R34 Running Hot, Temp Gauge Up And Down

[mrgilly]

Hi guys,

Have been having an overheating issue with my R34 sedan (mechanically stock) which isn't your standard 'runs hot temp gauge goes up' problem. Once the temp gauge goes up to the first high mark it will then fall back to operating temp after a minute or so - pop the hood and coolant is still sitting at the normal fill line. I can't find any leaks under the car when it's running. Oil temp sits below 100deg.

It's rather perplexing that the gauge goes up and down again... has anyone any advice for what to look for?

Any assistance would be greatly appreciated.

[PAV34]

My old 34 did this.

I bet you have a blocked radiator.

[blind_elk]

Under what conditions does the temperature go up? What causes it to come back down?

[mrgilly]

Thank you for the assistance so far.

Blocked radiator may explain it, pain in the ass to get it to a radiator shop for a few weeks though due to work/other commitments (thankfully we have another car).

There doesn't appear to be any correlation between throttle or use of accessories and the fluctuation in the temp, it simply climbs steadily over a minute or so, sits close to high for a few minutes before dropping over about the same period and sitting on operating temp.

[mrgilly]

Well I haven't been able to narrow it down any further, can anyone recommend a decent radiator shop in the ACT?

Cheers

[DECIM8]

May be air passing over the sensor i.e your system is not blead correctly. Has this been done?

[mrgilly]

It's only started doing it in the last week, and the car was serviced about a month ago (still trying to find out from the workshop if this included a coolant flush - I would usually assume it does).

Having a search around for guides to bleed the air - any specifically recommended for R34?

Cheers

[blind_elk]

You can test the gauge by earthing out the wrie at the sender. So maybe you have a wire that is shorting to earth, but somehow stops. Could simply be a faulty gauge, or a faulty sender.

[cuppas]

or it could be faulty thermostat. or even rad fan only working intermittently.

[Abo Bob]

I'm going for air in the system or thermostat too. If the thermostat is sticking the temp will rise badly but then it springs open and all is good again. Does it happen multiple times on a drive or just the once from cold?

[mrgilly]

I'm going for air in the system or thermostat too. If the thermostat is sticking the temp will rise badly but then it springs open and all is good again. Does it happen multiple times on a drive or just the once from cold?

It happens a few times on a drive, seems to be caught in a cycle, not just at the start of driving

[ztuned]

soz for high jacking the thread.

but im having a simliar problem, with the temp going upto 130 degrees while driving on the freeway at 100km/h

at 60-70k's around 2300rpm, the car stay at about 110 degrees. but once i go on a slope..the temp shoots up and the car knocks like crazy

the car normally stays at about 85-95 degrees, but all this started happening after i gave the car shit yesterday

giving the car shit shouldnt suddenly block the radiator lol? so what else could it be?

i have flush the radiator but i cant test the car atm, have to wait til tomorrow.

cheers

[Abo Bob]

It happens a few times on a drive, seems to be caught in a cycle, not just at the start of driving

Still could be either.

[Abo Bob]

soz for high jacking the thread.

but im having a simliar problem, with the temp going upto 130 degrees while driving on the freeway at 100km/h

at 60-70k's around 2300rpm, the car stay at about 110 degrees. but once i go on a slope..the temp shoots up and the car knocks like crazy

the car normally stays at about 85-95 degrees, but all this started happening after i gave the car shit yesterday

giving the car shit shouldnt suddenly block the radiator lol? so what else could it be?

i have flush the radiator but i cant test the car atm, have to wait til tomorrow.

cheers

Was the radiator full?

[mrgilly]

Ok, problem found - slight leak under the clamp on the heater hose, took the radiator shop a couple of tests to find it - no drips or anything under the car!

[blind_elk]

soz for high jacking the thread.

but im having a simliar problem, with the temp going upto 130 degrees while driving on the freeway at 100km/h

at 60-70k's around 2300rpm, the car stay at about 110 degrees. but once i go on a slope..the temp shoots up and the car knocks like crazy

the car normally stays at about 85-95 degrees, but all this started happening after i gave the car shit yesterday

giving the car shit shouldnt suddenly block the radiator lol? so what else could it be?

i have flush the radiator but i cant test the car atm, have to wait til tomorrow.

cheers

It should be able to hold thermostatted temperature at freeway speeds, or up hills even. Sounds like a failed water pump. The fins have probably fallen off the impeller wheel, so it can't move water around.

Or are you running a thermo fan? My experience is that the risk of cooking an engine isn't worth the couple of kW you get by replacing the factory fan with a thermo.