Rad cooling fans Vs airflow question

[The AJP Griff]

Just wondering if having my rad cooling fans on at high speed could actually impede airflow through the rad?I've started to wonder if having the fans running at what it obviously a fixed speed,would then only allow a certain flow of air through the rad,whilst if they werent running then more air might be able to pass through the rad at higher speeds?The rad is shrouded ,so only place for airflow is through the fan openings.I'm talking of motorway type speeds of 60mph and upwards,by the way.

[Steve_D]

At that speed you should not need fans. If you do, something else is wrong and will not be corrected by fans.

Assuming it does cool correctly at speed then the fans will only kick in when the temp gets up and the road speed is lower so in that case the fan flow would be higher than natural flow.

Steve

[The AJP Griff]

Thanks for the reply Steve.I realise that i shouldn't need the fans on,but wondered if it will be detrimental to airflow or not?

[MattYorke]

The fans will speed up as they unload. They won't be detrimental, but just won't do anything worthwhile extra.

[Steve_D]

MattYorke said:

The fans will speed up as they unload. They won't be detrimental, but just won't do anything worthwhile extra.

They will consume electricity which the engine has to generate.

Steve

[The AJP Griff]

Cheers gents.I went out to do a bit of testing last night,and if anything,the temp was 1 or 2 deg lower without fans,at a constant 80mph for a few miles.This might however have been due to a change in direction,and thus wind direction?Either way,i havent solved my initial problem,which i now suspect to be a partially blocked rad
Thanks for the suggestion of the dishwasher tablets,Matt,i'll give them a try

[HiRich]

In a car like the Griffin, this would be a bit odd. 80mph should not be particularly strenuous on the cooling system - the motor isn't working particularly hard, the water pump should be spinning away merrily, airflow good, and no turbo cutting in (and dumping extra heat into the system). Cooling problems normally occur when one of these is weak (high output, lower revs, low road speed).

I would suggest you take a good look at the airside of the radiator first - partly because it fits the symptoms, partly because it's easy and non-destructive:

• Inspect the front of the radiator for damage or significant blockages - bugs, plastic bag, etc.
• Inspect the back of the radiator, particularly running your fingers across it. A rare occurrence is "fin rot": the fins break up (losing cooling surface) and block airflow (more significant at speed). When this happened to me, the back of the radiator felt like is was coated in rock salt, what broke off was fragments of aluminium fins. Fix is a new radiator.

A blocked water-side may be more likely, but it's worth a few minutes inspection before you start removing hoses and what have you.

[The AJP Griff]

Cheers Rich,the car isn't quite std,infact both engine and rad are non std!I've now had a thermopoint gun on the rad and got a difference of a good 40oC from top to bottom accross the whole rad,so it certainly seems blocked.I'm going to whip it off and give it a good flush out to see if i can improve things.Cheers,Mike