I've been fixing up a few little things on my newly acquired Commodore VL Turbo over the last coupla weeks. You know, the kind of stuff that most lame-arse motorists can't be bothered fixing - the product of the "as long as it runs" attitude.
Well, on a few occasions, noticed the coolant temp needle creeping up to the wrong side of the scale - once to the point where I decided it'd be safest to switch off! Eeek. So, of course, I did all the usual rounds of the cooling system. The green fluid level was okay, the hoses and water pump had just been replaced, no passages were blocked, the thermostat seemed fine and absolutely nothing appeared out of order. Hmm, my head - it was a-scratched. But, while driving around over the next couple of days, I took a bit more notice and discovered a definite pattern emerging - the temperature was rising only when there was little (or no) airflow through the radiator core (ie the car was crawling along or sitting stationary).
Aha. Obviously, the problem had to be to do with the fan - not delivering enough stationary airflow. That explained why everyone else's VL had that characteristic (and hard-to-miss) roar, while mine seemed very, very quiet! So, with engine running at temperature and the bonnet popped, I stood peering down into the engine bay - but, sure enough, the fan was spinning away happily, smoothly and noise-free. Dammit. Everything seemed okay to me...
A couple of inquisitive phone calls later and I was onto it. It was the bastard viscous fan coupling that was stuffed - which is, apparently, quite a common occurrence on VLs/Skylines. So - that following weekend - I called into the local generic auto wrecker for a replacement coupling. I walked out proudly carrying one - only a mere $12 poorer (boy, I love the low cost of replacement parts for this car!).
Hooray! With the new coupling affixed, I could now hear the fan doing the traditional Commodore roar. And, oh, what a beautiful sound it was (well, at least it is when you know it's gonna stop the engine from boiling over!). Believe me, those next couple of days were a lot more laid back for Michael - who needs to worry about traffic crawls now? Not me! But I have to admit, I was a little concerned when some strange, painful noises started coming from the fan. God, this thing was s-o loud - plus it sounded like it was going all the time. I was gonna need a big stereo or a muffler-less 3-nch exhaust just to drown out all the whooshing! But I could really tell something major was up whenever I planted my right foot. The VL felt like it had lost a lot of power, and - at its now-strained higher rpm - the belts were starting to squeal in protest. Bloody hell, something sounded very stressed...
Back on the phone again, I asked, "the viscous fan coupling isn't meant to be engaged all the time is it?" - er, no - "and how easily should you be able to turn the fan blades by hand?" - well, pretty easy, came the reply. One particular source even told me I should be able to reach down and hold the fan blades and then start the motor! But, jeez, I wouldn't have put my fingers anywhere near these spinning blades! But then, maybe they just didn't like me...
The following weekend I was back at that same wrecker - this time, not so chuffed about my bargain $12 purchase. After explaining the situation, the guy behind the bench apologised for the inconvenience and handed me another coupling without hesitation (unusually polite, this particular wrecker!). So - again - I twiddled those little hard-to-reach 8mm nuts and installed fan coupling Number 3. And you know what they say about third time lucky... yep, this one did work a charm.
No longer does the General's lion roar non-stop and - more importantly - the coolant temps hold much steadier. And on-road performance? Well, it's completely been restored to what it was with coupling Number 1. It's almost like someone gave the car back the missing 1000 rpm and 50Nm to work with! I couldn't believe the difference - until I used AutoSpeed's trusty AC-22 Performance Meter to compare two (easy launch) 0-100 acceleration times:
Seized "full-time" viscous coupling - 8.7 seconds
Normal operating viscous coupling - 8.1 seconds
Pretty big difference, eh?! Obviously if you own a VL Commy, a Skyline (or anything else with a viscous coupled fan), have a periodic look to see if it's engaging and disengaging as it should. If it's seized in the "on" position, you're dropping performance equivalent to probably a couple of pounds of boost!
And - while we're talking cooling fan losses - have any AutoSpeed readers ever replaced a modern belt-driven engine fan (such as a viscous coupled one) with an electric fan? What results did you see? Certainly, it's a conversion that a few people told me to do in the case of my own VL - but does such a conversion really work? To me, the power losses and inefficiencies that occur through the alternator, the battery, cabling and - finally! - the electric fan motor all appear to be pretty substantial. And, at the end of the day, you also have to consider if the electric fan is still drawing the same volume of air through the radiator as the standard fan - after all, that's the sole reason for having a cooling fan! Those Holden VL fans (as do all RB series Nissan sixes - Ed) roar for a reason - they're dragging heaps of air through the rad!
I'm guessing the only advantage of an electric thermo is that there isn't a fan being driven when there's no cooling assistance required. But, then, the conventional viscous coupled fan is only freewheeling anyway... So the big question is - can an electric fan simultaneously deliver the same airflow and consume noticeably less energy than a conventional mechanical fan? If not, why would you bother with one (unless you're pushing for space)?
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