Radiator Fan Wiring help!?

[DunkG]

Hi,

I've had a look at the forum, seen plenty of instances where the reverse is true but I think this is unique!

The car is a 1993 chimaera 430. Pre serp, early example. Had it about 10 years, used to have an account on here too but my email address linked to it got closed so hello again!

The issue...
I've been having trouble with overheating. Especially in traffic. So I've gone to lots of trouble to address the system as a whole.
- I installed a temperature sensor on the swirl pot inward pipe which allows me to see the live temperature of the coolant.
- then I got paranoid because it's consistently higher than the dashboard temperature gauge!
- So, I wired in an override switch to the otter switch (swirl pot location) which just makes across the otter switch spade connectors. Great!
- But it still got hot in traffic.
- So I recored the rad. Lovely job by a local guy. Not cheap but quality.
- But it still got hot in traffic.
- So, to address heat soak inputs, I wrapped the exhaust from headers to the bottom of the downpipe.
- But it still got hot in traffic.
- I noticed my original fans were a bit weak so I replaced them with a really lovely spal set that shift nearly 2000l/m or something.
- But it still got hot in traffic.
- Increasingly frustrated I lifted the bonnet and looked to see the fans weren't running (I did test them by the way when I installed them)
- I realised they were not turning back on if they'd already been on and gone off. I stopped the car fully, restarted it with fans and it sat outside the train station while I waited for a colleague idling, with fans, and normalised at 76 degrees.
- Finally, we're getting somewhere. Although I learned that I probably didn't need the rad recoring, the heat wrap or the fans lol. The problem is in the switching.

Previously
- fans switch on and off but won't restart when the engine is running
- fans switch on and off as much as I like when the engine is off

Now (only a few days later) there are inexplicably different rules.
- fans cut whenever the engine is running
- I took the relay out and put a link wire in, they still cut out so problem is on the power circuit presumably.
- fans switch on and off as much as I like when the engine is off

Some details
- fans share a single relay (position 7)
- Fans share a (switching) fuse (position 21)
- Fans are (power) fuse positions # and #
- I've noticed the fans spin down slowly, a good 10s from running to stopped.

Questions:
- What's the consensus? Is there anything I've overlooked?
- does anyone know where the radiator fans earth to please?

What should I do?
- I can see a couple of options here, on one hand I could try to figure all this out and repair whatever is going on with the power circuit
- Or I could just put in a new circuit for fan power and switching control.

- I'll do a video, and post it below, please take a look if you have time.

[Belle427]

Bypassing the relay and not working suggests either poor contact at the fan connectors or a bad ground. Ground is at the o/s front lower chassis bolt which is a pain to get to but problems do happen here with corrosion and loose bolts.
I would add a temporary good ground if the connector checks out and see how it goes.
Fans also have a direction depending on how they are wired and which way the fan blades are, so make sure they are running correctly ie sucking fresh air into the engine bay and not pushing engine bay heat through the rad. ( think i have that right)

Edited by Belle427 on Monday 25th May 14:58

[DunkG]

Thanks Belle!

Yes, the fans are 100% turning the correct way.

I've located the earth point. Quite easy as the car is on stands with the wheels off. Assuming I've found the right point anyway...

Everything was tight and looked like it should, I got some continuity too when I tested it from rad fan connector -ve pin

The connectors on the fan look fine too.

I would link to my video but it won't let me post a link (fair enough) to my YouTube account which is called "hysterically inaccurate" and the video is called "TVR radiator fan piston heads help!"

Edited by DunkG on Monday 25th May 16:47

[FunkyGibbon]

Here's a link to your radiator video:

https://youtu.be/bhbWCXn1_-U?si=ICT9Wy8z5XJF2tWI

Sorry can't help with the problem!

Edited by FunkyGibbon on Monday 25th May 16:56

[DunkG]

Cheers FG!

You've probably helped someone who can, so thanks :-)

[Belle427]

Continuity checks are not much good as they can show ok on an electrical multimeter but not be able to carry the current. I would still run a temporary ground and see if anything changes.

[DunkG]

Roger that, I'll get on it tomorrow evening and report back, thank you!

[Loubaruch]

You have pointed out one main earth but there is another one underneath the fan on the off side where several wires earth at the front of the chassis:

TVR Chimera/Grifith earth points:

1. A main earthing point is on the left hand side of the tunnel under the whale tail and dash.
2. The second is on the right hand side under the whale tail and dash.
3. A third at the front offside where the body is bolted to the chassis.
4. The fourth is at the rear where the body is bolted to the chassis, the lower near side bolt.
5. The main engine earth has two leads from the engine loom and is connected to the chassis offside by a substantial cable.
6. The engine loom has two more earth leads connecting to the rear nearside of the engine.