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foxhound



Member Since: 02 Mar 2013
Location: United Kingdom
Posts: 363

United Kingdom 1995 Defender 110 300 Tdi SW Alpine White
300tdi Engine Temperature
Does anyone know the temperature at which a 300tdi engine is most efficient --its optimal working temperature?

Also what is the highest safe working temperature for a 300tdi engine?

thanks in advance 110 Defender 300tdi & Penman trailer with ally exped top and roof tent
Post #1042926 16th Aug 2024 3:57pm
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Will@LRW



Member Since: 04 May 2019
Location: UK
Posts: 181

 1997 Defender 110 300 Tdi CSW Alpine White
Assuming you mean coolant temps. The thermostat is 88c, so +/- 10c will be its happy range. I've done 10 hours driving in 35c and the thermostat housing hardly went over 80c on the laser gun. Exhaust manifold was about 140c

EGT can supposedly cause problems north of 650c, but you'd need to play with the fuelling to achieve that. I've only got to 550 in Spain; uncommon to get over 500 in the UK. LR Workshop
Find a Defender's history and spec: https://defender.lrworkshop.com
Post #1042949 16th Aug 2024 6:43pm
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foxhound



Member Since: 02 Mar 2013
Location: United Kingdom
Posts: 363

United Kingdom 1995 Defender 110 300 Tdi SW Alpine White
thanks, if the temp gauge sender measures the coolant temp yes that's what i'm interested in. so from what you say my gauge can read 88+10 = 98 C and I'll be ok. Any idea what the max temp the gauge could read and the engine not be cooked? 110 Defender 300tdi & Penman trailer with ally exped top and roof tent
Post #1043192 19th Aug 2024 1:57pm
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julian



Member Since: 17 Feb 2017
Location: Devon
Posts: 120

United Kingdom 1994 Defender 110 300 Tdi CSW Alpine White
Your question about max temp before engine damage is slightly misleading -

It's max temp before you loose coolant. The system is pressurized to keep the coolant a liquid at a higher temperature than it would otherwise vaporize at, but there are limits to this.

Exceed that limit (which is based on how well things seal up - your headset tank cap probably being the weakest link) and your coolant will gas and escape.

If you then decide to continue, that's when things start to melt.


But simply loosing coolant won't break the engine. Unless you then continue without coolant.
Post #1043200 19th Aug 2024 3:16pm
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julian



Member Since: 17 Feb 2017
Location: Devon
Posts: 120

United Kingdom 1994 Defender 110 300 Tdi CSW Alpine White
I think, but I've not looked for a while, that you can get different thermostat bulbs for whatever temp you want to run at.

Ie the point at which the thermostat opens and start running flow though the radiator.

So that's another variable - your 300 is unlikely to be on its original part, so it depends on what someone has fitted in the past.
Post #1043201 19th Aug 2024 3:18pm
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julian



Member Since: 17 Feb 2017
Location: Devon
Posts: 120

United Kingdom 1994 Defender 110 300 Tdi CSW Alpine White
Also -



Click image to enlarge



I took this photo a couple of weeks ago. Jet washing a 300 block.

The amount of crud that came out of the coolant ways was surprising.

I would suggest that the speed at which year is taken away from the block and head by the coolant had got to be dependant on the amount of scum / rust flakes in the channels.

What I mean is that's another unknown variable.[/img]
Post #1043203 19th Aug 2024 3:24pm
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Will@LRW



Member Since: 04 May 2019
Location: UK
Posts: 181

 1997 Defender 110 300 Tdi CSW Alpine White
On 300Tdis with A/C, there are two switches on the thermostat elbow sensing water into the top radiator hose. The first triggers at 100c and turns on the A/C fans in front of the radiator. The second triggers at 115c and turns off the A/C completely.

So 115c is where LR have decided its better to cook the occupants rather than the engine! LR Workshop
Find a Defender's history and spec: https://defender.lrworkshop.com
Post #1043224 19th Aug 2024 6:36pm
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