Temperature Gauge Issue 300tdi

[KyleBudd]

At a loss with this one, seeking some advice:

Car overheated due to coolant leak and fried the cooling system (luckily head gasket intact)
Following work carried out:
- Coolant housing replaced
- Water pump replaced
- Radiator hoses replaced
- Gaskets replaced
- Vacuum pump replaced

Since then once the car is running temp builds up to near the top of the gauge (not red) but isn’t affect when idling, can rev the car high, run heating or a/c, temp gauge steady. Only rises when moving, and is then affected by the indicators and headlights causing the gauge to rise and drop.

I’ve checked the thermostat, had a sparky check the earths and that resolved the issue for 2-days but its returned.

Coolant level is good, bled the system, no leaks, pressure is good, head gasket intact.

Last thing I can fathom is the picture attached, the wiring and plug to the temp sender looks fried - I unplugged it and the gauge doesn’t move and plugged it back in same issue. Can’t seem to find a replacement anywhere if you’ve got any ideas or suggestions?191419

[TonyC]

Hi Kyle, and welcome to AULRO.

If the gauge is moving with electrical load, then my guess is an earth problem.

Disco's have two temp sensors, are you sure your looking at the right one?
I assume the second on controls the AC fans, but I'm not 100% on that, my Defender only has one.

The temp gauge in these are "normalised" so thay show middle over a wide temp range, lots of folk fit a gauge that shows true temp.

In my Defender I have a mechanical VDO gauge, my son has a Gauge Innovations block temp and low coolant unit in his Disco.
Engine Temperature and Coolant Level Dash Gauge
– Gauge Innovations (https://gaugeinnovations.com/products/engine-temperature-and-coolant-level-dash-gauge)

There are a few different brands of units that do similar things

As you have discovered, a low coolant alarm is also a good idea.

Tony

[AK83]

high resistance plug/wiring will show higher temps(is my understanding).
I'd give that plug/wire a squirt with wd type spray to begin with and plug back in to see what happens.

I've installed a aftermarket temp gauge too. (actually a gauge kit).
The gauges use VDO type sensors.
For the coolant sensor, I decided on using the bleed plug, so removed the useless plastic bleed plug, and got a 1/2BSP to 1/8NPT(that what sensor types I got in the gauge kit).

Looks like this ... MADMAN adapter (https://shopglobal.madmandevelopments.com/products/12bspplug-1) ..... the NPT threaded coolant sensor needs to be the long type so that it reaches the coolant, not just the vapor.
Anyhow, because of the location, being high up, what would happen is that the connector I used, kept rubbing on the bonnet insulation and would come loose. Coming loose would cause higher resistance and I'd see very high coolant temps on the gauge, but no other indication of heating up. It was obvious what the problem was, so I'd pull over and plug the loosened connector again, and back to normal.
In the end I got tired of it coming loose frequently and finally soldered a wire on the sensor with a small lead and now the plug is not rubbing on the bonnet and all is good again.

I can't remember exactly, but I think the coolant sensor electrical plug is a bullet type connector.

[KyleBudd]

Thanks for the help gents, I’ve got an EngineGuard on order through the local Landry mechanic so just going to hope it doesn’t melt between now and next week.

I have a niggling feeling in the back of my head, *pardon the pun* that the head gasket might just be on its way out, it was checked less than 2000km ago and I’m still praying its electrical based not the effect of the indicators and headlights but it’s definitely beyond my ability now.

Will provide you an update for curiosities sake!

On a side note, where is the best place to mount the aftermarket temp gauge for aesthetics purposes in your opinions?

[Tins]

I have a niggling feeling in the back of my head, *pardon the pun* that the head gasket might just be on its way out,

They aren't usually on their way. They're blown or they're not. Exceptions exist though. How's the radiator itself?Why did it overheat in the first place? An overheat can dislodge stuff in the jackets that can lodge in the tubes. How did you check the thermostat? Has the injector pump tune been altered?
You say it's not losing coolant etc. I think the first question would be, is it really overheating or is it the gauge telling you it is. D1 is better than D2 in this regard, but it ain't perfect. Definitely recommend an aftermarket gauge/alarm. One with EGT would be even better.
Oh, and I've seen an overheat damage a temp sensor.



Will provide you an update for curiosities sake!



Please do, Too few people come back with what they did to fix something ( guilty yer onnor ).

[KyleBudd]

They aren't usually on their way. They're blown or they're not. Exceptions exist though. How's the radiator itself?Why did it overheat in the first place? An overheat can dislodge stuff in the jackets that can lodge in the tubes. How did you check the thermostat? Has the injector pump tune been altered?
You say it's not losing coolant etc. I think the first question would be, is it really overheating or is it the gauge telling you it is. D1 is better than D2 in this regard, but it ain't perfect. Definitely recommend an aftermarket gauge/alarm. One with EGT would be even better.
Oh, and I've seen an overheat damage a temp sensor.




Please do, Too few people come back with what they did to fix something ( guilty yer onnor ).

Tina thanks for the reply mate, whole cooling system got checked through in Sydney by a Land Rover mech, I’d just had surgery so placed it in their hands. They replaced everything as I initially listed they found was damaged, the initial overheating was due to a coolant leak.

I was optimistic it wasn’t actually overheating, however yesterday it cut out completely mid drive around 20km/h just leaving a compound, won’t turn back on. Battery is good, no knocking when trying to turn over, just won’t start. She’ll be on a tow truck before lunch. The saga continues.

[TonyC]

Check the fuel solenoid 12volt line on the back of the fuel pump.

I can't think of much else that would do that.

Tony

[AK83]

.....

I was optimistic it wasn’t actually overheating, however yesterday it cut out completely mid drive around 20km/h just leaving a compound, won’t turn back on. Battery is good, no knocking when trying to turn over, just won’t start. She’ll be on a tow truck before lunch. The saga continues.

Could be the fuel cut off solenoid. Either it's dead, or more likely wiring issue there .. eg. wire/connector come off maybe.

Simple check on the rear side of the injector pump.

[Tins]

I can't think of much else that would do that.

Tony

I can. The timing belt. But I'd go with the solenoid first as well. And it's associated wiring.

[TonyC]

I can. The timing belt. But I'd go with the solenoid first as well. And it's associated wiring.

Kyle said no knocking.
A broken cam belt will have bent push rods, broken rockers, and I'm pretty sure a fair bit of knocking and banging.

Simple stuff first.

Tony

[Tins]

A broken cam belt will have bent push rods, broken rockers, and I'm pretty sure a fair bit of knocking and banging.

Really?? Like this? 191456 I don't recall much banging.


Simple stuff first.

Tony

Agree. Like I said, go with the solenoid first.

[TonyC]

Really?? Like this? 191456 I don't recall much banging.



Agree. Like I said, go with the solenoid first.

Well I've never broken one, rushes to find wood to touch, so I'll defer to the experts, and stop jumping to conclusions 😁

Tony

[Tins]

Well I've never broken one, rushes to find wood to touch, so I'll defer to the experts, and stop jumping to conclusions 😁

Tony

To be fair, I don't hear so well.... But, the car just stopped. Valves were fine. It is an interference engine but the valves are in a straight line with the pistons. The pushrods, rockers, sometimes the rocker shaft, and sometimes the bronze cam followers can be "sacrificial". On mine it was just five pushrods and those rockers. Replaced all eight pushrods anyway.

[Jaquesdp]

same issue here

[Blknight.aus]

the head gaskets themselves dont just about go , but occasionally the bolts relax at operating temp. if your headbolts havent been over re used you can get away with retightening them in the correct sequence one bolt at a time.

the temperature gauge going bananas with the indicators and headlights is usually a body earth fault to the BECM or Dash cluster depending on the year of your vehicle. There is also a junction box attached onto the back of the fuse box, if this gets water in it over time the tracks corrode and if theres mud or dust build up in there as the copper oxide grows tracks can short together which can give you wierd electrical issues, if you disconnect the senders on the block, turn on the indicators and or lights that made the instruments misbehave and they then continuse to misbeave this is a likely suspect.

if the timing belt snaps, you'll bend pushrods or bust rockers occasionally both and sometimes damage a valve. Once the initial carnage is done with you wont hear any new knocking as the cams not turning so new valves are not being introduced to pistons, lift the oil filler and watch the edges of the rockers you can see while you bar the engine over if they move, its not a snapped timing belt, but that doesnt mean the belt isnt on the way and has skipped, Usually that doesnt lead to a no start.

Check the power feed to the solenoid on the back of the IP, if its got 0v with the ignition on then you've taken out a fuse.

if all esle fails, disconnect the solenoid wire and run a direct wire from 12v+ on the battery to the solenoid on the IP and give it a crank with the accelerator held flat, if it still wont fire up crack the injector unions and try again if you dont get spurts out of the injectors you have a fuel issue somewhere. Crack the bleed nipple on the fuel filter and pump away, if you cant get fuel out there then the lift pump has died. Occasionally the little rubber nib on the end of the solenoid gets stuck, you can remove the solenoide remove the nib and spring put the solenoid back and then (with the injector unions cracked open) crank it again, if you're not getting fuel at the injectors at this point you've got issues in the pump or with the timing belt.

Good luck.