M.O.T. Question re scavenger fan

[stuc]

Hi Liz. I agree with Simon, I checked mine with a heat gun and it switched on but it had to be very hot.
Do the short out test and if it works the sensor is knackered, but you could buy a switch and wire it in temporary till you get home then when you are climbing and getting hot you can manually switch it on. A few people have done this so they can control it and even switch it on early to cool before you start climbing or are stuck in traffic.
Hope you are enjoying yourself.
Stu

[bonglets]

Thanks Stu, we are leaving in the morning and coming back in short stages booked on train on Thurs so hopefully all will be ok and book her in to garage (again ), when we get home. Bit of a nightmare hol all round water leak and electric probs first night but Jim fixed electrics and using site facilities till we can sort plumbing in the summer. Still it is away from work, good food and good wine so not all woe.

[bonglets]

Electric probs and plumbing probs in static not bongo I should add.

[rita]

The scavenger fan will normally only operate when the engine bay temp is over 180+ deg C. If you are depending on this fan as your last line of Defence ...you are "Already Invaded".


Good Luck.

[mikeWalsall]

I am quite deaf so my scavenger fan may have 'kicked in' without me noticing ..

The only time I have really noticed it was when leaving the engine ticking over for quite a long time while waiting in the MOT garage for the Mechanic to sort out the emission machine ..

[stuc]

The scavenger fan will normally only operate when the engine bay temp is over 180+ deg C. If you are depending on this fan as your last line of Defence ...you are "Already Invaded".


Good Luck.

I think 180 deg C can't be right, that would be mega hot. you'd be struggling to sit on the seats if the engine bay was that temp I would've thought. 180 deg F perhaps? That would be 82C which is probably more acceptable.

[rita]

The scavenger fan will normally only operate when the engine bay temp is over 180+ deg C. If you are depending on this fan as your last line of Defence ...you are "Already Invaded".


Good Luck.

I think 180 deg C can't be right, that would be mega hot. you'd be struggling to sit on the seats if the engine bay was that temp I would've thought. 180 deg F perhaps? That would be 82C which is probably more acceptable.

It gets very hot in the engine bay owing to the Exhaust Manifold and the Turbo .I have actually witnessed in some vehicles the Turbocharger Glowing Red Hot. It has been known for some people to cook their dinner on the ex manifold

Good Luck.

[Simon Jones]

Not sure the presence of a turbo is that relevant. Two of the three engine variants don't have turbos yet the temperature sensor part number is the same for all three types.

[rita]

Not sure the presence of a turbo is that relevant. Two of the three engine variants don't have turbos yet the temperature sensor part number is the same for all three types.

You wouldn't think that if you saw it GLOWING in the dark, another contributing factor could be vehicles with catalytic Converters.


Just a bit of useless information.

[stuc]

I agree Rita, manifold and turbo would be extremely hot but don't think it would heat up the surrounding air in the engine bay that much.

[helen&tony]

Hi
Most of the time the airflow is diverted up and over the engine by the angle of the under-trays, and the engine doesn't get that hot. The turbo rarely boosts over 5 or 6 PSI when driving normally, so hardly heats up. It only ever gets to 12 PSI when absolutely flooring it, which isn't particularly high boost as turbos go, and it drops off when you stop overtaking. Exhaust temperature where I have the sensor put, very rarely sees 500C, and normally runs around 250/300 plus, and the inlet elbow just before the manifold is only up to 40-50C, but often around 30 , except on a very hot day. Oil pressure is factory spec. and taking all into consideration, it shows an old engine, highly unstressed, and hardly making a fuss.
Whilst it is fair to assume that some turbo engines might give out a lot of heat, the fact that the scavenger sensor is plastic , and sat over the top of the engine, plus there are a fair number of plastic components high on the engine, it's fair to assume that the motor never gets that hot at all if everything runs properly, and the heat in the engine bay is never colossal. The scavenger fan will cut in occasionally if left parked on a very warm day (in the upper 30s/ low 40s), and only then if parked for less than 15 minutes, but after that, the effects of immediate "heat soak" die off, and the head temperature really drops off. On the odd occasion when I'd popped into a shop on a very hot day, come out, seen the scavenger fan on (plus you can feel it), the engine temperature at the head drops off within a couple of minutes, with th coolant taking a little longer, and after less than a kilometer, the scavenger fan cuts out. I used to check the sensor every year before summer, but I haven't for a couple of years, as it's so rare that it needs to come on, but I might give it a go this year...Best place to check it is with a hair dryer in situ, as that's where it needs to be!....and probably best checked after a run, so that the hair dryer is not working to heat up the surrounding area...also, use a "salon type" as they are a bit more powerful.
As for how useful the scavenger fan needs to be???...probably only rarely needed in a traffic queue in sweltering heat, so in the UK it's fair to assume that for normal use it's not going to do anything but just sit there, waiting to do what it needs to if you sit for ages in traffic on the London Orbital Car Park whilst enjoying a picnic and listening to your favourite CD for a half hour or so!
Cheers
Helen

[Simon Jones]

Does your hairdryer get up to the 180C that is apparently required to trigger the fan ?

[helen&tony]

Hi
No...hairdrier...not hair shrinker! ...I should try using the digital heat gun...it has heat you can set...anything from shrink wrap to soldering...I reckon it should work a degree or two at a time if I really wanted to find what temp. sets it off...but I don't think I could be bothered... ...It's working, and that'll do!
Cheers
Helen

[teenmal]

Hi
Most of the time the airflow is diverted up and over the engine by the angle of the under-trays, and the engine doesn't get that hot. The turbo rarely boosts over 5 or 6 PSI when driving normally, so hardly heats up. It only ever gets to 12 PSI when absolutely flooring it, which isn't particularly high boost as turbos go, and it drops off when you stop overtaking. Exhaust temperature where I have the sensor put, very rarely sees 500C, and normally runs around 250/300 plus, and the inlet elbow just before the manifold is only up to 40-50C, but often around 30 , except on a very hot day. Oil pressure is factory spec. and taking all into consideration, it shows an old engine, highly unstressed, and hardly making a fuss.
Whilst it is fair to assume that some turbo engines might give out a lot of heat, the fact that the scavenger sensor is plastic , and sat over the top of the engine, plus there are a fair number of plastic components high on the engine, it's fair to assume that the motor never gets that hot at all if everything runs properly, and the heat in the engine bay is never colossal. The scavenger fan will cut in occasionally if left parked on a very warm day (in the upper 30s/ low 40s), and only then if parked for less than 15 minutes, but after that, the effects of immediate "heat soak" die off, and the head temperature really drops off. On the odd occasion when I'd popped into a shop on a very hot day, come out, seen the scavenger fan on (plus you can feel it), the engine temperature at the head drops off within a couple of minutes, with th coolant taking a little longer, and after less than a kilometer, the scavenger fan cuts out. I used to check the sensor every year before summer, but I haven't for a couple of years, as it's so rare that it needs to come on, but I might give it a go this year...Best place to check it is with a hair dryer in situ, as that's where it needs to be!....and probably best checked after a run, so that the hair dryer is not working to heat up the surrounding area...also, use a "salon type" as they are a bit more powerful.
As for how useful the scavenger fan needs to be???...probably only rarely needed in a traffic queue in sweltering heat, so in the UK it's fair to assume that for normal use it's not going to do anything but just sit there, waiting to do what it needs to if you sit for ages in traffic on the London Orbital Car Park whilst enjoying a picnic and listening to your favourite CD for a half hour or so!
Cheers
Helen

You could do your "Full Bulgarian" there.

[helen&tony]

Hi
Teenmal...
"Full Bulgarian"..........PURLEEEEESE...The Bulgarian food is appalling...quite possibly the worst on the Continent ......Baked 'tater with cheese (English Cheddar) and a little marmite wrapped in foil and wired to the top of the heat shield....mmmmm I'd say 60 kilometers at 55 MPH
Cheers
Helen