Twin cooling fan job

[makeitfit]

Update

I tried them in front of the rad with the blades going the right way:augie Broody rubbish, hot as a hot thing in a few miles :doh
So they're now back behind the rad and as suggested reversed the polarity
Went to Swansea yesterday (60 miles e/w) and the temp never got to half way
At 70 on the m/w I'm running 2500 and about a third the way up the temp gauge and NO fan on:thumbs
On the A roads working the little devil at say er well 60 ish :sly it still only makes half way
Well pleased and so so quiet

 

[Darwin]

I tried them in front of the rad with the blades going the right way:augie Broody rubbish, hot as a hot thing in a few miles :doh
So they're now back behind the rad and as suggested reversed the polarity
Went to Swansea yesterday (60 miles e/w) and the temp never got to half way
At 70 on the m/w I'm running 2500 and about a third the way up the temp gauge and NO fan on:thumbs
On the A roads working the little devil at say er well 60 ish :sly it still only makes half way
Well pleased and so so quiet

mine never get more than about 1/3 up , even when on my private test track.

 

[makeitfit]

I'm pleased with the result as I've lost a lot of air flow due to the bash guard under the winch bumper:sly
What fans you running?

 

[macabethiel]

fans

Can you not just reverse the wires if they are DC fans so they run in the opposite direction or are they earth returned ?

Just a thought !

 

[makeitfit]

That's what I did
It works a treat allbeit the blades are running backwards

 

[lacroupade]

No because the blades only work propery in one direction.
However I've found since that I can reverse the whole fan assy
I want the fans to pulling cold air through the rad, so the front of the rad is clear . That'll allow plenty of space for the winch and the reduced overhang at the front(next job)
Also means the rad can be pressure washed easily after the mud baths:sly

I'm being slightly thick here Pete; are you saying these fans are intended to sit in FRONT of the rad in their original RS2.8 installation, so that at the moment they are pushing air forwards back into the rad, instead of pulling it through?? And you're right about not reversing the direction of operation - they will work, sort of, but much less efficiently.

Can you not simply turn them around 180 degrees or are that your intention my dear?

 

[makeitfit]

Oooph, they were originally on the outside of the rad and designed to PUSH air through from the front on the 2.8. I mounted them on the back and my idea was they would PULL the air through. I just made a mistake as the rotation and so ended up pushing air from the engine out :doh
Then.............see above and then................reversed the polarity so the blades now go backwards and PULL air through t' rad
If you see what I mean:augie
Anyway, the system (nissan) is so good the electric fans dont need to come on at all, so far :thumbs

 

[lacroupade]

Oooph, they were originally on the outside of the rad and designed to PUSH air through from the front on the 2.8. I mounted them on the back and my idea was they would PULL the air through. I just made a mistake as the rotation and so ended up pushing air from the engine out :doh
Then.............see above and then................reversed the polarity so the blades now go backwards and PULL air through t' rad
If you see what I mean:augie
Anyway, the system (nissan) is so good the electric fans dont need to come on at all, so far :thumbs

Well it makes you wonder how often the vicious fan actually comes on

 

[makeitfit]

Well it makes you wonder how often the vicious fan actually comes on

I suppose a properly working one shouldn't be on much, BUT my old 'ting was a roaring away all the time
Now all's aaaahhhhh quiet

 

[BigBlack]

Well it makes you wonder how often the vicious fan actually comes on

Only ever heard mine kick in when towing caravan up long hills.... wondered what the hell it was first time it did it!!!! :lol

 

[lacroupade]

Only ever heard mine kick in when towing caravan up long hills.... wondered what the hell it was first time it did it!!!! :lol

Mines the same....never comes on:thumb2...but you haven't seen what Pete does to his truck have you....:doh

 

[Timbo_1975]

I also have twin electric fans (documented elsewhere!) on a thermo switch and manual over-ride.

In normal running they never come on! Even stationary for 20mins they dont.

Only when on a l-o-n-g uphill 2nd and 3rd gear with heavy trailer in 15+degC type temps do they come on where you might be at full power for prolonged periods.

On a standard truck or one with a tuning box (say 150bhp) twin fans would have no bother keeping it cool unless ambient temps were up above 25degC.

Temp gauge sits at just left of vertical at all times, which is where it should be on a truck running a 88deg C 'stat but bear in mind the gauge is driven from the ECU on the TDI and is NOT linear.

The a/c does place quite a lot of extra heat loading and air flow restriction on the cooling system though.

So, have an override switch, and keep an eye on the gauge when in extreme conditions.

 

[Thomas-the-Terrano2]

would say if roared all time, viscous was knackered.

should clear once coupling warmed and oil movinng in it,
and though spin only drag on coupling and not as fast as
engine turns/rpm.
know this cos mine is pooped and truck can generally
cool without it unless towing hard uphill in heat.

theres a theroy i found on a fourtrack site that all these
trucks are so overcooled that if never worked the visous
bit fails open or shut if latter than roar so extra over
cooled etc.

binning mine for twin set up as looks like can get new twins
and stat and switches for about price of s/h viscous/fan.
which would be off a 2.8 so older than my knackered one!

great pix, interesting about ecu gives gauge info so presume
likely more reliable. mine is certainly touch under half normal
then goes up to bit under end of angled line if very hot.

hope i'll have lots more room to work as engine bay longer
as designed for the cyl motor.

 

[snowdrop]

What if you reverse the polarity of the wiring, will the DC motors not run 'backwards' so they draw the air through?

 

[Timbo_1975]

Yes, but the fan blades are often 'handed' and will only work properly spun one way. You'll need to remove the blades from the motor and reverse for it to work.

 

[Thomas-the-Terrano2]

timbo, does the ecu driven gauge make it more reliable, presume its based on one
or more sensors on the engine.

was used a kit or bits obtained as working towards latter, doesnt seem to be
rocket science but suppose nice if one warranty covers lot?

hoping that should be straight forward and getting cowling and viscous fan off
will likely takely more time and effort.

 

[Timbo_1975]

timbo, does the ecu driven gauge make it more reliable, presume its based on one
or more sensors on the engine.

was used a kit or bits obtained as working towards latter, doesnt seem to be
rocket science but suppose nice if one warranty covers lot?

hoping that should be straight forward and getting cowling and viscous fan off
will likely takely more time and effort.

Not sure what you mean by 'reliable' ?

Certainly the ECU has alot of hysterisis built in when driving the gauge. i.e. there is alot of tolerance in actual engine temp at certain points in the curve where the gauge will not move. This would NOT be the case with a directly driven gauge. If you run in live data mode with a scan tool you can clearly see the gauge reach the almost vertical position long before the engine reaches 88degC and then stop there as engine temp goes past 95. At that point it swings almost up to the red.

 

[Thomas-the-Terrano2]

niavely meant not just any old probe but integral part of car's brain system
though guess can fail.

interesting about needle behaviour then, waiting for a digital thermometer
to arrive, probe type so see waht non marked out gauge actully equates
too.

what diameter are your twin fans, makeitfit and timbo.

know davemud squeezed pair of 17s on his trol, but biiggest i can easily
finy on the bay are 14 or 16".

reckon my rad is 90 cm wide by about 45 cm tall, my shroud will come
off in sections and one closes to rad supports over flow pipe to the
expansion tank so will see if can leave on as dont think will foul placing
of new fans anyway.

 

[Timbo_1975]

1 x 13"
1 x 16"

Switched via:

Thermo switch in the bottom hose as needed.
Over ride switch on dash + fans on warning lamp.
When a/c is on triggered from the condensor fan.

 

[snowdrop]

Sorry for my suggestion, I missed a page where you said you had reversed the polarity. I put it down to age and too much german beer and asbach