Otter switch chaos

[Aussie John]

I have now bought 7 switches from various suppliers, 3 intermotor and 4 from Febi-Bilstein. none of them work anywhere near their rated ranges, I want a 92/87, all these are way out, some bring the fans on then will not cut them off until the engine is off and cooled down. Where can I buy one that works? cheers, John.

[Zener]

Get a genuine Wahler one cant comment on the Febi/Bilstein but I would not trust anything Intermotor make to even break a window pane make sure there is no silt/sludge build up in the otter area of the swirl pot otherwise action will be erratic

[Aussie John]

Thanks zener, any idea where I can get one from?

[QBee]

You haven't denied having the otter switch in the swirl pot - I just wonder if there is a way of getting the rad converted to take the otter switch fitted there, as the later Chimaeras have it. That's where mine is. Mine did fail a few years ago, but I just got a decent one from Allwoods and swapped it over - do they have a branch near you?

There must be a reason (though maybe not a logical one, we are talking TVR here) why they moved it to that position in later cars. Any thoughts Zener?

[spitfire4v8]

Aussie John said:

I have now bought 7 switches from various suppliers, 3 intermotor and 4 from Febi-Bilstein. none of them work anywhere near their rated ranges, I want a 92/87, all these are way out, some bring the fans on then will not cut them off until the engine is off and cooled down. Where can I buy one that works? cheers, John.

Try putting the otter in the rad outlet not the input.
In the workshop you can easily get to a point where fans don't turn off if the ambient temp gets high. The water leaving the rad isn't cool enough, and once through the engine the water temp never goes low enough to switch the fans out.
Putting the switch on the rad outlet means it sees the coolest water temp, and will still switch in when the water temp goes high IE once the airflow through the rad isn't enough to cool the water enough.

[Aussie John]

Thanks guys, it is in a griff in a preserp and in the bottom of the swirlpot, but the originals seem to be ok why are the replacements so bad?

[Zener]

Like I say Intermotor stuff is ste and always was thats a 35 year hands on opinion Beru is also an OE brand and falls into your temp requirements https://www.ebay.co.uk/itm/Fan-switch-TVR-Chimaera...

[Aussie John]

Thanks Zener, I will order one today, cheers, John.

[O mage]

Of course the other reason for the fans staying on is its getting too hot could it be worth checking the thermostat is able to open fully if your running one you could just knock the centre of it out and try it. They are easy to replace.

[bobfather]

How are you measuring the temperature? The Otter switch is nowhere near the coolant temperature senders. Coolant temperature varies significantly throughout the system. If you're taking the measurement from the dash gauge then you are using a very poorly calibrated reading. Further, if you are still using the TVR sender position behind the distributor then you have absolutely no chance of getting an accurate gauge reading.

The only way to know what temperature the otter switch operates is by checking it on the bench with a meter, kettle and thermometer

[Aussie John]

I've checked every one using two industrial thermometers and hot water being careful to have everything suspended and only touching the water, cheers, John, I have a good 74' stat [wahler] which has been in for 2 years and a new radiator; it's a bit frustrating, I've ordered another off the link provided and will let you know what results I find.

[David Beer]

I used adjustable Strap the sensor on the outlet hose. Demon tweeks sell them, can’t go wrong, dial in the temp you want.

Edited by David Beer on Monday 20th July 17:38

[Aussie John]

Thanks David, another option.

[rigga]

I too at one point was replacing otter switches at regular intervals, mine a 500 with an alloy Rad and switch in there rather than the swirl pot, well there's also one in the pot, but that's not used.
Had enough changing them, so opted for an adjustable set up with a thermister tube taped to a coolant hose, been on there for many years, and has been ultra reliable.
CoG will be along to extoil the virtues of a Davies Craig controller, there are options available.

[Aussie John]

Hi Rigga, does this just tape to the outside of the hose, what brand was it that you used? cheers, John.

[Belle427]

https://www.pistonheads.com/gassing/topic.asp?h=0&...

Another option.

[rigga]

Aussie John said:

Hi Rigga, does this just tape to the outside of the hose, what brand was it that you used? cheers, John.

Yes just taped to the side of the rad hose, can't recall its make, got it from a kit car site, simple dial to set temperature control, very reliable, which is what's needed.

Identical to this

https://www.ebay.co.uk/itm/Adjustable-Fan-Controll...

[LLantrisant]

bottom of swirlpot is a quite hot area...

this said...to which temp. are you refering when the fans kick-in? to the gauge?

why i ask this? because the gauge often shows a wrong / different value and this value is not comparable to the fan-swtiching temp.

[Classic Chim]

You only need an old ECUmate or the more modern ROVERGAUGE software and lead to confirm what your temp gauge sender is reading. You can watch the ecu temp sensor readings which is in a high water flow area within the inlet manifold so gives far more consistent readings of which to then judge what your gauge reads. Anything out of the ordinary after that should tell you you have a problem. Mostly it’s when car idles or travels slow, heat soak increases the gauge reading though the water temp is often stable at around 90 especially if fans come on then off regularly.
This test in different driving conditions can often put your mind at rest when temp gauge does indeed rise over 100!
The water temp rarely does or there would be a lot more stories of blown head gaskets on these pages, it’s very rare infact from what I’ve read over the years.
The fear it will blow is every Tvr owners nightmare until you work your gauge out

Or do COG fabulous researched mod and move gauge sensor to the same area as the ecu sensor and have very accurate readings there on in

[ChimpOnGas]

Belle427 said:

https://www.pistonheads.com/gassing/topic.asp?h=0&...

Another option.

This Australian Davies Craig fan controller works a treat and really isn't expensive, stages fan activation too.

The new version has a plug in sensor which is better, this replaces the version where the whole unit needs replacing if the sensor wire gets damaged or you just need to replace the sensor itself.

Recommend!