Overheating issues

[Cerysm92]

Hi, Looking for some advice about my 1998 1.4 corsa b.
For the last two days the temperature gauge has been showing temperatures of between 100 and the red zone, obviously worrying, but once it reached 100 the fan would come on, and when parked the engine showed no signs of overheating (steam etc.). It also seems to just rise straight to 100 non stop when driving, and stay there no matter what speed you go. This happened a few times so we thought maybe the temperature sensor is faulty (since it used to drop a bit at speed), however today, the fan didn't come on and when I parked the car started steaming. It's gonna be parked up all day but then it wil have to do some rush hour traffic driving.

I've had the car for over a year and have replaced almost everything. It has had:
-new head gasket
-new radiator
-new fan switch
-new spark plugs
-new belts
-new fuses
-new thermostat
-new water pump

So most things to do with the cooling part of the car are less than a year old, bar the fan itself. There is definitely coolant in the car, and it's definitely circulating because the pipes are hot and firm.
I think I should mention the central locking has recently stopped working, and we thought it may be a sign that the ECU is on its way out, but there is no engine management light on on the dash, and I've read that fan/temp issues can be due to a ECU failure, but wouldn't I see the light on my dash?

Any advice on what to check/change would be great!

[andy w]

Looking at what has been put have ya changed the cts sensor

[johnny]

Have you checked to make sure there isn't a small air lock

Over heating generally isn't an ecu problem it's more than likely mechanical, it's also worth noting that old coolant or water won't act efficiently as new coolant and that the corsa isn't really the best at cooling to begin with so they tend to over heat in traffic

When you see it going for 100 turn the heat and blower on full and it will blow out any excess heat or you can wire the fan to a switch

[andy w]

Also to check the fan is working bridge the wiring to see if it works to begin with if it does them like johnny says have the fan on a switch or the other option is to make the fan permanently on but I wudnt do that one lol

[Cerysm92]

Thanks for the responses guys. Have had the fan on a switch before, just as the head gasket was going. Not bothered if it's permenantly on as long as the car is fine!
Just wanted to share my thoughts. Im not a mechanic, but shouldn't the car cool down if im driving at speeds, due to wind or something? It used to. I ask because I'm literally sat on the hard shoulder of the m4 right now because the gauge just went into red, although theres no steam coming from the bonnet.

[andy w]

Yes its true when ya are driving it should drop in temp but if there are any blockages or air locks it dont matter how much wind gets to it did ya have a new head on it before if so did ya get the head skimmed and pressure tested

[Cerysm92]

Ywah we had a new head on it last november, so its been a while. Couldn't get it skimmed at the time because of where i was living at the time, and i needed the car back asap, and it would have cost a lot more money i didn't have. Changing the head was expensive enough.
But weve had no signs of head gasket failure since then.

[andy w]

The downside to pressure testing and skimming can sometimes have.head failer to reapear not saying this is defo for ya case as is expense if it aint. Did ya do the water pump wen the head went on ya the first time and where abouts are u and ya partner from if ya dont mind me asking

[Cerysm92]

Yeah we had the water pump changed with the head. We were living in bangor North Wales, and our mechanic told us he'd have to send the head to Warrington for the skimming/pressure test, so we just opted out. We're now living in South Wales though.
Checked the fan today, weird it so it comes on all the time, but again when we drove it the temp went to 100+ and never cooled. Going to order a CTS now and check for an air lock tomorrow.