GU TD42 Dash temp Gauge problem

[Tip12345]

Help all .
I am having some problems with the Temp Gauge in my truck . It will sometimes go from 1/2 way to all the way in a split second .
I then stop and get out and check with my non contact thermometer . and it ant the case !!! I just for fun replaced the thermostat and temp sender . But it still not playing nicely
with the other bits . Any ideas . Thinking of pulling the dash and sending away for test and repair .

[MB]

Personally Tip Mate I’d suggest you’d be better off investing firstly in a decent aftermarket numbers gauge and attend to our woeful GU OEM ones when time and money permits as a backup thereafter.
From stock healthy new and perfect earth wiring they are horrible at best with my own tests across a few finding roughly 1/2 < > 2/3 a dead spot on the needle from some 70C < > 105C rise and fall IIRC.
Consensus with others found too appears to be they were designed in like that on our GU TD42/T/i’s for owner peace of mind without alarming of such large fluctuations?



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[mudski]

Moving that quick I reckon theres either an earthing issue an eleccy issue of some sort. Not just the engine overheating...

[MB]

Crikey, well done Mr Mark, have been searching to hopefully assist and you’ve jooged my nuffy noggin mate! It was Darren MudRunnerTD I believe that had his OEM guage down on Tassie adventures do the same incorrect fast flick up IIRC. Pretty sure it was well before Balfour Track sludge radiator issues too?


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[mudski]

Yeah could even be just a dodgy contact on the back of the dash. But i do know the earlier GU's like ours are renkown for shitty earth contact which will wreak havok in different ways.

[jff45]

I second the 1st suggestion of getting a real temp gauge, especially for a TD42. Probably also cheaper than getting the whole dash cluster tested..

[Tip12345]

well the engine is not overheating . bottom radiator tank is barely warm .
Down the injector area about 78C .
Looks like the VDO man in Melbourne is not there . Just a recorded message grrr
I need the tacko . repaired as well so will get the whole job done .
I might go looking for the earths and maybe run a couple of extras .
I do have a bit of kit to test the gauge so will dig it out and have a play .

[MudRunnerTD]

Crikey, well done Mr Mark, have been searching to hopefully assist and you’ve jooged my nuffy noggin mate! It was Darren MudRunnerTD I believe that had his OEM guage down on Tassie adventures do the same incorrect fast flick up IIRC. Pretty sure it was well before Balfour Track sludge radiator issues too?


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Yeah i had this issue. Drove me nuts and i did not have a second gauge to cross check. It really got in my head and to this day i lack a little confidence. I replaced the sender twice and got no joy at all. I decided that the error must be in the loom somewhere. I have a Solid Earth too Body and Too Chassis and too Motor. I know this is not the fault. I believe it is behind the dasha nd i was not willing to find it. Just not worth it.

My fix.... I removed the factory sender completely. This makes the factory gauge redundant and now is dead. I used the factory Sender position (Optimum Position) to install an Redarc Digital gauge and willl not look back. It is a pretty big learning curve and it is a direct reading of every degree of change but i just need to get my head around the range of use now.

It could cost a mountain of time and money to fault find it so i made it redundant.

[MudRunnerTD]

well the engine is not overheating . bottom radiator tank is barely warm .
Down the injector area about 78C .
Looks like the VDO man in Melbourne is not there . Just a recorded message grrr
I need the tacko . repaired as well so will get the whole job done .
I might go looking for the earths and maybe run a couple of extras .
I do have a bit of kit to test the gauge so will dig it out and have a play .

What is wrong with your Tacho? This is a very easy repair and i have had to do this too. 20 minute job mate. If you are handy then do this yourself as you will pay through the nose.

If you do pay an Auto Elec please come here and tell us how and where he found the Temp error...... Or do what i did above.

[Cuppa]

Yeah i had this issue. Drove me nuts and i did not have a second gauge to cross check. It really got in my head and to this day i lack a little confidence. I replaced the sender twice and got no joy at all. I decided that the error must be in the loom somewhere. I have a Solid Earth too Body and Too Chassis and too Motor. I know this is not the fault. I believe it is behind the dasha nd i was not willing to find it. Just not worth it.

My fix.... I removed the factory sender completely. This makes the factory gauge redundant and now is dead. I used the factory Sender position (Optimum Position) to install an Redarc Digital gauge and willl not look back. It is a pretty big learning curve and it is a direct reading of every degree of change but i just need to get my head around the range of use now.

It could cost a mountain of time and money to fault find it so i made it redundant.


First up it looks like an electrical fault to me. I have a similar issue with fuel gauges, both main & sub. Am convinced the issue is on the circuit board behind the dash. 90% of the time it reads correctly , but can suddenly lose half a tank in 30 seconds - but I've learned to live with it now, but always record the mileage when I fill up just in case.

Anyhow ..... just wanted to comment that it can be very useful to have more than one temp gauge. (oil pressure gauge too) When I fitted my Redarc temp gauge/oil pressure gauge I fitted the temp sender to a different location than the factory one, & the oil pressure gauge, I used a t piece for the sender unit, retaining the factory sender too.

Whilst in Tassie (perhaps there's a Tassie jinx) I had a couple of weeks where the Redarc temp gauge was telling all sorts of worrying fibs, which turned out to be the connector on the rear of the gauge having come slightly loose. Was reassuring to have the factory gauge sitting in it's usual stationary position & not heading skyward like the Redarc!

When driving in the Mornington Wilderness Camp property off the Gibb River Rd, the oil pressure alarm on the redarc sounded, scaring the whatsit out of me. It was registering zero pressure. It was stinking hot & no shade, but I felt Ok continuing on until we found somewhere to park in the shade some kilometres further on, because the factory oil light had not come on. When we did stop & I looked under the bonnet I found that the corrugations had completely destroyed the redarc sender unit. It was a number of weeks later, after a couple of thousand more remote kilometres that I got a new sender unit in Kununurra & all was good again. If it had been our only oil pressure gauge I'm not sure what I'd have done. Driving with no oil pressure gauge over the boulders & jump ups of the Munja track is probably not something I would have considered.

[MudRunnerTD]

Cuppa yeah I could not justify chasing the fault. I replaced the sender twice and confirmed it was in the loom somewhere so made it redundant.

If it suits me I will put tape over it so I can't see it. It really did my head in and sat on H at idle.

I'm not convinced yet that I have not done damage to the car but we will see. I have to learn the car again now as the factory gauge has a massive blank in the middle of the range where the redarc shows every degree. I just need to learn what is normal.

I run a double gauge in the GQ and took a fair bit of notice on the last trip what the aftermarket was reading against the factory gauge.

[Cuppa]

mudrunner My having put the coolant sender where most with TD42's do - screwed in just above the the water pump, may show cooler temps as a result? (Where is the factory sender located?).
I run with 80 to 90 degrees showing depending upon ambient temps. Only above 90 on long slog hills. I recently looked to see what Redarc gauges cost & was shocked. Did I really spend that much on them? But I am so used to driving with them now I'd hate to be without them . Oil Pressure/ Coolant temp on one, & EGT & boost on the other. Love'em.

81931

[Tip12345]

MY tacho .I have replaced the sender once !
my original Dash quit completely . so I purchased a dash from Patrol parts .
I then sent two dashes away to have one repaired . get the Odometer re set . and the clock knobs changed .
that was a few years ago . so the speedo works and the fuel gauges . and the pretty lights . but no Tacho .and a temperature gauge that does as it likes !
I am hoping I can get the dash fixed . I don't like a heap of gauges . I like it to look stock . all he extras only make it a target of thieves. I have had it smashed up twice to get the radio .
I hope to get to the bottom of it soon . my non contact thermometer is now in the glove box !

[MudRunnerTD]

MY tacho .I have replaced the sender once !
my original Dash quit completely . so I purchased a dash from Patrol parts .
I then sent two dashes away to have one repaired . get the Odometer re set . and the clock knobs changed .
that was a few years ago . so the speedo works and the fuel gauges . and the pretty lights . but no Tacho .and a temperature gauge that does as it likes !
I am hoping I can get the dash fixed . I don't like a heap of gauges . I like it to look stock . all he extras only make it a target of thieves. I have had it smashed up twice to get the radio .
I hope to get to the bottom of it soon . my non contact thermometer is now in the glove box !

You could fit the redarc gauge in a little gauge pod in front of het factory one and it would not been seen from the street and would get rid of the redundant factory one. On the TD42 the Engine Pulse sensor on the front of the motor drives the Tacho and it a very simple thing to replace. I was shocked at the price of a new one so grabbed a second hand one from patrolapart and fitted it. They should be fairly reliable for the life of the engine i think so was happy to risk a second hand one.

Sounds like your gremlins could be bigger than just a sender failure though if yuo have had a dash built from spares off 2. Let us know if you get to the bottom of it for sure.

[MudRunnerTD]

mudrunner My having put the coolant sender where most with TD42's do - screwed in just above the the water pump, may show cooler temps as a result? (Where is the factory sender located?).
I run with 80 to 90 degrees showing depending upon ambient temps. Only above 90 on long slog hills. I recently looked to see what Redarc gauges cost & was shocked. Did I really spend that much on them? But I am so used to driving with them now I'd hate to be without them . Oil Pressure/ Coolant temp on one, & EGT & boost on the other. Love'em.

81931

hi Cuppa,

Just around the corner from that is the factory sender out the side of that housing. THe only problem with what you have there is the length of the sender. If it is tucked up inside that adaptor rather than into the body of the housing then t will be giving you a slightly cooler reading and not as responsive as protruding into the water cell. It gets the job done though for sure.

81935

[Tip12345]

Hi brains trust ,
I did some testing over the weekend. I got a 500 ohm linear pot and made a test rig for the Gauge.
Disconnected the temp sensor and put the pot between the wire and earth .
This is what I found . there is a flat pot in the middle of the gauge …. it goes up nicely to the middle and then gets sort of stuck (maybe)
then goes flat out to the stop .just like when its on the sender .. so the plot thickens what to do .
might get another dash and have a play . there might be some sort of Damper in the gauge .ether mechanical or electronic .
just thinking out loud here ….. could be a capacitor that's not playing nice .

[mudnut]

Gq clusters are easy to get out and trouble shoot, but I have not looked at a GU unit. You should be able to swap out each individual gauge.

[MudRunnerTD]

The factory gauge is designed to sit wgen in the normal range of temperature so a flat spot makes perfect sense. It achieves operating temp then won't move up again until it goes outside the standard temperature range.

This is what is doing my head in with the Redarc gauge, it captures every degree of change so you see the movement. That factory gauge just says ......Normal.

[the evil twin]

Hi brains trust ,
I did some testing over the weekend. I got a 500 ohm linear pot and made a test rig for the Gauge.
Disconnected the temp sensor and put the pot between the wire and earth .
This is what I found . there is a flat pot in the middle of the gauge …. it goes up nicely to the middle and then gets sort of stuck (maybe)
then goes flat out to the stop .just like when its on the sender .. so the plot thickens what to do .
might get another dash and have a play . there might be some sort of Damper in the gauge .ether mechanical or electronic .
just thinking out loud here ….. could be a capacitor that's not playing nice .

Thats exactly what they (factory temp) are supposed to do.

The manuf of almost all passenger vehicles run a suppressed mid range (or normal range if you prefer) so that the gauge isn't dancing all over the place like a direct ratiometer version will.

[Tip12345]

but mine goes to the middle then waits ! straight to full noise eeeek over heating …. no . then stays there . Bugger of a thing .
I have water flow am worried.. not losing any coolant . Any ideas ?

[mudski]

mudrunner My having put the coolant sender where most with TD42's do - screwed in just above the the water pump, may show cooler temps as a result? (Where is the factory sender located?).
I run with 80 to 90 degrees showing depending upon ambient temps. Only above 90 on long slog hills. I recently looked to see what Redarc gauges cost & was shocked. Did I really spend that much on them? But I am so used to driving with them now I'd hate to be without them . Oil Pressure/ Coolant temp on one, & EGT & boost on the other. Love'em.

81931

The tip of that probe mate will barely be inside the s/tat housing, if at all. I have the same probe and they are quite short.

[Tip12345]

I think I will send my dash down to Garry at Ringwood speedometers . sounds like a good guy .

[Cuppa]

The tip of that probe mate will barely be inside the s/tat housing, if at all. I have the same probe and they are quite short.

As I recall the fittings were neccessary to match the Redarc thread to the thermostat housing, with not a lot I could do about it. I have become very familiar with the temperature readings I get, which whilst potentially a bit lower than what they really are, are a 'relative' thing. I would know instantly of there were anything unusual, so happy to leave it as is.

[MB]

I think I will send my dash down to Garry at Ringwood speedometers . sounds like a good guy .

Extremely knowledgeable team, haven’t needed their service for some 20 odd years but do remember top assistance if that was Garry still back then?
I’m sure he’ll honestly agree though that a real gauge is still a very good idea as first point of reference before the fixed OEM dash he’ll no doubt sort out easily too [emoji106][emoji106]



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[Tip12345]

Yes still there .

[MudRunnerTD]

As I recall the fittings were neccessary to match the Redarc thread to the thermostat housing, with not a lot I could do about it. I have become very familiar with the temperature readings I get, which whilst potentially a bit lower than what they really are, are a 'relative' thing. I would know instantly of there were anything unusual, so happy to leave it as is.

yeah i had the same problem. while in Enzed asking for the correct adapter (I took the factory sender with me and the new sender => Make this fit this please...) they cut a new thread for me which i expected to cost me drug money but it was only a couple of $. Winner. While i waited. took a couple of minutes.

[Wizard52]

The factory gauge is designed to sit wgen in the normal range of temperature so a flat spot makes perfect sense. It achieves operating temp then won't move up again until it goes outside the standard temperature range.

This is what is doing my head in with the Redarc gauge, it captures every degree of change so you see the movement. That factory gauge just says ......Normal.

Agree. My factory gauge gets to normal position at 60c (reading from VDO gauge) and never moves no matter what happens. The real gauge (VDO) goes up and down like a you know what depending on ambient temp of course and driving conditions so varies from 80 at normal to 105 when required. It is reassuring to have the backup of factory gauge just in case. The VDO oil pressure gauge is invaluable as well showing 70psi at cold start up reducing to 60psi at crusing speed. I love these 4.2tdi engines.

[MB]

Great Motors Agreed Wizard Mate!
I believe from my torturous eventual findings too you’re running perfectly healthy temp ranges by the sounds of it.
In our local yearly average Victorian climate we settled on an 88C thermostat year round for the family wagon and found 92C highway winter flogging it’s absolute best power and huge fuel saving economy.
FWIW: After extensively trialling 76.5C & 82C & its current 88C thermostats we found next to no difference on its highest 105C summer flogging temps. Only ran stupidly way too cold at idle on the 76.5C tropical global OEM thermostat :-(
My nuffy thread on it all is on here somewhere:-)

EDIT:
The OEM 88C’s idle at 88C
The OEM 82C’s idle at 82C
The OEM 76.5C’s I found can idle as low as 40C in our climate due to their missing ‘Jiggle Pins’ is my honest belief, happy to be tought other reasons but that’s all I could nuffy understand the one single difference [emoji106][emoji106]

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[GUte]

Hi all, sorry for the grave dig!
Just wondering if anyone has any up to date info on the fluctuating temp gauge problems? Also like to add my experience about this, might help someone else in the future

My 2004 GUIV ZD30 has the same problem. It started doing it basically as soon as I bought it a few years ago, I knew it wasn't overheating as it would just to normal temp before the first start of the day. Then constantly fluctuating from normal to boiling, tap on the dash always brought it back down to normal.

Then I ditched the ZD for an LBZ Duramax and the problem persisted...Getting annoyed, I bought another cluster from a very early ZD30, problem gone.. But I wanted the later model GUIV cluster design and have since purchased another 2x GUIV clusters and they all do the same damn thing. I'm pretty handy electrically, sparky by trade and have done quite a few Duramax patrol harnesses. I've checked and cleaned all earth's, connections, added body to chassis and chassis to block straps etc.

I have put fixed resistors in series with the temp wire to ground and the temp still fluctuates so that rules out the sender.
I have cleaned a cluster with contact cleaner and it made it worse if anything, could be a clue? Might look into applying something to the circuit board to help insulate any tracking etc?
I have seen a post about replacing transistors in the board, but I have tested between the faulty clusters and they're all seem comparable.

The early cluster is a different design, much heavier overall so maybe more like the GQ design and can't really compare the two. Less sensitive somewhere anyway!

Any thoughts appreciated!
Thanks guys

[Tip12345]

well here is the update .. pulled the head off . machined the head fitted new valves and hardened seats radiator replaced with a brass copper one . water pump , all back together and working fine .. had just the slightest mark on the head gadget around Number 5 cylinder . reco pump injectors ,, All fine no more problems .. The valves were receding into the head .. so fitted hardened seats . the head was still flat so just took the barest minimum to clean it up . . all good