Q: Thermo fan or not thermo fan?

[Mazdragon]

Hi all... just recently converted from 6 to 8 cyl, we re-used the fan that was on the 6, and it kept temp very well. Now, however, as it's getting warmer, of course it's not. So, need some advice: what is the diff between 6 cyl. fans and 8 cyl.? what should i look out for? Or alternatively, should i go thermo fan? Currently the fan sits further back due to the 8 being shorter, i do have a cowl over it, but there's a gap. Can't extend the whatever's to push the current fan further forward or apparently I'll bend the whatchayam'callits in the water pump...(i understand what i'd been told, just can't remember the technical terms... sorry) any advice please? best way to go? Thanx Maz

[ozbox]

maz does your van have a/c?..
is the fan a viscous hub type fan at the moment..freewheeling type?
or is it a fixed fan...?

i tried thermos on the sinbox and they didnt cut the cake even with the 5 core radiator and ended up going back to a factory type arrangement with viscous hub and a factory type shroud..no probs at all last summer even sitting in traffic on a 38 degree day.

in saying this the injected van has twin au ford thermos but with a pwr alloy radiator and it stays super cool even when doing a 3 min burnout on a pad in summer.

well over 1000 bucks spent in keeping it cool but sinbox was only 250 for new viscous hub and a new shroud.

[Mazdragon]

Hi Greg, no idea, will have to check whether it's freewheeling or not, by that i presume you mean can i spin it by hand or is it fixed and only turns when engine is running... shall check that tonite. and yes, i do have air con. Never used to have the problem with the 6 cyl. set up, my guess is cos the fan is a lot further back now in comparison....

[ozbox]

yep thats what i meen maz..
fan shouldnt be in any different position and 6 cyl and v8 viscous hubs and fan blades are the same.
did they put a v8 shroud on or mod the 6cyl to fit?
did you have a new v8 rad put in or second hand?
if it was second hand was it professionaly flushed ?
i know its a new motor and would presume they would have put a new thermostat in but double check that with the people that did the mtor..i had a faulty new thermostat in my gto which caused me grief.

[Mazdragon]

used 6 cyl. shroud, new radiator and new trans cooler and yes, new thermostat as the whole engine was stripped back to bare bones and rebuilt with all new stuff. thing is, it's been running fine, its only now that the weather is getting warmer that it's starting to heat up... i think the thermostat works, as even when it was cooler weather (cold melb weather that is), it fluctuated by a millimeter or so... it was was opening and closing. But now, it's going way over half way... to almost up the top white line and i really don't want to cook my nice new motor....

[HK1837]

I assume you mean viscous clutch fan, not thermo fan? Thermo fans are electric motors. Not sure how you got a 6cyl shroud around a V8 fan though. What I would do:

Fit a late long snout V8 pump and pulley to suit.
Use a 3 row (or more) radiator that is clean and not clogged up
Buy a factory V8 shroud off Greg.
Use a factory HQ-HZ viscous fan (not WB onwards as those square blade fans don't work with the earlier shrouds).
Makes sure there is a decent strap from the battery 0V/-ve terminal to the radiator support.
Run 2 x bottles of anti-corrosive additive (not green glycol as it goes all gluggy).
Use the right thermostat.

The above seems to keep Holden V8's nice and cool. With a manual 308 you can get away with a 3 row and a fixed 4 blade fan.

[Mazdragon]

thanks HK... it's 6 cyl fan and shroud.... may have to look into that... are the thermo fans any good?? it's been recommended to me but not sure which way to go... i'll try and load up a photo tonite of what i have which will help... at work at the mo and the van is at home anyways....

[ozbox]

as you are saying maz the fan isnt sitting in the shroud properly because its a 6 cyl one which is shallow compared to v8..if it has a viscous hub and fan from the 6 thats the same as v8..it may be as simple as fitting the correct radiator shroud..
as for thermos there is really no need for them as v8 holdens of that model has never really had a problem of staying cool with factory correct stuff...your viscous hub may be old and worn so buying a new one would help it..same hub from hx to vt com in all 5.0 litres..still available from holden for around 125.bucks.dont buy an aftermarket one from ebay.

[agr071]

I have got twin thermos at my place that i took off after a hot day.
Have a viscous fan on there atm. Once upon a time i had a plastic flexi fan on my HG and it worked well also.

[Mazdragon]

i can move the fan but not freely, i.e. it doesn't just spin but i can turn it. below are photos i hope you can see. It is the fan from the 6cyl. so maybe start with a v8 shroud eh?
P9268514_1.jpg
P9268515_1.jpg