Hi
I spent last night reading through the many posts on this.
Overheated out of the blue on a short run so i started by changing the sensor, then the thermostat ,then i replaced the radiator, then the water pump, i changed all the water pipes for new, i tried all of the various methods of bleeding air from system at least 4 times
It has no oil in water or water in oil, i get no bubbles in the header, i have good exhaust fumes, it sounds lovely! Heater blows hot air into cabin no problem, it loses no water.
Gauge gets up to hot slowly but gets all the way up and it does appear to be hot in the header tank but not boiling...the radiator doesn't get that hot but is warm and all pipes are warm...it feels to me that its not circulating properly but i cant keep flushing it (done 3 times) and not sure what else to change.
I can think of nothing else but gauge is wrong or head gasket (i have never had all of the above with a failed head gasket).
Anybody any ideas i have missed..i think i will change temp sensor again and finally the head gasket but was hoping some one would know better!
Any Advice gratefully received as ever
Matt

Doesn't sound 'hot' to me ....

Why do you think it's overheating ?
There are two types of sensors/gauges, you need to match the pair.
The key is the colour band on the sensor, is yours green or black ?

'Normal' is around 90 degrees C, you can test this by filling a cup with boiling water and dangling the sensor in it. The green wire (from the gauge) has 12V on it and the body is ground. the ground wire can go in the hot water but not the power/green wire.
If the gauge goes up to the Red, it's the wrong combination.

I've just changed mone for a Stack, if you want a working pair I can send you my old set for £60.

A laser temp gauge gun is cheap
I would check temp across the entire radiator - while motor is running and hot -
In my Saffa country its called a "tropics" mod - where 80 or 90 %blockage is put in the radiator side tank - closest to the intercooler - to force water to travel thru the whole width of the radiator

You can see the "blockage" from the top bung on the radiator

I can't see any reason why the "tropics" constrictor isn't applied to the mud island vehicles as well

miktdish said:

Doesn't sound 'hot' to me ....

Why do you think it's overheating ?
There are two types of sensors/gauges, you need to match the pair.
The key is the colour band on the sensor, is yours green or black ?

'Normal' is around 90 degrees C, you can test this by filling a cup with boiling water and dangling the sensor in it. The green wire (from the gauge) has 12V on it and the body is ground. the ground wire can go in the hot water but not the power/green wire.
If the gauge goes up to the Red, it's the wrong combination.

I've just changed mone for a Stack, if you want a working pair I can send you my old set for £60.

Click to expand...

Thank you my gut feeling is its not overheating too...i have changed sensor for a 300tdi one which i believe was green the gauge is the old 85 4c engines i would guess as it a bit of a triggers broom.
That gives me something to try..cheers

D1Nut said:

A laser temp gauge gun is cheap
I would check temp across the entire radiator - while motor is running and hot -
In my Saffa country its called a "tropics" mod - where 80 or 90 %blockage is put in the radiator side tank - closest to the intercooler - to force water to travel thru the whole width of the radiator

You can see the "blockage" from the top bung on the radiator

I can't see any reason why the "tropics" constrictor isn't applied to the mud island vehicles as well

Click to expand...

I have one somewhere i will dig it out...sometimes you need someone to tell you the obvious and actually test the temperature!

farriermatt said:

I have one somewhere i will dig it out...sometimes you need someone to tell you the obvious and actually test the temperature!

Click to expand...

Having said that - I had a new mechy that I thought was good do a cam belt change - and while you there flush radiator and new hoses etc

Turns out he didn't put the rubber linings on both sides and bottom of the radiator so nice cool African air was just spilling out the sides instead of going thru the radiator

Once I figured that out problem solved of running hot at the 120 kph mark

Sometimes it's the basics

farriermatt said:

.i have changed sensor for a 300tdi one which i believe was green the gauge is the old 85 4c engine ... <snip>

Click to expand...

Try a black one AMR3321 ... rather than the green one AMR1425

miktdish said:

Try a black one AMR3321 ... rather than the green one AMR1425

Click to expand...

Yeah I just researched and black for defender 300 and green for disco 300… mine is a defender engine… looks like I’ve changed a lot of bits for nothing!.. I hope. I’ll know on Tuesday when it arrives..

Apologies for this being my first post after lurking for many years - and disturbing your thread, but I have a similar issue in my '87 19J-converted to 300tdi 90.

Firstly, it had the wrong temperature sender (the green band instead of the black one), which then solved the problem with the gauge shooting up past the red zone, but alas, it did not keep in the middle at normal operating temperature, but bordered just on the red zone, sometimes going slightly into it, but it does, at least, not go past red! I assume this will be the same case for yours!

Assuming my motor is not overheating or running somewhat hot, I have resorted to thinking it must be a difference in gauges between 19Js (and NA diesels) and 300tdi's due to the difference in opening temperature of the different thermostats between the engines that must mean the white zone (or middle) of the 19J original gauge is set to a slightly lower temperature than a 300tdi gauge.

If this is the case, could this then mean that the 19J gauge, coupled to a 300tdi temperature sender and engine, at normal operating temp. reading hot/at the red zone - instead of the middle like it is supposed to? Or perhaps this is all wrong and gauges do not work like this?

Any updates on your issue? Did the new sender sort it out?

Also, any advice on differences between gauges for 19Js and 300tdi's is welcomed heartily!

It was purely black top is better than green top!… sender and all fine now..I did buy a 300 fuel gauge (came with a 300 temp gauge) that fixed my fuel tank float sender problem!.. this mix and match stuff gets expensive.