131mirafiori forum

Hello.
Just a quick question.
Anyone who has a Sport can you tell me at what temp does the rad fan cut in to cool the water temp when the engine is started and left on idle. ??
I just want to check as mine does not cut in till about 180 + im sure it was going on at a lower temp than this before.
Maybe im wrong ??

This must be 180 Farenheit    ???

Nothing unusual , it is more important how it behaves when the engine is a full operational temp driven on the road ( when the water pump is working at some RPM). When you start the engine is cool and at idle speed the water pump does not provide adequate circulation of the water around engine. Fiat DOHC experts say that the fan has to start and stop three times before the engine can be considered at full operational temperature.

Before I have put in new CG engine the previous engine behaved exactly the same. My 2.0 fi in a 124 Spider still does the same.

See picture : green - normal running temperature
                   red - it goes up to red line when hot
                   yellow- this is min temp at which the fun cuts off
                   Half way between and green is when the fun switch
                   cuts in.

Suggestion - get a 76-82 fun switch , and get a lower temperature thermostat, also check your radiator - it may not be as efficient as it used to be. Make sure you use Fiat Paraflu 50/50 solution with demineralized water.   Make sure you have a manual override switch. You may think of installing more efficient modern fan on the radiator.  

( see also : http://www.131mirafiori.com /smf/index.php?topic=4397.0

M            

The rad fan has no effect on the engine temp when the car is above 30 miles per hour.
It should cut in as soon as the temp sender See's the higher marked limit on the sender every time the water in the rad gets to that temperature, Usually 84 degrees c .Can be different as i have seen 4 types in 131 Rad's.

It is a thermostat issue, I think
If you start your engine and let it run idle, you will have the short loop without the radiator (thermostat closed)
The engine temp is indicated by the sensor in this "short loop"
The fan switch will only react on a hot radiator as it is in there.... thus only react when engine is hot and thermostat is fully open in combination with no driving speed and therefor not able to get rid of the heat.
So if your fan is reacting later on the heat it means the thermostat is opening later resulting in a higher gauge reading

Forgott to mention that it could be a faulty rad switch as well of course....

Ok thanks all.
Just wanted to check !!
I checked everything and all is fine. I think it as said because the engine was on idle and not under load so the fan cuts in later than normal.

doesn't matter really, temperature should always be the same

Well next time im near the garage where the car is i will give the whole system a flush out

You are right indeed. Getting a lower temp opening thermostat is a very good idea unless you tend to drive it all year round including the winter. I keep mine locked in a garage so for the winter so mine is set for warm/hot season only. Old DOHC typically run hot in standard configuration but under no condition the whole set up should allow for the engine to overheat after starting it cold and just waiting a while. First two suspects are thrmo and fun switch , but  cooling  the engine is quite a complex system of interdependent elements ( and here comes the list of all cooling system parst. Diagnosis should start with the simplest like coolant itself and go up the ladder to the most complex (cooling channel's in the block and head) but there can be different reasons as well i.e. from wrong plugs to wrong timing, to wrong mixture, wrong fuel, wrong carb setup or LPG use etc.

Typically for the engine to overheat there must be several reasons not a single one , though a stuck thermo switch or dead fan switch can do the trick. If you fix the thermo and the fan switch problems make sure all the rest of the elements are in good condition and the engine well tuned. This rally helps to keep the temp down.

By the have you tried to open the heater valve ?  How does the car behave while driving ?

Miro         

Djape,

This is true, but it assumes that all elements of the system are working correctly and the engine is in good mechanical shape,

Miro

PS : In real life only my late grandma's feet feet have a constant low temp.