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Discussion Starter · #1 · (Edited)
Hey guys, I really need help on this one. Please do give me your inputs.

My 97 Corsa-B (C14NZ 8v) is overheating. When the car is started and you run a few kilometers, its perfectly running fine; aircon is cool, everything seems to be stable. But after around 30 minutes or more and some traffic, the temperature indicator (MFD/TID display), goes up until around 60-70 C then blanks out ( -- C) during the time. The engine temperature also rises up around 100 C. I noticed that the radiator fan doesn't operate on HIGH setting (it usually turns up and becomes noisy when my engine temperature reads around 98-100 C). The Condenser Fan also stops rotating.

This happened a few years ago and somehow the mechanic that worked on my car just ended up hard-wiring the radiator fan to the ignition so it would just turn on with HIGH speed whenever the car is started (not to mention messing up with the other electrical wirings). Since then the MFD/TID was displaying correctly.

So right now I'm opting to bring it back to original settings but I'm afraid of it screwing up. The radiator fan kicking in after ignition gets a little annoying with all the noise, not to mention it causes the idling to drop a few minutes into driving because the engine's too cool.

It was suspected that it's the radiator thermoswitch that may be causing the fan problem, but what I don't understand is why my MFD/TID temp display goes beyond 70C and blanks out with --C in the process...

Also, is there any way to modify the thermoswitch to operate the rad-fan in high speed with just 90-95C?

Need advises please! Thanks a lot :D
 

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There are separate issues going on here.

Firstly - the MFD display has nothing to do with you coolant fan. What I think has happened is that the sensor for the MFD is behind the front bumper, in the middle, near the radiator. If it gets knocked out of position and gets too near the radiator then instead of reading the air temp it is picking up the radiator temp. That's why it is reading high as the car gets hot. Have a look underneath at the front and put the sensor back where it ought to be.

Secondly - I lost the thread of what has happened on your car and when - but I think your coolant fan is currently running all the time. On Corsas it is usual for the coolant fan only to kick in when the needle is just nudging the red line on the gauge. And they really only ever come on when stuck in traffic. So running all the time isn't keeping the engine at its optimum temp.

You need to find out why the 'mechanic' -(sounds like a bodger to me) hardwired it. He's probably just bypassed the thermoswitch in the radiator. Test that switch to make sure it's working, or replace it anyway, then reconnect the fan via the thermoswitch, and it should be OK.
 

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Discussion Starter · #3 ·
There are separate issues going on here.

Firstly - the MFD display has nothing to do with you coolant fan. What I think has happened is that the sensor for the MFD is behind the front bumper, in the middle, near the radiator. If it gets knocked out of position and gets too near the radiator then instead of reading the air temp it is picking up the radiator temp. That's why it is reading high as the car gets hot. Have a look underneath at the front and put the sensor back where it ought to be.
Do you mind describing what the MFD temp sensor looks like? What's weird is that it only goes up to the abnormal 70C to --C reading when it was still in the original condition (no hard-wiring yet). After the hard-wire was done, it doesn't occur anymore.

Secondly - I lost the thread of what has happened on your car and when - but I think your coolant fan is currently running all the time. On Corsas it is usual for the coolant fan only to kick in when the needle is just nudging the red line on the gauge. And they really only ever come on when stuck in traffic. So running all the time isn't keeping the engine at its optimum temp.
It is running all the time on high setting because of the hard-wiring...

You need to find out why the 'mechanic' -(sounds like a bodger to me) hardwired it. He's probably just bypassed the thermoswitch in the radiator. Test that switch to make sure it's working, or replace it anyway, then reconnect the fan via the thermoswitch, and it should be OK.
He probably hard-wired it because he couldn't find the solution to the problem before. Is the only way to test it is to just wait for it reach the high temp? Another weird thing that's occurring is that the condenser (A/C) fan stops working as well when the engine reaches 100 C or beyond...
 

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Remove hard wiring and try a new rad switch, would be first step, and buy an mfs sensor like the one above, nobody is going to comment, if someone has already told you what you need to do
 

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Discussion Starter · #8 ·
Great, just thought some people might have other ideas...

It was a real car screw up then and seemed hard to fix because it went through 2 mechanics (a backyard one and even the dealership) and it wasn't fixed properly.
 

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I don't know, I have the second one, just have at look at yours and see what one sit loks like and buy that
 
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