Scavenger fan sensor test

[Lewy]

As I've never heard the scavenger fan come on under ist own accord I thought I'd test it. Shorted the wires to get the fan actually working then popped the thermo sensor out and put the end in some 90 degree water - the resistance drop was not the 0.27 to 0.37 but more like 0.6 - also at 20 degrees it wasn't close to the 2.0 - 2.9 norm. So I imagine its not working. I bet there are loads out there not working too.

Does this fan make any real difference to the working temp of the engine when pressing up inclines? And can I test the rad fans sensor in the same way - but perhaps by running the engine rather than taking it out? What would the resistance norm be for that? Again my rad fans rarely if ever kick in - infact I think I've only heard them once at the top of a VERY steep hill that set my Mason alarm pipping.

Engine does seem to be running hotter at the moment according to my TM2 - no major over-heating incidents or boils - so will be going for flush and re-fill to see if that makes any difference before the hotter weather begins to kick in.

[SimonT]

Mike has just answered a similar question that I have to you about the scavenger fan.
http://www.igmaynard.co.uk/bongo/forum/ ... =3&t=29661

basically that it is doubtful that it contributes greatly to cooling the engine. I haven’t heard mine start either, and you are probably right that there are likely to be loads that are not working properly. Some of the posts on the scavenger fan on BF suggest introducing a switch into the circuit and controlling it yourself.

This is a good read
http://www.igmaynard.co.uk/bongo/forum/ ... n&start=45

[mikeonb4c]

Mike has just answered a similar question that I have to you about the scavenger fan.
http://www.igmaynard.co.uk/bongo/forum/ ... =3&t=29661

basically that it is doubtful that it contributes greatly to cooling the engine. I haven’t heard mine start either, and you are probably right that there are likely to be loads that are not working properly. Some of the posts on the scavenger fan on BF suggest introducing a switch into the circuit and controlling it yourself.

This is a good read
http://www.igmaynard.co.uk/bongo/forum/ ... n&start=45

Yup - I fitted a manual over-ride switch, partly as I do wonder if the sensor might fail with old age and you'd never know, but mainly as I thought it might be handy to get cool air flowing over the engine in order to reduce the unwanted warmth thatgets through to te centre console on a hot day when e.g. stuck in traffic. I've hardly used it to date, but at least its there if I need it there's a thread with pics on here somewhere - have a Search.

[Yamaha]

"As I've never heard the scavenger fan come on under ist own accord I thought I'd test it. Shorted the wires to get the fan actually working then popped the thermo sensor out and put the end in some 90 degree water - the resistance drop was not the 0.27 to 0.37 but more like 0.6 - also at 20 degrees it wasn't close to the 2.0 - 2.9 norm. So I imagine its not working. I bet there are loads out there not working too."

Lewy - can I ask where you got these figures from - couldn't find any info about the sesnor in the manual?

Mike

[bigdaddycain]

The radiator and scavenger fans can be tested quite simply by disconnecting the plug from the fan sensor switch (ignition on),simply reconnect the plug to disengage them.

[daveblueozzie]

I was at wheelquick yesterday, had a small leak ,soon sorted ,just needed a jubilee clip tightening.
I told Mike i thought the engine temp was running high, he said let it run and see if the scavenger fan came on.
Nothing ,not even my radiator fan came on, he said its the sensor, he had one in stock, £12 but he said do it myself, because it has to be done when the engine is cold. and told me to fit a switch to override the fan sensor if i thought it needed help to cool down the engine. the switch does the same job that Bigdaddycain has posted about, by unplugging the wires.
I changed the sensor using a 19mm long socket and an extension rod, otherwise you cant get near to it using a spanner. i also had to take the air filter pipe off to give me more room, you have to do an instant change over ,as the coolant comes out quite fast. i put about a half litre coolant back in the header tank after i had completed the job.i then cut into one of the wires (does not matter which one Mike said), extended them and fed the wire into the cab and fitted the switch in a handy place. I ran the engine up to temp for a good half an hour then switched the fans on ,the temp came down very fast. sorted.

NEW SENSOR


POSITION OF SENSOR


OLD SENSOR


WIRES EXTENDED FOR SWITCH( dont worry proper connections ,not scotch blocks, and then taped up)


Hope this bit of info helps.

[mikeonb4c]

Excellent Dave - I like the sound of that arrangement a lot. It also confirms my suspicion that ageing sensors may fail and you don't realise it. I wonder how often this could have been a contributory factor to an overheating (well, boiling over and spitting coolant out the header tank) issue. It makes me think it wouldn't be a bad idea for anyone in doubt to fit a new sensor anyway - how much did the sensor cost if it isn't rude to ask?

[lizard]

Hello chaps

This might be a stupid schoolboy question , but this sensor we are talking about, is it the rad fans sensor.

I ask this as when giving the jolly old bongo loads of speed up hill the the TM2 gauge rapidly reaches 105 (this is when I slow down and ready to switch off the engine) and the mason temp controled gauge is getting past 2 o'clock. This is extreamly worrying. Now I drive up hill letting all and sundry pass me.

Normal driving on the flat the TM2 hardly reaches 90 and the mason never goes past 1 o'clock.

Is there a problem or am I just having a Bongo panic

[mikeonb4c]

Hello chaps

This might be a stupid schoolboy question , but this sensor we are talking about, is it the rad fans sensor.

I ask this as when giving the jolly old bongo loads of speed up hill the the TM2 gauge rapidly reaches 105 (this is when I slow down and ready to switch off the engine) and the mason temp controled gauge is getting past 2 o'clock. This is extreamly worrying. Now I drive up hill letting all and sundry pass me.

Normal driving on the flat the TM2 hardly reaches 90 and the mason never goes past 1 o'clock.

Is there a problem or am I just having a Bongo panic

I'd 'Do a Dave' if I were you lizard. I'm tempted myself (love swiches and gadgets) though without a Mason Alarm I've no clue what's going on so I don't worry

[daveblueozzie]

Cost of the sensor was £12 from wheelquick. this was his last one ,but he is ordering some more (one for bigdaddy).
i only did this because Mike showed me how. would never dream of doing it by myself. so credit to Mike at wheelquick. i only tackle little jobs that i know i can do.

[dandywarhol]

I thought the scavenger fan scavenged the engine bay of excessive heat and remove it rather than soak into the engine bay and vehicle compatrment

[mikeonb4c]

I thought the scavenger fan scavenged the engine bay of excessive heat and remove it rather than soak into the engine bay and vehicle compatrment

Sounds right to me, but its the same thing I'd have thought when you get down to it. By increasing the 'windchill' factor less heat gets transmitted across the engine block to the underside of the covers and thence (by radaition) into the passenger compartment. I reckon all this becomes most relevant when stuck in a traffic jam on a hot day. When on the move there ought to be reasonable scavenging just from airflow past the engine undercover creating a sort of venturi effect and pulling hot air out of the engine bay area - but I'm guessing here.

[Lewy]

"As I've never heard the scavenger fan come on under ist own accord I thought I'd test it. Shorted the wires to get the fan actually working then popped the thermo sensor out and put the end in some 90 degree water - the resistance drop was not the 0.27 to 0.37 but more like 0.6 - also at 20 degrees it wasn't close to the 2.0 - 2.9 norm. So I imagine its not working. I bet there are loads out there not working too."

Lewy - can I ask where you got these figures from - couldn't find any info about the sesnor in the manual?

Mike

Yep - search the tech forum with the key words thermo test - and it comes up second thread down I think - not sure how to post links to threads -sorry.

Wow - some nice responses here - i will defo invest in a new fan sensor from Wigan - will give them a call this week - not sure about bothering about the engine bay sensor - 50 quid from Bongo-bits seems a bit steep.

Some excellent posts here - as ever

[Lewy]

Daveblueozzie - would you clarify the wiring of the switch please for a dunce - you say one wire but wouldn't you have to have to cut into both wires coming out of the plastic end of the sensor i.e a loop or circuit and then put a switch in there for the cab? Sorry a bit confused

[daveblueozzie]

Daveblueozzie - would you clarify the wiring of the switch please for a dunce - you say one wire but wouldn't you have to have to cut into both wires coming out of the plastic end of the sensor i.e a loop or circuit and then put a switch in there for the cab? Sorry a bit confused

I have done it the way Mike at wheelquick told me.
you cut only one wire,Mike said it does not matter which one, you connect one wire to one cut end, and another to the other cut end, you then take the two wires you have connected into the cab and connect them to a simple on off switch. 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.