Hi I have a 1996 fiat ducato 2.5d in my Hymer B564 when i bought it the 2 cooling fans were seized,I managed to get 2 from breakers and fitted but they do not come on.When i run power to either one they run but i assume 1 should come on when the engine is up to temp and the second if the temp reaches 90 degrees plus.
Question is are there 2 sensors 1 for temp gauge and 1 for cooling fans if so where are they.

We have the 1996 2.5 TDI. Is that the same as yours?
The cooling fan I think you refer to, on ours doesnt come on until the temp is quite a few degrees over the normal running temp, which is about at the 1/4 mark on the gauge. Pretty noisy fan noise so we know its running. Often comes on when the motor is turned off and runs for up to 3-4 mins until the temp drops back to that 1/4 mark. Our engine does take a long drive to get it up to operating temp for the first fan to work. When temp here is say around 17 degrees C, I have to drive maybe 20-25 kms at around 50kmh before it reaches temperature for fan to come on.

bladeabroad said:

Hi I have a 1996 fiat ducato 2.5d in my Hymer B564 when i bought it the 2 cooling fans were seized,I managed to get 2 from breakers and fitted but they do not come on.When i run power to either one they run but i assume 1 should come on when the engine is up to temp and the second if the temp reaches 90 degrees plus.
Question is are there 2 sensors 1 for temp gauge and 1 for cooling fans if so where are they.

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The thermal switch does both temperatures its in the bottom of the radiator I think its bottom left under the bottom hose. At least one fan is seized in most ducatos because they almost never come on its a rare thing indeed for the bottom of the radiator to reach 80+ degrees.

Carpe Diem said:

We have the 1996 2.5 TDI. Is that the same as yours?
The cooling fan I think you refer to, on ours doesnt come on until the temp is quite a few degrees over the normal running temp, which is about at the 1/4 mark on the gauge. Pretty noisy fan noise so we know its running. Often comes on when the motor is turned off and runs for up to 3-4 mins until the temp drops back to that 1/4 mark. Our engine does take a long drive to get it up to operating temp for the first fan to work. When temp here is say around 17 degrees C, I have to drive maybe 20-25 kms at around 50kmh before it reaches temperature for fan to come on.

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That would indicate to me that you need a new thermostat. My 3.0L motor gets to full temp in 2 or 3 km from cold and fan cuts in and out regularly in traffic situations.

oigle said:

That would indicate to me that you need a new thermostat. My 3.0L motor gets to full temp in 2 or 3 km from cold and fan cuts in and out regularly in traffic situations.

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The 2.5 and 2.8 are very cold running in winter it can take 20-30km to reach normal range. But the fan starting on for 3-4 mins us definitely not normal those fans push a huge amount of air if the bottom part of the radiator takes that long to cool down I would suspect the radiator core is blocked/sludged.

Once you locate the sensor in the bottom of the radiator I would check the pins in the plug coming from the loom. They are female connectors and very fragile.
I changed the sensor in my Peugeot but had to cut the plug off the loom and solder the wires onto the sensor.

andytw

corcai said:

The 2.5 and 2.8 are very cold running in winter it can take 20-30km to reach normal range. But the fan starting on for 3-4 mins us definitely not normal those fans push a huge amount of air if the bottom part of the radiator takes that long to cool down I would suspect the radiator core is blocked/sludged.

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Thanks oigle and corcai. Now you got me worried.
We completed a 3000 mile trip late last year around the South Island and have done probably another 6-700 miles since then. Topped the water up only once during that time and it was only about a cup full or so. Used no oil since last change.
The temp did get over normal on a couple of hills (we were very heavy with water, fuel and all the other bits and ices one has to carry), but the temp always came down again quite quickly once we got over the top and down the other side.
Thanks for the heads-up tho. Will do a radiator service before our next trip I think.

Carpe Diem said:

Thanks oigle and corcai. Now you got me worried.
We completed a 3000 mile trip late last year around the South Island and have done probably another 6-700 miles since then. Topped the water up only once during that time and it was only about a cup full or so. Used no oil since last change.
The temp did get over normal on a couple of hills (we were very heavy with water, fuel and all the other bits and ices one has to carry), but the temp always came down again quite quickly once we got over the top and down the other side.
Thanks for the heads-up tho. Will do a radiator service before our next trip I think.

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You'd be amazed the crud that will come out after 15 years all kinds of oxides and salts.

For the health of the motor it is good to have it running at as constant a temp as possible. Getting hot up hills and then a rapid cool going down is not desirable. An efficient system with good cooling and a properly operating thermostat will get to temp quickly and then hold it within a few degrees all the time. One cannot avoid a few degrees of increase when in arduous conditions but temps shouldn't vary by more than 10 degrees in average operating conditions. Depends on what temp the fan cuts in at. Usually around 8-10°C above thermostat opening temp.
Not sure with Fiat but my Benz fan can come on after stopping, for a short period, to get the rad temp back down if it is running hot. It also has a water circulation system that operates for a short period after stopping the engine in above normal temps. Helps to cool off turbos etc. Fiat could easily have something similar.

Thanks for the prompt replies the only way I found both fans seized went up a 7% hill following a 40ton mobile crane towing a car the temp gauge slowly kept rising to about 90 at the top of hill I parked up and had a cup of tea waited for it to cool down did another 3000km getting home and gauge kept at normal all the time no water or oil use I checked fans back home and found them seized the rest is in the first post.Once again thanks will look for thermal sensor and check connections and order a new one if required.

bladeabroad said:

Thanks for the prompt replies the only way I found both fans seized went up a 7% hill following a 40ton mobile crane towing a car the temp gauge slowly kept rising to about 90 at the top of hill I parked up and had a cup of tea waited for it to cool down did another 3000km getting home and gauge kept at normal all the time no water or oil use I checked fans back home and found them seized the rest is in the first post.Once again thanks will look for thermal sensor and check connections and order a new one if required.

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What temp do you call normal? Most diesels now are supposed to run around 90°C If yours is running much under that, you need a new thermostat as I previously said. Running at 70 or less will be detrimental to economy and performance generally.

I think it is running at about 50 as for economy I am gettint around 28 mpg I thought that was fairley economical,when I fit the new thermal switch I will put a new thermostat in aswel.
Cheers

bladeabroad said:

I think it is running at about 50 as for economy I am gettint around 28 mpg I thought that was fairley economical,when I fit the new thermal switch I will put a new thermostat in aswel.
Cheers

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You almost reflect my exact experience. We run at about 55, going up to about 75 if going up a long hill with a big load on. Never pulled over to let it cool down as its still miles away from the red zone. Never been up to 90. Temp always comes down again of its own accord. Our fuel consumption varies, depending on weight on-board and the type of use (highway vs round towns) between 22 mpg - 30 mpg. Both fans are free to spin and not seized.
(Vehicle total mileage 54432 miles)

Just been out in mine it runs at 70 not 50 have ordered a new thermal switch will fit that and see if fans work

bladeabroad said:

Just been out in mine it runs at 70 not 50 have ordered a new thermal switch will fit that and see if fans work

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can you not connect to two wires up and see if the fan works
think thats the way

oigle said:

What temp do you call normal? Most diesels now are supposed to run around 90°C If yours is running much under that, you need a new thermostat as I previously said. Running at 70 or less will be detrimental to economy and performance generally.

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we are talking about a 1996 2.5 Diesel here,

pretty OLD-tech

they were NOT like common -rails

my old 2.5 was at 1/4 MOST of the time.., and up to HALF on hills

BUT agreed below 70'C is pointless..,

Charlie

varesecrazy said:

we are talking about a 1996 2.5 Diesel here,

pretty OLD-tech

they were NOT like common -rails

my old 2.5 was at 1/4 MOST of the time.., and up to HALF on hills

BUT agreed below 70'C is pointless..,

Charlie

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Even old tech diesels need to run reasonably hot to get the best from them. Biggest issue really is to keep the motor at a steady temp. Varying by up to 40° going up and down hills is very bad for the motor with the expansion and contraction going on with those variations. By running at higher temps as a minimum, these variations are reduced greatly.
Ian

bladeabroad said:

Just been out in mine it runs at 70 not 50 have ordered a new thermal switch will fit that and see if fans work

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Its not suppose to be 50 thats wayy too cold the temperatures are on the picture I linked. The only way to accureately check is with a thermometer and a heat source, boiling water will do if you allow time for the switch to soak the heat.

corcai said:

Its not suppose to be 50 thats wayy too cold the temperatures are on the picture I linked. The only way to accureately check is with a thermometer and a heat source, boiling water will do if you allow time for the switch to soak the heat.

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Just don't bung the switch into boiling water though - will kill it. Put it in cold water and bring to boil.

Hi if you look at previous post i said i had checked temp and it is running at 70 as for connecting the fans and trying them I have done that so the next thing is the thermal switch I have ordered one will let you know what happens when it is fitted