Dreaded temperature.....

Apparently the sensor needs to be matched to the gauge and it's cheaper to change the sensor rather than the gauge. Later defender gauges should give correct temp reading but are relatively rare to find (thus eggspensive).

Agreed and I think it's at the gauge end. I'm away for two weeks (work) but as soon as I get back I'm stripping the dash again and inspecting the earths.........

Keep us posted how you get on NH.

Well thats the first bit underway ... Got the 'existing' sensor out the way, and its definately the 'fine thread' version .. ( 6 threads )... so a new one has been ordered from Steve Parkers.

The existing one is in a bit of a state, and if i've got a handle on this correctly, its basically a variable (by temperature ) resistance switch, and as Gratch rightly said, the cheapest place to try and find the cure, initially.

Thinking further into this today.. and given that loads of people seem to be having the same or similar issues...
my thinking is going along these lines..

1. All was fine with the Reading on the gauge.. sat about half way up the scale normally.

2. One day recently, within a very short disytance of setting off cold from the house.. Temp gauge goes up into the red within 2 miles of setting off.

3. Changed Thermostat for genuine Landrover one ( TWICE ! )
Problem still there, so asked James Martin if airlock could be the problem following stat change ( which he confirmed as a possibility and required checking .. Cheers JM ! )

4. On suspicion of airlock - replaced 'orrible plastic plug on top of radiator with a nice brass "doofer" allowing cooling system to now be filled from bottle AND rad.

5. Tried again -- with now 'confirmed' full & bled system ... same problem !

6. No coolant is being lost - so have kinda ruled out HGF ( Correct to do that ? )...

7. Suspicions now turned to several options as to the cause. :
(a) Cooling System Temperature Sender Unit.
( b) Wiring from the sender to the Gauge
(c ) Gauge itself.
(d) Vehicle earth(s) in general. ( no other faults evident with '90 )
(e) Water Pump.
(f) Sludged up system

Getting plenty of heat through the heater matrix - and into cab.
Got 'hot' pipes either sides of the thermostat.
Rad is hot at top, lukewarm at bottom
No lossses of coolant.
Yet Guage still going into red ( under load on engine .. i.e. 'being driven', not just running / idling on drive )

So if we go back to point 7 .. I'll start with the cheapest options first, and work my way through them ...
I'll let you know what transpires, BlueHaze.

My money, if I were a betting beastie, is on the sender unit / wiring ( earths ).
Be an interesting outcome ! Will keep you informed.

Loads of people seem to have this issue, and the info surrounding the results I got from searching is a bit inconclusive... so hopefully this little exercise may help some other 'non-pro's' in future too

Have you had ya rad flow tested Ninj? Or at least checked to see if the fins are a) still there and/or b) not blocked up- especially from the fan side.

Ninja Haggis said:

Well thats the first bit underway ... Got the 'existing' sensor out the way, and its definately the 'fine thread' version .. ( 6 threads )... so a new one has been ordered from Steve Parkers.

The existing one is in a bit of a state, and if i've got a handle on this correctly, its basically a variable (by temperature ) resistance switch, and as Gratch rightly said, the cheapest place to try and find the cure, initially.

Thinking further into this today.. and given that loads of people seem to be having the same or similar issues...
my thinking is going along these lines..

1. All was fine with the Reading on the gauge.. sat about half way up the scale normally.

2. One day recently, within a very short disytance of setting off cold from the house.. Temp gauge goes up into the red within 2 miles of setting off.

3. Changed Thermostat for genuine Landrover one ( TWICE ! )
Problem still there, so asked James Martin if airlock could be the problem following stat change ( which he confirmed as a possibility and required checking .. Cheers JM ! )

4. On suspicion of airlock - replaced 'orrible plastic plug on top of radiator with a nice brass "doofer" allowing cooling system to now be filled from bottle AND rad.

5. Tried again -- with now 'confirmed' full & bled system ... same problem !

6. No coolant is being lost - so have kinda ruled out HGF ( Correct to do that ? )...

7. Suspicions now turned to several options as to the cause. :
(a) Cooling System Temperature Sender Unit.
( b) Wiring from the sender to the Gauge
(c ) Gauge itself.
(d) Vehicle earth(s) in general. ( no other faults evident with '90 )
(e) Water Pump.
(f) Sludged up system

Getting plenty of heat through the heater matrix - and into cab.
Got 'hot' pipes either sides of the thermostat.
Rad is hot at top, lukewarm at bottom
No lossses of coolant.
Yet Guage still going into red ( under load on engine .. i.e. 'being driven', not just running / idling on drive )

So if we go back to point 7 .. I'll start with the cheapest options first, and work my way through them ...
I'll let you know what transpires, BlueHaze.

My money, if I were a betting beastie, is on the sender unit / wiring ( earths ).
Be an interesting outcome ! Will keep you informed.

Loads of people seem to have this issue, and the info surrounding the results I got from searching is a bit inconclusive... so hopefully this little exercise may help some other 'non-pro's' in future too

Click to expand...

i will tell you my story..... 1985 2.25 petrol, always run in middle of temp gauge, changed to 200tdi, i couldn't get the sender from the petrol so kept the tdi sender, on the drive it goes up to around the 1/4 if i go for a drive around the block it goes just over half, if i drive it hard it went in red.

I then ordered sender pcr6663 this is the same but it don't quite go in the red but very top of white.

Before i put the engine in i flushed the rad(it doesn't look very old) new water pump and new thermostat, i checked the temps with a gun and i am happy with everything, i was taking temps driving a few hundred meters and checking again untill the stat opened and looks good,

I ordered the 2.25 petrol sender but it has a course thread so dont fit but the later course thread senders have a different number so i wonder if this is why

I might see if i can tap my housing to take that sender but im not decided yet.

I saw an adaptor for sale on the deamon tweaks site.

NH - they are exactly the symptoms I'm suffering from. In addition I've changed the old and battered water pump and radiator.

As I said above, on return from the next trip I'm stripping the dash and checking all the earths.

bluehaze said:

I saw an adaptor for sale on the deamon tweaks site.

NH - they are exactly the symptoms I'm suffering from. In addition I've changed the old and battered water pump and radiator.

As I said above, on return from the next trip I'm stripping the dash and checking all the earths.

Click to expand...

i ordered an adaptor but its bigger than the hole

GRATCH said:

Have you had ya rad flow tested Ninj? Or at least checked to see if the fins are a) still there and/or b) not blocked up- especially from the fan side.

Click to expand...

Havent had it tested Gratch ... however, there's no fan ( Kenlow or V/C type ) and has never been one since i had the landy...
It does mean that i can get great visuals through the fins , which all seem to be still there, and pretty much clear. - I am a bit suss over the insides of the core of the rad & intercooler... they do 'seem' to be operating relatively successfully, but I dare say that I wouldn't be the first to believe all was well, only to find out later that it isn't !

One of the searches I found did talk of a lad who had taken both the rad & intercooler out, flushed them to the best of his abilities and understanding.. but later found out that they were the source of the problem... so I will take nothing for granted there, and will be mindful that they can be very much an area for suspicion and investigation.

Hopefully get to the bottom of this over this coming weekend.. fingers crossed !

Cheers for the 'heads-up' on the radiator side of things... I'll definately keep this to the forefront of my thinking too.

just to add to the above too ...
the amount of crud and ****e thats caked around and in the spade connector, plus all the usual oily crap that follows the wire as it disappears into the 'snake' of other cabling, is something quite fearsome !...( i mean off the sender now.. )

So the opportunity to be bolloxing up the voltage is relatively high, i reckon ..
there is a lot of opportunity for something to be tracking to earth, at least partially.. which I reckon could also lead to the same symptoms.
It will benefit from a good clean-up and re-spade-ing / insulating.

GRATCH said:

Try these.

200 Tdi Discovery > 90/110 Temp Sender - 200 Tdi Discovery > 90/110 - Conversions

Click to expand...

Mark-D ... this is the one ( above ) that is the exact match for the fine-threaded one in my 90.

its sold as a 200tdi into 90 conversion sender... is this what you may need >?

Ninja Haggis said:

Mark-D ... this is the one ( above ) that is the exact match for the fine-threaded one in my 90.

its sold as a 200tdi into 90 conversion sender... is this what you may need >?

Click to expand...

Thanks below is from a different thread on here, it why i have not gone with it

chunkymunky said:

Have spoken to steve parker himself today. Prc6663 should have done it. He says he now recommends using disco sender with disco gauge or a stand alone.

Click to expand...

May be of help to some:

VDO temperature sender and VDO gauge | Landroverweb.com

Ok.. Update on the state of play :

New Temp Sender unit arrived from Steve Parker's... so we tackle the task of trying to get to the bottom of this weird issue earlier this evening.
Here's what happened. :

New Sender fitted, no problem...
Refilled cooling system via exp bottle and rad plug, ensured a good 'bleed' and airing..
& happy all is ok.
Fired up Landy ( its -2degC ) and the cab is very very cold ! ... so let it tick over on the drive to get a little bit of heat start to generate...
Gauge lifts off its resting position and starts to register on the 'cold' end of the scale.

Put a light block weight on the throttle, just to increase the revs a tad... as she continues to take the chill off the cab, which allows me to check on the integrity of everything in the engine bay .. all good.

Jump into cab, and give the throttle a wee bit of 'the beans' .. not too much, just to try to get the engine warm...

Gauge rises to between quarter and halfway ( halfway being the old 'normal operating temperature position, before the shennannigans started )....

Gauge continues to climb... gets over 'halfways' and approaches 3/4 mark ... thermostat opens and gauge plummets to 1/4.

Then gauge starts to wildly fluctuate from 1/4 up to right at the far end of the red... back to 1/4, back to half... settles there for a moment or two.. back to right off the scale at the hot end, back to 3/4 and then back to right off the scale at the red end, where it then stops making movements at all, and just sits there.

Well, at least I know the thing is definately not overheating at this point...
I'm getting heat through to the vents in the cab, but not massively hot yet.. and certainly no way the engine is up anywhere near operating temperatures.

Sod it... into the house and have a cuppa... leaving the Landy running on tickover..

Tea quaffed, back out to observe, and gauge still right off the scale.

OK.. lets see what happens under load... so we take off ...
after about 500 yards.. gauge suddenly instantly drops to halfway 'normal' operating temp position.

Then over a 20 mile run, the gauge settles to between the centre normal position and 3/4 hot. -- and doesnt fluctuate over the entire 20 miles.


Confooosed ? hell yeah ! ...
So we've kinda proved ( i think ) that water pump is ruled out, HGF is ruled out,
the new sender unit is working ( 'of sorts', anyway )...

So what conclusions do I draw ? ... difficult to define,..
but what i 'think', is that we're partially sorted.. but I still have suspicions that we may be leaking "signal voltage" ( apologies if that terminology is incorrect ) from the sender unit, and that the wiring from sender to gauge could potentially be still a bit suspect, and the same goes for the gauge itself... it behaved very erratically at the start of the evenings efforts.... although it seemed to setlle under load.

What i dont know.. is if the thermistor ( sender unit ) needed that little 'kickstart' of a proper run to settle it into "working" .. seems unlikely, but in the absence of proper knowledge of it, or previous experience.. I will give it the benefit of the doubt.

So to conclude...
We're in much better shape than we were... we have at least a 'reading' that is in the realms of what is acceptable, and more to the point, 'believable' ...
but i think we have to continue and change out the gauge itself, plus the wiring from sender to gauge, and also try to check the vehicle's main earthing.. although everything else appears to be working 100%

I'll need to drain the system down and refill with the proper concentration of Anti-Freeze solution, and give the beastie another good run,

I reckon we'll change the gauge and wiring.. and see what kind of performace or otherwise, we end up with, as a result.

Its certainly an 'odd fault' ( or it is to me !! )...
and one which now seems partially sorted, but 'could do better'... B+ !!

Will continue you update the thread as this progresses, hopefully to a finish thats totally acceptable !

How annoying....a guage 'crying wolf' int very helpful

My scaling is way off but reliably so. If it gets over halfway I know I'm in trouble!

Its have to confess BB ... its doing my tits in.

I'll get there, but I'm glad i'm not paying me by the hour !

I reckon there's probably a 'sliding scale' of whats considered acceptable, and each landy is (ideally) positioned somewhere along, but within that scale.

Every day's a school day, as they say !

I'd try putting a voltmeter across the gauge to see what it's actually receiving.

Try to fit a new wire from the sender to the gauge. Had the same problems with my 200tdi conversion. Readings of red hot after 3 minutes of driving, fluctuations between 1/4 and red and back in a matter of 30 seconds. Changed the sender, changed the gauge. In the end I made a temporarily wire from sender to gauge to see if that was the problem. And it was. Grounding is not an issue, since the sender gets it ground from the engine.

It's cheap and took me about 20 minutes to fit.

I'm changing the sender and gauge for a vdo set now, because I want to know more about the temp than "rather cold", "right in the middle" or "maybe a little bit too high"

Good luck!

joachim

Thanks Dogsbody and Joachim ..

yes, this is the 'plan' for the weekend... we'll rewire it and probably change out the gauge itself.

I dont know what the 'prescribed voltage' is actually supposed to be ...
but if take it at the sender end from Thermistor to ground, and then replicate that at the back of the gauge from the Thermistor wire to ground, I guess the reading should be 'give or take' the same... and if not...
Robert's yer mothers brother, and the 'suspect wire' is then proven to be a culprit.

Thanks again guys..
much appreciated.

All input regarding this type of symptom / problem is probably good, as it seems to affect lots of 'fenders....

good stuff

Ok .. bit of an update from yesterday.

I took a bit of a deep breath before dismantling the dash, and thought.. just make some more final checks, and I'm kinda glad i did ...

I was kind of 'aware' that I was stressing the wire that emerges from a loom, and connects to the sender ... not by much, but it was just a little too tight for what I considered to be acceptable, so we 'cut back' a little and made a short 4" Flying lead with suitable insulated connectors at either end, fitted that from the sender to the wire, and gave it a good 'protect up' with heat and water retardant tape ( £6.50 a roll, FFS ! ), and ran the vehicle again...

Needle comes up to the old 'standard' halfway position up the scale ... and stayed there for a 60 mile 'stop /start' periodically run... after which it then got another 40 miler, later in the day ... absolutely no problem evident now, and all is operating as it used to, and without issue.

So .. to conclude my contribution hopefully ...
Fault was a very dirty, ( aye, really badly gunked up ) connector to the sender, combined with a goosed sender itself ... and replacement of both has seen a complete return to normal.

I can now get on with the business of waiting for the next 'charachter building issue' to develop with my landy

Thanks to those who helped me -- very much appreciated.

Glad that you are sorted.

I've just driven 200 miles with the needle sitting at the end of the white area. When pushed hard the needle rises to the red then falls back to its normal position. I checked the temperature several times, using my new toy, and it read between 81 and 92 degrees. Therefore it is definitely not over-heating. Why has the gauge started telling me that it has? I've checked the electrics and all seems in good order. I wonder if there is a difference between the TD and 200TDI gauge? Either way it's probably going to be changed for a VDO type.