otter switch cut in?

[jeff jackson]

Hi All,
Might be a daft question, but my otter switch has packed in. I am
loathed to pay the ?35-?40 for a new one, so I am knocking up a circuit
to run off the temperature thermistor in the cylinder head, to drive the
fan.
I just wondered if anyone knows what temperature the otter switch is
supposed to close at.
Regards
Jeff 72+2

[poiuyt]

Why not just put a manual switch in the circuit? I have this
arrangement in my 1969 S4 and usually leave it on all the time unless
I am on a highway at speed or the air temperature is cool (Fall,
Winter).

Doesn't fail and you don't have to worry about another place for the
coolant to leak.

Steve B





--- In ***@***.***, "Jeff@..." <jeff.taylor-
jackson@...> wrote:

[richboyd]

Steve,

I remember when I could count on my memory for things like
turning-off the radiator fan at highway speeds. Now? I sometimes find
myself revving happily along in 4th gear at highway speeds when I
should have shifted into 5th long ago (No, not in the Elan). I guess
it doesn't hurt to leave the electric fan on all the time (fan used
to be attached to the water pump pulley, yes?), but my memory sure
won't shut it off reliably.

What about a thermo-switch and a manual over-ride? Yes, one more
potential leak - but if you get a modern threaded thermo-switch and
bung rather than the Otter hope-it-stays-in system, there should be
no leakage problem. Thermo-switch to handle the day-to-day cooling
needs and the manual over-ride to allow for thermo-switch failure or
those "special occasions" that pop-up (all too often).

Rich Boyd


At 03:06 PM 5/12/2006, you wrote:

[fatboyoz]

Jeff,
In answer to your question about the otter switch temp's. The Elan
book mentions that the fan should begin to operate between 81 and 89
degrees C when retrofitting an electric fan using a sensor screwed
into an adaptor that is fitted in the top hose. It also mentions the
old Kenlowe sensor (switch), that is no longer available. The temp's
associated with this sensor are 90 degrees C with either a 71 or 78
degree C thermostat fitted or 95 degrees C with an 88 degree C
thermostat fitted. The Otter switch replaced the Kenlowe switch, but
no specific temp's are given in the book for it. Viewing the radiator
from behind, the Kenlowe switch is on the right hand side on the rear
and the Otter switch is on the left hand side on the front directly
opposite the top hose.

I bought a used Saab (don't know the model) radiator from a motor
wrecker that had the temp sensor, for the electric fan, fitted into a
threaded insert soldered into one of the radiator tanks. I added
heat, from a blow torch, and soon had the threaded insert in my hot
(literally) little hand in no time. Took my S4 radiator to a radiator
repairer who cut a hole and soldered the threaded insert into the top
tank in the same position as you would find the otter switch. The
good thing about this installation is that the threaded insert takes
a variety of European car temp sensors in varying temperature ranges
so it would be possible to find one that suits your need. The brand
name of the sensor I have fitted to the radiator is Wahler (82-77
degrees C). I think my thermostat is 74 degrees C.
Colin.

--- In ***@***.***, "Jeff@..." <jeff.taylor-
jackson@...> wrote:

[gwnorth68]

All this endless talk about "otter switches", leaking, radiator mods for
thermo swithches, etc, etc, are a bit tiresome For less than $150 Canadian
Hayden makes a neat, clean electric fan that snaps on the back of any
radiator and also provides a choice of fixed temperature or adjustable
temperature thermo switch which is merely inserted into the rad fins.
Electrical harness for the switch is part of the switch kit, sold separately
from the fan kit. I bought mine from Canadian Tire but Hayden products are
available everywhere I assume. Check it out on Google.
Tom Moore

[poiuyt]

Rich,

My fan runs through a cut-off switch under the dash and gets its
power when the ignition is on. Therefore, unless I shut it off it
will run when the ignition is on.

Nothing to forget, and if you do, the temp guage reminds you.

Steve B



--- In ***@***.***, Richard Boyd <richboyd@...> wrote:

[jeff jackson]

Hi Colin
Thanks for the info. I have bought an electric fan from a wreckers. It
was off a Citroen ZX and is the correct size, and weighs a fraction of
the old Lotus one. I intend to keep the lotus fan for originality.
I also got the harness from the citroen containing the relay. All I want
to do ( as a bit of fun for me, ) was to knock up a circuit to take the
place of the thermoswitch.
I fitted a manual override to the Otter switch as soon as it became U/S,
but having an automatic system is preferable as it takes away worrying
about when to switch the fan on, and also saves a bit of fuel.
I did remember reading somewhere that the fan cut in around 90 or so.
Thanks for the info...
Regards
Jeff

fatboyoz wrote: