Overheating Disco 300TDi

Hello there.

I purchased a '95 Discovery before Christmas and had been really happy with it. It copes beautifully with the slippery drive to the cider orchard and makes it up the grassy hill, even with the road tyres.

Whilst driving up to London the weekend before Christmas I noticed it suddenly got chilly in the cab. When I checked the temperature gauge it had gone off the scale. Luckily I was right next to a petrol station so filled it up with water and carried on my way, carefully checking the temp gauge all the way. No problem.

Drove around London the next day, in traffic, no problem. Headed down to Brighton and got stuck in a 40 minute hold up on the motorway. As I pulled away after passing the accident (NASTY) the heater stopped working and the temperature gauge went quickly up to the red. Stopped, filled up with water and was fine... ...until the next time.

I had the expansion tank sniffed today and there are no exhaust fumes present. Changed the cap and went for a drive. The heater went cold and the temperature gauge went up. I slowed right up and the temp gauge went down again. On the way home the gauge was going up and down and it didn't seem to be losing much water, just what came out with the pressure. One time, as it went up and I was looking for somewhere to pull over it just went down again...

1. No milky-milky in the oil
2. Heater stops working, then temperature goes up
3. Seems to happen particularly under load
4. No excessive bubbling through the header tank
5. No exhaust fumes in the header tank

I'm putting in a new thermostat tomorrow and will flush through the radiator whilst I'm at it.

Any other ideas?

Thanks,

Dominic

Take the fan off and have a VERY good look at the rear of the radiator. Mine did similar, rad looked fine from what anyone could see ... until we took the fan and rad cover off, and most of the rad had blown out fins at the rear, thus cooling maybe 1/10th what it should ... most of the oil cooler side was blown out, which I believe was the 'real' issue ...

Thanks Paul, I'll have a look at that in the morning.

Any thoughts on the best way to flush out the rad and cooling system?

Get the engine up to temp, use the car for a journey then soon after let it idle and get up to temp, if you can take the fan off so that it doesn't get any cooling.

Get the gauge up to about 3/4 then start looking for leaks in the pipework and rad etc...

You need to spot them quickly as any water can steam off the hot metal quickly, with the fan at the moment it will draw the steam away so quickly you won't see it.

Flushing - take the hoses and pipes off and run hoses through them.

If you unto the top rad hose first, then the bottom one, it will very quickly drain and pull crud with it.

If you flush the engine flush it the way the water flows.

Or fill the system with that cooling system cleaner and run that round for a while, then undo all the pipes and let it drain out (faster the better its more likely to draw crud).

Did mine with a garden hosepipe ... but you have to be careful, it's not too high a pressure ...

Long while since I did a full rad, cooling system and heater matrix flush, but recall it as being pretty easy.

So, this morning I went and picked up a new thermostat from Land Rover in Yeovil. I also got some "BARS Flush" and some *more* antifreeze.

I put the flush in and took it for a spin round the local lanes. The heater wasn't working (bbbrrrrrr) and the temperature gauge occasionally went up to nearly the red then dropped back down. After about 20 minutes it went up into the red and it chucked out all the water. I filled it back up and went home, slowly.

Got back and then had to de-freeze the hose-pipe so I could give the engine a bit of a flush. As it was getting late I only gave it a cursory rinse out. Put the hoses back on and fitter the thermostat.

When I went out again the engine was at normal operating temperature within a couple of miles from home - about usual. And the heater started working straight away, and it's never done that before - it usually takes another few miles before there are any signs of hot air.

But a mile or so later the heater had stopped working again. And after about five miles the temp gauge went up towards the red and dropped back down again. Then up and back down again. And again.

I'm going to take the fan housing off in the morning and have a really good look. Any ideas for re-corers in Dorset? Any ideas of anything else I should be looking for? :confused2:

Thanks for your help so far..!

Look for your local SERCK intertruck. They are pretty good:

Serck Intertruck - Welcome

discomania said:

Look for your local SERCK intertruck. They are pretty good:

Serck Intertruck - Welcome

Click to expand...

i dont fink there is one around ere

Just checked their website and there's one down in Bournemouth. I'll bell them in the morning.

I was just talking to a mechanic mate of mine and it reminded me that the rise on the temp gauge particularly happens when the engine is under load, i.e. accelerating hard in 4th or 5th uphill at lowish revs. Ring any bells with anyone yet?

Mine did the same thing .Turned out to be the rad was old and blocked.Put new rad on ,cost around £100 easy to fit.sorted.

I get overheating on mine under hard load in 5th and the gauge goes right up to the red, if I back off or slow down the temp returns to normal. I know mine is down to a nackered radiator, most of the cooling fins have disappeared over time, so its not getting rid of the heat properly.

I have never had the problem of losing water though, and suggest you really need to find where its going.

The up and down gauge sounds like you are getting air trapped in the system as the water level drops causing an air lock.

Ive got a 97 with air con that regularly goes offroad through water and fords etc. Over xmas I had to drive 130 miles and around half way my temp guage started to rise towards the red. Having blown 2 300's before, I backed off and went to the inside lane of the motorway expecting to be on the hard shoulder with a blown engine waiting for the AA (again).
This time tho the temp fell to normal.
I limped to Fleet services where I let her cool down and when I checked the header tank it had'nt lost a drop ????????
When I got to my parents place I had a good old look around to see whats up and couldnt fault it. I then drove 100 ish miles round town etc never putting any strain on her and never had a problem.
On the way back home up the motorway at 70ish the gauge started rising again so I again slowed down and went to the inside lane and sure enuf within a few mins she was back to normal.
Once home I decided to have a good look and took the grill off to have a proper look at the rad.
There was the problem staring me in the face!
Half a forrest of leaves sat between the A/C matrix and the rad and the rad was full of dry mud.
Out came the hosepipe and after several rinses all was clean so thought I would hammer her up the M1 to try and recereate the hot spell and it was gone.
Even with that whirling monster fan there was no effective cooling when the engine was under full load at high revs. I will also add that it was -2 when she got hot on the way home ?????

As far as the heater going cold you must be looking at a blockage of some kind or an airlock.
Please take my advise and dont push it when you are running hot or hope it will get you home as I have in the past . I have killed 2 300tdi motors when they were hot and beleive me it is pretty easy to do.
Beacause the water pump is so high on the front of the engine you only need to lose 2-3 litres of coolant from your system for the pump to be inaffective. It becomes a splasher rather than a pump.
When you fill your system are you just topping up the header tank or filling from the thermostat housing plug?
When you are running hot and you have no heater have you felt the heater matrix hoses to check they are warm?
And before you fitted the new thermostat did you check it in boiling water to make sure it opened? ( On a series 3 rebuild I did last year we tried 3 from diffrent suppliers and none worked!!!)

had the same with mine gettin hot.....was full of mud

I haven't checked the front of the rad... hhmmmm.

Had a look at the back today and it looks nearly new, nice and solid. And a mechanic friend had a look inside and from what he could see said it was good and clean. And I was just about to shell out £150 on a re-cored one.

Even when it's cooled down after a run - like the mile and a half up to the yard - it needs to spew out a litre of water. I'm kinda thinking that gases are 'somehow' getting into the cooling system. I really don't want to, but I'm starting to think that I'm going to have to take the head off.

As you have said its got hot a good few times, I would be very supprised if the head gasket is still good. They are not that bad to do compared to some that ive done.(DOHC engines).
You will need to get an angulator guage or make one up yourself. If you are a competent diy machanic then it should only take you half a day to do the job. If and when you do just make sure everything is good and clean and its always a good idea to get the head pressure tested as being alloy they are prone to internal cracks that you cant see just by looking.
Its always good to have a mate handy for the day too.
1 tip I will pass on is to make sure that the head bolt holes in the block are clean and dry as they will get oil and coolant in them and will compress if left in there giving an inacurrate torque reading when you tighten down.

You could always get a coolant pressure test done by a local garage as this will show up any leaks.

Forgot to mention, we did a coolant pressure test today and it didn't build up excessive pressure even running a 4k rpm for a few minutes. And then didn't lose any when switched off. And then spewed out what must have been a litre of coolant when we took the pressure tester off.

Don,t pay £150 for recore ! Paddocks do them new for £99.94 +vat

In the short time I've had the Disco I've heard nothing but bad things about Paddocks though, many on here! And is that for a complete rad or just the core?

Paddocks are ok as long as your not in a rush!
They do however supply the cheap and nasty tat that is available thats how they are the cheapest in the country. Cheap dont mean quality tho.