Thread: TD5 viscous v electric, who's done it. what are the options?

Originally Posted by manic

The way I see it these engines have radiators and cooling systems sized up for the engines requirements, but both pull air with a similar size fan+cowl set up, turning similar RPMs, pulling similar amounts of air through cores that are similar in thickness. A TD5 full width radiator would probably require two e.fans to effectively cover the surface area, where as the TDI only needs one on its smaller rad. So considering this, its possible a dual e.fan set up on the TD5 could give similar results to my single fan TDI set up.

I would need to see data before completely accepting that a belt-fan+cowl actually draws twice the flow through the radiator than my e.fan set up. Considering my setup has been tested over many years in all types of conditions with a temp guage (vdo coolant, and CH surface sensor) plus over-temp alarm (that has never gone off), I'd be amazed if it was all achieved with only half the amount of airflow through the radiator. If that's the case, then the belt-fan is using twice as much power than it needs to (on a TDI) , hugely oversized.

Its easy to see a belt-fan is capable of moving more air, its huge, but I'm not convinced the cowling set up is that efficient. For example, in the Puma Defenders there is a mod for the fan that moves it deeper into the cowling to improve its ability to pull air through the radiator. If I had a way of measuring, it would be interesting to compare the actual airflow pulled in from front of rad on my two setups, stock vs e.fan.

Fair point on the intercooler, ideally you would prefer to have air pulled through the IC even at idle/low-speed/low-temps, which the belt-fan does. Although with gaps between the Rad/IC/Condenser, a good chunk of that draw would bypass the IC. Likely negligible effect on EGT/Performance.

The cooling system in the D2 is designed for European conditions Not Australian conditions and Maybe you would get away with using an E-Fan over there But here in Aus they are a recipe for disaster.
The cooling system is barely adequate for Australian conditions as it is and that is why it is vital to maintain the cooling system is 100% effective here.
Bypassing the factory thermostat and fitting an "in Line" unit to make the cooling system more effective seems to work (at the expense of the heaters) But reducing the amount of airflow through the radiator by using E-Fans is Not a good idea.

Originally Posted by trout1105

The cooling system in the D2 is designed for European conditions Not Australian conditions and Maybe you would get away with using an E-Fan over there But here in Aus they are a recipe for disaster.
The cooling system is barely adequate for Australian conditions as it is and that is why it is vital to maintain the cooling system is 100% effective here.
Bypassing the factory thermostat and fitting an "in Line" unit to make the cooling system more effective seems to work (at the expense of the heaters) But reducing the amount of airflow through the radiator by using E-Fans is Not a good idea.

Hi is there a link for this inline thermo, i can live in Nth QLD , heat not an issue. Baz

Personally, I'm not against e-fans, I had good success with them for over 10 years on my RRC with it's worn motor(600+K klms), and running a dodgy rad(rusted) for two years during that 10 year period.
Once I replaced the rad with a new one, I only ever had one heating up moment crossing the Finke river sand bog(at Finke), but it soon settled back fine. Problem was I wasn't expecting it to be so slow half way through and got caught out in high range, instead of low range. Lost a fair bit of oil leaking through front main seal too .. I just majorly stuffed up at that moment.
Only reason I ran my twin 12" fans was due to getting fed up with expensive viscous unit(way back then) needing replacement every 50-100K or so.

The major downside of e-fans is that when they fail, you're stuck with nothing, and murphy's law will dictate they they fail when you need it the most.
With a viscous, you whack in a tek screw and lock it hard, and you get home at least.

But overall I'm not inherently against e-fans .. just that you need to work out which one will do the job.
the majority of cars running about nowadays use electric fans, so it's not like they don't work!

When I did my twin electric conversion in my RRC, not being smart in any way back then .. and doing it 'rough and cut' .. I didn't account for the amount of current they required to run, when they ran.
Add high wattage headlights, and high wattage spots on the bullbar, and the poor little 60A alternator couldn't cope on a hot humid night coming back from Ayers Rock.
I could see the lights getting dimmer as the current draw, was more than the alternator could replenish!
(got a Bosch 80A to fix that .. but the point is if you do it just because you can, as opposed to do it in a well researched and thought out manner .. you get caught out in one way or another!

I also don't ascribe to the theory that the cowl does as much as folks think they do.
I've been running my Tdi without for over a year now(as I broke mine). I haven't had any heating up issues that I haven't had with it on either.
I've worked out on my Tdi that the two biggest air flow restrictions on the D1, are the grille and more so the twin electric fan design on the A/C condenser.

It's much colder weather now, so grille and A/C fans are back on, but before next summer, I'm looking to remove those A/C e-fans and replace with something less restrictive.

With the Td5 tho, you have so much more heated material(intercooler, A/C and gearbox cooler) ahead of the coolant radiator, you're going to need a monumentally powerful electric fan ... well over 40A and more likely 60+ ... and as already said will just put that load back on the motor in the form of alternator draw.
The Tdi is less complicated. I've thought about it, but the money spent won't be worth any gain, if any was available.

ps. the fuel saving in my RRC(79, no A/C) was about 1/2 to 1km/lt with the e-fans. I highly doubt you'd see anything like that on a diesel.

Originally Posted by trout1105

The cooling system in the D2 is designed for European conditions Not Australian conditions and Maybe you would get away with using an E-Fan over there But here in Aus they are a recipe for disaster.

You know there are places in Europe that get bloody hot. I'm now thinking of a 40C drive through Greece. My experience is that the right e.fan setup can deliver even at 40C in Australia (I tested mine on the hottest day of the year 40+C, highway run to state park, then low range).

Disclosure:
- I do not tow
- I do not run AC
- My success is with a TDI Defender, not a TD5 Discovery.
- Generally I would not recommend fitting an e.fan to replace the belt-fan.

Seeing as members of this forum default to slamming any discussion on e.fans, I felt compelled to offer my own experiences to show that there are some applications where they can be used to effectively keep a diesel at temperature, even here in Australia. But really, unless you need to clear space in the engine bay or have some twisted sense of fun - just keep the belt drive!

Now I'll put this out there, some e.fan installs are rubbish, so if you do feel the urge to experiment with e.fans try and do it right! On a TD5, perhaps skip past the universal ones you can order online. These include kenlowe/flex-a-lite/derale/etc. At 16" these fans will pull around 12-20amps. For my TDI application this has been enough (I'm pulling 17amps), but if you go to the wreckers you can find fans that pull around 30-40 amps at full speed.

Consider the fan found on the Vovlo 850 (1990s), this comes with a two speed relay and pulls around 15-20amps at LOW speed! At full speed its up around 40 amps. Its a monster. If you could attach a couple of 16" Volvo fans to a healthy TD5 rad would these fans ever need to go past the low run setting? There is also a Ford twin fan set up that is supposedly a beast puller, I cant remember which exact model/variant but if you can test a few at the yard through an ammeter, you'll get to know what's what.
For install, do not attach the fan with zip ties through the core!! (confession: I have done this before ). Fab a plate/shroud over the radiator frame and attach the fan so that it is positioned close to the radiator. The shroud should be completely sealed to the frame so that all of the air is pulled through the core (seal all gaps). If any significant areas of the core are blocked by the shroud, cut slots and cover with a rubber flap. These flaps should blow open at speed, and seal shut when the fan is doing all the pulling.

Now if anyone in Australia has any success with a TD5 on efans, keep it to yourself - no one will believe you.

Efans have their place. Their place is not on a TD5!

Unless you fully shroud them like the pics below (spaced away from the face of the radiator so they draw through the entire surface) they are hopeless.



Then factor power requirements, air through intercooler (you’d need one always on at a minimum), the drag on the engine via the alternator and you’re adding potential issues.

Originally Posted by Tombie

air through intercooler (you’d need one always on at a minimum), the drag on the engine via the alternator and you’re adding potential issues.

Why would you need a fan on the intercooler? The intercooler only really comes into effect when the turbo is pushing boost and thats almost always at speed when the airflow through the IC is greater than any fan. I've never seen EGTs go anywhere near alarm high on a trail in low range with a fanless IC. Sure it would help dissipate some residual heat at low speed but would that translate to any real world performance increase - I doubt it. Happy to be proved wrong, I could always do with more power!

Drag on the engine from a locked up viscous fan probably compares somewhat to the drag through a 120amp+ alternator when pulling high amps. But e.fans are only on when needed, and a two or three stage fan set up could help manage those loads better.

YouTube

Originally Posted by manic

Drag on the engine from a locked up viscous fan probably compares somewhat to the drag through a 120amp+ alternator when pulling high amps. But e.fans are only on when needed, and a two or three stage fan set up could help manage those loads better.

The viscus fan only locks up when it is needed, It doesn't run all the time.
The extra draw on the alternator from the high amperage needed to run enough fans to do the same job as the viscus fan wouldn't help with the longevity of the alternator and at night with a couple of decent spotlights running the amperage needed for the e-fans could exceed the output of the alternator I would imagine.
Why reinvent the wheel when the viscus fan does the job very well anyway and is a lot easier to replace, more reliable than e-fans and No modifications whatsoever are needed to fit them.

Good video, aside from audio sync at some points!

Wouldn’t last 5 minutes of scrutiny in an office at work.

No measurement of airflow
No heat in the equation - the plastic flex fan for example, needs warmth to become for flexible.

Flex blade goes on to prove their claims are rubbish though!


We’re not here to build drag racers, we’re here to run 4wds... heavily loaded, lugging up hills at up to legal highway speeds, in deserts, through creeks etc..

I’ve personally witnessed several efans die (fail to start) after a water crossing. And mud into them is a nightmare.