Ferrari Mailing List: 512TR temperature sending unit

[Larry Bard (larrybard]

Catching up with some month-long issues after being away for the last 30 days driving around the country (almost 9,000) miles with two friends -- in their Ford hybrid.  (Yeah, would have been a lot more fun in one of my cars, but they wouldn't have exactly gotten over 36 MPG.)

Anyway, just before I left my 1992 512TR went to a local, apparently competent, mechanic for its annual inspection.  Everything was fine -- except for (according to him) the temperature sending unit, and (also according to him) the gauge itself.  I had noticed that the last few times I had driven the car the gauge seemed to read normally, and then stopped registering at all.  On and off, typically for minutes at a time.  Cooling system seemed to be working okay (fans coming on when temperature reached about 195).

If I understood him correctly, the mechanic wants to charge me $350 for both (not each) a new "temperature sending unit" and replacement gauge, plus an additional $350 labor.  They would first replace the sending unit, and if the gauge then worked properly of course not replace the latter, but they said that based on their tests the gauge was not sweeping correctly.

I am almost undoubtedly one of the least mechanically knowledgeable people on this list, so please forgive the possibly naive questions, but:

• if indeed the sending unit is malfunctioning, I would have guessed that the gauge might well not also need replacement because it might be functioning properly, with the erratic readings solely attributable to the sending unit.  So what are the chances that the sending unit needs replacement, but not the gauge?  (Seems easy enough to do what they propose and change the sending unit first and then see if the gauge is working correctly before also replacing it; and if the mechanic were one of my regular trusted mechanics I wouldn't be wary.)
  
• Assuming, for the moment, that both the sending unit and gauge require replacement, $350 sounds to me to possibly be excessive parts cost and labor cost for replacing just the former (a quick search shows that a sending unit is apparently available from Rutlands for about $60 plus shipping), and possibly even for replacing both.  (All Ferrari Parts seems to sell gauges for $165. http://www.allferrariparts.com/147163.html )
  

Any thoughts would be appreciated.

Thanks,
Larry