discool said:
No it isn't, the air flow is still the same which is the capacity of the fan. You confused with flow and pressure.
Click to expand...

Maybe I am missing something here, but two fans side by said can almost be classed as two seperate set ups (aside from some mixed air disturbance) so the air flow would then be almost double?

If that is not the case, can you explain your workings out?
 
This thread is absolutely fascinating!
Sooooooooo technical!
Being old skool I just took my viscous off (on my 300tdi) and replaced it with a random fan bought from a scrapyard, they had a load on shelves so I looked for the biggest one I could make fit!
I wired it positive permanent with the negative switched via a relay, manually from the cab. Relying on the ordinary temp gauge.
Even though I used it to tow a huge box trailer on motorways to the south-west of France in the summer, I very rarely needed to switch it on. Only on very hot days in traffic, and bizarrely never while towing.
I do have A/C and I suppose the A/C fan must also push air through the rad.
I have never overheated nor blown the head gasket.
I carry the viscous in the boot, "just in case".

In my defence I have to say this was before I picked up on Landy Zone.
(I can feel the head shaking from here!)
 
robhtid said:
I'm not doubting your knowledge as there are some very clever people about and I'm sure you are one of them but I would like to understand this.

Are you saying there is no improvement in cooling using two fans instead of one as there is no increase in airflow?
Click to expand...

I started saying that the flow is the same with two fans, now your asking if I'm saying there's no improvement using two fans, there is i sure you pleased to know, but not due to air flow but air pressure which has increased.
 
There is no increase in pressure but there is an increase in flow/volume over the surface area provided by two fans. What you are suggesting is if one fan is ontop of another! Anyway let's agree to disagree I'm not one for going back and forth. All the best :)
 
lynall said:
Maybe I am missing something here, but two fans side by said can almost be classed as two seperate set ups (aside from some mixed air disturbance) so the air flow would then be almost double?
If that is not the case, can you explain your workings out?
Click to expand...

No! That would mean going back 40 years or more when every day I studied fluid and air flows and associate kit for five months along the other subjects over the years to eventually get called an M&E Engineer, all for stuff that I wouldn't use but told needed to know... such is life as I then eventually joined my father's electrical firm.
 
discool said:
No! That would mean going back 40 years or more when every day I studied fluid and air flows and associate kit for five months along the other subjects over the years to eventually get called an M&E Engineer, all for stuff that I wouldn't use but told needed to know... such is life as I then eventually joined my father's electrical firm.
Click to expand...

But you said you could see it in an instant!.

Please explain.

Cheers
 
Stanleysteamer said:
Being old skool I just took my viscous off (on my 300tdi) and replaced it with a random fan bought from a scrapyard, they had a load on shelves so I looked for the biggest one I could make fit!
I wired it positive permanent with the negative switched via a relay, manually from the cab. Relying on the ordinary temp gauge.
Click to expand...
Two huge mistakes here:
1. dont ever compare a 300/200 Tdi with a Td5 when it comes to engine cooling or overheating cos the Tdis are running colder from factory
2. never rely on the dash gauge :cool:
 
neilly said:
But you said you could see it in an instant!.

Please explain.

Cheers
Click to expand...
The water flow into the bucket wasn't replenished. But each pump was delivering the same amount of water.
The same could be said with a sealed room and one or two extract fans which would evac the room quickest.
But with an engine radiator there's an unlimited amount of air to push through the rad or pull if you like, like a viscous fan.
The fan like the water pump flow is still delivering the items designed amounts.
So let's say you your standing up, just about, in front a powerful water hose, then another Identical hose is turned on the increased of pressure would knock u over.
 
discool said:
The water flow into the bucket wasn't replenished. But each pump was delivering the same amount of water.
The same could be said with a sealed room and one or two extract fans which would evac the room quickest.
But with an engine radiator there's an unlimited amount of air to push through the rad or pull if you like, like a viscous fan.
The fan like the water pump flow is still delivering the items designed amounts.
So let's say you your standing up, just about, in front a powerful water hose, then another Identical hose is turned on the increased of pressure would knock u over.
Click to expand...
yes but 2 fans side by side move twice as much air
 
sierrafery said:
Two huge mistakes here:
1. dont ever compare a 300/200 Tdi with a Td5 when it comes to engine cooling or overheating cos the Tdis are running colder from factory
2. never rely on the dash gauge :cool:
Click to expand...
There's loads of posts over the years with the owner's of the 200 & 300series removing the fan and stowing it in the back just in case it gets hot, which appears never to happen... as u know:D
 
discool said:
There's loads of posts over the years with the owner's of the 200 & 300series removing the fan and stowing it in the back just in case it gets hot, which appears never to happen... as u know:D
Click to expand...
it does especially the 300,head gaskets were my a good source of income 10 years back, started at easter hols first longish trip in warmer weather
 
discool said:
You have mistake with the quantity of the water and air there's a difference.
If u have an HNC qualification, like me you should see it instantly.
Click to expand...

discool said:
The water flow into the bucket wasn't replenished. But each pump was delivering the same amount of water.
The same could be said with a sealed room and one or two extract fans which would evac the room quickest.
But with an engine radiator there's an unlimited amount of air to push through the rad or pull if you like, like a viscous fan.
The fan like the water pump flow is still delivering the items designed amounts.
So let's say you your standing up, just about, in front a powerful water hose, then another Identical hose is turned on the increased of pressure would knock u over.
Click to expand...

Do you read what you write? I have a HNC as you say you do and I think you are talking rubbish.


Cheers .
 
Im off to bed, early site meeting tomorrow on why the A/C fans in four mortuary's, are not working very well.
Well it's the main contractors spec we only arranged the fitting and commission., we stated they need additional split units. I can see some VOs on the way.
 
jamesmartin said:
how much colder a couple of degrees?
Click to expand...
`i'd say more than a couple cos i have friends with 300 Tdi who have additional ECT gauge and they've never seen more than 90*C after hard drive while i've seen 110 even 115 on the Td5 not once and mine stays at around 92 on motorway while the 300s around 82 (all mesurements taken with factory viscous fans off course)
 
sierrafery said:
`i'd say more than a couple cos i have friends with 300 Tdi who have additional ECT gauge and they've never seen more than 90*C after hard drive while i've seen 110 even 115 on the Td5 not once and mine stays at around 92 on motorway while the 300s around 82 (all mesurements taken with factory viscous fans off course)
Click to expand...

I have a 300tdi and a thermocouple in the head ( egr temp point ) quite often measures 95 ~ 102 C. With the factory viscous fan.
Where were they taking the measurement from?

Cheers
 
sierrafery said:
`i'd say more than a couple cos i have friends with 300 Tdi who have additional ECT gauge and they've never seen more than 90*C after hard drive while i've seen 110 even 115 on the Td5 not once and mine stays at around 92 on motorway while the 300s around 82 (all mesurements taken with factory viscous fans off course)
Click to expand...
stats arent that different,td5 is more powerful so produces more waste energy,not as much as a v8 but they are inefficient petrols,but the engines run at similar cooling system temps,and 300 isnt as good as 200 or td5 system so is vulnerable to over heating, no fan is needed when moving at speed,but it is at idle
what i mean is most engines run at similar temps power output varies but so does the cooling system to cope , they are all vulnerable if system isnt upto scratch
 
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