(G) Engine Temperatures!

Hi,

Just a quick question of interest, due to the smashing and hot weather we are currently having in the UK!
I have a mk1 Uno 45 (903cc) and was just wondering what the ideal operating temperature for this engine should be. I only ask as I have been a bit concerned with all this hot weather about overheating - I saw many cars pulled over on the M4 the other day!
Anyway, I took her up the M4 on Sunday - it was blinding hot - and the hottest the engine reached was about 94 degrees C - the fan was cutting in all hunky dorey - just wanted to know is this a good temperature for my car to be running at? I assume that as the red line on the temp gauge is at about 120 then this is fine, but knowing that water boils at 100 degrees C, it still concerns me!

Cheers!

Marko

Ideally it should stay at 90 which is halfway when the fan kicks in. A little over is ok but anything other may indicate problems in the cooling system somewhere such as a blockage or leak etc. And make sure that there is enough coolant in the tank as well especially in this weather. I always carry a bottle in my car just in case.

F R O $ T Y

also the water wont boil at 100 degrees as long as the system is pressurised as it raises the boiling point.

worth checking your cooling system though to find where the extra heat is from

Fro$ty and Custard Boy are both spot on.

Most Uno's should run temperatures at a max of 90 degrees, about the mid point of the temperature gauge. In this really hot weather we've been having it's ok if it goes a little bit over that, but the electric fan MUST be coming on and the temperature should drop when it does.

And as Custard Boy says, the cooling system is pressurised so that the boiling point of the coolant is quite a bit higher than 100 degrees. That's why the first sign of radiator failure/ headgasket failure is the temperature gauge shooting up to the red zone. In those conditions the pressurising effect of the cooling system is lost and the coolant boils.

Don't forget as well to check the coolant/ antifreeze strength. The coolant also aids cooling, as well as being a corrosion inhibitor and antifreeze. Correct mix is a 50/ 50 mix. Basically half coolant and half water (de-ionised water is better than tap water if you can get hold of it).

Keep the cooling system in good shape and you shouldn't have any problems.

As mentioned above, mix water and coolant 50/50. There are several advantages of this.

1. Prevents corrotion of iron block and tearing of the aluminium head.
2. Prevents icing in winter. As we know from basic physics, water expands when changing shape into ice, hence it may crack your engine from the inside.
3. Keeps a higher boiling point, which in turn prevents overheating.

Morten.

Sounds all fab then guys - my car only went just above 90 on that very hot day and yes the fan is definitely working too.
Came back down the M4 again today - again very warm, and it was sitting nicely at 90.
So seems that all is well!

Thanks guys!

Marko

Yes Marko,
I'd say that 90 degrees is great... my Alfa 164 runs at 100 during all types of weather.
Standard cooling system pressure raises the boiling point to at least 120 degrees, so, no worries there.

-Alex

Do any of you know what mix i should be using in a 1108 FIRE engine in my cinq?

I always put in about 25% antifreeze to 75% water, because that is what it says on the antifreeze bottle. I noticed when i had my engine apart the block was fine but the head looked badly corroded around some of the waterways. should i be using a 50/50 mix in this engine?

thanks

Phil

Hey Phil,

25% coolant and 75% water is the minimum recommended concentrate. 50% coolant and 50% water will give you better results all around. Greater freezing protection, greater cooling and greater corrosion prevention.

Some furring of the waterways is normal, but not too much.

One problem is the 'hardness' of the water you use, and that depends on where you are in the country and who provides your water. Hertfordshire water is notoriously hard, and can cause problems with limescale. Check inside your kettle for the white crusty stuff!

As the Uno doesn't have a large cooling capacity, it's a good idea to use de-ionised water such as the stuff you use to top up car batteries and steam irons. It's not that expensive, and it doesn't have the impurities in it that tap water does.

Mix it with 50% coolant and your engine will be happier for it!

Chas

If wanting to drain out the coolant, would bleeding in be required once new coolant mixture is poured back in?

Hi Marko,
my engine works for 11 years at these temperatures (85-95) almost all the time when i am in the city, and never had any problems. I just check the coolant level more often especially the summer where the temperature rises at 38-40 C.

Yes, I suppose it does. Fill up with preferred mixture. Start engine and let idle until fan cuts in. This means your thermostat has opened a while ago and let water flush through the engine. This might lead to a "loss" of coolant in the filler container besides the radiator. Top up to "max". Open the bleed screw at the heater intake (in engine bay) and set "open" heater matrix so hot water flushes through it. Let some water pipple out of the bleeder screw. This will let air out of the system. Close the bleed valve. Have fun...

This is just how I remember right now. It might be another bleed valve on different engine layouts etc.

Morten.

If you're going to drain your cooling system you might as well 'back flush' the system as well. Especially if the coolant looks more like pond water than cooling water!

You'll need to disconnect the radiator top and bottom hoses, and also remove the thermostat. Make sure the heater controls inside the car are set to 'hot'. Then place a hosepipe into the thermostat housing, and pump water through the system.

Backflushing is effective if gunge has built up inside the engine block and hoses. By reversing the flow of water it sometimes dislodges muck that otherwise would stay stuck.

If you want to be a perfectionist you could also disconnect the heater matrix hoses under the bonnet and flush that out as well (both ways).

Keep flushing until all the water turns clear. Then do the same with the radiator (it's easy to remove, two spring clips at the top then simply pull it out). Flush it out both ways as well.

While the old one is off you might as well fit a new thermostat as they have a habit of failing every now and then. Then reassemble everything, fill with new coolant/ water mix and bleed the system. My Uno had one bleed screw near the heater matrix hoses, and another on the radiator itself. Be warned that the rubber 'o' rings under the screws might not seal properly after they've been disturbed, so buy a couple from Fiat before you start.

Once done, you'll have a cooling system that will be nice and clean, more efficient, and good for a couple of years before the next change is due.