Greetings
Apologies if this is an often discussed topic, but I need some ideas.
I have a Corolla from the 80's (11/1985) AE82, so a FWD 1.6 L SOHC 4AC. It has done a moderate amount of distance (240 000 km). Ambient temp 5 - 15 degrees celcius.
Question is, are the temp gauges on these things reliable and accurate? I have only been using it for freeway driving in the last while and before this the coolant temp has been quite normal (i.e. In the normal range). Recently, I was traveling at 100 - 110 km/h and the gauge showed mid - 3/4 scale, then after 100 kays, it jumped up to 7/8 of the scale and then would not come down. I checked for leaks etc, nothing there.
I changed the thermostat and radiator cap and put new coolant in. Operating temp reached sooner, all good. Travel at 100-110 km/h and then about 100 kays into the trip, up jumps the gauge.
I pull over and check again, no leaks, belts there etc etc. I pull the fan sensor wire so that the fans will kick in. they roar for 5 minutes and the radiator is cool to touch, but the needle remains at 7/8. I even (with caution) removed the radiator cap, needle stayed at 7/8 of scale.
I trundle off, and the needle drops, only to jump into the red at the next "sniff" of a hill. Needle stays there, no steam, no obvious signs of overheating. Oil is clean and free of mayonnaise, coolant free of oil and hasn't lost any volume.
What do you reckon? Water pump nucleating water to give false temp? Sender had the gong? Gauge reading too high? Really overheating? Cracked head? What temp should the coolant be sitting at?
I came into town, and coasted down a few kilometres of hills traveling some
70 km/h. Guage heads towards mid scale. Nice. I accelerate at the next set of lights back up to 80 and within 800 metres, the gauge is sitting on the upper of normal mark. Then it stays there until I pull into where I am staying. Radiator cap is cool enough to touch, radiator fans turn on for a 10-15 sec blast and the go off for a minute or so and the needle stays at the 7/8 to top of normal mark?What is your thoughts?
Cheers
Hammo
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Your thoughts would be greatley appreciated