coolant is hot. It seems to be an intricate piece of kit - I'd say my all means test it's operation but avoid messing about overiding it cos "the ECU says "NO"!

Thanks to Little Britain for bastardising a sketch

Bah humbug - I bought a Bongo to live dangerously with

[daveblueozzie]

you don't need a power supply all your doing is switching the current already in the original wire to either on or off. with the ignition on or the engine running you can turn the fans on or off as needed, if its in the on position the sensor takes over the control, if its in the off position the fans come on and you control them,by putting the switch to off position its like cutting the power as if you had unplugged the wires. Mike did say you must turn them back to the on position before you turn the engine off. that's it simple. it has to be simple for me to do it.

ive never quoted myself before.
Mike did say he does not know what current is in the sensor wires so dont put 12v to it , it may cause problems .

[bigdaddycain]

Sounds odd that to me Dave as I'd have thought you needed to leave the original setup working so the fan could be switched by the sensor setup. You would then take another feed direct from the battery and run that via a suitable rated ON/OFF switch to the fans so that you supply power direct at any time if you wished, over-riding the sensor controlled circuit. That's what I did with my scavenger fan set up. A refinement would be to use a relay to avoid high current through the ON/OFF switch. Mine gets a bit hot (though it is supposed to be adequately rated) and I may fit a relay if I get a Round Tuit.

Hi Mike, the original ECU controlled set up is (should now be) working on dave's bongo. He has NEVER heard either the scavenger, nor radiator fans operate under any temperature, or any conditions, that includes uphill motorway running with a caravan in tow!

Chances are the fan sensor switch (pictured in dbo's post) was fluffed. New sensor has now been fitted, but engine temp hasn't yet been hot enough to trigger the ECU to switch on the fans to test it has been fixed.

As i mentioned earlier,if the fan sensor switch plug is unplugged, scavenger and rad fans operate, plug it back in, fans stop.... The switch dave wired in effectively breaks the circuit,(like unplugging the connector) Thus fans engage.

I consider it a handy back up system in cases such as lizard highlighted in his post above. I'll be copying dave's set-up (shock) Just so i have the option of overriding should i so desire in the future.

We have some long uphill climbs ahead of us during our scottish tour, i'll be switching fans on starting a 13 mile ascent,rather than risk the fan sensor switch packing up on the start of the climb,and not kicking them in at all!

We'll have to ensure the switch isn't left on accidentally though... As it also switches off the glowplug relay too!

[mikeonb4c]

Sounds odd that to me Dave as I'd have thought you needed to leave the original setup working so the fan could be switched by the sensor setup. You would then take another feed direct from the battery and run that via a suitable rated ON/OFF switch to the fans so that you supply power direct at any time if you wished, over-riding the sensor controlled circuit. That's what I did with my scavenger fan set up. A refinement would be to use a relay to avoid high current through the ON/OFF switch. Mine gets a bit hot (though it is supposed to be adequately rated) and I may fit a relay if I get a Round Tuit.

Hi Mike, the original ECU controlled set up is (should now be) working on dave's bongo. He has NEVER heard either the scavenger, nor radiator fans operate under any temperature, or any conditions, that includes uphill motorway running with a caravan in tow!

Chances are the fan sensor switch (pictured in dbo's post) was fluffed. New sensor has now been fitted, but engine temp hasn't yet been hot enough to trigger the ECU to switch on the fans to test it has been fixed.

As i mentioned earlier,if the fan sensor switch plug is unplugged, scavenger and rad fans operate, plug it back in, fans stop.... The switch dave wired in effectively breaks the circuit,(like unplugging the connector) Thus fans engage.

I consider it a handy back up system in cases such as lizard highlighted in his post above. I'll be copying dave's set-up (shock) Just so i have the option of overriding should i so desire in the future.

We have some long uphill climbs ahead of us during our scottish tour, i'll be switching fans on starting a 13 mile ascent,rather than risk the fan sensor switch packing up on the start of the climb,and not kicking them in at all!

We'll have to ensure the switch isn't left on accidentally though... As it also switches off the glowplug relay too!

Doh - got it now. Well that's a neat little trick Does this mean tthough that flicking the switch to break the circuit will activate both the radiator fans AND the scanger fan?

I wonder how the sensor and circuit work, in order to do that. No, lets not go there

[daveblueozzie]

Yes MIKEONB4C the radiator and the scavenger fans are switched at the same time. i would think that i would only use it if stuck in traffic for a long time, or driving up big hills in Scotland later this year. it really is a simple fix, well its gotta be that way, otherwise i don't bother.

[mikeonb4c]

Yes MIKEONB4C the radiator and the scavenger fans are switched at the same time. i would think that i would only use it if stuck in traffic for a long time, or driving up big hills in Scotland later this year. it really is a simple fix, well its gotta be that way, otherwise i don't bother.

Cripes! I imagine you'll probably get an extra 2mph due to the extreme turbothrust from the booster motors

[lizard]

Yes MIKEONB4C the radiator and the scavenger fans are switched at the same time. i would think that i would only use it if stuck in traffic for a long time, or driving up big hills in Scotland later this year. it really is a simple fix, well its gotta be that way, otherwise i don't bother.

Excellent, I must give this a try . Some of the hills are a bit long and winding and I reckon the Bongo would explode before it reached the top.

[bigdaddycain]

Me next for the fan switch DBO...I'll bring my bag of scotchlocks!

[not so old]

This sounds like the problem we had while driving to Mablethorpe on Thursday. We were driving along a very busy fast road when the TM2 alarm went off. The sound is earpiercing! I tried shouting above it asking Jim to pull in before something blew up(don't understand the water cooler thingy) Anyway he eventually pulled off, but not in the safest of places We could not silence the alarm, so he cut the wires, which I knew would make no difference and told him to rejoin them quick. The heat sensor on TM2 was 105 and rising still. I kept pushing that little button and realised it resets the Max Temp ,so took it up to 120 to ensure we got to our destination. However I still worried about it and on the way back home I kept an eye on it. At the bottom of one hill temp was 88, but by the time we got to the top it was 105 and continued to rise while we stopped at the traffic lights. We have not as yet taken the caravan to Scotland, but will be in a couple of months, so this is very worrying. Better get one of these fan sensor thingys quick I think. So glad I seen this Thanks. Now to work it all out Just wondered also, if anyone can tell me please. The alarm was showing a high temp, but the car gauge(Hot/cold) was showing between hot and cold Is that worn out too!

[bigdaddycain]

Have you a "mason alarm" fitted anne? The standard mazda temp gauge is slow and unresponsive, and in many's opinion, over-dampened. A mason alarm gives the full range of the needle,and is more indicative of actual coolant temp.

[not so old]

Have you a "mason alarm" fitted anne? The standard mazda temp gauge is slow and unresponsive, and in many's opinion, over-dampened. A mason alarm gives the full range of the needle,and is more indicative of actual coolant temp.

Hi BDc'
We have Haydn's dual TM2. It watches the coolant and I thought the oil, but it is obviously the engine heat. It is digital and shows the temp in degrees. I am absolutely useless at this technie thing, but learning from you guys Jimmy is not technically minded either,and has problems with remembering etc.
So it seems that the temp gauge in the bongo, may not work properly either Thanks for trying to help. I really appreciate it

Anna

[francophile1947]

Have you a "mason alarm" fitted anne? The standard mazda temp gauge is slow and unresponsive, and in many's opinion, over-dampened. A mason alarm gives the full range of the needle,and is more indicative of actual coolant temp.

Hi BDc'
We have Haydn's dual TM2. It watches the coolant and I thought the oil, but it is obviously the engine heat. It is digital and shows the temp in degrees. I am absolutely useless at this technie thing, but learning from you guys Jimmy is not technically minded either,and has problems with remembering etc.
So it seems that the temp gauge in the bongo, may not work properly either Thanks for trying to help. I really appreciate it

Anna

Sorry Anna, I didn't realise that you were talking about problems on the way to Mablethorpe, when we were talking about your alarm .
Bongo temperature gauge is rubbish - it stays at 11 o'clock until the engine is cooked anyway.
105 is not a problem, unless it stays there under normal driving. Your Bongo and caravan had more stuff in it than most 40 tonne artics so the occasional increase in temperature would be perfectly normal if going fast or up hills. As long as it returns to normal under your average driving conditions, I don't think you have a problem

[mister munkey]

About the 110/115 degree mark is when you need to start worrying.