Geoff,
I have removed the original TR6 fan and replaced it with an electric fan
controlled by a fan switch and relay. Although it doesn't meet your specs,
so far it is working wonderfully. That said, I've only been on the road for
a couple of weeks since a total restoration.
Just like you, I spent a lot of time looking for just the right fan switch
only to find that most fan switches close at temperatures much higher than
your spec of 190. Thinking about it, it doesn't make much sense to turn the
fan on at nearly the same point most thermostats open. Almost all modern
cars use a 196 degree thermo. The fan switch I ended up using turns on at
211 ascending (NAPA ECH FS118 from a GM application with a 3/8" pipe
thread). It has one post that goes to ground when triggered. Although the
post appears threaded it is ribbed and will accept a connector like the
female side of the Lucas bullet connectors used through out the TR6. When
the fan switch closes it grounds a relay (NAPA LIT 192D) and turns on the
fan. You can always add a toggle switch to manually provide a ground to the
relay. Now the heat gauge will nearly reach the 3/4 mark in traffic before
the fan comes on but quickly drops and the fan cycles on and off as needed
automatically. Over 30 mph the fan isn't often required.
This fan switch is located in the bypass hose just below the thermostat. You
can see a photo of the set up at
http://topshamautoparts.com/tr6/Spring2003.htm however the photo shows a
coolant temp sensor to be used for a future fuel injection conversion. The
fan switch looks similar except the connection is the single post. At first
the plan was to mount it in the top of the thermostat housing so I have a
housing readied for just such an installation with a 3/8" pipe bung to be
welded to the top. That set up would work well with the fan switch but not
so well with the coolant temp sensor because the actual engine coolant temp
could not be measured until the thermostat opened. Fine for the fan switch
but the coolant temp sensor needs to report back to the computer low
temperatures as well. Hope that makes sense.
The relay is wired via a separate fuse to the positive battery post allowing
the fan to run after the engine is shut down. Not sure if this is the best
method but it is easy to swap the control circuit over to a "key on" source
that will only run the fan with the ignition on.
I've rambled way too long but if you have any questions don't hesitate to
contact me.
Rick Patton
75 Delft Blue
http://topshamautoparts.com/tr6/
patton@suscom-maine.net
> Date: Wed, 25 Jun 2003 19:57:42 EDT
> From: Gameparker@cs.com
> Subject: Need recommendations for a radiator fan sensor
>
> List,
> removing my stock fan for a little fun and I need a
> suggestion/recommendation
> for a sensor to install in my radiator to turn on a B.A. electric fan
> (relatively low amps, though). I have tried (in vain) to find out what
> would be
> suitable and have literally spent weeks on the net and an hour or two at
> various
> part house before they get sick of me. Here are my specs: two
> single-prong
> connectors and on at about 190 and off at about 180. Oh yeah, and from a
> domestic or abundant import car would be nice (no BMWs or Saabs, etc).
> Seems simple
> enough, right.
> Please help so I can fire her up this weekend.
> Thanks and Regards,
> Geoff
> 74 TR6
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