Temperature guage what do u normally see ?

[HKGriff]

Thanks Dave. I already have the Davies Craig pump on order.

Please forgive me for what might either be a Noddy - but correct - explanation as to how this all works or totally incorrect! If the latter, please do correct me!

The otter switch is a sensor that reads the engine coolant temperature. The otter switch is not powered by anything at all (i.e. there are no live/earth that 'power' it), and it sits beneath the swirl pot.

In a bog-standard set up: -

(1) the otter switch, when it reaches a predetermined temperature, sends a message (via an electrical cable) to the fan (or fans) which triggers the fan(s) being activated;

(2) when the coolant temperature falls below the predetermined temperature, the otter switch tells the fan to stop and they do; and

(3) because the fan(s) only run when the ignition is on, and in the case of the mechanical water pump, when the engine is running and the belt turning, the fan and mechanical water pump will stop once the ignition is turned off.

In your modified set up: -

(1) you have connected the fans (or at least one of them) and electric water pump to a permanent live. I presume these are now connected to the permanent live feed from the alternator. (Is this correct?).

(2) in this permanent live state, if your otter switch senses that the coolant temperature remains higher than the predetermined level, even though you have turned the car off, the the fan(s) and electric water pump continue to run until the otter switch senses that the coolant is less than the predetermined temperature;

(3) when the coolant temperature falls below the predetermined temperature, the otter switch tells the fan(s) and electric water pump to stop.

Noddy or correct (and a hint please on how you are powering the electric water pump)! Photos would be better still.

I assume, but can you confirm, that the impeller in the mechanical water pump does not prevent the electric water pump from pumping coolant around the system when the ignition is off.

You have, I believe also fitted the Mod-Wise 2-Stage Cooling System. If the otter switch were to fail, presume therefore the fan(s) and electric water pump would not receive that signal to turn themselves on. Have you therefore linked the electric water pump in with the Mod-Wise kit so the Mod-Wise temperature sensors (on the radiator outlet hose) tell the electric water pump when to start (with the electric water pump still connected to the permanent feed.

Thanks in advance, from Noddy's brother.

[Pink_Floyd]

ChimpOnGas said:

I've been running a staged fan and electric booster pump set up for some time now,

Can you describe which pipes you have spliced the ebp into and where you have placed the ebp.

[ChimpOnGas]

HKGriff said:

Thanks in advance, from Noddy's brother.

No problem its really simple, first an otter switch is just a switch like any other, rather than flicking it on with your finger the circuit is completed when a predetermined temperature is reached and broken when if falls below a different lower temperature (IE on at 90 degrees and off at 87 degrees).

Now keep in mind you need both a live & and earth to complete an electrical circuit.

Otter switches are typically switched to earth, that means the fan & pump see a live feed and the switch just earths the circuit when (in my above example) 90 degrees is met, at which point the fan & pump will run. TVR wired the live side from the ignition switch so even if the otter switch has earthed the circuit the live is only present with the ignition on.

All I've done is replace the live from the ignition switch as TVR wired things, with a permanent live directly from the battery via a relay triggered by the otter switch, this way when you turn the ignition & engine off, lock the car and walk away, the fan & pump will still run until the coolant falls below 87 degrees.

The second fan is controlled by my after market replacement ECU from Canems engine management systems, this has an output to trigger the fan 2 relay, I can set the on/off temps on my laptop using the Canems software which is possible because the ECU always knows what temperature the engine coolant is.

Otter switches with different on/off temperature switching points are freely available, once I'd selected the appropriate otter switch I then chose different values when programming my fan 2 ECU output. This gave me a staged fan system, IE fan 1 comes on earlier than fan 2 which removes the big voltage drop issue you get with both fans coming on together which can cause a dip in engine idle speed.

Hope this helps?

When I get a moment I'll try and get some photos of the electric booster pump and how I've plumbed it in.

Dave.

Edited by ChimpOnGas on Thursday 25th August 18:02

[HKGriff]

ChimpOnGas said:

Hope this helps?

When I get a moment I'll try and get some photos of the electric booster pump and how I've plumbed it in.

Dave.

Edited by ChimpOnGas on Thursday 25th August 14:47

Thanks Dave. Might get an auto electrician to help out with this bit "with a permanent live directly from the battery via a relay triggered by the otter switch" unless you are feeling overly generous with a step by step guide, size of relay etc. Understand if not!

Look forward to the photos though!

Terry

[ChimpOnGas]

HKGriff said:

Thanks Dave. Might get an auto electrician to help out with this bit "with a permanent live directly from the battery via a relay triggered by the otter switch" unless you are feeling overly generous with a step by step guide, size of relay etc. Understand if not!

Look forward to the photos though!

Terry

You've got the fan relay already Terry, all you need to do is replace the switched live (the way TVR wired it) with a permanent live, this will ensure the fans still run on switch off. If you're not confident with wiring get an auto electrician to help, point him in the direction of the existing TVR fan relay and tell him you want your radiator fans (and EBP) on a permant live.

Ask him to replace the otter switch with a twin value three terminal type that will give you staged fans, an M22 x 1.5 88-83/92-87 would work perfectly.

http://www.ebay.co.uk/itm/TO-CLEAR-NEW-INTERMOTOR-...

With this otter switch wired correctly your fan one and EBP will come on at 88 degrees and go off 83 degrees, and your fan two will come on 92 degrees and go off at 87 degrees. What you'll find with this set up is 90% of the time fan one and the EBP will maintain temps below the fan two trigger point of 92 degrees, engine coolant temps will be controlled at a perfect 88-90 degree average with fan two mostly only ever come into play when idling in traffic of hot days.

A twin range three terminal type otter switch with the correct M22 x 1.5 thread is cheap, reliable, readily available, and fits right where your current otter switch is... so represents the simplest way to give you staged fans.

Change TVR's switched live set up with a permant live and for very little money or wiring changes you'll effectively have the same system as me.

Dave

[HKGriff]

ChimpOnGas said:

... all you need to do is ...

Thanks again Dave. My first thought was, why didn't TVR attend to all this at the outset. My second thought was, there is no end to the mods that can be done, and would have resulted in a car out of the bracket of most PHs!

Again, thanks.

[ChimpOnGas]

HKGriff said:

ChimpOnGas said:

... all you need to do is ...

Thanks again Dave. My first thought was, why didn't TVR attend to all this at the outset. My second thought was, there is no end to the mods that can be done, and would have resulted in a car out of the bracket of most PHs!

Again, thanks.

In my opinion it seems clear the people responsible for designing and making up the looms at TVR in the 90's did not benefit from formal automotive wiring training

There are a number of inexplicable elements to the loom and quite a few school boy errors too, add this to the fact TVR used the engine bay and ECU loom from a Range Rover then spliced their own effort to it, and you have a recipe for issues.

I don't think anyone could argue the way TVR wired these cars was executed well, but the truth is it's 90% there, the remaining 10% isn't very good at all and that's being charitable. To my mind the objective should be to resolve the elements TVR got wrong in the simplest way by introducing as little as possible so adding minimal complication.

To this end you can resolve the back to front way TVR wired the immobiliser by simply bypassing it on the starter motor circuit only, and you can put the rad fans on a permanent live so they stay on after switch off like any other car, then use a twin value three terminal otter switch to give you staged fan operation.

These type of improvements are cheap, simple and add little or no complication or points of failure... indeed they improve the functionality and reliability of the car in a way that will only be of benefit and enhance your feeling of trust in the car's dependability.

The great thing about these cars is they're 90% there, the 10% that isn't as good as it should have been is what puts a lot of buyers off which in turn keeps the Chimaera market value to within the grasp of common man. Best off all when you really sit down and look at that 10% it's all stuff that's super easy and cheap to resolve, once sorted you have a car that compares extremely favourably with a some very high value and financially inaccessible classics and all for a price mere mortals can afford.

It also makes sorting that 10% a very worth while (and rewarding) exercise indeed

[Steve_D]

I'm sure this must have been discussed before but is there not a 'correct' sensor that works across the whole range with the Caerbont gauge?
With that correct sensor in hand there are a number of more suitable places it could be installed and thus avoid the add on resistor issues.

I'm going to change my fans to have permanent supply and two stage switching.

Steve