How hot is too hot?

Just a quick question around how hot an engine runs before it is too hot and breaks something catastrophic...

So I've got a 1987 90 with a 200tdi Disco engine transplant and I wondered how hot your temperature gauge indicates before you start going into a blind panic? Mine seems to run warm/hot nearly all the time.

Anything over half way on the gauge for me and I'm starting to worry. It tends to get up to this level if it has driven uphill (at all) or with any grunt anywhere. Prolonged standing still (like five mins) also gets a hot engine. You know it's getting warm when it's a ice cold day and your feet feel boiling hot due to the engine warming the bulkhead.

Anyway avoiding the obvious "when it's in the red" - simple as it sounds, how hot is too hot?

Ive heard that the land rover gauges are very vague. For instance 75 degree will appear the same on the gauge as 90 degrees.

Therefor a more accurate gauge is required with the correct sender, or as a quick alternative try an infared temp gun.

The engine shouldn't be pushed too hard in a 90, unless you're towing something heavy.
You should be able to (just) keep your hand on the top rad hose when it's at running temp. May be just a slightly blocked rad, or water pump past it's best. A rad replacement is an easy job, and can make a big difference. Best to actually measure the temp frst, as stated above. And don't trust the LR gauge!

Mine sits a shade under half until a big long hill and it will climb,

I chased over heating for ages but i have changed everything rad stat water pump ect, I now think my gauge is wrong as the heaters aren't any hotter and it doesn't smell hot,

Let me guess, the temp sender hasn't been changed ?

200tdi ayre said:

Let me guess, the temp sender hasn't been changed ?

Click to expand...

Haha genius why haven't I thought of that!

Ive become a real temperature nerd lately.
Since putting the disco 200tdi in I've been concerned about the gauge reading very hot so built some electronics to read what is actually happening. Now have a digital temp sensor fitted in the waterflow just under the thermostat, one in the radiator return hose and one ambient sensor under the bonnet.

At tickover, mine takes about 30 mins to get up to temperature (~90 degrees). Having fitted the supposedly correct new temp sender from steve parker, when the water at stat is at 90 degrees, the dial is just fully into the red section. It is hitting 100 when the needle touches the white band at the extreme top. Needle upright actually signifies 70 degrees on my landy.

An infrared thermometer gun is accurate on surface temp, though does under-read when pointed at the thermostat housing (mine showed 65 when water inside was running at 85).
Ir thermometer pointing at the engine block (specifically at the engine number) was surprisingly accurate when compared to water temp.

Attached photo shows what temperature my '85 dial shows...

Hope this helps

Oh, and a 12" fan running drops the coolant return temperature by approx 35degrees. Well worth having in my opinion for when it does get hot.

Mine sits just under your 70 mark 99% of the time but on one strech of road every time it climbs to about your 85 mark but no idea what the temp actually is

All,

be very careful using IR temp gun, they sound fantastic, and they are if used in the right place for the right thing, when you use one remember they have a cone of area they measure over, so the further the distance the bigger the circle of area you are measuring the temp of, even if they have a laser pointer. Also they will measure different depending on the shiness/ gloss of the surface you are measuring ( IIRC it is called emissivity) this is why they often come with a black matt tape.

Just want to make sure no one makes a listake using a cheap IR gun.

cheers

neil

An engine that has it's coolant in it is very unlikely to suffer any serious damage even if very hot. [some aero piston engines of the 1930's were steam cooled to save weight] The problems start when the coolant is lost because of a leak or the temp pushes the pressure beyond what the system can handle. Once it's all gone then the temp rise's very rapidly to a point where damage will happen.

200tdi ayre said:

Let me guess, the temp sender hasn't been changed ?

Click to expand...

This without a doubt!

Mick

Yarp. 200tdi conversion here too, original sender, temp always sits on the mark below red, just learned to read this as normal. It's somewhere on the list of things to be sorted!

Just bin your gauge and fit one that reads in Degrees C rather than apples or bananas. I was once told that the Land Rover gauge will sit in the middle anywhere between 75 and 110 degrees. I've got a cheap TIM gauge fitted to my 300tdi. On a hot day (and believe me, hot days in Malta are hot indeed) it runs at around 85 degrees. It's just above the mid-way point and I'm always uneasy about it. It has been like that since I fitted the gauge in 2004 so it's high time that I stop worrying about it.

What Tim gauge do you have? Mechanical or electrical

Some really interesting replies on here - thanks very much.

...and glad it's not just me who worries what "middle temperature" might mean. I am still none the wiser but if everyone else's engines haven't blown up then the chances are that mine might not too.

(Cursed it now)

Mines has had a new rad on now and runs cooler but still don't know exsactly what temp it is, going to buy an aftermarket gauge as the heaters aren't that hot and it doesn't smell hot neither

Sorry for not replying earlier. I have an electrical gauge. I would have preferred mechanical but if I recall correctly, the thread on the sender wasn't compatible with the thread on the engine.