Cooling

[Titan the Robot]

It's my first time on here so hope I'm doing this correctly.
I've got a 4.5 and my cooling fans don't seem to be coming on, I've checked the fuses and the relays and the temperature gauge is working so it can't be the sender, or can it?
Any idea's welcome.

[JensenA]

They should only come on when the Temp reads about 100. Are you saying you have tried that and they don't come on? If so, check the fan wiring connections (just in front of the radiators) Also bleed the cooling system as air in the system will prevent the fans coming on.

[Titan the Robot]

Hi thanks for that, I've not taken it up 100, as soon as it gets around 90 the oil pressure start to drop a bit below 40. I've had the car off the road for a while for a full re-spray and I'm sure the fans used to come on at about 85 before.
Sorry not much of a mechanic. Does the car have a fan switch?

[optimax sniffer]

Temp gauge normally over reads. To get an accurate reading the only real way is to connect a laptop to the ecu.

[Titan the Robot]

Mmm think we are getting a little too technical for me now.
Do you know where the fan switch is (if it has one) or is that controlled by the ECU.

[Tanguero]

The fans are controlled by the ECU - the only way to check this really is by connecting a laptop.

[Titan the Robot]

Ok thanks for that. I'll be booking it in for a service soon so i'll get them to check it out then.
Can't believe I've had the car for over 6 years and only just joined this.
Thanks again.
Nik

[sonnylad]

Titan the Robot said:

I'm sure the fans used to come on at about 85 before.

Thermostat only opens at 84 so i would run it up to about 100 first just to check, as all is possibly fine.

[redeye]

my fan comes on about 95 acording to the temp gauge ,then over heats about 125 steam and all.
i only have one fan fitted on a 96 4.2, ive seen a few with two fans??? anyone fitted extra fan with over ride from the cockpit, is there a problem with keeping them cool say 70??
will wetter water drop the temp that much ???

[ro_butler]

redeye said:

my fan comes on about 95 acording to the temp gauge ,then over heats about 125 steam and all.
i only have one fan fitted on a 96 4.2, ive seen a few with two fans??? anyone fitted extra fan with over ride from the cockpit, is there a problem with keeping them cool say 70??
will wetter water drop the temp that much ???

Ok, this is my pet topic so I'll add my 2p.
The cars with 2 fans are ones fitted with aircon. However, I am not sure if later non-aricon cars also had 2 fans fitted.
You should only need 1 fan so something is wrong. If the fan is coming on then it isn't a relay or fan issue and connecting a laptop will rule out the temp sender.
The car will never stay at 70C even if it is cold outside as the thermostat opens at 84C. Water wetter will drop the temp but you need to fix the original problem first,
the car should not need it.
Assuming the temp sender is ok then it could be that the thermostat isn't opening properly, blocked rad, water pump issue or head gasket issue.
Another common cause of overheating is that the cooling system is not pressurising properly, i.e. there is a leak somewhere, it could even be as simple as the
expansion tank cap has failed.

I have fitted a fan override switch but another option is a new ECU chip with the fan cut-in temperatures lowered so they come in earlier.

It can be a pain to find these problems so start with the easy/cheap tests first. Good luck.

[ro_butler]

Titan the Robot said:

It's my first time on here so hope I'm doing this correctly.
I've got a 4.5 and my cooling fans don't seem to be coming on, I've checked the fuses and the relays and the temperature gauge is working so it can't be the sender, or can it?
Any idea's welcome.

It could indeed be the sender as this is what the ECU uses to determine the coolant temperature and thus decide when to operate the fans.
The temp gauge is a mechanical capillary device and is not connected to the fans in any way, it is solely for display.

[C3BER]

2001 4.5 with twin fans:
95c and 97c before they come on.

I had a whole load of hassles with temp problems last year.

1. Started over-heating?
2. Checked water levels and air locks, nope not that.
3. Boiled over...f-me, no fans???
4. Was it a false boil, i.e air in the system via a crack, nope not that.
5. Plugged it into a laptop and f-me everything looks fine.
6. Another slow trip out and im blowing more steam than the flying scotsman, fans not on.
7. Mmmmmm maybe a faulty reading via an iffy temp sensor.
8. Thats the problem, new sensor and bingo sorted.........nope, boils again.
9. Have the fans sorted so their on all the time rather than trusting the ecu etc
(un-plug the switch).
10. Temp now 75c and never gets above this, yipee we are getting there.
11. Another temp sensor and 95c and 97c and fans kicking in.
12. Amazing the fault was down to iffy sensors

I'm now an expert on bleeding air out of the cerb system, hi ho.


Oh and a a new slave cylinder and clutch sort of kept me off the road at the start of the year.

[Titan the Robot]

Wow sooo many replies, why didn't I join this years ago.
I was going to sell my Cerbera after a full re-spay and sort out all the little niggles but after doing this I have fallen in love with the bloody thing again.
I've had a few cooling problems before with bleeding etc and it's not that. I feel it's a plug thing. Something really simple. It's only in traffic that it heats up more than I want her too. It's almost the more you get your Cerbera sorted the closer you get to the light at the end of the tunnel. And I'm so close.
Anyway she wont be getting sold any time soon.
6 and 1/2 years and counting :-)