Temperature Gauge Fluxuation

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lillypad
Posts: 3
Joined: Thu Oct 22, 2020 8:12 am

Temperature Gauge Fluxuation

Post by lillypad »

DMax 3.0 2009
lillypad
Posts: 3
Joined: Thu Oct 22, 2020 8:12 am

Re: Temperature Gauge Fluxuation

Post by lillypad »

Sorry new at this...

Symptoms:
When underway, after awhile and engine is at running temp, temp gauge is at center as always.
When slowing/stopping, needle goes to H then after a few seconds stabilizes again.
Also, temp raises to H when it is placed in to 5th gear.
When downshift to 4th, gauge stabilizes again.
No temp light. No engine light.

With various issues, Ive spent thousands on this car (and I love it), probably more than its worth.

My car has had a very sad experience with a very dishonest mechanic. She is missing a lot of her original parts and she and I have had a hard time since. Here's what I KNOW has been changed (I know my car well, she was all original before)

Radiator was replaced with a plastic one
Clutch no longer the same (growls upon return to me, when clutch is in, no growl)
Evidence that transmission was dropped

Can any of these things cause the temp gauge to behave as mentioned above?

Things "I" have replaced:
SCV sensor
Air Intake sensor (air filter case now missing a clip and doesn't seal properly)

I really need help of knowledgable pros here. My savings is exhausted and my beauty worse than when she left
mydmax
Posts: 1704
Joined: Sat Oct 12, 2013 8:36 pm

Re: Temperature Gauge Fluxuation

Post by mydmax »

I would remove and clean EVERY earthing points where the LOOM wiring (usually ) black has to be connected to the body. Also look/investigate if any body to chassis and battery negative connections are loose, dirty, or been left off and unattached to their original earthing points. I have added additional, chassis, to body panel and to battery neg to eliminate/reduce solar resistive path reasons. If any of the above are a bit sus, when there is a gear change or other electrical change it quite possibly will alter a close gauge item, ie, temp Gauge.
Mine is a 2011 and the growl will be the gearbox tooth and or bearing noise when free running with no load. I use some ( a few Mls) NULON G70 additive in mine to smooth things and make the whole thing last longer. A little of it also assists with change smoothness in both gearbox and Transfer case. Maybe the oil level in the gearbox is low too.

When you say, the radiator replaced with a plastic one what do you mean? They come from factory with plastic resin top and bottom tanks.

What was wrong with the AI sensor? they usually have a very long life but may require to be cleaned sometimes.

If the airbox doesn't seal, then some dirt will enter the intake stream to the turbo vanes and eat it away. Best to fix that one asap. I had to replace a dozer turbo where the intake sucked granite dust. There was NO, vanes left on the compressor wheel of the turbo. None at all, totally smooth touch so cleanliness of intake is very important.

PS, The overdrive unit, ie, 5th gear, is between the clutch and the gearbox. When 5th is selected, the gearbox remains in 4th gear and the OD section in front of the actual gearbox speeds up the gearbox input shaft. This is reversal of position to nearly all other gearing systems in modern vehicles.
lillypad
Posts: 3
Joined: Thu Oct 22, 2020 8:12 am

Re: Temperature Gauge Fluxuation

Post by lillypad »

Thank you for your reply. I will be looking in to these things.
I will take the air intake very seriously, some duct tape for now until I can find clips.

The question about the AI sensor: My truck has intermittently been losing power, not shutting off but the gas when pressed it would not accelerate (and always in a sticky location like the middle of a river or trying to mount a hill, or take the truck off the ferry with impatient people behind). This is why the AI sensor and all the SCV changed.

The jury is still out if either of those things were actually the problem.

Or... if this problem is also related. Its all pretty frustrating.
mydmax
Posts: 1704
Joined: Sat Oct 12, 2013 8:36 pm

Re: Temperature Gauge Fluxuation

Post by mydmax »

The turbo vane controller uses vacuum to alter the angle of vanes in the exhaust ring inside the turbo outer case. It directs more or less so more or less boost is created when there is sufficient hot exhaust gas exiting the engine. IF, the vane control chamber is dodgy,(read diaphram cracked or holed) then the vacuum won't alter the vane ring and less boost will be the result. On my 2011, I suddenly lost all boost and cleared the code with my scan Gauge but also found the vacuum hose where it pushes over the boost chamber inlet pipe was missing. Found it fallen down and as I went to refit it, I realized the hose was too big ID to be able to seal and grip the chamber pipe dia around 4mm. "Factory built in failure". It simply dropped off and now is wound with a wire circle to keep it ON. Your vac pipe may be spilt or loose at that point OR cracked somewhere else in the vacuum line from the vac pump, (on LHS of front engine case). If there is a loss of vacuum you WILL NOT get full boost and it may in fact be minimal sometimes. Look for damaged, spilt, loose hoses. They are all small hoses.

The earlier Dmax often had a fuel pressure regulator fault and it allowed the flow straight back to tank and insufficient pressure for the High Pressure pump. If could be the fault. Any pressure test between the tank pump and the fuel filter, ie, inlet side to fuel filter, would reveal the pressure it is running at. Usually around 6 to 7 psi. Worth a check there! The regulator can be changed fairly easily as it is bolted to rear of High Pressure injection pump. Cleanliness of the job is of paramount importance because it is on the CLEAN fuel side of the filter.

No power can be a result of no boost, or no fuel, burning fuel heat makes boost, so if one is missing or reduced there will be less power developed.
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