2.5 Petrol Non Viscous Fan?

[DavidW]

Hi All

Firstly, thanks to everyone who posts on here for all the information available. I've managed to answer most of my questions from the first few months of Land Rover ownership just by reading previous posts.

I've had a suspicion that the viscous 4 blade fan on my 2.5 petrol was locked on as it is too stiff to turn when switched off and always seems to be going round making a sound like a plane taking off. Also the engine temp gauge never seems to get that warm i.e. it never reaches the half way up the dial.

I looked in the parts book to check what part I would need to replace and it looks like I may have a fixed fan coupling.

Should I leave it and not worry about unnecessary over cooling (or small loss of performance on my slow petrol), replace with a viscous unit (is it a straight swap?) or fit an electric fan.

All help much appreciated.

David P.S. I will at some point replace the engine when I have more time to spare. For time being it's only done 58k miles and runs very sweetly.

[western]

It is possible to fit a viscous hub/fan to your engine have a look at items 7 to 13 inclsive on page 82 of the parts book.

[Quagmire]

I had a 2.25 in my 90 and that was a lovely engine- just a bit underpowered on the motorway. If i had just been toddling around town in it I would have kept it- I had it running LPG so it was cheap.

I wouldn't change the engine for the sake of it unless you have a specific reason to do it, you like tinkering, or the current one blows up!

On the fan front, I'd go electric with an x-fan controller- when I fitted one to my 2.25 it became much more free revving. Having a fan whirring about on a Tdi or v8 may not make much difference to performance, but it didn't help my 2.25 at all.

Just my 2p worth- at the end of a day its a Land-Rover, and what's great about them is that you can do whatever you want with them. The choice is yours!

[DavidW]

Thanks for the advice guys.

Having looked at the cost of the bits I'd need, I've gone for a mondeo fan and x fan controller which seem to be a popular choice.

Quagmire - I do actually quite like the 2.5 petrol engine (but I suppose I do have a another vehicle to go fast in). I can do 65mph on flat bit of road and I suppose it is quite quiet for a defender. Bit thirsty, but I don't go that far in it.

[Aragorn]

If the engine never warms up then i'd be suspecting a dodgy thermostat.

Even with the fan locked and going full tilt, the stat should close and stop the engine temperature dropping below 90.

[UdderlyOffroad]

My two-pence worth:

I have a 2.5 petrol, which I found slow and thirsty, so I'm midway through a rebuild and 200 TDI conversion, but I wouldn't encourage you to go down the same road unless you're sure you need it.

But that's not the point, what I actually wanted to say was: whether or not you think you'll end up leaving the engine in long-term or swapping it out for an oil-burner/V8, take the time to fab up some mounts for the fan. Do not use those cable-tie-esque things, or even real cable ties, to secure the fan to the rad. The previous owner of my truck did this, which meant he pierced through the fins. This started off a process that some wag has described as 'fin rot' - i.e. the fins start to flake off and you end up with half a radiator. Now it may be of course that my rad was already past its best, but either way, piercing through fins just seems like a bad idea to me.

HTH

[Quagmire]

... Do not use those cable-tie-esque things, or even real cable ties, to secure the fan to the rad. ...

I would second this, I made that error- thinking I would get the fan on with the cable tie things and then properly secure it when I had more time.

I never got round to it and about 6-8 months later I needed a new rad. Luckily for me the old rad was coming out for a bigger one when I put the v8 in anyway, but that's not the point... Its all nicely secured to the frame of the new rad and no problems as all since.

[DavidW]

I've got my X fan switch and am preparing to fit. The temperature switch that comes with it is 88-83 / 92-87 degrees.

I suspect most of these are sold for diesel engines and I'm wondering if this ok for a petrol engines (which for some reason I have it in my head that they run a bit hotter)?

I think my Mondeo fan is single speed so which contacts should I be using? Or a different sender?

My new thermostat is a standard one which I think opens at 84 degrees. Am I aiming to cool the water to the point the thermostat closes?

Thanks for your help.

David

[DavidW]

My new thermostat is a standard one which I think opens at 84 degrees.

I checked and it actually opens at 82 degrees.

[Aragorn]

I'd use the 92-87 switch, assuming ofcourse that you install it into the rads top hose.

If you use the lower one it will probably never turn off again after it kicks in.

Some people use the bottom hose, but imo by the time the bottom hose hits even 88c the engine temp could easily be over 100c.

The thermostat sits in the top hose, and any switches controlling electric cooling should be in the same place.

[Diff]

I'd use the 92-87 switch, assuming ofcourse that you install it into the rads top hose.

If you use the lower one it will probably never turn off again after it kicks in.

Some people use the bottom hose, but imo by the time the bottom hose hits even 88c the engine temp could easily be over 100c.

The thermostat sits in the top hose, and any switches controlling electric cooling should be in the same place.

I have the same on my 2.5 petrol too, 92-87 fan switch in the top hose with an early mondeo single speed fan. I use an 88 degree thermostat. The engine warms up quickly and the fan only comes on in prolonged heavy traffic jams and slow speed offroading. In normal everyday use it doesn't come on and the engine temp stays steady. The fan brings the temp down pretty quickly too when needed.

Regards, Diff.

[britishnick]

I'd use the 92-87 switch, assuming ofcourse that you install it into the rads top hose.

If you use the lower one it will probably never turn off again after it kicks in.

Some people use the bottom hose, but imo by the time the bottom hose hits even 88c the engine temp could easily be over 100c.

The thermostat sits in the top hose, and any switches controlling electric cooling should be in the same place.

Hi - I have just picked up on this thread.

By putting the thermostat in the bottom hose, aren't you allowing the radiator to do its work first, then if it can't cope (i.e the exit temp from the rad is still climbing) you bring the fan onto assist?

It would be interesting to know the standard differential across the radiator to understand the difference in entry and exit design temp.

Nick

[Tanuki]

Standard practice is to put the thermoswitch in the bottom of the radiator/bottom-hose. Look at any current-production car with an electric fan and you'll find thats where the thermoswitch is.

The temperature of the water coming out of the engine doesn't really matter - you could be storming up a glacier at full-throttle and if the ambient-air temp is -20 then the radiator will be quite capable of holding the engine-temperature at a sensible value without running the fan. And, let's face it, Land-Rovers are fitted with radiators that are massively-oversized for any kind of 'summer' we'll get in the UK. A hot-running engine is an efficient engine - ideally you want bulk-coolant temperatures around 90-95 degrees and the oil a bit hotter (110-140 degrees with modern synthetics) to ensure any condensation is boiled-off.

[Snagger]

I'd refit the original fan. It'll keep the engine temperature cool, rather than allowing it to rise and then trying to lower it, which is waht an electric fan does. It's also more reliable, more effective and more efficient. the stats about electric fans' benefits to economy and perfomance are complete lies - for a bench mounted engine, yes, but for an engine with ram airflow from the vehicle's motion it's complete horse.... - the forward motion of the car means that the air the fan is sweeping through is already at high speed, so the fan slices rather than scoops the air, leading to almost no fan drag at all. Furthermore, the original fan was taking its kinetic energy directly from the crank shaft - no wasteful changes from kinetic to EM to electrical in the alternator and back into EM and kinetic again in the fan motor, and no electrical resistance to worry about. You won't have to worry about the sensitivity or reliability (both suspect) of the thermostatic switch, the reliability of the electric motor once it has been submerged in mud, and you won't need to worry about the fan depleting your battery.

Electric fans are one of the biggest cons in the LR after-market industry. If they are so good, why do all car manufacturers still fit viscous or fixed fans wherever possible?