Electric fan only - a no-no on a big diesel?

Willy, I'm not sure if this is helpful, as I don't have specific knowledge of old, big diesels.

But looking at the problem logically, the object of the exercise is to get air through the radiator core quickly and efficiently. So I can't see what difference it makes if you "blow" (fan in front) or "suck" (fan behind). But I do agree that the risk of fan meeting rad is not a good idea - been there, done that, heard the noise, got the bill. I can only think that there is a possibility that the physical presence of a front-mounted fan unit might interfere with airflow under some circumstances.

As I'm sure you know from my previous ramblings I'm best on XK engines - not as irrelevant as it may sound, as it's basically a bloody big lump, ancient design and often fitted in compartments with inadequate airflow so known for overheating. On my E I have a Kenlowe behind the rad; a friend with an XK150S (basically same engine) has a Kenlowe in front of the rad - no room behind - and neither of us has overheating problems, even under the worst possible conditions (think traffic jam, London, heatwave).

I can't see why the fact that it's diesel should make any difference at all; all internal combustion engines need cooling no matter what you pour into the tank.

OK, I'm being an armchair mechanic, but my thought would be to fit the fan you have in front of the rad, definitely remove the original as it will only cause drag/mechanical loss and keep a careful eye on the temperature gauge (it does have one? If not, lash one up soon as poss!).

Good luck,

Geoff MacK

Likewise, my Triumph PI is a big lump with a need for adequate airflow. I bought it with the fan removed and in a cardboard box in the boot, and rather than fit it back, I put an Austin Maestro fan in front of the radiator. Under most circumstances the forward momentum of the car is sufficient to keep the engine at normal running temperature (the Maestro fan has relatively narrow blades, so it doesn't obstruct the airflow much), and only when I am stationary or crawling in traffic do I need to put the fan on (when it creates quite a gale - much more powerful than a Kenlowe).

Diesels are more efficient than petrol engines (hence more mpg), so I would have thought that the heat you need to remove would be less than for a petrol engine of equivalent size. I can't see any reason why you should need the engine driven fan - unless it is integral with the pulley that the fan belt goes round.

Jim

Thanks Geoff, a very useful answer as always!

... which has reminded me that I'd fitted a Kenlowe to my Vitesse after the fan was pulled through the radiator in a flood. And I never had any problems with that either.

That makes sense. Thinking about it a bit, I have a feeling this engine originally came out of a forklift truck or something similar, so would probably have had more restricted airflow than it will in the Land Rover.

I'll give it a go...

I've not much experience of diesels - but the small amount I do have says they take longer to reach operating temperature than an equivalent petrol so produce less waste heat?

Again this makes sense. I'm starting to think that what I'd read may have been more of a general "don't alter the cooling system from standard" kind of advice, perhaps because diesel engines are more likely to be seriously damaged by overheating. Higher compression and all that. As Geoff suggests, I'll make sure there's a working temperature gauge and take care with the fan's switching system.

I'd guess that the shear weight of this engine will soak up a fair bit of heat too.

I had a 1969 109 S2a with this engine in, it only had an electric fan, it ran with no problems, even offroad.

You do need an overdrive for normal road driving, excelent engine though, I remember getting stuck in a big muddy hole and for some reason got confused about which lever did what and tried to drive out in 4 wheel drive high range, after breaking all the teeth off first and reverse gears I then released what I had done and drove out in second low. Parts where very cheap for the engine, from the main agent.

Steve

Excellent, just what I needed to know! Thanks Steve.

Got one ready for it. There was one fitted to the Land Rover I took it out of, but it was in a pretty worn state. I've since read that you have to be careful not to pull away with overdrive in 1st or 2nd with such a torquey engine or exactly that kind of wear can occur. Seems the previous owner hadn't been told.

Crumbs! One reason I like it, is the way the donor vehicle would fire up so easily even after standing for a month or two, without the flame-start device connected up and with half an inch of water sloshing around in the glass bulb thing. That's the kind of bomb-proof reliability I want in a Landie.

Applies to any overdrive. To avoid over specifying one - and therefore adding cost and weight - most makers fitted an inhibitor so it would only work in top gear - or perhaps third and top. As like any gearbox it has a torque limit.