Temp gauge faulty?

[SpeedySub]

Hey all

I have had problems with my temp spiking in the car, it goes up super quick and then can drop really quickly once I turn the fan on high on hot. The other day it spiked I got frustrated and smacked the top of the dash! suddenly the temp dropped back to normal, its happen a couple of times since and have done the same thing and its always dropped to normal temp. Could the dash gauge have a fault that causes it to up to high? like a loose connection or electrical fault? or am I just hiding what is actually a real temp problem in the engine. I would of thought if it was an engine temp issue smacking the dash should not make a difference.

[Joker]

replaced any pipes in the car or played with the radiator? sounds like air-lock OR gunk in one of the cores

there 'might' be a 'bleed procedure' in the FAQ

or just get it warm, nose up, cap off << ymmv

have seen / heard of cutting the bum off a coke/2L drink bottle & screwing that in the header tank & fill it up too (gives better head 'lol')

[SpeedySub]

I haven't replaced any hoses. But it did get a new radiator and thermostat about 14 months ago. I bled the system a while ago. It just seems strange that the gauge drops to normal when i hit the top of the dash. I was thinking of picking up a cheap temp gauge to check that its reading properly, but I'm not sure how hard it is to set up properley.

[Marky]

Yeah I should probably send that cable hey

[SpeedySub]

 Marky said:

Yeah I should probably send that cable hey

If you could that would be great. Just want to find out where the problem is.

[boon]

Hrm I would be rapidly getting some independent confirmation of the temperature.

This car is a 2.5 N/A that's been overheated in the past right?

Get a TK test done.

[SpeedySub]

 boon said:

Hrm I would be rapidly getting some independent confirmation of the temperature.

This car is a 2.5 N/A that's been overheated in the past right?

Get a TK test done.

Yeah has overheated in the past a couple of times. I think in the past it was air getting in in the overflow tube. It was leaking out the top of the tube. How much is a TK test? and whats involved.

Im just not sure whats happening, as I cant see any bubbles in the overflow or any other normal HG issues apart from the temp spikes, and happens very sporadically. I took it for a long drive on the weekend About 120ks flat and some small hills and some gravel roads and never missed a beat!

(I'm looking at getting a second engine and rebuilding it after April when funds allow, as long as theres no serious issues with this motor)

Edited January 10, 2016 by SpeedySub