I hope the diagnostic experts out there can advise. My Cruiser (1988 FJ62, 3F engine, about 430 000 km or 270 000 miles) is experiencing hot flushes.
Symptoms: during driving, with no evident or repeatable reason, the temperature gauge goes up, over the red, hovers there for a second or two, and comes down to normal, all within twenty seconds or so. And just to confuse issues, it happens more frequently when my wife drives than when I do. When this happens the engine compartment does not feel abnormally hot, the oil temperature is stable, everything else carries on as normal. It has been occuring for the past few years, but then had radiator problems and the like. Now it gets worse.
Case history: I bought the truck in 2010, and have had some temperature problems: at first the radiator was partly blocked, so that anything above 2000 rpm would cause an overheat. I have since had the radiator rodded out, had the top tank desoldered, then replaced, the bottom tank desoldered, and 20 000 km ago had a new Toyota radiator, new thermostat, new pipes fitted. No other recent work that could affect the temperature gauge (New tyres, gearbox overhaul). There is some wiring problem around the radio, the aircon lights sometimes work, sometimes don't. I fitted a new sensor element, which gives a higher, but stable reading, but she still has hot flushes. And real overheating takes some 20 minutes to cool down, not 20 seconds. On a recent 3300 kn (2 000 miles) trip into the desert to look at the flowers we had day temperatures of 35 degrees Celsius (95 degrees in inches) and the fan did come on from time to time, too often to my liking, but within the realm of normality. Especially when the aircon is running. So I know it works.
My thinking: Someone mentioned a bad earth in the instrument cluster. But surely the power comes from the instrument main, through the gauge, and earths through the sensor. If there was a short to earth earlier in the circuit surely the gauge indication should drop and not increase? Earthing the sensor wire to the block reproduces the same symptoms: a rapid rise in the indication, and a slower return to normal when you break the connection..
I suspect: A short circuit somewhere in the cable bundle between the gauge and the sensor. If someone has an idea where this would be likely, please advise. I would like to fit a second temperature gauge but cannot find a place, if anyone knows where please advise. I also plan to flush the engine and radiator to see what comes out. Eventually I intend servicing the viscous coupling, but, as I said, I think it is working normally.
Workaround: At the next full moon I can slaughter a black chicken, and dance around a fire naked, but, in the southern hemisphere, should I dance widdershins or anti-widdershins? Experts please advise!
Symptoms: during driving, with no evident or repeatable reason, the temperature gauge goes up, over the red, hovers there for a second or two, and comes down to normal, all within twenty seconds or so. And just to confuse issues, it happens more frequently when my wife drives than when I do. When this happens the engine compartment does not feel abnormally hot, the oil temperature is stable, everything else carries on as normal. It has been occuring for the past few years, but then had radiator problems and the like. Now it gets worse.
Case history: I bought the truck in 2010, and have had some temperature problems: at first the radiator was partly blocked, so that anything above 2000 rpm would cause an overheat. I have since had the radiator rodded out, had the top tank desoldered, then replaced, the bottom tank desoldered, and 20 000 km ago had a new Toyota radiator, new thermostat, new pipes fitted. No other recent work that could affect the temperature gauge (New tyres, gearbox overhaul). There is some wiring problem around the radio, the aircon lights sometimes work, sometimes don't. I fitted a new sensor element, which gives a higher, but stable reading, but she still has hot flushes. And real overheating takes some 20 minutes to cool down, not 20 seconds. On a recent 3300 kn (2 000 miles) trip into the desert to look at the flowers we had day temperatures of 35 degrees Celsius (95 degrees in inches) and the fan did come on from time to time, too often to my liking, but within the realm of normality. Especially when the aircon is running. So I know it works.
My thinking: Someone mentioned a bad earth in the instrument cluster. But surely the power comes from the instrument main, through the gauge, and earths through the sensor. If there was a short to earth earlier in the circuit surely the gauge indication should drop and not increase? Earthing the sensor wire to the block reproduces the same symptoms: a rapid rise in the indication, and a slower return to normal when you break the connection..
I suspect: A short circuit somewhere in the cable bundle between the gauge and the sensor. If someone has an idea where this would be likely, please advise. I would like to fit a second temperature gauge but cannot find a place, if anyone knows where please advise. I also plan to flush the engine and radiator to see what comes out. Eventually I intend servicing the viscous coupling, but, as I said, I think it is working normally.
Workaround: At the next full moon I can slaughter a black chicken, and dance around a fire naked, but, in the southern hemisphere, should I dance widdershins or anti-widdershins? Experts please advise!