farmershort

farmershort

Well-Known Member
Hi All,

Just having a chat with Allisport to try and spec out a rad and oil cooler setup for my JE 4.6 v8. The rad is pretty simple, and they have an off-the-shelf which the sell to folk in dubai with 5L v8's in them - should be good enough. The most the vehicle will have to cope with is a few weeks in spain or something like that... still, that can be 40 degrees C if you pick the wrong week.

They mentioned that there's a twin electric fan set up, but maximum cooling is achieved by using the viscous fan. My engine does not currently have a viscous fan fitted, but I think it's the standard for the original 3.9v8 in disco and rrc spec.

Allisport say that the electric fans should be sufficient if I'm not using it in really hot countries, but now they have planted the sed of doubt. I've always thought that electric fans are far simpler and easier to work with/on. Is this misplaced? Should I be looking into fitting an OE viscous fan?

(seperate full length oil cooler will also be part of this)

Thanks

Adam
 
Both have advantages and disadvantages - electric you can "fine tune" by having thermostatic switch plus with twin fans it's unlikely both would pack up at the same time so you've got a manual override back up - but Viscous seldom go wrong and often when they do the worst that happens is they overcool. Do you have the right w/pump pulley for viscous? Please tell me you're getting a proper mechanical temp gauge?! Good luck
 
Tbh I haven't got as far as temp gauges, thermostat etc...

The JE engine has a water pump on it, power steering, etc, but no belt... So I'm trying to figure out what I'm going to need for the next phase once the engine is on the rolling chassis.

The donor was a 3.9 serp from a disco, so that's my go-to as far as default parts go.

All of this is a first for me, so I can only apologise for the knowledge gaps... This is as much about figuring out what I need to figure out, as it is actually figuring anything out... Hope that made sense.
 
I'm tempted to change my user name to "mech gauge fanatic" as this comes up so often, TBH you're spending a tidy amount of money on a sweet engine - good idea to have the best, most accurate temp and oil pressure gauges - they ARE the mechanical type......................... Serpentine engines outside my experience - I'm old school 3.5 on carbs etc. Don't apologise for knowledge gaps - we all learnt by asking questions.................... good luck
 
I had plans to have 'all-of-the-gauges'... In that sort of 80's rally sort of way. I know that there are vdo version of, for example, oil pressure gauges with an oil sender, or an electrical sender... I guess that's what we're talking about? In the oil example, it's much more desirable to have the actual thing your monitoring flowing to the gauge, rather than an electrical interpretation?

I haven't had a look at temp gauges yet, but would the oil analogue mean that system water was routed to the temp gauge in a mechanical one?
 
Yes to oil, a tiny pipe [carefully routed] from engine to gauge - no for temp, it's a bi-metal system [magic] with a thick copper line also carefully routed from engine to gauge - I'm sure you can get matched ones - Demon tweeks best place to look for starters. Electric temp gauges just have to many potential problems, sender, connections, earths, the gauge itself etc.................... Mechanical temp is one piece so you feed sender from dash back to engine - good time to plan it's route early in the build.
 
Had just as much trouble with 'mechanical' gauges as electrical, both types have their good and bad points.

Gauge on my D2 V8 has worked reliably for 6 years without fault. Oil switch failed with a leak through the spade terminal, but otherwise no problems.

Same with the Viscous fan, been reliable, son's V8 electric fans seized up with salt in the motor bearings....

Peter
 
Haven't had any problems with either, but when I went to Morocco I had a electric fan fitted and it was nice to be able to turn the engine off but leave the fan running during short stops in the day, I'm sure it helped, and although that was a 300tdi I was driving it hard in low range 2nd in 30+ degrees and cooling wasn't a problem. It's also nice in general to just hear the engine noise instead of the fan and good if you ever plan on doing any wading as well (ok maybe not in a V8..). Electric fans are obviously easier to fix if they go wrong, I took a spare just in case.
 
So electric fans are easier to fix :D

Let me see electric fan not not spinning, so is it an iffy temp sensor, is it lack of 12v, fuse/faulty wiring or the fan its self, l better get my meter out :(
Viscous fan not working, it can only an iffy viscous coupling, so spin off the coupling from the water pump, undo the screws holding the fan to the coupling, fit the fan to a new coupling and tighten screws, spin the coupling back on. Job done :) :cool:
 
listerdiesel said:
Had just as much trouble with 'mechanical' gauges as electrical, both types have their good and bad points.

Gauge on my D2 V8 has worked reliably for 6 years without fault. Oil switch failed with a leak through the spade terminal, but otherwise no problems.

Same with the Viscous fan, been reliable, son's V8 electric fans seized up with salt in the motor bearings....

Peter
Click to expand...
Really? how many mechanical temp gauges have you had fail? and how many electrical? Either way you cannot deny that mechanical have less elements to fail - therefore are more reliable - glad to hear yours has been working for 6 years................... [the original mech one on the 1934 Hudson I owned was degree perfect! ]
 
discool said:
So electric fans are easier to fix :D

Let me see electric fan not not spinning, so is it an iffy temp sensor, is it lack of 12v, fuse/faulty wiring or the fan its self, l better get my meter out :(
Viscous fan not working, it can only an iffy viscous coupling, so spin off the coupling from the water pump, undo the screws holding the fan to the coupling, fit the fan to a new coupling and tighten screws, spin the coupling back on. Job done :) :cool:
Click to expand...
This scenario kind of makes the case for mechanical gauges as well....................................
 
I had a Viscos fan which was buggered, My 200tdi heaters were useless so I thought by fitteing and electric fan it might improve the heaters and might give me a quicker warm up time. I also read that an electric fan would give me better MPG. I went for what I thought was the best which was a Kenlowe fan.
The Kenlowe worked perfectly well. It was fitted with a sensor which tripped the fan in when needed. Driving round France the fan would trip in maybe twice or three times a year as 200 tdi's are over cooled engines.
It didn't make any difference to engine warm up time and didn't it make any difference to the heaters.
I did a trip across Morocco with the Kenlowe and it worked perfectly. There it did trip in many more times when the engine was being worked hard through deep sand etc. Without the Visco's fan there was a lot more room to work on the engine in the engine bay. Fitting the electric fan did not make any difference to the MPG
I found myself always wandering if the Electric fan was going to trip in or not as the temperature gauge used to fluctuate from the half way mark to just below the red. Not into the red but it used to move about. The sensor was correctly set up.
I had to change the rad and I took the decision to go back to a Visco's. My thinking was Land Rover made Defenders with a Visco's so it must be best. With the Viscos fan you don't have to worry if the fan is going to trip in or not. The Temperature gauge just sits in the same position all the time no matter what terrain you are going through. My thinking is also that with the Visco's there is less things to go wrong and as someone has already stated, when they do go wrong it only over cools the engine.
Which do I prefer. The Visco's fan purely for piece of mind. Less things to go wrong. I don't bother watching the temperature gauge any more. Plus a replacement Visco's is far cheaper than an electric fan. I still have the Kenlowe in my garage somewhere.
 
I have a Kenlow fitted to a 40year old car I own, the temp sensor failed to trip once while in for its mot, so it boiled over, but survived.

Following the Kenlow installation instructions the temp sensor should be set something like 5deg above the normal running temp to stop the continue running of the fan, ok this may be ok with an iron block but with an all alloy V8 engine I would think the normal running temp,which is hot anyway, is as far the engine temp to go.
If my standard gauge went north by a few degrees I'd have some concern, but it doesn't even on a hot day in traffic with the AC on, but the viscous coupling knows by the the roar sound of the fan locked-up.

In my yoof I had cars fitted with additional gauges but have never felt there was a need for them since, now l just wait for a LED warning to illuminate which although fitted don't on modern cars. :)
 
Last edited:
Thanks all. Sounds like the electrics will provide sufficient cooling, it's more the reliability and failure mode that's the concern... Ok, I'm veering toward viscius... Here's a little shot of the front of the engine:

20160221_164956.jpg
 
discool said:
A viscous coupling with the fan attached will simply spin on. Job done :)
Click to expand...

That sounds far too simple.... something will break!

are there "options" when it comes to the viscous fan? more blades, less blades, blah blah, or is the standard 3.9 efi spec sufficient for everything?
 
discool said:
I have a Kenlow fitted to a 40year old car I own, the temp sensor failed to trip once while in for its mot, so it boiled over, but survived.

Following the Kenlow installation instructions the temp sensor should be set something like 5deg above the normal running temp to stop the continue running of the fan, ok this may be ok with an iron block but with an all alloy V8 engine I would think the normal running temp,which is hot anyway, is as far the engine temp to go.
If my standard gauge went north by a few degrees I'd have some concern, but it doesn't even on a hot day in traffic with the AC on, but the viscous coupling knows by the the roar sound of the fan locked-up.

In my yoof I had cars fitted with additional gauges but have never felt there was a need for them since, now l just wait for a LED warning to illuminate which although fitted don't on modern cars. :)
Click to expand...
The OP has spent good money on a nice engine - IMHO he'd be better off with accurate gauges that tell him what's going on rather than a led that says something has gone wrong!
 
farmershort said:
That sounds far too simple.... something will break!

are there "options" when it comes to the viscous fan? more blades, less blades, blah blah, or is the standard 3.9 efi spec sufficient for everything?
Click to expand...
Have you got room for both? Kenlowe do a slimline I believe, or ist here room for a "pusher" fan in front [behind the grill] That way you've got a back up and if wired separate of the ignition some run on after the engine has stopped..........................
 
waldamar said:
Have you got room for both? Kenlowe do a slimline I believe, or ist here room for a "pusher" fan in front [behind the grill] That way you've got a back up and if wired separate of the ignition some run on after the engine has stopped..........................
Click to expand...

I wont know till I fit it all... perhaps this is one to keep in the back pocket for further down the line.
 
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