Wiring an Electric Fan

[Guest]

I've mounted a 16" electric fan to my radiator (puller) and plan on installing my heat sensor into the middle of the top radiator hose (from my water pump to the radiator) using one of those alloy Tee's that everyone removes from later model TR6's. I found a new one. What temperature should I select as ideal for the sensor probe to activate at to automatically turn the fan on. There are a number of probes available that screw into this Tee and allow the probe to sit right in the middle of the coolant flow to accurately sense the temp at it's hottest point. Too, I have an ideal location to get my 12 volts from, straight off the back of my Delco alternator that is fed to the battery with a really heavy gauge wire (8 gauge). Trying to reduce the extra lengths of wire to the battery or even the starter. If I can keep all my wiring on the left side of the engine bay, I can place my relay and access my fuse block a lot more neatly. Will use a DPDT switch to override the sensor as needed, all lighted on the dash to monitor fan activity. Will of course hard wire in the appropriate inline fuse where appropriate. Following Dan M.'s diagram.

Bill

 

[71tr]

Bill,
Can I ask what wiring kit or sensor/switch setup you are using? I've got a 16inch fan which I will be installing soon myself and need to iron out the wiring details. I do tend to agree with mounting the temp probe high on the radiator or your local where the fluids are the hottest.

 

[LastDeadLast]

For what it's worth, my radiator shop guy said the best place to mount the sensor is on the bottom. Less chance of air messing with the temp reading.

I think a good place to mount a sensor would be into the metal pipe coming up from the radiator. You could get a nut welded on the pipe and just screw the sensor in. It would be strong and out of plain sight.

 

[Guest]

There does seem to be a difference of opinion on where the temp sensor should be located. I think I will go along with where I am installing it in the hose pipe. The little dumaflatchie that I got (Tee pipe, OE) will serve me well, except for the fact that that will allow me two more places for leaks to occur. The ends of the Tee are ribbed so the hose pipe will stick well. Anyway, just follow Dan Masters" diagram <www.hottr6.com/triumph/images/FAN.jpg> (hope Dan doesn't mind people ripping his stuff) (ps get Dan's book, a treasure trove of TR6 electrical stuff). I just came in from the electrical store to pick up my Relay, a DPDT toggle switch and a small blue (nice contrast) indicator light for the interior. I pretty much am following Dan's book on the install. I riveted the fan to the frame with some narrow metal strips so the install is neat. I like to make all the wiring neat, with plenty shrink wrap and want it to look factory. Again, just follow the diagram, you can get all your electric gizmos from a good electrical store (Radio Shack pretty much got out of the electronic parts business). The heat sensor I picked up from NAPA will open up the circuit at 200 degrees, which might be a little on the high side. That is why I am asking the forum if lower temp might be good. The big issue with mine is I definately want a manual override (also lighted) so I can control when I feel the need.

Bill

 

[Guest]

The writeup I was going to follow when doing this mod used a sensor with a 180 degree setting. I believe the guy used a BMW temp sensor. IMO 200 might be a little to high for comfort. I believe most thermostats are set to open at 170-180, somewhere in there. You wouldn't want the fan to kick on before the t-stat opened, wouldn't do you much good, but you wouldn't want it to lag far behind either.

 

[Alan_Myers]

Hi Bill,

I agree that the bottom (return) hose is the best location for the sensor, if at all possible. As mentioned, in the upper hose there is the chance it will be effected by any air bubbles and upper hose coolant temps tend to fluctuate a lot more. Plus the sensor should be most concerned with keeping the temp of the coolant that's returning to the engine within a proper range. So, the return hose is recommended by most installers.

I use a non-adjustable sensor in my TR4 that's set for 185F on/170F off. It's not a 6-cyl. motor like yours, of course, but IMHO most TRs like to run a little on the cool side.

Another thing I'm using is a self-resetting circuit breaker in the fan circuit, instead of a fuse that might blow and need replacment out on the road.

If you haven't already bought one, www.summitracing.com sells inexpensive wiring kits that include nearly everything needed to set up an electric fan on almost any car. It included the circuit breaker, a relay, the sensor, plenty of wiring to work with, and more.

Some photos of the installation on my car can be seen at https://www.triumphowners.com/640 if you wish.

BTW, I've heard it's a good idea to isolate the fan from the radiator with some rubber mounting, just to be sure vibration doesn't eventually effect the radiator. I've not done this yet on my car, but it's a minor project planned for the future.

Alan Myers
San Jose, Calif.
'62 TR4 CT17602L

 

[Geo Hahn]

Not what you want to hear, but I too think that it is the temperature at the lower end of the radiator that is most relevant to the operation of the fan... i.e., so long as the coolant going back to the engine is not too hot then air flow is sufficient and the fan not needed. Alan's temps (185on/170off) sound about right.

That said -- if you are mounting the sensor on the inlet to the radiator then 200 might be appropriate. You don't want the fan kicking on every time the tstat opens -- you don't need the fan running when you're cruising down the road at 70 mph -- but if inlet temps gets to 200 then it is probable the radiator could use some help.

 

[Andrew Mace]

[ QUOTE ]
Hi Bill,

I agree that the bottom (return) hose is the best location for the sensor, if at all possible....

[/ QUOTE ] Same here, based on limited personal experience. Had a Saab 99 once (relevance: Triumph designed the engine originally) with a factory electric fan. Sender for that fan was, as I recall, in or very near the top of the radiator. Fine...except that when the coolant level dropped, the sensor no longer sensed. Not a brilliant design as far as I was concerned.

 

[Guest]

Just got off the phone with PermaCool, the maker of my fan. A couple of things: He agreed with me that locating the temperature sensor at the hottest point on the radiator was the proper way to install. Locating it inline in the upper radiator hose he felt was ideal. Now that said, the temp limit of the sensor should be the same as the thermostat in the water pump. True, if the water level goes down, the sensor might not sense, but that might mean that the thermostat will open and the fluid would freely flow, low or not, and the sensor would work. He also said that the fan works best when the water is not flowing, ie, the thermostat is closed. Throw that one in the mix. The mounting of the radiator is quit sturdy, riveted into the frame of the radiator, whereas the plastic housing really doesn't vibrate much. I have place some rubber pads to lessen the vibration. I like the idea of a resetable circuit breaker. I will check that one out with Summit.

Any other ideas or comments?

Bill

 

[Guest]

Hmmmm, Summit's circuit breaker is actually made into the relay. Is that the way your's is, Alan? How about just a plain relay and a separate ciruit breaker in lieu of an inline fuse, working as both? Is there such an animal? Gotta find a thermal sensor that fits 1/2 NPT thread. Maybe they make a fitting that will choke it down.

The joys of building a resto-mod TR6. That will go....

Bill

 

[Guest]

It seems that I have now three potential wiring setups available to me or on hand and only want the one that works best in my almost unique application. I think if I keep chipping at it, I will find what is ideal. Dan Masters, where are you when I need you?

Bill

An infinite number of rednecks
In an infinite number of pickup trucks
Firing an infinite number of shotguns
At an infinite number of roadsigns
Will eventually reproduce all of Shakespeare's works in braille

 

[Rick O.]

I have the 16-inch Permacool puller and set the fan's T'stat to kick in when the cockpit temp gauge is near centerline. That way the coolant is not overcooled, but there is sufficient lag to keep the temp gauge from going 3/4 scale. It also minimizes the fan's run time.

I also powered the bits directly off the battery through a fused harness that's hidden beneath the passenger side wing flange. IMHO, you should avoid going through the stock fuseblock for a tap-in.

 

[Guest]

Rick, have any idea what temp the probe or sensor that you used is set to activate at? I had one that was a 200 degree threshold but most think that is too high. Most seem to think 180+ degrees is about right.

Bill

 

[vettedog72]

Bill:
I have been working up a fan and sensor for an American car and developed several ideas. First, if the sensor is sampling the temp of the water coming out of the motor, and you don't want the water to be over 180, then additional cooling should have been made before the coolant got to 200. As an aux fan, that setting may be OK but as a primary fan, the 180 sounds right to me. Second, many new cars have the ability to run the fan AFTER the engine is shut down to keep temp and pressure from building after the motor is off. Even though I think this is a good idea, I don't see any of these aftermarket systems having that feature.

 

[Rick O.]

[ QUOTE ]
Rick, have any idea what temp the probe or sensor that you used is set to activate at? I had one that was a 200 degree threshold but most think that is too high. Most seem to think 180+ degrees is about right.

[/ QUOTE ]I can only guess about the setpoint temp--maybe 190? To know for sure, you'd have to stick a thermometer into the rad or use one of those IR thermometers. My temp sensor is located at the bottom of the top third of my radiator. I turned the potentiometer on the T'stat to kick the fan ON when the cockpit gauge nears half. That's the best way to do it IMHO (as opposed to simply dialing in a temp setting--you have to take the sensors location into account).

 

[Rick O.]

[ QUOTE ]
I turned the potentiometer on the T'stat to kick the fan ON when the cockpit gauge nears half.

[/ QUOTE ]What I meant to write was 'just past' half. That's for the 'stuck in traffic' mode. At speed, your fan should rarely, if ever, come on.

 

[Alan_Myers]

[ QUOTE ]
Hmmmm, Summit's circuit breaker is actually made into the relay. Is that the way your's is, Alan? How about just a plain relay and a separate ciruit breaker in lieu of an inline fuse, working as both? Is there such an animal?

[/ QUOTE ]

Hi Bill,

Yes, there is such an animal. That's what I've got: A separate self-resetting circuit breaker (looks somewhat like a miniature of the Lucas relays used on most TRs) and a relay (a black plasticky thing that's now mounted to the side of my radiatior).

These were both parts in a fan wiring kit that came from Summit. It might be a Mr. Gasket brand kit, since that's the brand of fan I'm using, but I don't recall for certain. You'll need to watch the amp ratings of relay, wiring and circuit breaker, probably a little more with a 16" fan like yours, than the 14" fan I'm using.

If Summit doesn't have it, you might check Jegs, JC Whitney or locally.

[ QUOTE ]
Gotta find a thermal sensor that fits 1/2 NPT thread. Maybe they make a fitting that will choke it down.


[/ QUOTE ]

Should be possible to find an adapter, but it might position the sensor's probe wrong, i.e., out of the flow of coolant.

The 1/2" NPT is in the Tee you got? Could a different size bung be welded into it? Weldable steel bungs are easy o find. Or, make one from standard plumbing fittings, although they can be difficult to weld or braze if made in China of some mystery "alloy". I've had pretty good luck with "black pipe" fittings. Galvanized pipe fittings can be used, too. But the galvanizing needs to be removed before welding since it spoils the weld and gives off toxic fumes.

As to the sensor's temp rating, I think TRs need to be pretty cool, around 180F on/170F off. I'm going to be running that with a 160F thermostat, so the T'stat should always be fully open before the fan kicks in.

Note that many modern cars ECUs don't kick the fan on until 225F approx. That's probably done in part for emission reductions and the entire cooling system needs to tolerate pressures of 14 to 20+ psi. A lot more than the 4 to 7 psi typical to Triumphs, depending upon model.

Have fun resto-modding!

Alan Myers
San Jose, Calif.
'62 TR4 CT17602L

 

[Rick O.]

[ QUOTE ]
Bill:
many new cars have the ability to run the fan AFTER the engine is shut down to keep temp and pressure from building after the motor is off. Even though I think this is a good idea, I don't see any of these aftermarket systems having that feature.

[/ QUOTE ]My PermaCool setup does run sometimes after shutdown.

 

[Rick O.]

[ QUOTE ]
As to the sensor's temp rating, I think TRs need to be pretty cool, around 180F on/170F off. I'm going to be running that with a 160F thermostat, so the T'stat should always be fully open before the fan kicks in.


[/ QUOTE ]Alan--Unless WOT racing, I think you will find the 160 stat is way too cool--both engine performance fuel economy will decline. Not an advisable change IMHO.

 

[Alan_Myers]

[ QUOTE ]
[ QUOTE ]
many new cars have the ability to run the fan AFTER the engine is shut down to keep temp and pressure from building after the motor is off. Even though I think this is a good idea, I don't see any of these aftermarket systems having that feature.

[/ QUOTE ]My PermaCool setup does run sometimes after shutdown.

[/ QUOTE ]

It should be easy to wire any aftermarket kit to operate this way. Just use a circuit that is hot all the time, even with the ignition turned off.