How To Fit An Electric Fan

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Buying a gold XX flat-front (the Golden Girl) gave rise to a few changes in ideas for The Girl's KE70, also known by her (wryly, I suspect) as The Blue Beast...

 

Both made in 1983, the flat-front had a problem which showed as having new plugs, new leads, new dizzycap, points etc.. So someone had been chasing the misfire it had when it started every morning.

 

Also, it had a new radiator... Instant answer! The rad had died, the engine over-heated and the head gasket is weeping. Chasing this around, I found the water pump bearings were ratshit and it had a rigid fan. Leaving the Toyota factory some 6months later, The Beast as a slanty had a silicon fan.

 

So the Golden Girl was fitted with The Beast's silicon fan and water pump and I bought a new pump to put on the slanty. I was about to finally fit the electric fan I'd been planning to for ages! It was also time I had the frame soldered back onto The Beast's radiator, the chassis flexing had worked it off a year back and I'd just put a piece of wire across the back of the rad to hold it in place! So out with the rad and into it!

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First, a donor car- Down at the wreckers I looked through his caravan full of electric fans, but they were all old junk. I searched through the cars until I found one with a modern narrow flat motor, in a Mazda 121 that was just the right size. I bought that and a set of brand-new looking KE70 front brake hoses, and a pair of rear shocks for $20, so I don't know what the actual fan was worth.

 

I trimmed the plastic surround back until it sat 10mm off the rad and put the long arm over the rad drain plug. I'd planned on using that plug hole for a thermoswitch, but this was plan C or maybe D already. The fan had sat in holes with pins in the Mazda, but I'd turned it sideways & made a long bracket for the pins, and the 4^th attachment was a piece of alloy too. An extra hole in the rad frame made sure that mount couldn't turn.

 

 

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Originally I'd been chasing thermoswitches at the wreckers too, for that drain hole at the bottom of the rad. No such luck, that drain is only 10mm and the switches were all bigger. Plan B moved it to the top, into the vacuum switch hole on the thermostat housing. Naturally this was 3/8, and everything 3/8 at Tridon is 3/8Gas while the KE70 uses 3/8NPT. 3/8Gas, also known as BSP, (British Standard Pipe) has 19threads/inch, while NPT has 18tpi. We decided this was not a big deal, some sealant would help and NPT is National Pipe Taper, so it would tighten up sooner or later.

 

I bought a TFS111 for $30something dollars, it opens at 90-95deg, hotter than most as it will be at the top of the rad. Its a single-wire, so it can only earth the relay.

 

http://www.tridon.com.au/Products/Product.aspx?SG=8&S=35&G=483&P=2014

 

The relay was the final component, and as I wanted to keep the wiring as stock as possible I thought I'd use the KE70 relay box. I found a relay that fitted the plug labeled “radiator fan” but it was 'normally closed'. I needed a 'normally open', so it closed when the thermoswitch went to earth and the relay fed power to the fan.

 

This opened up days and days of research into the many relays and generations of plugs, with the final final answer being that.... there is no 'normally open' relay that fits a KE70 relay plug! KE70s are the first of the relay-box systems, where earlier cars just had random relays around the engine bay and later ones had mini-relays (then micro-relays) in printed circuit boxes. That funny black box is a mechanical monstrosity, made of layers of 2mm plastic sheet with strips of aluminium running around between them. This was all to take power from a wire to a relay or fuse and back to another wire without ever crossing a third one.

 

So I grabbed a NO mini-relay from a late 80s Camry and wired it to a relay plug in the KE70 box. Nope, every relay plug has one terminal going to earth, and with a single-pole thermoswitch I need all 4 wires live at some point. I ended up wiring two relay plugs to the new relay, and being unused by the factory it was easy to find 3 unused wires and a 12V ignition supply. However this meant ages tracing every contact in the box to see where it went and make sure it didn't join something else. The wrecker 'donated' a box to me that I ripped apart and worked from.

 

You can see that some of the wiring loomb comes inside the relay box, while other plugs are 'outside' under a rubber boot. I ended up using three terminals on the factory “radiator fan” relay, and one on the un-named relay plug beside it. The Camry mini-relay just sits there, its the perfect size and can't move around.

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Here's the wiring diagram-

 

Once I had the relay wired in it was easier to hook it up. The 12V ignition live is already there, that powers the relay switch, and it earths out through the thermoswitch. That's the terminal in the next relay plug as I couldn't have that going to earth.

 

Main power from the alternator I took from my headlight mods a few years back, and then it goes out to the fan motor through the only terminal inside the relay box. As my box lies down where the battery used to be, it will be at the bottom of a stock relay box.

 

I kept the fan plug and just used a strip connector to wire power in and earth out to a handy spot on the thermostat housing.

 

It all tidied up reasonably and it works when I short out the thermoswitch wire. When I'm keen I'll take the rad cap off and stick in a 110deg thermometer, then leave the motor idling until the fan starts.

 

Firing it up the first time and I was amazed how much quieter it was! The fan adds a lot of roar to the background noise. That's where the extra 20bhp comes from! True story!

 

A 377ci Windsor, with all the good stuff, was tested on a Street Dyno. The stock clutch fan was virtually identical to the flex-fan, actually having a 1 HP advantage.

Mark VIII electric fan = 323 RWHP & 365 ft-lbs

Flex-a-lite Fan (18") = 299 RWHP & 339 ft-lbs

 

http://phystutor.tripod.com/stang/fans.html

 

 

:laff: