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Volvo Penta 2002B 18 HP Deluxe Panel Temp Gauge
On Tue, 06 Apr 2010 23:49:41 +0100, goofball_star_dot_etal
wrote: On 06/04/2010 21:33, goofball_star_dot_etal wrote: On 06/04/2010 21:04, Armond Perretta wrote: My 2002 (1993) has 3700 hours and runs well. The deluxe panel also was fine with all gauges except the tach performing properly. I have replaced the original tach with the latest (both wires removed from the old sender and one of these to "w" on the alternator, the hour meter wire removed and set aside, etc.). I just started up the engine for the upcoming season and the new tach is fine. However now I have a new issue with the temp gauge. Here are the symptoms. Prior to starting, when I turn the key one click, all gauges including the temp move a bit, indicating that the wiring is fine to all instruments. Nothing happens with the tach of course. When I then start up, all gauges including the new tach perform as designed, except that the old temp gauge (which ran perfectly last year) pegs to the left once the engine starts, giving what looks like reverse polarity connection symptoms. I did not change any wiring to this gauge when fitting the new tach. Next, when I shut down after running the engine under load and letting it come to temp, all the gauges including the temp show what appear to be correct readings, but only when the engine is NOT actually running. That is, it seems the temp sender is OK and sending correct info, the oil sender same, the voltage meter same, the tack off of course, etc. I think this means the temp sender is fine, but that running the engine is somehow sending the incorrect voltage to the meter. Only when I start up and the engine is actually running (and the tach showing the revs) does the temp gauge peg to the left. Is it possible I just picked the wrong one of the 2 old tach wires for the new tach to connect to "w"? No other wiring changed from the time the temp gauge was OK. Ideas welcomed. Check for voltage drops between various earth points when the alternator is charging. In particular, check the integrity of the alternator earth path (since it seems that the error is associated with charging current), the engine earth path (since, probably, the temperature sensor thermistor uses the engine as earth), and the instrument earth (since that is where you see the problem). In an ideal world one would have a single point earth but this is not always practical. I'm a bit confused. Assuming a normal inboard engine installation, the alternator earth is normally either through the case to the engine block or through a separate earth connection to the same place. The engine is normally grounded/earthed by a direct connection back to the negative side of the battery. It almost has to be connected this way as the starter, which IS earthed through its case to the engine block will never develop its normal power without an adequate earth/ground path back to the power source; the battery. Cheers, Bruce (bruceinbangkokatgmaildotcom) |
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