406oc.co.uk

Hi people. I’m not convinced that the auxiliary electric fan is working. I’m in Portugal, and the daily temperature is around 30. I live in the mountains so much climbing involved too. The temp gauge is hovering a tad short of 90 and I’ve never heard that fan kick in.
How can I test it ? Cheers. 1999 2.0 HDI 406 estate

Easiest way is to let the engine idle when hot with the bonnet closed and observe the temperature gauge while listening for the fan starting.
Coolant will not boil in a pressurised system at 100 degrees so it will be safe to allow the temperature to rise naturally until well past 90 degrees, perhaps half way to the next value, (130 degrees? I think).
If the temperature gets to what you estimate is about 110 degrees, stop the engine.
Assuming your fan and controls are ok it should start by about 100 degrees.

It's surprising how effective the 406 cooling system is and how rarely the fan is needed. Even in your temperatures you may need to park facing a wall to reduce any draught cooling the radiator to get it hot enough to start the fan.

Hi Doggy, thanks for response. I had thought of doing a test like that but I was more thinking of sticking 12 volts up its jacksie somewhere, maybe at wherever the sensor is ?
I’ll admit that I was worried about overheating the engine and hadn’t factored in the higher boiling point under pressure. Thanks
Temperatures due to be around 40 for the next couple of months, I’d like to be sure !

I agree with Doggy that the cooling system is very effective. I have a HDI 2.0 and have never noticed the fan kicking in due to engine temperature rising.

The fan does kick in when switching on the aircon. Maybe you can do that to test?

I have a D9 with a single electronic fan. I think you have a D8 with two fans, controlled via relays?

Hey, Doggy thanks for reply. Switching on air-con starts cabin circulating fan but not the cooling fan in front of radiator. I only have one fan there. The cooling system seems to be working fine anyway. The motor was first registered June 1999 and the paperwork says it’s an 2.0 HDI 110. Don’t know where the D8 D9 thing comes in .
I have more questions- maybe I should start new threads ? For instance: What colour antifreeze should be used ? I’ve never seen a heater plug sign on the dashboard but it seems to start fine anyway.

D8/D9 refers to the early or later body shape. Most obvious difference is the front end, D8:

and D9:

They changed over around 1999 so yours could be either.

D8 and early D9 cars were wired so the radiator fan would run slowly if the aircon was on, but later ones don't always as they switch the fan on when condenser pressure rises. It's likley but not ceratin yours should be turning when the aircon is working.

Antifreeze should be the organic acid (OAT) kind. Peugeot official version is blue/green but the more common generic ones that are widely available are orange/red.

There normally is a glowplug indicator light, but it goes out virtually instantly in hot (for us) weather. Direct injection engines like yours should start easily even if the glow plugs don't work - their main contribution is in helping the engine to idle evenly after a cold start.

Thanks for reply, looks like I’ve got an early D9. No glowplug light even for an instant. Starts no probs anyway and runs like a dream.
The small fan in the courtesy light cluster above the interior mirror makes a noise. From threads on this site seems to be regulating aircon? Does it turn all the time, whether aircon is on or off ?
Sorry for delay in replying, been busy !

The small fan runs all the time to pass air over the interior temperature sensor, (a small bead thermistor locted immediately in front of the fan blades).

Pop the cover off and try cleaning the dust off the fan blades by blowing air through a straw at it - worked for me.

Hey Doggy. Thanks for that. Me mate’s got a compressor. I’ll blow it out with that. Is the cover easy to unclip?

You don't need a compressor, the fan is tiny and would probably be destroyed by overspeeding.
Cover just clips on - see this post: viewtopic.php?f=10&t=8793&start=30