Temperature read normal while driving.

[Blaster]

So today in this heat of 37C my temperature gauge got to normal while driving at 40ish.

[Tuga2112]

So today in this heat of 37C my temperature gauge got to normal while driving at 40ish.

the car was test driven in death valley as part of overheating testing as far as i heard. it does kinda check out.

[lotusflasherman]

What's "Normal"? Depends on your thermostat.
I use a 89°C thermostat (Diesel Astra Van) as it gives a better heater for winter use and better engine efficiency (from when I did Thermodynamics at college). Never had problems in summer, but it does get to 'Fans On' sooner.
I did some measurements years ago that's on an ancient thread but in this heat it's topical so I'll repost the info. As long as the fans work there shouldn't be a problem. They switch On around 97° and OFF just below 90°
"H" is 110°C and coolant will boil around 125°C with a 15psi pressure cap - though the head may have local hotspots around the exhaust valves that reaches that while the remainder is lower so I wouldn't rely on that extra 15°.

temp.jpg

[chrism]

...and in case anyone's wondering 15psi = 103kPa, and our our 120kPa caps = 17.4psi.
(Presumably this is the origin of the '120' etched into the coolant header cap?)
So lotusflasherman, I reckon you can stretch your thermodynamic efficiency a stage further; many Vauxhall apps seem to be 140 kPa...

[lotusflasherman]

...and in case anyone's wondering 15psi = 103kPa, and our our 120kPa caps = 17.4psi.
(Presumably this is the origin of the '120' etched into the coolant header cap?)
So lotusflasherman, I reckon you can stretch your thermodynamic efficiency a stage further; many Vauxhall apps seem to be 140 kPa...

Lotus Service Notes Section TDH Page 5 - "Header Tank Pressure Cap 110 kPa (15 lb/sq.in). " ... is what I was quoting. Personally, I'd have rounded 15.954 psi up to 16 psi, not 15.

Your presumption that the 120 means 120kPa is correct and my two SE's on my drive both have black '120' caps - my first SE, long gone, had a yellow cap marked 110.

The Service Notes also say Fans On at 110°C and Off at 103°C (KD.4 Page 7) but mine were 97 & 90 - whether my Rad Fan Thermal Switch was suffering from Premature Ejac ... er .. Operation I don't know but I was quite happy it was 'too early', better than 'too late'.

Lockwood supply different colour instrument backgrounds and give more useful information than Lotus/GM's "Cold or Hot".

Lockwood temp gauge.jpg

[HJ2]

… but the gauge is not as lineair as the lockwood dial

[Simon_P]

The Service Notes also say Fans On at 110°C and Off at 103°C (KD.4 Page 7)

110oC is the 3/4 mark on the standard dial and set-up.

[Grosbard]

I have the normal thermostat installed, but a different radiator fan thermal turn-on switch installed. My fan turn-on switch is a 185/195 Fahrenheit unit which means 85/90 in Celsius. So when I'm driving and it's hot outside (I live in California), the water temp is pegged at the 1/4 mark or maybe a tiny bit higher (which Lotusflasherman's post above describes as 75 Celsius). So, I'm wondering, is this too cold for optimal engine health? My intuition is that the thermostat wouldn't even open if the engine wasn't warm enough, so my situation is totally fine, but wanted to get other opinions on this. Thanks!

[FunElan]

I have the normal thermostat installed, but a different radiator fan thermal turn-on switch installed. My fan turn-on switch is a 185/195 Fahrenheit unit which means 85/90 in Celsius. So when I'm driving and it's hot outside (I live in California), the water temp is pegged at the 1/4 mark or maybe a tiny bit higher (which Lotusflasherman's post above describes as 75 Celsius). So, I'm wondering, is this too cold for optimal engine health? My intuition is that the thermostat wouldn't even open if the engine wasn't warm enough, so my situation is totally fine, but wanted to get other opinions on this. Thanks!

Kieran - does it rise at all when you are sitting and idling? Or do the fans come on at the 1/4 mark

[Grosbard]

Generally, I'd say the temp is locked at exactly the 1/4 mark when the car is moving.

The only time it goes higher is when I'm idling or if I'm moving on a pretty warm day (above 80 Fahrenheit (about 27 C)). In those situations the temp is locked at a tiny bit past 1/4 (I'd estimate about 5/16ths). I believe that's the point that the fans kick in.

The data above tells me that I'm probably not "over cooling" because on cooler days when I'm driving (and therefore the fans are NOT on), the temp is pegged at 1/4, which must mean that 1/4 is safe. But wanted to see if I'm thinking about this properly.

[FunElan]

Generally, I'd say the temp is locked at exactly the 1/4 mark when the car is moving.

The only time it goes higher is when I'm idling or if I'm moving on a pretty warm day (above 80 Fahrenheit (about 27 C)). In those situations the temp is locked at a tiny bit past 1/4 (I'd estimate about 5/16ths). I believe that's the point that the fans kick in.

The data above tells me that I'm probably not "over cooling" because on cooler days when I'm driving (and therefore the fans are NOT on), the temp is pegged at 1/4, which must mean that 1/4 is safe. But wanted to see if I'm thinking about this properly.

You are. Seems like Eddie just didn't want to watch the gauge crawl up or ever have any thought of overheating. Technically, it's not bad for the engine to run warmer than 1/4, but normal operation is that it climbs to 3/4 (with stock sensor) and then comes back down with the fans or motion (airflow).

Back to your discussion, OP

[Grosbard]

Eek! I hope I wasn't hijacking this thread. If so, I sincerely apologize!