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308 guage trouble

Discussion in 'Technical Q&A' started by corse driver, Aug 19, 2004.

  1. corse driver

    corse driver Rookie

    Aug 19, 2004
    15
    My '82 308 GTSi is having trouble with the water temp guage and the oil pressure guage.

    The water temp guage is never consistent, somtimes it will work, (however I beleive it to be reading a bit low), sometimes, it will flicker between nothing and the temp it is trying to read, and other times it will just not work at all.

    It does seem that if it is not working at all and you wind the car out through some gears it will want to come back to life a little, maybe, but I am not sure.

    The oil temp guage usualy give me a good a true reading, but sometimes this guage will flicker and die.

    What causes this? Bad guages, bad contacts somewhere, sending units? Thouse guages are too important to be messing up. Luckily all other guages are working correctly so far. I appreciate any help any of you may give in tracking this down.
     
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  3. Darolls

    Darolls F1 Veteran
    BANNED

    Jul 2, 2003
    6,799
    Full Name:
    Sparky
    It could be bad gauges, or bad thermistors?

    Might even be a bad ground. Do the old 'pound on everything' test.

    If you don't get results with that, replace the thermistors first. They're inexpensive.
     
  4. Birdman

    Birdman F1 Veteran

    Jun 20, 2003
    6,687
    North shore, MA
    Full Name:
    THE Birdman
    Most electrical issues like this are just dirty connectors. Start by cleaning and tightening the connectors on the sensors, then the fusebox. You may find that the aweful fusebox of the 308 is part of many electrical issues. If the voltage to the sensor varies due to a bad contact in the fusebox or contact in the wiring harness someplace, it looks like a bad guage or sensor.

    Birdman
     
  5. f355spider

    f355spider F1 World Champ
    Rossa Subscribed Owner

    May 29, 2001
    17,073
    USA
    Full Name:
    Hugh G. Rection
    As cars get this old, you have to start with the basics, and dirty grounds a common problem. I would have to say "ditto" with the others and clean, tighten everything you can find. You may even want to add an additional ground to the two offending gauges. If all else fails, then get new senders, they are not particularly expensive...

    I had my oil temp sender go on my previous 308...started reading very high temps for no reason...new sender and all was well.
     
  6. corse driver

    corse driver Rookie

    Aug 19, 2004
    15
    I just realized that if the oil pressure guage stops and then I hit a good bump it would work again. I am sure that that is a connection.

    I am not sure about the H20 temp guage. Where is the sender for that?


    Thanks
     
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  8. Birdman

    Birdman F1 Veteran

    Jun 20, 2003
    6,687
    North shore, MA
    Full Name:
    THE Birdman
    The sender for the water temp is under the carbs in the center of the "V" of the engine, on a water pipe. You can't see it without pulling the airbox and maybe the carbs, but you can feel it. Follow the wire, pull it off the connector, tighten the connector a little with some needlenose pliers, and plug it back in. Jam it on and off the sensor terminal a few times to clean it, or even better, use some contact cleaner.

    It has no "ground" you can check, just one wire. It is basically just a thermister--a resister that changes resistance with temperature. It is grounded to the chassis through its own threads into the aluminum plumbing. The wire comes from the guage. As the engine gets hotter, the resistance goes down, more current flows, and the guage reads higher (basically, it's just an ammeter circuit). VERY simple to troubleshoot--everything is in series. There is the connector on the sensor itself, and a few in between the fusebox, guage and sensor. One of them is flaky.

    I have no direct experience (yet!) with the oil pressure guage, but I'm sure its a similar arrangement.

    A good place to start is ALWAYS the fusebox. 308 fuseboxes are TERRIBLE, AWFUL and generally LOUSY all around. I can't tell you how many electrical issues that I started troubleshooting on the "logical" end of the circuit (i.e. where the problem manifested itself) and traced it all the way back to the fusebox before I found it. Always start at the fusebox, IMHO.

    Birdman
     
  9. corse driver

    corse driver Rookie

    Aug 19, 2004
    15
    Hey birdman, Thanks for your help. You seem to really know your stuff.

    Anyway, I'll check that out. I am pretty sure it is not the connections at the guage. I am waiting for my workshop manual, in the meantime how do you acces the guages?
     

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