TR8 with air con fan switch

[Chris59]

Hello,

 

I have a problem with a TR8 : I don't find, even in the workshop manual, at what temperatures are supposed to be switched on/off the cooling fans ?

 

I need to replace the switch (it's broken) in the radiator, but can't find the temp values on this

 

Can you help, thanks ?

 

Cheers,

 

Chris.

[John390]

Hi Chris, sorry I can't help but please let me know when you find out as mine has been by-passed and the fans are on slow the moment you turn the ignition on!

 

Cheers John

Edited May 20, 2010 by John390

[Odd]

OK, here goes:

The TR8 EFi OEM sensors were:

the Radiator [Low temp] Switch: ON at 93C / OFF at 82C and

the Engine [High temp] Switch: ON 102->108C/ OFF at -?-

 

These two separate switches can be exchanged for one single SAAB 4086682 dual

temp switch fitted into the hot tank M22 bung: The SAAB switch have three wires:

The blue wire is for low temperature operation, and

the white wire is the high temp operation, and

the black wire is common

 

and the SAAB 4086682 dual temp switch temperature ranges are:

Low range ON at 92C / OFF at 87C

High range ON 106C / OFF at 101C

 

I have this solution in my TR8 and it works very well controlling the [twin electric fans]

relay cluster. (- And! All the wiring concentrated into the front left engine bay corner

without any de-tour out onto the engine intake manifold...)

[John390]

My cooling system is the same with 2 fans. Where do you mean by: 'the hot tank M22 bung' please. I have several SAAB's so I may have one of these switches.

 

Cheers John

 

ps sorry if I have hi-jacked the thread.

Edited May 20, 2010 by John390

[Chris59]

Thanks Odd,

 

I know that the EFI have one more temp sensor (in the middle of the "V" ?) than the carb (with air con) model.

 

When there is no air con on a carburetted model, the fan is viscous, not electric, me think, but I may be wrong.

 

So, I should try to find a 93/82° switch : it should be easy to find this kind of switch from one of my locals suppliers, thanks.

 

John, no problem, forum are made for this

 

Chris.

[Odd]

Where do you mean by: 'the hot tank M22 bung' please.

The brazed-in threaded 'nut' in the hot radiator tank

- where the low temp switch normally sits...

[John390]

Chris, I have a carb car with air con but I have the two temp sensors as the EFI. Does that help or hinder?

 

Cheers John

[Chris59]

John, we have the same model of TR8.

I have also a temperature transmitter in the middle of the "V", but I don't think it has something to do with the cooling fans, although not sure of this.

 

What ever, the only sensor I need is the one who is screwed in the radiator, I will see (very soon hopefully ) if I need -or not- to replace the temperature transmitter.

 

Odd, just realized that you are from Sweden (far North !) : it may be a safe choice to use a fan switch who engage/disengage at lower temperatures, as this TR8 will be used in rallys, sometime in the sunny and hot South of France........

 

Cheers,

Chris.

[Odd]

Remember - You don't want the fans to go on to close to the full opening of the thermostat!

 

Low speed ON at around 92-93C is what you want with an 85 ±3 degree thermostat in the engine.

 

You can always fit a manually triggered ON for the high speed... I have such a device using a time relay (set at 3 minutes)

that I can trigger if ever I feel a need for extra cooling - but (just like automatic high speed operation) that haven't happened

yet, ever. I just use it to check for the high speed function being 'alive and operational'... Automatic low speed have been

enough for sufficient cooling even in 30+ degree summer heat. Now, with the Porsche Boxter fans low speed is rather windy,

but high speed - well it's outright stormy and overkill... The oem fans was the same - but used more electric current for

the same effect.

Edited May 20, 2010 by Odd

[Chris59]

Odd, do you mean that originals TR8 fans are "on" or "off" separatly, and that they have two speed ?

 

Will check this asap in the workshop manual and in situe on the car.

 

They are certainly less efficient than the modern Porsche fans you are talking about....

 

 

Chris.

[John390]

Chris, the fans on the TR8 are controled via some relays which put them in series (slow running) or parallel (fast running). The relays are operated depending which thermal switch is operating.

 

Cheers John

[Chris59]

Argh, it is really less simple than expected....

 

Ok, I will try a switch as recommanded by or Swedish friend, Odd,and tell you if it work.

 

But don't expect a reply immediatly, I am now trying to solve a brake drum problem on my Caterham .....

 

Thanks both for your kind help,

 

Chris.

[Odd]

It really is an amazing design:

two temp switches (or one siamezed switch), three relays and two 12V fans give you a marvel of function

- and you find it all spilled out in Gene Thompsons Wedgelab page regarding TR8 fans

.

Edited May 21, 2010 by Odd

[Chris59]

Odd, thanks for this very usefull link .

 

I may have another problem : I have removed the air con from this car, and will not reused it.

 

And the fans electrical system is linked to the air con.....

 

Chris.

[Odd]

Both yes - and no... My AC is removed (at the moment) and I had no problem separating them

into two separate harnesses. You shouldn't either...

[Chris59]

"My AC is removed" : who need an AC in a TR ?

 

"You shouldn't either..." : I hope so, dear Odd

 

Cheers,

 

Chris.

Edited May 23, 2010 by Chris59

[Odd]

"My AC is removed" : who need an AC in a TR ?

I can assure you it will be going back in again in the future - but in a R134a filled version, and with a Sanden scroll compressor, a pair of LandRover Discovery pusher fans in front of the condenser taking care of AC fan requirements AND the two TR8 (Porsche Boxter) sucker fans behind the radiator taking care of engine cooling fan requirements. Both pairs fully independent of each other of course. [Running all four simultaneously will probably lift the bonnet up at the rear... ]

 

Nothing beats putting the roof up (when the sun becomes unhealthily scorching) donning a scarf and a hat - and letting the AC cool you sane again - when all the other Club members around you (in older technology Triumphs) are slowly roasted. "Only mad dogs and Englishmen go out in the mid day sun" I think they once said down in the imperial jewel - India...

Edited May 24, 2010 by Odd

[Chris59]

Sorry, Odd, can't follow you there : if I'd wanted a convertible with a modern cooling system and AC, I'll buy a modern convertible, Porsche, Mercedes or BMW (BTW it will never happen, I don't like modern cars...)

 

I have been for some years in the rather sunny and hot South West of France, and still prefer to be "cooked" with the hood down rather than cool in a close ( )convertible, after 25 years of Triumph driving....

 

I am not English, so I am a mad dog

 

Forget to say : I have removed the AC from my old Range Rover V8, from my now defunct Volvo estate, and never use it in my wife's modern japanese box

 

Chris.

 

PS : I really enjoy to drive with the hood down under heavy rain, or when it's ice cold outside : should I ask for the English nationality ?

Edited May 23, 2010 by Chris59