Author Topic: Engine coolant temperature dropping  (Read 590 times)

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Engine coolant temperature dropping
« January 09, 2018, 10:24:15 »
Hi everyone! As you can probably tell I'm new here; new to the i30 world actually. I bought an ex-fleet (I know...) 2013 i30 1.6 CRDi Blue Drive Active as my first 'big boy' car after my 2006 Fiesta sadly retired a couple months ago and, for the price, I'm very pleased with what I got.

Unfortunately, in the short time I've owned the car, I've had a couple of issues. The first one being a handbrake that didn't hold on a hill - a quick trip to the dealer sorted that out. The second issue though seems a little more complicated. I've noticed that, when I've got my heater and fan at full blast and idling for more than a couple of minutes, or when I let my foot off the gas pedal (downhill for instance), my engine temperature drops significantly, sometimes even dropping a 'bar' or two on the dash. I used my little OBD2 adapter and Torque and the drop is showing at about 20 degrees C (from 88 to about 68).

Now I'm not too clued up on things like this as I've only got experience from my previous car (which got to operating temp and stayed there no matter what) but it doesn't seem normal. When researching the issue it seemed like a thermostat problem, but this can now be ruled out because I had a new one fitted this morning and the problem remains.

I was wondering if anyone here has had a similar issue and, if so, what was it? Any input would be a massive help.


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Re: Engine coolant temperature dropping
« Reply #1 : January 09, 2018, 11:22:37 »
Gave you checked all leads are full home?

Was the rad cap replaced as well?

Did you get a warranty with the car?
If so, ask them to look at it
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Re: Engine coolant temperature dropping
« Reply #2 : January 09, 2018, 12:14:01 »
Apologies but what does full home mean? I'm very doubtful the rad cap was replaced as well so that's worth looking into. Can something that simple cause this problem?

I did get a warranty with the car - 2 months. The thermostat replacement was under warranty thankfully. I was just hoping for some pointers from experienced i30 owners before I go back to them.

Thanks for the quick reply, I'll definitely look at replacing the radiator cap. Are they readily available?
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Re: Engine coolant temperature dropping
« Reply #3 : January 09, 2018, 12:21:14 »
Apologies but what does full home mean?

Wires Not loose or chaffed , making full connection,

Just as an aside.
Are any other instruments playing up, such as  rev counter or panel lights flickering?

Presume they replaced antifreeze and correct strength etc
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Re: Engine coolant temperature dropping
« Reply #4 : January 09, 2018, 13:37:27 »
No the wires all look good. Everything else seems to be working fine, no complaints there. Not sure if it's significant but it makes no difference to the problem if the AC is on or not.

That's a good point about the antifreeze - the antifreeze that was in the car when I bought it (and is still in it) is green. The only green coolant I can find in the uk is Comma g48, which is a 'silicate technology based coolant' whereas Halfords part finder only recommends OAT based coolants. What coolant is meant to be in the i30?
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Re: Engine coolant temperature dropping
« Reply #5 : January 09, 2018, 20:11:32 »
 :welcome: lewo,

I think the green coolant is the good stuff. Mine is green in my 6 month old MY 18 model.
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Re: Engine coolant temperature dropping
« Reply #6 : January 10, 2018, 00:56:08 »
Well, the new car is a diesel, the fiesta I presume was a petrol. Diesels take a lot longer to heat up and cool  down faster because they generate less heat (which is where you get your increased fuel economy from).

Mine can also drop a bar or two commuting at 70kph in the winter, climbs back as soon as I hit a hill.

Heater on full blast will drain the heat from the coolant fast even when driving!
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Re: Engine coolant temperature dropping
« Reply #7 : January 10, 2018, 05:30:15 »
:welcome: lewo,

I think the green coolant is the good stuff. Mine is green in my 6 month old MY 18 model.

Thanks Dazzler, glad to be here  :D Green stuff it is then. It's crystal clear as well so there's really no use changing it out.

Well, the new car is a diesel, the fiesta I presume was a petrol. Diesels take a lot longer to heat up and cool  down faster because they generate less heat (which is where you get your increased fuel economy from).

Mine can also drop a bar or two commuting at 70kph in the winter, climbs back as soon as I hit a hill.

Heater on full blast will drain the heat from the coolant fast even when driving!

You're exactly right. Never thought of it that way. So you're saying it's normal then? That's reassuring. Thanks for your help everyone!
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Re: Engine coolant temperature dropping
« Reply #8 : January 10, 2018, 13:05:00 »
Haven't driven GD diesel, but FD seems to keep temps up quite well in low temps. But that is common issue in cold temps as modern diesels do not produce heat as much as they used to. Many people cover the masks during winter as the engines tend not to heat up. When it goes -10'C I cover also the mask from my FD. Otherwise the engine will not reach the operating temp during my 11km commute. In longer trips it is not an issue. Seen some Italian diesels (fiat) which are required to block the mask during winter as they will not heat up in low temps. One colleague drove his FD diesel in-25'C without an issue. With his Lancia he covers the mask...
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Re: Engine coolant temperature dropping
« Reply #9 : January 10, 2018, 17:27:14 »
I've had a diesel and petrol and once the temp got to the normal it never dipped due to increase/decrease in road speed or use of the heater air con on or off.

The diesel did take longer to reach normal temp than the petrol.
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Re: Engine coolant temperature dropping
« Reply #10 : January 10, 2018, 17:41:40 »
Haven't driven GD diesel, but FD seems to keep temps up quite well in low temps. But that is common issue in cold temps as modern diesels do not produce heat as much as they used to. Many people cover the masks during winter as the engines tend not to heat up. When it goes -10'C I cover also the mask from my FD. Otherwise the engine will not reach the operating temp during my 11km commute. In longer trips it is not an issue. Seen some Italian diesels (fiat) which are required to block the mask during winter as they will not heat up in low temps. One colleague drove his FD diesel in-25'C without an issue. With his Lancia he covers the mask...

Haha it's not that cold here yet... Close, but not quite. It does seem worse in the colder weather. We're averaging between -2 and +4 at the moment.
I've had a diesel and petrol and once the temp got to the normal it never dipped due to increase/decrease in road speed or use of the heater air con on or off.

The diesel did take longer to reach normal temp than the petrol.
Well that's thrown a spanner in the works... I'm wondering whether or not it's worth taking it back to the dealer whilst it's under warranty? Or if it's something that is just part of the car. You're saying it's not normal?

Really appreciate all the help here guys.
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Re: Engine coolant temperature dropping
« Reply #11 : January 11, 2018, 11:28:37 »
This is completely normal behaviour. It does it in mine and every single other i30 we had in our fleet. With the blowers on full it's taking more heat out of the system than is being generated, so it cools down. Especially under low load. As soon as the engine is under stress it goes straight back up again.

Around mine there is an exceptionally long hill where you end up with 0 throttle input. The car will drop several bars during this bit of my journey with the heaters on high, purely because the engine is doing so little work. Couple that with the cold air in to the radiator and it's bound to cool down.

Nothing to worry about! Don't run the fans at full power and it will stay warm :)
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