OK boys and girls. Here is the scenario. I built a 1916 with 8.4 to 1 comp. Engle 110 cam, twin 40mm dellortos. Bandido 043 heads, stock crank. Car runs sweet as. Changed the main jets down from 140 to 130 on Sunday and drove it home. The temp gauge didint read any hotter than with the 140's.

But it runs hot. Bloody hot. Or so the gauge says. I drive it and the gauge says 100 degrees celsius. Thats hot. I stop the car, let the needle fall back and switch it back on and the highest it reads is 90 degrees.

I reckon the gauge and sender are OK. Trust me.

One of the gurus here has said that perhaps the gauge is reading high because I now run an alternator (converted it from a generator) and the system is taking relatively high voltage. Maybe up to 13 or 14 volts.

Will high voltage cause the gauge to read high? Or is my guru pulling my chain.?

Old Hutcho

ps. Isnt it great to see Wendell Sailor and Lote Tuqiri playing their hearts out for NSW. Thats pride for you.

Possibly.

The temperature senders work by changing the resistance of the sender as temperature varies, and the gauge works by displaying (effectively) the voltage drop across that resistance. So, if your battery is flattish or dying and your regulator is set normally to about 13.8 V (thats the proper voltage in a nominal 12 V system), you indeed get a difference between engine on/engine off. Could also happen with an OK battery but Voltage regulator set overly high.

You can:
- check that your regulator is set correctly and that your battery is healthy and by appropriate adjustment get the engine running / not running readings aligned or
- live with it. The reading is not particularly important (it is, after all, only the oil temperature at one particular point), but variations are important i.e. when it climbs to 115 on a hot day then you might want to back off.

I think your guru may be the real thing.

hth

Many car dashboards have a voltage regulator in them to deliver a steady accurate 10V to the guages, otherwise the guages would read differently under different battery and driving conditions. Our after-market guages on our VWs don't have a regulated power supply and so they do vary a bit. The trick is to get used to what is normal guage behaviour for your car and then watch for readings that are unusual. As for how hot your motor is running... if you can hold the top end of the dipstick comfortably, the motor is not overheated.

What idle jets are u running,your still on your idle jets till 2500-3000rpm.

[ Edited on 18-2-2006 by lugnuts ]

Lugnuts

I am running 60 idles, and now 125 mains

Old Hutcho

I know u said the sensor and gauge are fine but if u get some spare time :P u could try the sensor with gauge attached in boiling water to verify,preferably still attached to car and engine running.

how long does it take to read 100???

Under what conditions???

cruising round town or a hr blast along the Princes??