Disco 300tdi, no heat and fluctuating temp gauge

Hi all,

First post here, so hope this is ok?!

Just got a 94 300 TDI, and there is no heat. and the temp gauge tends to fluctuate, when idling it sits rock steady at 9 o'clock when doing 60-70 it goes up to the red, and then goes back down to 9 o'clock when going through a 30 limit.

I have replaced the stat today, which has made no difference! So what should I try next. I am new to Discoveries, so please go gentle on me!!

Cheers
Nathan

Hi Nathan, I'm having similar problems see my thread "Heat - or Lack of" It may give you some ideas. Pretty certain my problem is a knackered water pump.

Let me know how you get on.....it might help me!!

Sounds like a problem I had when I first got my Discovery. I really wanted it NOT to be the head gasket so changed the stat, water pump and P gasket, flushed through the coolant and checked the micro bore pipes. In the end it was the head gasket. It wasn't too had a job, had it off in an afternoon, skimmed and back on the next day and it's been fine since [touch wood].

Good luck!

Sounds like the rad is fooked. New one about £100 from Paddocks.Fit it yourself [easy job] Its a common fault with old Disco's.

It could just be that both your radiator and heater matrix need flushing out.

Richard Martin said:

It could just be that both your radiator and heater matrix need flushing out.

Click to expand...

Thats what I would do. ^^^^^^^^

Hi thanks for making me feel welcome!!

I think I'll try flushing rad and matrix through first, although fully expect it to be head gasket

But...... How do I flush it through? And where is the heater matrix?

Many thanks
nath

Take the hoses off the rad then flush it through using your garden hose providing its not frozen solid as for the heater matrix it depends on your car but I always try to find the feed pipes in the engine and use these to flush the heater matrix

oh and don't forget to fill it all back up afterwards with a good proper coolant cos just plain water is the worst thing you can put in it

nathsea said:

Hi thanks for making me feel welcome!!

I think I'll try flushing rad and matrix through first, although fully expect it to be head gasket

But...... How do I flush it through? And where is the heater matrix?

Many thanks
nath

Click to expand...

Run your vehicle up with the rad cap off, once it comes up to temp and the thermostat opens you should see circulation, if there is loads of air in the header tank then head gasket is probably gone, and its this air thats foking up your flow


Make sure you have bled it properly, fill it through the header tank but with the thermostat plug out, once it spills out of there run it up until its hot with the cap off keeping it topped up.

nathsea said:

Hi thanks for making me feel welcome!!

I think I'll try flushing rad and matrix through first, although fully expect it to be head gasket

But...... How do I flush it through? And where is the heater matrix?

Many thanks
nath

Click to expand...

The easiest way to flush the heater is to remove the sound deading sheet on top of the engine, then disconnect the heater flow pipe. This is the rubber hose rising vertically from the head at the top rear of the head. Connect a garden hose to the vertical metal pipe you took the hose off and turn the hose on. The rubber tube you took off will blow engine coolant. Give it a minute at full bore, thats it. Refit rubber hose.

This will have the effect of diluting the engine coolant ie not enough antifreeze so the next thing to do is remove the radiator and flush it inside and outside.
On reassembly refill with correct amount of antifreeze thro the rad plastic bung and the thermostat plastic bung and bleed the system thro the plastic bung on the top of the thermostat housing.
This shows how to flush a radiator.

Radiator Flushing - LR4x4 - The Land Rover Forum

Best of luck

hi thanks to all for your replies so far.

I have noticed today that the radiator fan appears to be running all of the time also, having done some reading this appears to suggest it is faulty.. aaahhhh

So do i just need a new coupling and a 32mm cranked spanner?

Would this stop the engine from warming up, and stop the coolant from flowing around to the heater matrix?

Also if i leave the lid of the expansion tank i note that the water gets higher, but no bubbles in it, is this just due to the water getting hotter, or indicative of head gasket?

Cheers again
Nathan

nathsea said:

hi thanks to all for your replies so far.

I have noticed today that the radiator fan appears to be running all of the time also, having done some reading this appears to suggest it is faulty.. aaahhhh

So do i just need a new coupling and a 32mm cranked spanner?

Would this stop the engine from warming up, and stop the coolant from flowing around to the heater matrix?

Also if i leave the lid of the expansion tank i note that the water gets higher, but no bubbles in it, is this just due to the water getting hotter, or indicative of head gasket?

Cheers again
Nathan

Click to expand...

to test thermostat and waterpump, no need to pull things apart, just get it to operating temp, (with leather glove on if ya got soft hands) squeeze top hose and rev engine at same time, you should feel water expanding hose, if not one or tother is shagged.

Fan will run all the time, when engine is at red like you say, fan should be fully engaged and roaring loudly, if not it's shagged.

thanks for the reply... fan runs all the time from startup when freezing cold ? I take it this is correct then?

it is difficult to get car up to temp without taking for a run, and dont want to damage anything, even when left running for five mins the temp gauge doesnt move. Although if i leave the lid of the expansion cap the coolant rises.

have changed the thermostat already, as this is what i thought was wrong with the car when i brought it (how niave!)

when i leave the bleed cap off the top of the rad, i dont see any water moving as such, but if i leave the one off the top of the thermostat housing water gushes out.

does this help diagnose the problem, or should i just sell the motor??!

Cheers
Nathan

nathsea said:

hi thanks to all for your replies so far.

I have noticed today that the radiator fan appears to be running all of the time also, having done some reading this appears to suggest it is faulty.. aaahhhh

So do i just need a new coupling and a 32mm cranked spanner?

Would this stop the engine from warming up, and stop the coolant from flowing around to the heater matrix?

Also if i leave the lid of the expansion tank i note that the water gets higher, but no bubbles in it, is this just due to the water getting hotter, or indicative of head gasket?

Cheers again
Nathan

Click to expand...

I would still flush out the heater and radiator before you do anything else.
The coupling on the viscous fan may well be seized , they often do but it has no bearing on the circulation of water thro the heater or radiator.
If you live in the UK just take the fan off for now 300tdi's run quite happily without them especially in winter. A stuck one could be over cooling the engine. I haven't had mine on the car for the last 2 years.
I'd also go for a new thermostat, they're cheap enough and at least then you know it's not the problem.
The water level in the expansion tank will rise as the water heats but the rise could be due to a head gasket problem. To see gas bubbles in the coolant it's better to take the bung out of the thermostat housing and look there.

nathsea said:

thanks for the reply... fan runs all the time from startup when freezing cold ? I take it this is correct then?

it is difficult to get car up to temp without taking for a run, and dont want to damage anything, even when left running for five mins the temp gauge doesnt move. Although if i leave the lid of the expansion cap the coolant rises.

have changed the thermostat already, as this is what i thought was wrong with the car when i brought it (how niave!)

when i leave the bleed cap off the top of the rad, i dont see any water moving as such, but if i leave the one off the top of the thermostat housing water gushes out.

does this help diagnose the problem, or should i just sell the motor??!

Cheers
Nathan

Click to expand...

All of the above sound fairly normal, although the water in the expansion tamk, yes it will raise and even brim over as it heats up with cap off.

Can you park it on a fairly steep hill, nose in the air and take the bleeder screw outa radiator, just maybe some trapped air in there, and air will always rise to top.

cool, thanks for all your help guys. Just been out to have a look , and being the numpty i am i cannot see how to get to the bottom rad hose, have managed to get the hoses of the matrix assembly fine, so once outside taps thaw out I shall give that a blast through!

thanks again for all your help guys
Nathan

ah also, how do i remove the fan, do i need one of those cranked 32mm spanners to pop that off? Cheers

nathsea said:

ah also, how do i remove the fan, do i need one of those cranked 32mm spanners to pop that off? Cheers

Click to expand...

Viscous Fan Hub Tool 32 & 36mm - 4x4 Store

cheer sean

Sean said:

Viscous Fan Hub Tool 32 & 36mm - 4x4 Store

Click to expand...

Dont' forget it's a left hand thread, so you need to turn it the "wrong way" to undo it.

Although the fan turns all the time it shouldn't have any resitance when the engine is cold. If its not easy to turn the fan by hand with the engine cold and stopped, then the viscous coupling has seized.