GU TD42 Dash temp Gauge problem

[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.

Attachment 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



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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

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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