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300 TDI runs hot...

El Stiemo

OK the following problem is now bugging me on Muehle...

The temperature gauge gets up to middle running temperature quite quickly, no fuss


when I drive for an extended amount of time (more than an hour, say) it starts going in direction hot...

It then usually runs at about 2/3 of the way to the red, but on the last trip down to the coast she went almost up to the red.

Yes, it is very warm here at the moment, but still, she's not done it this bad before. She is also sensitive to wind.. wind from the back - Temp goes up above the middle, anybody else experienced this?

Suggestions thus far have been:

Flush the radiator (maybe build - up)
get a bigger radiator (mine was built in England, and I know that some of the South African Defenders had other radiators fitted)

Could it be a problem with the thermostat?

I just need some independent advice from here before I go out throwing money at her. She is a 1995 model 300 TDi, no oil consumption, fuel consumption is around 11,5 l / 100 km, stable, regularly serviced... and 215 000 kms.

Any suggestions greatly appreciated.
I've got the same prob, tried changing a couple of ose pipes - helped a bit. I've also changed the thermostat but didn't make any deifference. In my case I'm thinking that the temp gauge isn't giving the correct reading, but I doubt it
Have to agree....the radiator can get blocked externally by mud, dust and even bugs and flies. I had the same problem so took off the front grill and ran a hose over the rad. Some 3 hours later!!!!!!!!!!!! I was still washing bits out.

Ofter that she ran beautifully....don't forget to do the intercooler too!

Hope this helps.
Suggest you try the external blockage first.
Then see what it's like inside. I had the same problem on my Last visit to Namibia. A trip to a radiator specialist and a new core seems to have sorted it.
Yes there is a difference between ZA and UK rads but Ididn't have any problems over there with mine.

A couple of other comments.
Have you thrown away those silly plastic plugs on the top of both the radiator and the top of the thermostat housing.
Look on www.REEDX.net to see wah size the metal replacement is.
Keep your eye on the P gasket behind the water pump.

Thanks for the replies,

AFAIK there is no external blockage, but I will try to give it a hose down. I doubt it though. I always have the grass net on if doing "deep grassing" (as opposed to wading in the UK...) and haven't had it immersed in mud either, but will check.

I'll keep you updated.

She runs well otherwise, it's just that I hate this feeling of - "is this still normal or too hot yet, is it going to go up further, if yes, how far", etc...
Just to throw this one into the mix.

Have you noticed a difference when you have your lights, wipers, radio on? The reason I ask is, if the temp guage shows hot quicker with more electrical equipment on then I would investigate if you have an earthing problem. I'm no expert on this but if you do a search I'm sure there are a few good threads on here.

Andy I believe that he has the same problem as I had on my last visit to Namibia.
I had two other problems that didn't help.

I have a SS grill, I'm told that they don't cool as well as the plastic one. :confused:

The other was as described above. The seed net. Taking mine off did help. However I still had an overheating problem when I got back to the UK in the December. The radiator needed a new core because that was blocked with crud.
I know it sounds daft but have you put your demisters on in the landy with the fans on full blast? see if it makes a difference, has your coolant in the rad been dropping?, look for leaks under the heater matrix for the demister, mine went, took me ages to find it, now ive bypassed it and am removing it completely...............keith
Hi guys

didn't have time to continue on this today as I am still in the office.

However - No, it makes absolutely no difference whether or not electrical equipment is on or off. When driving long distance gravel and tar, I usually have the fridge on, the lights, the radio, the GPS and aircon on. But I can turn off what I want, the symptoms remain the same. It will be fine for the first hour or so and then all of a sudden will go up. What's worrying me is that is going up further, so maybe really partially blocked radiator.

There are no coolant leaks, neither from the expansion tank nor from the radiator itself.

I normally do not drive with the seed net on, I just put it on if required.

Excuse me for sounding stupid, but where is this "heater matrix" thing? I don't think I have ever used the heater, don't know if it works, even... Ahh, the joys of living in Africa...
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The heater matrix is the box that has a small radiator in it, which some of the coolant goes through. Its situation on the top right corner of the bonnet (looking from the front of the car) although for you that'd be the top left. It's a black box that has the two pipes from the engine going into it (the coolant in/out)
I guess you'd probably notice water leaking from somewhere if that was damaged though. Especially as you never use it!

before throwing any money at it , establish whether the coolant is actually getting hot.

The gauge on my 200tdi 110 always reads 2/3 but the fan never cuts in. I checked the coolant temp with independant gauge which showed that nothing was wrong.

Must be electrical , never found out what causes it . yes it worries me travelling along way in the summer fully loaded,one eye on gauge and the other on the road but its been like it for 6 years and 50k miles .
My problem was similar. Used to maintain temperature under normal driving conditions. Climbs up almost to the red when under load (up hills, heavy right foot driving, etc). Checked everything I could, last possibility was the radiator. Removed it, put it on the ground, and half the fins fell off when it hit the ground. Inside was partially blocked too. A recore fixed the problem forever. Now it sticks in the middle no matter what I throw at it, in any temperature.
My problem was similar. Used to maintain temperature under normal driving conditions. Climbs up almost to the red when under load (up hills, heavy right foot driving, etc). Checked everything I could, last possibility was the radiator. Removed it, put it on the ground, and half the fins fell off when it hit the ground. Inside was partially blocked too. A recore fixed the problem forever. Now it sticks in the middle no matter what I throw at it, in any temperature.

I had problems with mine last year, I changed everything. Starting with cheap stuff like the thermostat, temperature sender, expansion tank cap and similar, then working through the hoses, the bubble trap, the fan, viscous coupling, head gasket and radiator. None of which did the trick. It turned out to be a hairline crack in the bottom of the "well" in the top of the expansion tank
The plot thickens.

I've had Mühle at the workshop today and she came back with the following comments:

They disassembled the radiator and the intercooler.

They cleaned the radiator which had exterior blockage of about 50 % of its capacity by... DUST, which had caked because of moisture, thereby solidifying betwen the fins.

They flushed the intercooler as well which had loads of gunk in it.


Will take it for a good hard run on the weekend to find out whether this cures it.

I really would not have thought that there could be so much blockage of the radiator (especially as it was not visible from the outside), it just goes to show you...

Lets hope this solves it. Will keep you updated.
Muehle is having her service again today and the workshop just phoned whereupon I went over there to have a look.


The problem with the hot / warm running had gotten better but not completely gone away after their last cleaning effort. However, I am allergic to high engine temperatures. So I told them to take out the radiator and solder off the side plates and have a look at the radiator underneath.

Oh joy. Rust and gunk everywhere. The radiator inside was also full of dust, caked like on the outside. Is it normal for dust to get in there between the radiator core and the side panel...?

So now she needs to get a recore. Am going for the heavy - duty radiator. Interestingly, I still had the original English radiator in with four rows but narrower at I think 55mm wide for the whole thing, while the South African manufactured Defenders apparently had the same width radiator at three rows only. The new one going in now will be 66 (or 62? mm wide with four rows...

Why would they have fitted different versions? Strange.

She also needs a new water pump as that casing had cracked and it was leaking lightly. Not a train smash as such but I want that vehicle in as good condition as possible as I do not want to be stuck somewhere in Angola between a rock and a hard place.

Not a nice surprise. Will keep you updated how the shiny new radiator performs...

BTW has anybody fitted a VDO temperature gauge instead of the standard one? Electrical / Mechanical? Worth it?

Cheers Frank
I went and fitted a SPA-UK water temperature gauge. Not cheap I will say but very good. I have the analogue version. Needle vertical at normal running temperature. That's 86 Deg C over here. I've just upped the warning ligh as it was coming on at 90deg and worrying me so it's now at 95 deg and I'll see what it's like.

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