2003 VY 3.8 constant spike in temperature

[jays2]

Update :
took the VY for a test drive today. Went great for 145km.

Then suddenly temp gauge shoots up , alarm goes off , "Engine Temp HOT" on dash. But comes back to normal running temperature within 20 seconds.
Turn around heading for home. Temp needle creeps back up again 2 minutes later. Fans come on , alarm going off, Dash gauge reading Hot.

Jumped out and grabbed the digital infrared temp thermometer. Top hose 77°C & bottom hose 40°C while dash gauge is still reading H. Comes back to normal temperature.

Shoots up and goes down again a few more times .

Any ideas?

 

[Immortality]

I'm gonna suggest the temp sender is playing up, but...

Did you check the top radiator hose for pressure?

Did you hear any boiling/bubbling noises?

 

[jays2]

I'm gonna suggest the temp sender is playing up, but...

Did you check the top radiator hose for pressure?

Did you hear any boiling/bubbling noises?

No boiling or bubbling noises.
Top radiator hose is firm

 

[jays2]

I just put a new temp sender in it , the one under the thermostat. Is that the only one?

 

[Immortality]

No boiling or bubbling noises.
Top radiator hose is firm

Well that suggests the system is maintaining pressure, a good sign.

I just put a new temp sender in it , the one under the thermostat. Is that the only one?

Sure is.

 

[krusing]

Sometime ago I had a fault of loosing coolant,
Not leaking it, not a drop on the garage floor.
But the engine was consuming it,
And I did notice a lot of steam out the exhaust while idling,
I pressure test it, and would not hold preassue, and not leak it, so it had to be going somewhere,
I put it down the LIM gaskets,
I have since replaced those, and it’s been running great,
That said,
I did read you replaced yours, just wondering If you cleaned the inlet surfaces on the manifold and head surfaces, as the surfaces on mine were just gunk from the radiator, I even used a smooth file and ran it side ways to clean/re-surface the inlet manifold.

After all the prep work, as mentioned, it’s running great.

Cooling systems are a bit tricky to fathom out sometimes.

 

[jays2]

Sometime ago I had a fault of loosing coolant,
Not leaking it, not a drop on the garage floor.
But the engine was consuming it,
And I did notice a lot of steam out the exhaust while idling,
I pressure test it, and would not hold preassue, and not leak it, so it had to be going somewhere,
I put it down the LIM gaskets,
I have since replaced those, and it’s been running great,
That said,
I did read you replaced yours, just wondering If you cleaned the inlet surfaces on the manifold and head surfaces, as the surfaces on mine were just gunk from the radiator, I even used a smooth file and ran it side ways to clean/re-surface the inlet manifold.

After all the prep work, as mentioned, it’s running great.

Cooling systems are a bit tricky to fathom out sometimes.

Yes. Did exactly that. After scraping and cleaning and rubbing back the heads & the inlet manifold with wet and dry, I wiped it down with wax and grease remover then when it was clean , fitted the MACE LIM gasket & the manifold.
It took forever.

 

[Immortality]

Did you use a thread locker or some type of sealant on the bolts?

 

[jays2]

Did you use a thread locker or some type of sealant on the bolts?

Thread locker

 

[Immortality]

It's not fitted with an aftermarket LPG system?