Temp Gauge Disco 2

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the_yorkshireman

New Member
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66
Hi there 2000 disco 2 td5 auto
Temp gauge from cold goes upto about a quater way up initially then 5 to 10 mins later continues to half way up where it stays is this normal just had recon head fitted etc and new thermostat did this before also so not just since head was fitted anyone throw any light on it please
 
the_yorkshireman said:
Hi there 2000 disco 2 td5 auto
Temp gauge from cold goes upto about a quater way up initially then 5 to 10 mins later continues to half way up where it stays is this normal just had recon head fitted etc and new thermostat did this before also so not just since head was fitted anyone throw any light on it please
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Sounds normal to me. TD5 has a complicated cooling system (see manual) but basically it warms up a bit by circulating the coolant through heater matrix and (I think) fuel cooler. The ten minute jump is your thermostat opening, which allows the fully heated water from the engine into contact with the sensor for the first time. Mine has just had a new head and is the same. If you DON'T get the sudden jump to half way, that's when you've got problems - means the stat is stuck and you're probably going to overheat and buy another head gasket!
Incidentally, it's one of the main reasons for anti-freeze. Until the stat opens your rad is cold and subject to wind chill.
 
Thanks the bloke who did the head said it was ok but i am a worrier and tend to like to be 130% sure of things as i cant remember it doing it when i first got it in september. Had the new head on a week now and seems to be fine otherwise still same level of water etc so things looking good and i done about 350 miles in it too with some motorway work at highish speeds for a period of time
 
It is arranged like that to try to get the vital parts of the engine up to best temperatures as soon as possible after starting up.

ALL the coolant circulates from start, up through the block into the head, to the waterpump, but when cold it by-passes the radiator and just goes down through the waterpump and back into the block. This way only half of the coolant gets heated up to start with so it heats up faster.

The temp sender is located so that you can see when the thermostat opens up a bit. At that stage the coolant is up to heat, but it will take 50 miles or more before the engine really starts to "hum".

I suppose you all notice that on long runs?

CharlesY
 
yes ma please i got answers thanks
just found it strange the temp gague only going a quarter way up then a few miles further it going upto its final resting position of half way up the gague
 
the_yorkshireman said:
yes ma please i got answers thanks
just found it strange the temp gague only going a quarter way up then a few miles further it going upto its final resting position of half way up the gague
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It's actually more complicated even than that. From memory (don't have manual here) it circulates to the heater matrix up to 1500 rpm, then other bits like the fuel cooler kick in above that speed. As CharlesY says, it's all down to getting the engine up to temp asap. And it goes without saying that as engine speed is involved it's yet another thing that depends on the electronics (sigh). I find that if I take mine out straight onto a fast run (not a common occurrence in SE London) it heats up much faster. Surprise.
 
I have the m62 right next to me well about a mile off and when i take it on there it usually trakes a couple of miles before its to correct running temp
 
PASTMASTER said:
It's actually more complicated even than that. From memory
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My memory is rubbish:eek: . CharlesY is right (as always). It IS a bit more complex than usual, but there's no electronix involved. Running cold at over 1500 rpm there's a spring loaded valve opens to allow coolant through the bypass. Under 1500 it all goes through the heater until warm enough for the main stat to open. The flow around the stat and bypass is done in a complicated way so that the temperature in the block can be raised by up to ten degrees in cold conditions.

You still don't have anything to worry about - what you're getting is normal!:)
 
PASTMASTER said:
Sounds normal to me. TD5 has a complicated cooling system (see manual) but basically it warms up a bit by circulating the coolant through heater matrix and (I think) fuel cooler. The ten minute jump is your thermostat opening, which allows the fully heated water from the engine into contact with the sensor for the first time. Mine has just had a new head and is the same. If you DON'T get the sudden jump to half way, that's when you've got problems - means the stat is stuck and you're probably going to overheat and buy another head gasket!
Incidentally, it's one of the main reasons for anti-freeze. Until the stat opens your rad is cold and subject to wind chill.
Click to expand...
Hi, I'm a newbie on this forum and just found this post. I have problem with my TD5 that temp only jumps 1/4 way up (goes 1/2 way under load eg when accelerate hard up hill), seems genuine temp as system does not pressurise. I've changed thermostat & flushed system, but no change. Could uncontrolled coolant flow through fuel cooler be enough to keep temp down when ambient cold?
 
Well I have learned heaps from this thread!

But as the TD5 engine is very efficient, LESS heat goes into the coolant cocmpared to a crazy inefficient gas-guzzler. So it takes LONGER to get the engine warmed up, which isn't good for the engine, emissions, power or even economy.

So LR designed the cooling system to do the best it can to heat the engine up quickly as possible and the HEATER (Hooray!), and by design or by chance the temperature gauge sender is placed in the coolant flow where we actually get to see something going on!

I like my TD5 as long as it's running well. Decent power, great economy considering, comfortable, safe, amazing off road, and no sunroofs.

CharlesY
 
geo said:
Hi, I'm a newbie on this forum and just found this post. I have problem with my TD5 that temp only jumps 1/4 way up (goes 1/2 way under load eg when accelerate hard up hill), seems genuine temp as system does not pressurise. I've changed thermostat & flushed system, but no change. Could uncontrolled coolant flow through fuel cooler be enough to keep temp down when ambient cold?
Click to expand...
This is getting a bit complicated for me! What you have is classic symptom of open or missing thermostat, but you say you've checked that, so must be something else. I wonder if you have a problem with the cooling fan - if the viscous coupling is stuck and making the fan operate all the time you will get too much cooling. Recently found mine was stuck on idle and therefore not driving the fan at all - since it was replaced the engine is noticeably slower to warm up. I'd be inclined to run it without the fan blades (there should be a way of doing this although I never have and it won't damage the engine under normal British conditions) and see what happens. I don't think the fuel cooler would make a difference - once the engine is warm this will increase coolant temp.:confused:
 
ALL TD5 Discos behave from cold as his description.

It's the way the system is arranged.

There's nothing wrong with it.

CharlesY
 
CharlesY said:
ALL TD5 Discos behave from cold as his description.

It's the way the system is arranged.

There's nothing wrong with it.

CharlesY
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I'm assuming he means it goes back down to quarter when NOT going up hills. If it goes up and stays up then you're quite right CharlesY, no problem. Once it gets up to temp it should stay there.
 
Pastmaster is correct temp drops to 1/4 after a while following running at load. I've tried running with heater off, blocking off part of my radiator, removing viscous fan and removing fuse for electric aircon fan (electric fan on all time even though have aircon set to ECON), but still same coolant temp at 1/4. Normal dailey commute is 15 min drive for 7 miles on flat country lanes, as not many hills in East Yorks to give engine some load. However, also noticed temp same on longer weekend drives. On old & new thermostat could not see spring valve on radiator by-pass for start-up below 1500 rpm. Radiator was changed, as old one holed with a stone after local off road run at Driffield in May (I've not noticed any signs of blown head gasket from this incident). I love my Disco, and wife thinks I'm looking for jobs to do (not many 'new' vehicles you can work on). Maybe I'm becoming a car hypochondrac, but can't help wondering where heat is going from the engne. Also heater struggles to warm car with low coolant temp (pleased I've got heated seats). Is there a large oil cooler fitted as standard?
 
geo said:
Pastmaster is correct temp drops to 1/4 after a while following running at load. I've tried running with heater off, blocking off part of my radiator, removing viscous fan and removing fuse for electric aircon fan (electric fan on all time even though have aircon set to ECON), but still same coolant temp at 1/4. Normal dailey commute is 15 min drive for 7 miles on flat country lanes, as not many hills in East Yorks to give engine some load. However, also noticed temp same on longer weekend drives. On old & new thermostat could not see spring valve on radiator by-pass for start-up below 1500 rpm. Radiator was changed, as old one holed with a stone after local off road run at Driffield in May (I've not noticed any signs of blown head gasket from this incident). I love my Disco, and wife thinks I'm looking for jobs to do (not many 'new' vehicles you can work on). Maybe I'm becoming a car hypochondrac, but can't help wondering where heat is going from the engne. Also heater struggles to warm car with low coolant temp (pleased I've got heated seats). Is there a large oil cooler fitted as standard?
Click to expand...
I've run out of ideas on this one. All I can say is - mine stays at 1/2 once it has got there (mine is a 1999 TD5 and doesn't have aircon). It even does this in the arctic Yorkshire climate. I'm surprised yours is running so cool but maybe that's just the way it is. Heater on mine doesn't really get working for about 15 mins - even when stat has opened it still takes a while to start blasting out the really hot stuff. Final thoughts/answers:
Manual says: the thermostat housing contains a wax element thermostat and a spring-loaded bypass flow valve.
Oil cooler is standard fitment on LH side of engine behind oil filter.
Fuel cooler uses bottom 4 rows of radiator. There is a thermostat in the fuel cooler T piece to prevent cold climate operation.
It does sound as though yours is just running cool and the main stat is closing to compensate. Remember the temp is measured on the radiator side of the stat, so if the stat is closed the gauge will go down, even if engine temperature is OK.
 
Is there any way of checking that the correct radiator has been fitted, in case fuel cooler works over all radiator not just bottom row? How check thermostat on fuel cooler (I couldn't back flush through fuel cooler)? Is this in hose or fuel cooler? I was thinking of thrying to fit temporary clamp on coolant lines to fuel cooler to check whether restricting flow helps. Many thanks for help.
 
geo said:
Is there any way of checking that the correct radiator has been fitted, in case fuel cooler works over all radiator not just bottom row? How check thermostat on fuel cooler (I couldn't back flush through fuel cooler)? Is this in hose or fuel cooler? I was thinking of thrying to fit temporary clamp on coolant lines to fuel cooler to check whether restricting flow helps. Many thanks for help.
Click to expand...
This is getting right out of my league! It looks like you just have a super-efficient cooling system, which may be a result of the backflushing. Mine has just had a new rad, but I don't think he backflushed the system and so there's probably 105 000 miles of gunge in there. As I said before, the temp sender is situated between rad and stat, so if the stat closes to keep the engine temperature up, the gauge should show the coolant getting cooler. I'd say you only really have a problem if your fuel consumption is poor (although it will be anyway on those short runs) as that would demonstrate too much cool running. On the distances you normally do, it won't really heat up properly anyway.
 
My temperature light works the same way. After 2 miles the needle hovers above the blue. Then at 4 miles it springs upto halfway where it stays come rain or shine. Always worked like this for the last 6 years...
 
OK mine is a Disco 1 but here in Spain its pays to be a gauge watcher, from cold the needle moves steadily to just past halfway mark and hovers there for a few minutes and then drops back to just under halfway once the thermostat opens. On a long hill climb the needle will go to just past halfway and drop back as soon as the hill levels off. It has done this since I owned the vehicle, it does have a Spain spec radiator (bigger tubes) but the viscous fan has been removed and replaced with an electric one. The head gasket was replaced due to a small oil leak and the rad was recored due to some tubes being blocked. Despite repairs/mods the gauge movement remains the same.

regards

Dave
 
Dave 2000 said:
OK mine is a Disco 1 but here in Spain its pays to be a gauge watcher, from cold the needle moves steadily to just past halfway mark and hovers there for a few minutes and then drops back to just under halfway once the thermostat opens. On a long hill climb the needle will go to just past halfway and drop back as soon as the hill levels off. It has done this since I owned the vehicle, it does have a Spain spec radiator (bigger tubes) but the viscous fan has been removed and replaced with an electric one. The head gasket was replaced due to a small oil leak and the rad was recored due to some tubes being blocked. Despite repairs/mods the gauge movement remains the same.

regards

Dave
Click to expand...
The gauge in the earlier discos reflects engine temperature quite accurately in my experience (I sold the 200TDi when it started overheating on motorways). Not the same as the TD5, where the position of the gauge between stat and rad means it reflects the temperature of the coolant at that point, not the engine temp.
 
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