Sigma running hot

[Old Git]

My sigma has until now run at a rock steady 70 -75 degrees or so in all conditions except heavy traffic. Last 2 mornings it has been running most of the time at just over 80 degrees indicated, with the radiator fan running most of the time. (It’s a little erratic and sometimes does drop to “normal”.) Air temperatures have been low. There’s plenty of coolant in the header tank, although it did need half a pint.

 

Question – is it the sender for the gauge or is it something else e.g. a duff thermostat. But don't thermostats fail safe (fully open) so the angine runs cool?

 

Thoughts – if the radiator fan switch and the gauge share the same sensor, then the problem could simply be the sensor. If the fan switch has its own sensor, then the engine really is running hot. Am I right, and does anyone know if the fan switch shares the sensor with the temp gauge?

 

 

Tim N

[Eccles]

Hi Tim,

 

From memory I think the fan is controlled by the ECU and therefore by the gauge sender.

 

Interesting that yours used to run at about 70-75, my Sigma takes a long time to warm up (could be the cold mornings) and then never goes below 80+ with the fan cutting in and out while driving along.

 

Out of interest does yours have the coweling(?sp) fitted? Mine does, but I have noticed that these have been removed from the build manual and the fan is now mounted directly on the back of the rad again.

 

I was thinking my car was running hot and needed looking at but your problem sounds like a dicky sender (or connection) for it to happen so quickly. Any chance you could let me know what you find?

 

Regards

Ivan

[Old Git]

Will do. Can't remember if the fan is in a cowl, and the car is all wrapped up now!

 

cheers, Tim

 

Tim N

[The Boy]

Hi Guys

 

My 150 has the cowel and warms quite quickly - is the modean fitted to the 125 as well. Believe this is to aid warm-up.

 

Mine was consistent at 80 most of the time as well. Back at CC for a repair at the mo ☹️

 

Old Git - have you changed oil type, or added an additive? I've been tald this can effect oil temp.

 

Its finally finished :-) 3500 miles completed. Back at CC now :-(

[gfinlayson]

I also have a Sigma 150 that warms fairly quickly up to 80, and then stays there without the fan kicking in, unless I have to stop and idle for a bit. I never considered 80 to be hot for this engine, given that the K series fan did not kick in until it reached 94 (IIRC)

 

Graham

 

Sigma 150 - SE07VEN

[John Howe]

Don't know the engine bay on a Sigma but nomally the fan switch is built into the radiator i.e. is separate to the water temperature sender.

 

This tends to be a fairly accurate switch, therefore if the fan is kicking in where is hadn't previously then it might be fair to assume that your car has started to run hot.

 

Could you have created an airlock when you added additional coolant.

 

JH

Deliveries by Saffron, the yellow 230bhp Sausage delivery machine

[Old Git]

My main concern is that it definitely seem to be running hotter than previously, and this was before I topped it up. No additives etc. I haven't had it out since last weekend but I'll give it another blast tomorrow, weather permitting, and if it's still seems hot I'll have a chat with James G at CC. Thanks for the posts

 

Tim N

[Old Git]

Got to the bottom of it. Small but persistent leak from top seam of radiator.

 

Engine temp does seem sensitive to volume of coolant available even if level in header tank is only a little below min, so that probably the cause of running hot and fan switching in/out. One other side effect seemed to be that the thermostat wasn't effective at keeping the engine at a constant temperature - gauge showing anything between 60 & 80 on a run even with loads of coolant available.

 

Rad changed by CC and all seemed back to normal on the way home

 

Tim N

[Steve Cornford]

Hi Tim,

Same thing happened to me. Twice!

Got my 3rd radiator fitted on 2nd January.

Lets hope we have used up the faulty batch now.

 

Sigma SteVe

[CageyH]

OG,

 

FYI, wax thermostats tend to fail closed, not open.

So if the temperature continues to rise, stop!

 

Only dead fish go with the flow....!

[Old Git]

Thanks, Cagey... worth knowing

 

Tim N