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hi there, got a little problem with my pug. yesterday i noticed my engine was running way to hot so had a good look around. coolent lvl is fine but i noticed that the 2 radiator fans wernt going around. let the car run idle to warm up and the temp topped out at around 90! it normally sits bang on 75 whilst driving flat out.
came on this forumn and found an article about unplugging the temperature sensor for the fans, as soon as i did that they kicked in at super speed and carried on running fast for a good 10 mins after i had turned off the engine and locked the doors.
now im assuming that by bypassing the temp sensor the fans will run all the time.
is this true, and will this cause comlications from running like this?
how much will it cost to fix the temp sensor ish? and is it a novice diy kinda job?
if there are nor problems on running the fans like this i dont mind not fixing it, i had a similar problem on my rover and it ran with the fans on for years.

cheers in advance
allen

dethanor01 wrote:hi there, got a little problem with my pug. yesterday i noticed my engine was running way to hot so had a good look around. coolent lvl is fine but i noticed that the 2 radiator fans wernt going around. let the car run idle to warm up and the temp topped out at around 90! it normally sits bang on 75 whilst driving flat out.

That's perfectly normal for a petrol standing still. Over 100 is "too hot" and in the 70s is what you get by having a 70mph wind entering your engine bay

If the fans weren't coming on at around 90 (they only fire up now and again) then the temperature would continue to climb. Also if the temperature sensor were defective you'd have a noticeably rough engine from what I understand.

If you still want to replace the temperature sensor, they're about £15 from the dealer and to fit them you'll need to drain the coolant, unscrew the old one, fit the new one, refill the coolant and bleed the air out. Accessibility to get a spanner on the sensor varies greatly with engine type

sorry should of said its a diesel. ive been driving it for a couple of days like this now and the temp is now running bang on 70 even at speed on hot day. the fans remains on for a while when the car is parked with the engine off.
if this is no threat to the engine i dont mind leaving it like this, but if the sensor also controlls something else then i need to look into getting it replaced.

cheers
allen

Probably little too late to reply on this, in my thinking and as I've been advised, its not good to let the fans run at top speed all the time due to few reasons,

1. engine runs below the working/operating temperature affects the MPG
2. puts on additional load on the battery and the alternator all the time which again affects the MPG
3. Running fans high speed all the time cause high wear 'n tear of the fans.

this could be the fan control unit and this sensor does not affect the fuel mixture or anything. (I'm referring to the system with three separate temp sensors/probes)
1 for temp gauge
1 for ECU
1 for fan control unit

ok i changed the temperature sensor on the engine control one that i had preveously disconnected, and still no fans.....
i took the car temp up to 90 and still nothing, what temperature are they suposed to come on at anyways?

its my first diesel so it may be fine and im just over cautious, if i let it get to 100! will i brake it or will the fans come on then? i assumed they would be on by now.

There meant to run at 90 ish, wouldn't expect the fans to come on til after at least 95. The temp getting up to 100 shouldn't be a problem, but shouldn't happen unless your stuck in traffic.

If the temp drops down to 75 when driving then you probably need a new thermostat (and coolant change while your there).

oh so i shouldnt worry to much then? ive not taken it past 90 so far as i was worried about damage. maybe i should just keep my eye onit