ENGINE OFF - COOLING FAN ON or OFF ???

[Guest]

Hello.

 

I have often thought is it worth having the electric fan running after switching the engine off or not ??

 

Sometimes I think it probably will be worth having it set-up that way, and then other times I am not so sure.

 

Currently it is rigged to switch off when the ignition is switched off. I know a few modern vehicles (i.e. some Volvos) have it set to carry on running, if it is required, after the ignition is switched off - so there must be a reason for that choice, rather than just the toss of a coin in the R&D department !!

 

Any thoughts / views welcome.

 

Thank you.

 

Richard. 

[Steve P]

My Spal fan is run on its own circuit from the fuses and is permanent so when i`m parking it in my lockup after ticking over for a bit the fan starts up after i turn the engine off.Does it make any difference?,who knows..

Steve

[Guest]

Thanks Steve.

 

As you say "who knows", I think perhaps it may be beneficial if the car is then fired up again after say a ten minute stop where conditions have induced the fan to kick in prior to switching the engine off.

 

Regards.

 

Richard. 

[dougbgt6]

My Peugeot 306 had the fans run on when the engine stopped. Actually in the normal course of driving they were rarely on. In it's later life the wiring failed (Peugeot!) and I wired in a toggle switch to turn them on when needed, which was generally in a heavy traffic jam. On a long run down the motorway the inrush of air through the grill was enough to keep the temperature gauge down and it would only start to rise when I stopped. I presume the fan over run was to ensure no overheating engine damage.

 

A new member at East Berks has a very nice GT6 just returned from the restorers, it has an electric fan and I noticed it ran on for a good 5 minutes once he parked up.

[Clive]

I would have it run on.

 

My fan has been whirring away on my spit, only comes on for a short time before the temp drops to the off temp I think it is 92 on and 88 off, but not certain without taking it out)

 

I think it is beneficial, as it cools the water in the rad even if the water pump is off, and should help convection currents circulate the water. Besides all modern cars seem to work this way, so there must be a reason!

[rlubikey]

I would say that, once you've cooled the water in the radiator, the thermostat will soon close and there will be little circulation. However, I believe that older cars such as ours suffer from "heat soak" under the bonnet, where the petrol - and other things - get pretty warm from engine & exhaust. Having the fan run on with the radiator sender only keeps it going for half a minute on mine. A heat sensor at the back of the bonnet area to keep the fan turning over and wafting air through would be a big help I think. Designing one is on my "to do" list! I would have it on a timer for, say, 10-minutes so that, if anything fails, you don't come back to a flat battery

 

Cheers, Richard

[Guest]

Folks.

 

Many thanks for all those responses, I will change to "Engine Off - Fan On".

 

Regards.

 

Richard.

[dave.vitesse]

If you check the temp gauge after stopping the engine all the small four and the six cylinder, engines, increase in temperature for a short while before dropping. So I guess the answer is yes it is a good idea.

 

But watch out for the battery drain if you have a dodgy battery.

 

The slant four OHC engine doesn't increase after turn off, it just drops.

 

I don't know about the wet liner four, Vanguard, or the V8 engines so can't comment.

 

Dave

[Guest]

Hello Dave.

 

Is there a known rationale as to why the slant 4 does not increase in temperature ??

 

Regards.

 

Richard.

[dave.vitesse]

Hello Richard, Bigger cooling system and the aluminium head will not store the heat as a cast iron type will.

 

Dave 

[Gary Flinn]

Interesting?

 

I found with my Stag fitted with the Standard Engine and Radiator that if you stopped on a hot day and switched the engine off, the Temperature Guage would head off into the Red

 

Gary

[dave.vitesse]

Interesting?

 

I found with my Stag fitted with the Standard Engine and Radiator that if you stopped on a hot day and switched the engine off, the Temperature Guage would head off into the Red

 

Gary

 

Gary, Never had any experience with the Stag so can't comment. Apart from Help!

 

Dave

[Gary Flinn]

I never had any problems with Overheating during normal driving even with a standard radiator?

 

This particular occasion was whilst touring in Wales going up a very steep hill, on one of the hottest days of the year, the car soon settled down going down the other side    

 

I did have an Head Gasket fail though after 6 years of reliable use on the way back from a Classic Car Show at the NEC ,

 

the Stag engine is a gorgeous sounding, free revving engine when in good fettle, but needs regular oil changes and coolant flushing to keep it reliable.

[rogerguzzi]

Hello.

 

I have often thought is it worth having the electric fan running after switching the engine off or not ??

 

Sometimes I think it probably will be worth having it set-up that way, and then other times I am not so sure.

 

Currently it is rigged to switch off when the ignition is switched off. I know a few modern vehicles (i.e. some Volvos) have it set to carry on running, if it is required, after the ignition is switched off - so there must be a reason for that choice, rather than just the toss of a coin in the R&D department !!

 

Any thoughts / views welcome.

 

Thank you.

 

Richard. 

Hello Richard

                     I have my 1500 Spitfire wired to run after engine off and after a hot run or stuck in traffic etc it will run for 30seconds to 1 minute my sensor is a dual one ( motoquip VRF327) 83/79deg and 88/83deg in the bottom of the radiator and 2  9" fans usually only the first one comes on plus manual over ride with 2 leds to show if running.

 

Roger

 

ps that should be Intermotor 50101 the other is 88/82 and 92/87 degs which I found let engine get to hot