Engine is running much hotter in the cold weather

[RossMac]

Chimaera 450

Noticed this morning that the engine warmed up considerably quicker and reached 100°+ (according to gauge) in less than half a mile. Normally temp struggling to get past 70° before I dump it in the station car park after the 2 mile drive. I wondered if the radiator had frozen.

Came back this evening (forgetting about this morning). Sat with engine on to demist the car and temp rose to 110°. In the summer it never goes above 100°

Drove home with temp sitting at 110°, not going higher but fans not kicking in.

Checked reservior and header tank when engine temp supposedly 110° - both fluid. Topped up during the summer with antifreeze so reckon mixture is OK.

What should I do? Not drive it until weather warms up and see if the radiator is split? Call the AA? Drive it down to Fernies (<5 miles)? Temp sensor knackered?

Is the dash temp gauge the same a used to kick in the fans?

[ian8542]

Normally by the time the temp guage has reached 110 degrees C, the expansion tank cap will be letting off steam.
check your guage against something more reliable.
The otter switch causes the fans to cut in and is usually quite accurate, switching at 92 degrees.

[prunus]

I take it you've checked the fuse for the fan?

Mine blew last summer and gave me a worrying few minutes.

[RossMac]

prunus said:

I take it you've checked the fuse for the fan? Mine blew last summer and gave me a worrying few minutes.

nope - will read bible to find out where it is

If the fan fuse has gone shouldn't the temp just kept rising and blown ?

[prunus]

My temp went up to 110 from its normal 80ish and then stayed there

If I recall, the fan fuse is a 30 amp one which also controls the horn?

I swapped it for a 40,no problems since and nothing seems to have melted or caught fire. Yet.

[deeen]

Yes sounds like fans not working, yes start with fuse - cheapest/simplest first. My next guess would be temprature sensetive switch (called otter switch - no idea why - on my 500 it's on top nearside corner of the radiator, just under the top hose ). Easy to check, short accross the two wires that plug in the back of it (with the ignition on) and the fans should start.

[wildeep]

Sounds like your thermostat is stuck shut, this would cause the engine to get hot very quickly. Check to see if the radiator is getting hot. If its stuck then you will get no flow through the radiator and the fans will not turn on as the fan switch is on the rad. The sensor for the gauge is separate to the fan switch.

Dean, its obvious why its called an "otter" switch, because it turns on when the water gets 'otter

>> Edited by wildeep on Thursday 2nd December 09:54

[RossMac]

checked all fuses 20A or above - all fine (largest was 30A).

Configuration of fuses bore no resemblence to any listed in the bible, so no idea where the radiator fan fuses are. I even have some 40A fuses in anticipation.

However - ran the car again (parked) to check. Temp still rose quicker than usual to 70°, hoverred about 90° for 10 minutes, then up to 100° (according to gauge) BUT fans cut in this time.

Could this mean the otter is on the way out and needs replacing?

[chimyellow]

Once the fans cut in did the temperature drop?
and
Does the radiator feel hot? (painfully so if it really is at 100C)

And PLEASE BE CAREFULL when touching anything that could be hot, especially when it is indicating a temperature that is 100C!!!

>> Edited by chimyellow on Thursday 2nd December 18:51

[david beer]

Sounds like the otter( something that lives in water ?) much better off with an adjustable one with a 3yr warranty, also no need to touch any water as it straps to the hose. Deemon tweeks sell them.

[GreenV8S]

The guts of an otter switch are a bimetalic strip. This material is designed to curl slightly as it heats up. In the cold state it's curved slightly, like a (. As it heats up it tries to bend the other way, into a ). It's fitted in compression so it can't do this gradually, it has to stay curved one way until the tension is enough to make it buckle, then it flicks to curved the other way. I think the name 'otter switch' comes from the similarity between the bimetalic strip and an otter's tail.

[RossMac]

ian8542 said:

Normally by the time the temp guage has reached 110 degrees C, the expansion tank cap will be letting off steam. check your guage against something more reliable. The otter switch causes the fans to cut in and is usually quite accurate, switching at 92 degrees.

could be right

No steam even though temp (according to gauge) was supposedly up to 110°+

Could be a faulty sensor as car appeared to be running normally and no cloud of steam in front of me

Left the car at Fernies today

[MacGD016]

My guess is its your thermostat as you are getting inconsistant results. When they start to fail they sometimes open sometimes not and sometimes only open partially.

[RossMac]

Nice and simple - car back after temperature sender replaced

Think I'll see about some other little jobs as car came back valetted

Great job from Fernies