In reply to Keith Tanner :
Or he could use a 2 pin switch instead of a single and ground the outlet of the switch couldn't he?
In reply to Keith Tanner :
Or he could use a 2 pin switch instead of a single and ground the outlet of the switch couldn't he?
If you're made of money and can afford switches with two pins, mister fancy pants. 
Plus all that extra weight!!!, What was I thinking?!... Carry on
I'll need a 2 wire switch because the MR2 fuse/relay block I'm using is wired up to use +12V to kick the fan relay in. With a 1 wire, I'd need an additional circuit or relay to switch it to get the +12V for the fan relay.
If I remember, the thermostat housing has a hole and a bung in it now for either the dash temp gauge or the ECU temp gauge. I think it's the dash. And there is virtually zero room between it and the frame tube now, so I don't think I can go there. The aluminum radiator I'm using just barely fits in the nose cone. There's no bung for a sender and I don't think there is even a drain hole/spigot. Even if there was, I don't think there's room between the bottom tank and the nose cone. The system is full of Toyota Red antifreeze. I would also like to avoid having to drain it, drill, clean, maybe weld and start over. If anything, maybe weld a tapped block of stainless to the existing tubing and screw a sender in it. I mean, it doesn't have to measure the water. The stainless tubing should be at about the same temp as the water. You can MIG steel tubing full of water, right? As long as I don't blow through, I think I'd be OK. It wouldn't even need to be real strong, just sort of beyond tacked on. But I would like to avoid that.
I had thought about building a voltage comparator circuit thingie off of the dash gauge sender and triggering off that, but again, I think that's a sub-optimal solution and would add more complexity, as would building a controller based on an Arduino. I've been working on this thing too long as it is. 18 years. I need faster, "plug this in" solutions for the remaining problems. After it is wired, the last problem will be the rear fenders.
Given the application, what did you do with your heater outlets? I know you're trying to avoid draining and refilling the cooling system, but you're going to be more annoyed if you use a less reliable way of switching the fan and it fails and you end up damaging your engine. Sometimes you have to go backwards to go forwards, as frustrating as it is.
The heater outlets are blocked off. I'm kinda leaning towards the bulb worm clamped to the return pipe. That will be plenty reliable. I will also have a manual "on" switch on the dash like Europas came with. Probably 7's too, but I never had one of those.
rslifkin said:...No OEM I know of does it.
Just for the record, my 07 Rx-8 will run the fan for a the while after the car is shut off, and Toyotas do it too, based on walking through the parking lot at work. Mostly the Priuses, it seems.
Are one of the heater outlets in an accessible enough location they could be modified to accept a switch?
WonkoTheSane said:rslifkin said:...No OEM I know of does it.
Just for the record, my 07 Rx-8 will run the fan for a the while after the car is shut off, and Toyotas do it too, based on walking through the parking lot at work. Mostly the Priuses, it seems.
I would wager most OEM'S do it.
I know VW's have since the 70's. My clubman S does, the wife's Kia does.
Interesting. SWMBO's gen 2 Prius has plenty of gizmos that make noise for a bit after shutdown, but the radiator fan doesn't seem to be one of them. I know turbo VWs have a cooldown pump for the turbo, didn't realize they also ran the fan. I'd expect their control of it is a bit more than just temperature though. I've seen cars at car shows with always-hot fan setups where the fan cycles every minute or so for at least 30 - 40 minutes after shutdown. Definitely not worthwhile at that point. Maybe a time delay to cut it entirely after 2 minutes or something would be better.
In reply to daeman :
No, not really. They are on the back of the motor too. The 4age 20 valve was a FWD only setup. Putting one in a RWD configuration requires some fiddling. In FWD, everything is just right there on the left side front of the car. In RWD, it's all up against the firewall, including the dizzy.
Where can I get a through the radiator switch? What are they called? Maybe just get the bulb one up above from Jegs and zip tie it to the bottom tank of the radiator.
In reply to Dr. Hess :
I put something similar to this on the Goldwing to switch the fan on and off. Works pretty well, actually, with the probe in the fins of the radiator. The one I used I think I just got from one of the FLAPS.
In reply to wae :
That one looks suprisingly similar to
https://www.jegs.com/i/Speedmaster/746/PCE184.1005/10002/-1
at half the price. That's kinda what I'm leaning towards. I actually might be able to do something with the heater output on the back of the block, as I think about it. But that would be the engine temp, not the radiator temp, where the control really needs to be. Probably not that important, as discussed, but if I'm going to have a temp control, it may as well be optimized for what it's controlling (too hot radiator.)
Anyone ever installed an ambient air temp sensor that triggers the fan as well? Been considering something like that in an old Elan...underhood temps get pretty toasty when the car is idling, not much ventilation.
G-car Esprits have a fan in the engine compartment to cool it off.
In reply to monkeyodeath :
X1/9 Fiats have a switch bolted to the cylinder head which turns on a fan to blow on the carb or injectors #2&3 at 190f only when the engine is turned off. Switch would do your job, just wire the relay so it works anytime. That said, I have a lot of Elan time and found no thermal issues so long as the radiator was large enough, which it was not on a stock S4.
Do it the Stampie way. Throw the damned thing away and call it weight reduction. You don’t neeed no steekin fan!
You could get by without a fan on a 20v MR2, but not on a Locost. The 7-esq vehicles have a long history of overheating, or inadequate cooling. Even the woman that took Number 6's car with the flat complained of it.
The fan on my Fairmont has a relay on the positive side to control it. I would put it on the negative side for longer contact life, were I doing it again. The coil of the relay gets its power from an accessory-switched fuse on the factory block, and has two ground paths; one through a switch on the dash for manual on operation, and one that gets turned on by the Holley Terminator controller at 195° (on a 160 thermostat). Before the Terminator was a thing, it used an Autometer oil temp light sender that turned on at 210° and off at 185 for "don't berkeley up the motor" safety. I drilled and tapped a hole in the thermostat housing to mount the sender, so that it got the hottest coolant the engine had to offer.
Dr. Hess said:You could get by without a fan on a 20v MR2, but not on a Locost. The 7-esq vehicles have a long history of overheating, or inadequate cooling. Even the woman that took Number 6's car with the flat complained of it.
Mine’s never had a problem once I got the rad sealed up. Pusher fan triggered by the radiator inlet temp and a good size rad. Hood lovers to help with tunnel heat because that hot air has to go somewhere.
I suspect that whatever gets this car out of the garage will be the best choice at this point.
I would recommend just upstream of the thermostat vs just downstream in case your thermostat fails in the closed position.
I ordered the $12 one from Jegs. $20 delivered. Isn't upstreem of the thermostat inside the block? I've never had a Toyota thermostat fail closed. Worst case was a stock 22R thermostat not opening in sub-freezing weather when warming up. There was a TSB for it and a replacement Toyota thermostat recommended, which I put in the two 22R motors I had at the time. Still have one. The replacement had a thermostat within the thermostat. Haven't had the problem on any of the other Toyota motors I have or have had: 1uzfe, 2uzfe, 2zzge, 3sfe, 3sgte, 4age. Dunno about the 1nzfe, hasn't run yet, but I'm going with "probably not."
I have an vented "power bulge" but no louvers. I'd like the louvers but don't know of a shop to punch them for me. Not too sure about the wood block method in "The Book." The hood isn't painted yet.
Yeah, I need to keep moving on this project. I'm trying to do a wire a day on it. That's much better progress than no wires a day.
In reply to jfryjfry :
If the thermostat was failed closed, what good would it do to have the fan running? Not getting cooling water flow to the engine, so the temperature of said water is pretty well irrelevant is it not?
Dr. Hess said:I'm kinda leaning towards the bulb worm clamped to the return pipe. That will be plenty reliable.
That's how I did it on my Samurai, it's very consistent.
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