Temp fluctuation

[avromo]

Hi, another post, sorry!

I noticed that on the motorway today my temp was on halfway which is what I am used to. But when I slowed down it seemed to go down to 75ish and sometimes even lower, when I increased back to motorway speeds went back to middle, is this usual?

Thanks

[DanMK7uk]

Should sit in the middle really… how long does it take to warm up and get into Center ? Within 10 minutes ? Suspect thermostat if it is any longer

[avromo]

I think it gets upto temp in reasonable time, just randomly drops when I was stopping at junction or going slower, went up pretty quick when I sped up.
I recently changed the thermostat and housing actually
Could it be because I only have water in coolant at moment? Did it after fixing before putting coolant in to make sure no leaks

[metalworker0]

you have a 2.4 rwd which mean it has a viscous fan ... these don't last forever.

They wear out internally become weak and don't turn at full speed, they usually do need replacing once in the lifetimes of a vehicle
A way to see how worn they are ...is to attempt to spin it by hand with cold engine, engine stopped ..there should be some resistance to turn, if they just spin with very little resistance (freewheel) or have rock in them ,...then they have had it .
Going up hills they should be locked and turning at the same speed as the pulley once at running temperature.
looked on ebay are are 2-3 different types ..my description above is for testing the alloy finned type.
found a better description than what i could give :

A thermal clutch fan operates using silicon fluid as a viscous coupling medium. When the clutch is cool and disengaged, most of the silicon fluid is stored in the reservoir allowing your fan clutch to slip relative to your water pump shaft thereby spinning at a lower RPM than the water pump. This saves you money because the horsepower from your engine is not wasted driving a clutch fan when it's not needed. As your engine heats up, the thermal spring on the front of the clutch expands, which opens a valve allowing the silicon fluid to drive your clutch at an increased RPM. This provides more air flow through your radiator, preventing your car from overheating.
A thermal clutch fan operates using silicon fluid as a viscous coupling medium. When the clutch is cool and disengaged, most of the silicon fluid is stored in the reservoir allowing your fan clutch to slip relative to your water pump shaft thereby spinning at a lower RPM than the water pump. This saves you money because the horsepower from your engine is not wasted driving a clutch fan when it's not needed. As your engine heats up, the thermal spring on the front of the clutch expands, which opens a valve allowing the silicon fluid to drive your clutch at an increased RPM. This provides more air flow through your radiator, preventing your car from overheating.

other how to test it :

https://www.wikihow.com/Test-a-Fan-Clutch

Had a couple in the past worn out before 80,000 miles.
so typically if you've done some mileage they will be worn out .

all the best.mark

[avromo]

I have 75k
It does seem to spin easily by hand so maybe on is way out
Do you know why this would cause temp to drop when it should be sat the whole time in the middle
Also as long as it is not going over halfway all I ok to keep driving like this

[metalworker0]

I'm saying when high demand is on the engine .. and in 6th gear (lower revs) if you have such a box .. the viscous fan isn't quite doing its job .
When you slow down its coping as maybe your in 5th, less damand (higher revs fan turning faster) . i don't know how you drive ... so cools well at that time ..

Middle of the gauge
Well that's a matter of the owners here to tell you what's normal ... my van, a connect will only go to the middle of the gauge on the hottest day of the year .. and that would be briefly , most of the time its between one 3rd and the middle.

Thermostats
Well you may think it should keep it at an even temperature... not if there is plenty of air moving over the engine giving extra cooling.. like running down long hills, it may cool down below that the thermostat is supposed to keep it at.. especially in the winter.

All i'm saying is that; this may be the first signs of the viscous fan playing up ... as we approach winter again .. it may be next summer before you see it play up again.. maybe next time even worse ..... its usually a slow and gradual failure for this unit . and i suppose its effected by age as well as mileage.

all the best.mark

[Burn2]

Hello Is it the 2.4 euro 4?

If yes you should read temperature from forscan.
The gauge only show an ect calculated from cht sensor and will stay on the middle if ect calculated is between 75° and 115°.

As it something estimated it could move fast.
But well in normal usage it should stay in the middle if engine is at normal temp.

Are you sure that your thermostat is not stuck open?
Original thermostat open at 88° so at normal drive cht should be near 80/90° ( or more when load in hot summer ).

But you nead to take a look on the temp and see if temp are real.
In your case i would read live temp when driving to see, same in idle and from that lock the viscous fan run in idle to seehow it grow to compare with the nominal.

If viscous is allways engage, you should ear it easly at 3000 rpm when accellerate in 2 or 3 gear.

[knobby1]

Hello Is it the 2.4 euro 4?

If yes you should read temperature from forscan.
The gauge only show an ect calculated from cht sensor and will stay on the middle if ect calculated is between 75° and 115°.

As it something estimated it could move fast.
But well in normal usage it should stay in the middle if engine is at normal temp.

Are you sure that your thermostat is not stuck open?
Original thermostat open at 88° so at normal drive cht should be near 80/90° ( or more when load in hot summer ).

But you nead to take a look on the temp and see if temp are real.
In your case i would read live temp when driving to see, same in idle and from that lock the viscous fan run in idle to seehow it grow to compare with the nominal.

If viscous is allways engage, you should ear it easly at 3000 rpm when accellerate in 2 or 3 gear.

My 2.4 140 never moves from the middle of the gauge...even in the middle of summer where we can have 45C+ temps...CHT sensor readings are always in the 90C +/- 3C range once warmed up.

The CHT sensors are known to fail sometimes....might be worth replacing it if you're worried about it. Pig of a thing to get at on the 2.4 though.

Lord Knobrot