How does my fan work?

[yosini]

Hi,

Whilst replacing all the water pipes on my 4.2, I have found a few questions - first one is quite simple, what is the brass looking thing that I unscrewed from the metal water pipe - I'm assuming this is some kind of temperature sender, but how does that work then?

And more puzzling is, I have traced my fan wiring back and it seems to only go to that connector in the picture - which wasn't connected to anything.... the car never used to overheat, and I'm sure I've seen the fan spinning once when I checked with the car up to temperature. I couldn't see any obvious wires dangling anywhere that I might have knocked off either.

Curiouser and curiouser.

[mikesr]

The brass thing is the sensor for the water temp gauge.

The loose plug is likely for the second fan that is fitted to aircon cars.

[Mad Mark]

The brass looking thing is a capillary temperature sensor that is used only for the gauge in the car. There should be an electrical sensor near where you unscrewed the brass one from that tells the ecu the temperature. This is what is used to switch the fans on and off.
Some Cerbs have two fans. I am not sure when this was introduced and on which models. I am sure someone on here will know the answer to that. The fans cut in at different times. That connector looks like it is for a second fan. Does it go into the same conduit as the 'other' fan wire?

[Tony69]

Hello,

The good new is the brass thing is the temperature sender and it simply operates by the fluid within the pipe expanding/contracting with heat. the bad news is that you have a fan missing...

From what I can see... you don't have the factory fit radiator that has two fans and a cowling that aids air flow as the fans suck air firstly through the air conditioning condenser and then the radiator itself.

You don't have a specifically design alloy replacement radiator either... if you did, the radiator would be enclosed and have fitting for the two fans you should have....

when the engine starts to get hot... the ECU switches in the first fan... then if the temperature increases beyond the next preset, it will switch in the second fan to assist cooling. The temperature presets will depend on the cooling chip fitted to the ECU. I would need to check if you need to know what the exact figures are.

it is difficult to see from the picture but it looks like the second connector you have there is for the second fan... compare the two connectors, they should be the same and enter the loom at the same place.

Sorry it's not all good news but it's all quite easy to correct.

Let me know if you need more data or a picture or two.

Regards

A.H

[Gray_101]

Early none air con Cerbs only had one fan.... and the fan is in the right place for a none air con cerb.

Id say it is standard TVR fitted fan

[ukkid35]

Gray_101 said:

Id say it is standard TVR fitted fan

Does that mean it gives adequate cooling?

[ukkid35]

Looking more closely (and after re-reading your post), it appears you have removed one of the coolant pipes, that contains the fittings for both the gauge sensor and the ECU sensor.

Be very careful with the capillary bulb, it is a very fragile integral part of the gauge, and getting the gauge refurbed is a PITA.

I'd remove the other pipe as well and do whatever you can to stem the corrosion. £170 for the pair seemed a lot to me so I just dipped and coated mine in POR15, as well as plugging a hole with metal epoxy which has lasted remarkably well.

Edited by ukkid35 on Saturday 9th June 18:42

[Gray_101]

ukkid35 said:

Gray_101 said:

Id say it is standard TVR fitted fan

Does that mean it gives adequate cooling?

Well TVR thought so when they first started making them.... i was looking at one a couple of weeks ago. But i bet late ( 2000 on ward ) none air con cerbs have double fans. it stands to reason as TVR was constanly changing the spec to over come problems

Edited by Gray_101 on Saturday 9th June 18:44

[Tony69]

oh... I've never seen a Cerbera with anything other than two fans. I have a MkI 1997 4.2 AJP V8, it looks like this...

Section 'N' "cooling" of the workshop manual only seems to picture two fans but the text does say "if A/con" remove the largest fan first" so perhaps there was a single use radiator fitted with a single fan on the non-aircon Cerberas and two fans for the A/C Cerberas.

Section 'N' of the workshop manual does answer all the other questions though.

Thanks for correcting me... sorry for any confusion.

A.H

[Gray_101]

Tony69 said:

oh... I've never seen a Cerbera with anything other than two fans. I have a MkI 1997 4.2 AJP V8, it looks like this...

Section 'N' "cooling" of the workshop manual only seems to picture two fans but the text does say "if A/con" remove the largest fan first" so perhaps there was a single use radiator fitted with a single fan on the non-aircon Cerberas and two fans for the A/C Cerberas.

Section 'N' of the workshop manual does answer all the other questions though.

Thanks for correcting me... sorry for any confusion.

A.H

lovely looking engine bay.... how do you find the ally rad ? Id like one but im worried my car would run too cool and walop fuel, my engines not quite standard and already runs very cool about 70 degrees at the moment.

[cerb4.5lee]

I have two fans & air con, but the fan on the right side has never worked on mine, i just thought it was part of TVR ownership where some things work, some things dont!!

I might have to get rid of the one on the right then, its unwanted weight!

[Gray_101]

cerb4.5lee said:

I have two fans & air con, but the fan on the right side has never worked on mine, i just thought it was part of TVR ownership where some things work, some things dont!!

I might have to get rid of the one on the right then, its unwanted weight!

Lee are you sure it doesnt work ? The second fan comes on at a higher temp than the first.... its like an emergancy back up for when it really gets hot

[Tony69]

Hi,

The engine does run a few degrees cooler (5/7 I would say) but what I really notice is how quickly the heat is dissipated when the fans cut in during hot weather. The alloy radiators just seem to be so much more efficient at cooling and dissipating the heat.

I my case, the alloy radiator was a very good move especially after suffering with a "hot stall" or two during the summer... at the most embarrassing time it could of happened of course....

Thanks for your comments... I've put a lot of effort into my Cerbera, she has still only covered 14K miles and she's factory standard, with the exception of the alloy radiator, silicone hoses and some braided fuel lines. I only replace the original set of Bridgestone tyres last summer...

Regards

A.H

[cerb4.5lee]

Gray_101 said:

cerb4.5lee said:

I have two fans & air con, but the fan on the right side has never worked on mine, i just thought it was part of TVR ownership where some things work, some things dont!!

I might have to get rid of the one on the right then, its unwanted weight!

Lee are you sure it doesnt work ? The second fan comes on at a higher temp than the first.... its like an emergancy back up for when it really gets hot

I think you could be right Graham, i never pretend to be an expert when it comes to TVRS!

Hope your road burner is doing you proud

[Gray_101]

Tony69 said:

Hi,

The engine does run a few degrees cooler (5/7 I would say) but what I really notice is how quickly the heat is dissipated when the fans cut in during hot weather. The alloy radiators just seem to be so much more efficient at cooling and dissipating the heat.

I my case, the alloy radiator was a very good move especially after suffering with a "hot stall" or two during the summer... at the most embarrassing time it could of happened of course....

Thanks for your comments... I've put a lot of effort into my Cerbera, she has still only covered 14K miles and she's factory standard, with the exception of the alloy radiator, silicone hoses and some braided fuel lines. I only replace the original set of Bridgestone tyres last summer...

Regards

A.H

5-7 is not to much of a drop in temp... i may upgrade to one very soon. Thanks for the info.

[Gray_101]

cerb4.5lee said:

Gray_101 said:

cerb4.5lee said:

I have two fans & air con, but the fan on the right side has never worked on mine, i just thought it was part of TVR ownership where some things work, some things dont!!

I might have to get rid of the one on the right then, its unwanted weight!

Lee are you sure it doesnt work ? The second fan comes on at a higher temp than the first.... its like an emergancy back up for when it really gets hot

I think you could be right Graham, i never pretend to be an expert when it comes to TVRS!

Hope your road burner is doing you proud

You ve no idea mate... its bloody fantastic.... i should be updating my thread in the next few weeks.. thanks for asking

[scotty_d]

Gray_101 said:

lovely looking engine bay.... how do you find the ally rad ? Id like one but im worried my car would run too cool and walop fuel, my engines not quite standard and already runs very cool about 70 degrees at the moment.

Hi Gary i have a Alloy Rad as well and it sits around 70-80 Degress on a steady motor way run so not too cool.

[Mad Mark]

i think the first fan cuts in at around 90 and the second around 100 or is it 80 and 90 lol something like that! But remember this is set by what the ecu see's via the electrical temp switch not by the gauge which is via the capillary switch. It is unlikely they both read the same.

[Gray_101]

scotty_d said:

Gray_101 said:

lovely looking engine bay.... how do you find the ally rad ? Id like one but im worried my car would run too cool and walop fuel, my engines not quite standard and already runs very cool about 70 degrees at the moment.

Hi Gary i have a Alloy Rad as well and it sits around 70-80 Degress on a steady motor way run so not too cool.

Cheers Scotty.... mines currantly running at 60 - 70... my worry is it will run too cool. decisions decisions

Edit to add.

my mistake... its running 70 -80... i guess it will be ok

Edited by Gray_101 on Saturday 9th June 20:12

[scotty_d]

Sounds like your thermostat is past it's best at a guess. My old Chim was like that running very cool as the States spring over time became weak and it was opening way to soon. Once i fitted a new one even with the alloy rad it was spot on. Pitty you can't test the Cerbs one as it is buried in that stupid housing.