Otter switch - how did we get here ?

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Otter switch - how did we get here ?

Post by mark rudder » Thu Sep 13, 2018 11:38 pm

On a practical level, do we know the switching temps for Otter switches for motors using
88 deg & 82 deg thermostats? My radiator is currently being rebuilt & I'm changing to a 82
deg thermostat. The bloke is not happy with current mounting system, so while its out I
may as well put the correct temp range my 6B Cologne.


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Otter switch - how did we get here ?

Post by willholderogri » Fri Sep 14, 2018 6:31 am

My fan kicks in at 82 degrees (I have a digital temp guage in my se5a


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Otter switch - how did we get here ?

Post by scimjim » Fri Sep 14, 2018 8:38 am

Changing the stat won’t change the running temp (just the temp it’s fully open at) and the otter switch is the same for any stat. The otter switch is sited half way down the radiator, so the temp it sees is different to your gauge which is sensed almost at the stat input.

To run the engine at optimum temp, the stat and fan (in combination) should stop it going above 95 or below 85 (approx - measured at the stat), so an 82 deg stat should always be fully open once the engine is up to temp.

I think the otter switch hysteresis is something like 87/82 (on at 87, off at 82) - as measured halfway down the rad as mentioned.


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Otter switch - how did we get here ?

Post by scimjim » Fri Sep 14, 2018 8:38 am

willholderogri wrote:
Fri Sep 14, 2018 6:31 am
My fan kicks in at 82 degrees (I have a digital temp guage in my se5a
Where’s the sensor for your digital gauge sited? 82 at the stat is way too low.


Jim King

Current: SE5 (8Ball), TI SS1 (snotty), 1600 SS1 (G97), 1600 SS1 (C686CCR), 2.5TD SE5a (diesel 5a), 6 x random other SS1s.
Previous: SE5, 3 x SE5a, 2 x SE6a, 3 x SE6b, GTC, 2.9i GTC, 3 x 1600 SS1, 1300 SS1, Mk1 Ti Sabre, Mk1.5 CVH Sabre
Chief mechanic for: 1400 K series SS1 (Megan3), 1400 CVH EFi SS1 (Grawpy), Sabre/MX5 auto (The Flying Broomstick),
1300 SS1 (Number One) & Sarah's coupe.
CURE THE FAULT - NOT THE SYMPTOMS

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Otter switch - how did we get here ?

Post by ScimmyMike » Fri Sep 14, 2018 9:41 am

According to Reliant WSM Jim it's on at 80 rising then off at 80 falling


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Otter switch - how did we get here ?

Post by scimjim » Fri Sep 14, 2018 9:45 am

Unlikely to be 80/80 - it would be on and off every few seconds.


Jim King

Current: SE5 (8Ball), TI SS1 (snotty), 1600 SS1 (G97), 1600 SS1 (C686CCR), 2.5TD SE5a (diesel 5a), 6 x random other SS1s.
Previous: SE5, 3 x SE5a, 2 x SE6a, 3 x SE6b, GTC, 2.9i GTC, 3 x 1600 SS1, 1300 SS1, Mk1 Ti Sabre, Mk1.5 CVH Sabre
Chief mechanic for: 1400 K series SS1 (Megan3), 1400 CVH EFi SS1 (Grawpy), Sabre/MX5 auto (The Flying Broomstick),
1300 SS1 (Number One) & Sarah's coupe.
CURE THE FAULT - NOT THE SYMPTOMS

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Otter switch - how did we get here ?

Post by willholderogri » Fri Sep 14, 2018 12:10 pm

scimjim wrote:
Fri Sep 14, 2018 8:38 am
willholderogri wrote:
Fri Sep 14, 2018 6:31 am
My fan kicks in at 82 degrees (I have a digital temp guage in my se5a
Where’s the sensor for your digital gauge sited? 82 at the stat is way too low.
that's 82 from the normal qauge sensor location on top of the inlet manifold


1962 mini, bedford CA , KR200. morris 1000, mini pickup.several escorts,ford grandad.ford cortina X2 ,astra, SE5A x 2 ,ford focus.

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Otter switch - how did we get here ?

Post by scimjim » Fri Sep 14, 2018 12:29 pm

willholderogri wrote:
Fri Sep 14, 2018 12:10 pm
scimjim wrote:
Fri Sep 14, 2018 8:38 am
willholderogri wrote:
Fri Sep 14, 2018 6:31 am
My fan kicks in at 82 degrees (I have a digital temp guage in my se5a
Where’s the sensor for your digital gauge sited? 82 at the stat is way too low.
that's 82 from the normal qauge sensor location on top of the inlet manifold
that's too low - what temp does your engine run at then?


Jim King

Current: SE5 (8Ball), TI SS1 (snotty), 1600 SS1 (G97), 1600 SS1 (C686CCR), 2.5TD SE5a (diesel 5a), 6 x random other SS1s.
Previous: SE5, 3 x SE5a, 2 x SE6a, 3 x SE6b, GTC, 2.9i GTC, 3 x 1600 SS1, 1300 SS1, Mk1 Ti Sabre, Mk1.5 CVH Sabre
Chief mechanic for: 1400 K series SS1 (Megan3), 1400 CVH EFi SS1 (Grawpy), Sabre/MX5 auto (The Flying Broomstick),
1300 SS1 (Number One) & Sarah's coupe.
CURE THE FAULT - NOT THE SYMPTOMS

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Otter switch - how did we get here ?

Post by AJL Electronics » Fri Sep 14, 2018 1:03 pm

A hot engine is an efficient engine. Reducing the run temperature will give you knock on effects that are undesirable, including mixture control etc that have all been calibrated for normal temperature.


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Otter switch - how did we get here ?

Post by willholderogri » Fri Sep 14, 2018 6:12 pm

High 70 s I will have to check with my infra red thermomer


1962 mini, bedford CA , KR200. morris 1000, mini pickup.several escorts,ford grandad.ford cortina X2 ,astra, SE5A x 2 ,ford focus.

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Otter switch - how did we get here ?

Post by scimjim » Fri Sep 14, 2018 6:22 pm

Are you on LPG with a throttle body Will? Should definitely be around 90 at the stat for max efficiency.


Jim King

Current: SE5 (8Ball), TI SS1 (snotty), 1600 SS1 (G97), 1600 SS1 (C686CCR), 2.5TD SE5a (diesel 5a), 6 x random other SS1s.
Previous: SE5, 3 x SE5a, 2 x SE6a, 3 x SE6b, GTC, 2.9i GTC, 3 x 1600 SS1, 1300 SS1, Mk1 Ti Sabre, Mk1.5 CVH Sabre
Chief mechanic for: 1400 K series SS1 (Megan3), 1400 CVH EFi SS1 (Grawpy), Sabre/MX5 auto (The Flying Broomstick),
1300 SS1 (Number One) & Sarah's coupe.
CURE THE FAULT - NOT THE SYMPTOMS

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Otter switch - how did we get here ?

Post by willholderogri » Fri Sep 14, 2018 10:19 pm

On lpg with a mixer I will definitely have to check it .runs ok though


1962 mini, bedford CA , KR200. morris 1000, mini pickup.several escorts,ford grandad.ford cortina X2 ,astra, SE5A x 2 ,ford focus.

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