Really stupid annoying fever

4A-GE · Post by **4A-GE** » Wed Apr 02, 2014 12:03 pm

Cooling system has been flushed out 3 times since january. Once cuz I was bored, once with the thermostat, and again when the new radiator went in.

The gauge was bouncing around the other day. I mean, literally dancing between normal temp and danger time - Now I know a shonky ground would explain that I'll worry less. I'm going to get a whole bunch of contact cleaner onto all available pluggy bits I can and see what happens.

Contact cleaner I can afford and have the time to do, lol.

WideOpenThrottle · Post by **WideOpenThrottle** » Wed Apr 02, 2014 1:11 pm

Definitely a wiring/sensor/gauge problem for it to be bouncing erratically surely?

A faulty alternator can cause weird problems too!

4A-GE · Post by **4A-GE** » Wed Apr 02, 2014 1:23 pm

God, not another alternator issue.

marcellarius · Post by **marcellarius** » Wed Apr 02, 2014 5:17 pm

If it's jumping up, not down, it's probably a gauge circuit shorted to ground, bypassing the thermistor.

Skip the contact cleaner and start looking for wires rubbing on metal or hot things. Eventually the insulation wears through as it vibrates and can then cause an intermittent short circuit.

4A-GE · Post by **4A-GE** » Wed Apr 02, 2014 5:21 pm

I can't read electronics diagrams. Can you dumbify it in paint or something when you have the time? (Or tell me which bits of wire to look out for)

Pleeeease?

marcellarius · Post by **marcellarius** » Wed Apr 02, 2014 5:45 pm

So, a basic principle of electric circuits is that you need a complete path from the positive to negative side in order for electric current to flow.

In all modern cars, the negative side of the battery is attached to the metal chassis. This is referred to as the 'ground'. Most circuits will be from the positive side of the battery, through the devices being powered, and then to a ground point somewhere on the chassis or engine.

For the temp gauge, the circuit runs from the positive terminal, through some fuses etc. to the gauge. From the gauge there is a wire that runs to the temperature sensor (the zigzaggy thing), and from the sensor it goes to ground and back to the battery via the engine.

When electricity flows through the gauge, it heats up a little bimetallic strip and moves the needle. The more current flow, the higher the gauge will read.

The temperature sensor is a variable resistor: it makes it hard for electricity to flow when the coolant is cold, but easy when it is hot.

If there is an easier path to ground which will bypass the sensor, then the electricity goes that way, you'll get lots of current flow and the gauge will shoot up to shit-shit-shit.

The problem will likely be somewhere between the gauge and the sensor. It could be the sensor, but I'd check the wiring before spending money on a new sensor.

4A-GE · Post by **4A-GE** » Wed Apr 02, 2014 7:34 pm

Aye aye captain! Will be looking for dodgy wiring. Will electrical tape around the shitty bits [if any] do the trick?

Angreal · Post by **Angreal** » Wed Apr 02, 2014 8:22 pm

You changed the water pump right?

4A-GE · Post by **4A-GE** » Wed Apr 02, 2014 9:06 pm

No water pump yet.

marcellarius · Post by **marcellarius** » Thu Apr 03, 2014 8:23 am

Yep, electrical tape will do fine.

If you do find a place where wiring is rubbing on something, try and cabletie it back, make sure rubber grommets are in place where wires go through the firewall.

4A-GE · Post by **4A-GE** » Thu Apr 03, 2014 12:31 pm

Day 3: Still behaving.

Whatever, car.

Angreal · Post by **Angreal** » Thu Apr 03, 2014 1:22 pm

Found a car on the motorway that decided it didn't need coolant. Poured water into the radiator and it came straight back out at the base of the engine. Radiator was also full of rust.

Anyway, I couldn't help him

4A-GE · Post by **4A-GE** » Thu Apr 03, 2014 2:58 pm

Welp, sounds like that guy had a shitty day. If anything I think mine is running cooler than it was when I bought it, and it was [relatively speaking] pretty healthy then.

4A-GE · Post by **4A-GE** » Tue Apr 08, 2014 8:27 am

Day 8: Car still behaving. Not a single issue to speak of.

MrGrey · Post by **MrGrey** » Tue Apr 08, 2014 8:59 am

good to hear, I have my fingers crossed for you mate

4A-GE · Post by **4A-GE** » Tue Apr 08, 2014 9:22 am

Maybe the radiator just ... Needed to settle? If it plays up again, the sender will be the first thing I look at.

bgnz · Post by **bgnz** » Thu Apr 10, 2014 6:33 am

Really stupid annoying fever

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