britishnick Posted July 15, 2011 Share Posted July 15, 2011 I have just installed an electric fan in to replace the old engine driven one on my Defender. Should I suck warm air from the engine bay over the radiator, or draw cold air from the outside across the radiator. Thoughts ? Quote Link to comment Share on other sites More sharing options...
CwazyWabbit Posted July 15, 2011 Share Posted July 15, 2011 Regardless of the air temp you don't want your electric fan to have to fight against the air flow generated by driving. So draw air from outside. Quote Link to comment Share on other sites More sharing options...
MONKEYCOPPER Posted July 15, 2011 Share Posted July 15, 2011 have you fitted it in front or behind (engine side) of rad ? Paul Quote Link to comment Share on other sites More sharing options...
SPendrey Posted July 15, 2011 Share Posted July 15, 2011 I have just installed an electric fan in to replace the old engine driven one on my Defender. Should I suck warm air from the engine bay over the radiator, or draw cold air from the outside across the radiator. Thoughts ? Are you sure you didn't mean to ask "Should I push or suck air through the radiator, i.e. mount the fan infront or behind?". Blowing already warm air from around the engine block onto the water/radiator you're trying to cool is a bit mad. Like CwazyWabbit says, your fan won't be able to compete with air blowing in at 40+ MPH anyway (probably much less in fact) so the question is where to mount the fan rather than air flow direction isn't it? Scott Quote Link to comment Share on other sites More sharing options...
britishnick Posted July 15, 2011 Author Share Posted July 15, 2011 Thanks chaps for the quick response as usual. The fan is on the inside and is now drawing air through the rad, although the fan never seems to come one ! Nick Quote Link to comment Share on other sites More sharing options...
crclifford Posted July 15, 2011 Share Posted July 15, 2011 Thanks chaps for the quick response as usual. The fan is on the inside and is now drawing air through the rad, although the fan never seems to come one ! Nick I've had an elecy fan in my truck now for a while, and don't think it's come on once either. But as lots of people have said in other threads some of the old lumps are overcooled any way and therefore your fan probably won't come on unless towing something heavy, up hill, on a 30+ day, ie working the engine very hard! Or the other simple answer is you haven't wired it correctly!! HTH Quote Link to comment Share on other sites More sharing options...
Buzza Posted July 15, 2011 Share Posted July 15, 2011 Have a look here; http://www.vehicle-wiring-products.eu/VWP-onlinestore/accessories/radfan.php Steve Quote Link to comment Share on other sites More sharing options...
Briarston Posted July 15, 2011 Share Posted July 15, 2011 Just as an aside, and roughly on topic, some years ago a friends son had an MG Midget which he felt was getting a little over warm. He got a multi blade fan and after a long struggle (car had a deep fan cowling, working inside it)and many plasters he got the new fan fitted. Time for a road test, engine was close to boiling after a couple of miles. Turned out the fan he had fitted was from an early Mini with the side mounted rad. and the engine driven fan blowing out through it, air exiting under the wing. Fitted to his MG (front mounted rad.) the fan was fighting against the natural air flow, hence rapid overheating. Moral - Whichever side of the rad. you mount the fan, do make sure it pushes (or pulls) the air in the right direction! Quote Link to comment Share on other sites More sharing options...
Snagger Posted July 16, 2011 Share Posted July 16, 2011 The air must be drawn from the front side of the rad through to the engine. "Puller" fans, mounted behind the rad, are more efficient than "pusher" fans (fitted in front of the rad). Be very careful to check your fan - I bought a puller from a LR after market supplier. The packaging and instructions were all for a puller, but on opening it up, I saw the fan was on backwards (so the hollow sides of the curved blades were facing the rad) in the pusher configuration. I reversed the fan and fitted it, thinking no more of it. The engine was fine until driving up the Alpine passes, at which point it got pretty hot. Of course, the wiring polarity was also set for a pusher fan and had to be reversed. After that, the engine temperatures were fine. My point is that you must check the fan orientation and airflow direction during installation and not rely on the packaging and labelling. One question - why replace the engine driven fan? It's more powerful, more effective, more efficient and far more reliable than any electric fan. Don't believe any of the advertising for electric fans with figures on the power sapped by engine driven fans - they're all for engines at max rpm on a bench, not engines idling or at medium rpm on a moving vehicle. They're so false that I regard them as fraud. The sole advantage of an electric fan is that you can switch it off to avoid drenching a petrol engine's ignition system when wading. The only reason I have an electric fan is that the original fan wouldn't fit behind the chassis after fitting the Discovery engine to a 109. That is the same reason that car manufacturers use electric fans - they always use engine driven wherever possible and only use electric where the engine or rad position don't allow a mechanical fan. Quote Link to comment Share on other sites More sharing options...
Retroanaconda Posted July 16, 2011 Share Posted July 16, 2011 The sole advantage of an electric fan is that you can switch it off to avoid drenching a petrol engine's ignition system when wading. Not quite true, I have an electric fan on my 200Tdi and so now have a good 12" of free space in front of the engine, very helpful when working on it Quote Link to comment Share on other sites More sharing options...
britishnick Posted July 16, 2011 Author Share Posted July 16, 2011 All - thanks for your help, very interesting to hear the different thoughts people have. Final install - Mondeo fan, pulling air through the rad, internal switch wired for on/off/auto (thermostat). Engine now looks a little lost in the engine bay, hmm perhaps I need a bigger one. Nick Quote Link to comment Share on other sites More sharing options...
crclifford Posted July 17, 2011 Share Posted July 17, 2011 All - thanks for your help, very interesting to hear the different thoughts people have. Final install - Mondeo fan, pulling air through the rad, internal switch wired for on/off/auto (thermostat). Engine now looks a little lost in the engine bay, hmm perhaps I need a bigger one. Nick lol....they do look lost with out the old fan on there don't they!!! could always fit Off Road Toads v8??? i would if i had the money! Quote Link to comment Share on other sites More sharing options...
Mo Murphy Posted July 17, 2011 Share Posted July 17, 2011 After years of electric fans, I went back to a viscous fan on the current 90. On our recent trip to the Pyrenees, with high ambient temperatures on many days, steep climbs in low gear/high revs and fully loaded the temp gauge never moved off normal. I'm now sold on the viscous fan Yes, getting to anything is a pain with cowl in the way but the benefits in stable cooling far outweigh the inconvenience of having to remove fan and cowl. Given the Tdi head's intolerance of overheating, this can only be a good thing Mo Quote Link to comment Share on other sites More sharing options...
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