300tdi defender running hot

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Leechy

New Member
Posts
8
Location
Cumbria
Hi all, I’m having some difficulty with my defender and wondered if anyone could share some wisdom.

I have a 1991 defender 90 with a discovery 300tdi in it which I’ve owned for about 6 months and been daily driving for about three Recently it’s started to run on the upper end of the temperature gauge. it has an electirc fan instead of a viscous it doesn’t work currently but has run fine without since I bought it. I’ve done the water pump thermostat and replaced all the hoses but this has not helped and is now running slightly hotter than before. when trying to bleed it the header tank would fill but the radiator would only fill so far before stopping so I’m thinking possibly a blocked radiator but then have always seen some things saying it could just be the temp sender reading wrong as it’s from a discovery or just a bad earth

has anyone else had similar experience?
 
Leechy said:
Hi all, I’m having some difficulty with my defender and wondered if anyone could share some wisdom.

I have a 1991 defender 90 with a discovery 300tdi in it which I’ve owned for about 6 months and been daily driving for about three Recently it’s started to run on the upper end of the temperature gauge. it has an electirc fan instead of a viscous it doesn’t work currently but has run fine without since I bought it. I’ve done the water pump thermostat and replaced all the hoses but this has not helped and is now running slightly hotter than before. when trying to bleed it the header tank would fill but the radiator would only fill so far before stopping so I’m thinking possibly a blocked radiator but then have always seen some things saying it could just be the temp sender reading wrong as it’s from a discovery or just a bad earth

has anyone else had similar experience?
Click to expand...
Faulty sender and/or gauge would be a possibility.

I find an infra red heat gun is useful for cooling system faults, you can see the actual temperature of parts of the cooling system.

To fill the cooling system, you need to remove the plug from the top of the radiator as well as filling the header tank.

Reverse flushing the radiator with a garden hose never does any harm, and you will see how much gunk comes out of the rad, and possibly clear blockages as well.
 
Thank you I’ll try with an infared gun, yeh I had both bleed plugs off but the header tank would overflow and the radiator wouldn’t fill up the radiator is also cold in the centre when running
 
Leechy said:
Thank you I’ll try with an infared gun, yeh I had both bleed plugs off but the header tank would overflow and the radiator wouldn’t fill up the radiator is also cold in the centre when running
Click to expand...
Remove top & botttomhose to make sure the rads not blocked. Was through with hose. Once cleaned re fit pipes.
Leave the 1 bung in the rad & remove the 1 from the engine as it’s higher. Then fill header till it comes out the top of the engine.
Try this to get out the air
 
How good is your radiator? Try poking the fins with your finger and see how strong they are. On a RRC V8 I had and my Defender the radiators looked OK. On touching them with a screwdriver or my finger the fins turned to dust. After swapping them you can't help help poking the fins to see how bad they are, and in both cases about 75% of the fins turned to dust.

The V8 radiator replacement wasn't cheap, but the Defender cheap and nasty replacement was around £100 - obviously you could go for a better one!
https://www.ebay.co.uk/itm/RADIATOR...2349624.m46890.l49286&mkrid=710-127635-2958-0
I really wanted an Ali one but lead times were too long when I was looking. I ordered this one via click and collect and had it in less than 24hrs!
 
They need to be filled in a certain order to get the air out until it has reached temperature for the first time, but assuming it is reaching temperature then dont worry about that bit.
Next is never assume the new stat is any good.
I am assuming for the first three months the engine temp was reading okay? if so that sort of rules out sender/gauge issues, but you can confirm that with the temperature gun.

The its onto the ugly stuff like head gasket failure, is it using any coolant? is it pressurising when hot? when hot and you remove the oil filler cap does it chuff like an old steam train?
Good news is head gasket is easy to do, no need to skim head unless its fubar, head bolts can go again.

As for no cooling fan, that is going to bite you in the arse at some point, and could possibly have caused the issues you now have.
Its a real fine line between okay temp and kin hell shes cooking, been there done that more than once!
I have even coked a 200 and that really takes some doing, 300 not so forgiving.
 
lynall said:
They need to be filled in a certain order to get the air out until it has reached temperature for the first time, but assuming it is reaching temperature then dont worry about that bit.
Next is never assume the new stat is any good.
I am assuming for the first three months the engine temp was reading okay? if so that sort of rules out sender/gauge issues, but you can confirm that with the temperature gun.

The its onto the ugly stuff like head gasket failure, is it using any coolant? is it pressurising when hot? when hot and you remove the oil filler cap does it chuff like an old steam train?
Good news is head gasket is easy to do, no need to skim head unless its fubar, head bolts can go again.

As for no cooling fan, that is going to bite you in the arse at some point, and could possibly have caused the issues you now have.
Its a real fine line between okay temp and kin hell shes cooking, been there done that more than once!
I have even coked a 200 and that really takes some doing, 300 not so forgiving.
Click to expand...
Also begs the question of why they had to fit the electric fan in the first place. Viscous fan works pretty well.
 
Turboman said:
Also begs the question of why they had to fit the electric fan in the first place. Viscous fan works pretty well.
Click to expand...

To be fair the 200 and 300 viscous fans do really cut into what little power the engines have especially when the weather is cold.
Hill start loaded in winter in a manual 300 not fun at all.
 
lynall said:
To be fair the 200 and 300 viscous fans do really cut into what little power the engines have especially when the weather is cold.
Hill start loaded in winter in a manual 300 not fun at all.
Click to expand...
That is true. But I haven't had great experience with the electric fans either.
I fitted twin Kenwood fans on my Ninety, but they were noisy, and took a lot of power on the electric side, so I took them off and put the viscous and cowl back on.

Hill starts, or any starts with a loaded trailer, I used to pull away in 1 low, then up through low range to 3 low, then rolling change into 2 high when I was on the flat. A 19j is less powerful than a Tdi.
 
Check that she is actually running hot

My 300 gauge slowly creeps up when input my lights on due to a bad earth somewhere (il fix it one day ! )
 
Turboman said:
That is true. But I haven't had great experience with the electric fans either.
I fitted twin Kenwood fans on my Ninety, but they were noisy, and took a lot of power on the electric side, so I took them off and put the viscous and cowl back on.

Hill starts, or any starts with a loaded trailer, I used to pull away in 1 low, then up through low range to 3 low, then rolling change into 2 high when I was on the flat. A 19j is less powerful than a Tdi.
Click to expand...

I remember my first M reg 300 manual disco in summer so a/c on, steep hill start, 7 people on board, poor clutch!
 
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