gjc5500 Posted May 15, 2007 Share Posted May 15, 2007 In my 73 240z my oil pressure and water temp gauges will suddenly start to drop. they make it about 3/4 of the way down and start to come back up. then they fall. happens when im driving. if i hit the dash below the gauge it will work for about 30 sec then start doing it again. coudl this be the guage betting ready to go out? Quote Link to comment Share on other sites More sharing options...
caszboy Posted May 15, 2007 Share Posted May 15, 2007 i would say either gauges or wiring. Quote Link to comment Share on other sites More sharing options...
A. G. Olphart Posted May 15, 2007 Share Posted May 15, 2007 In my 73 240z my oil pressure and water temp gauges will suddenly start to drop. they make it about 3/4 of the way down and start to come back up. then they fall. happens when im driving. if i hit the dash below the gauge it will work for about 30 sec then start doing it again. coudl this be the guage betting ready to go out? If the gauges are moving in tandem (as you seem to indicate), they are not the problem. (I don't see two gauges plotting to fail in exactly the same manner at exactly the same time). That leaves a common wire/loose connection as the culprit, which you have confirmed by hitting the dash. You even know about where to look... Many vehicles (my wife's 69 Datsun roadster included) have a bi-metallic strip regulator in the gauge circuit that fails with age. (Your Z's diagram at Autozone doesn't seem to show one): http://www.autozone.com/az/cds/en_us/0900823d/80/1d/1d/80/0900823d801d1d80/repairInfoPages.htm When the regulators go flaky, they cause similar problems. The roadster regulator is a little rectangular can with a tab for screwing it to the car, and a spade connector on each end of the crimped in place plastic lid. <> Quote Link to comment Share on other sites More sharing options...
Austin240Z Posted May 15, 2007 Share Posted May 15, 2007 When the regulators go flaky, they cause similar problems. The roadster regulator is a little rectangular can with a tab for screwing it to the car, and a spade connectors on each end of the crimped in place plastic lid. OOOOH, that's what those are... i noticed two when i was taking my dash out and wasnt sure what those regulators were for, and was too lazy to stick my nose back in a book and find out what they were (i work in a parts store and my nose is always buried in parts books) Quote Link to comment Share on other sites More sharing options...
gjc5500 Posted May 15, 2007 Author Share Posted May 15, 2007 ooook. i figured it might be a common ground. what woudl be the best way to get to the ground without pulling the dash? its my DD so i cant relaly pull the dash out now. Quote Link to comment Share on other sites More sharing options...
GrommitZ Posted May 15, 2007 Share Posted May 15, 2007 To remove the gauge. You don't have to remove the whole dash, just the center air/heat/fan panel. To remove it, you have to remove your stereo, the four phillips screws in the corners and disconnect the 4 wire control cables under the dash. There are 2 on each side. I just replaced my gauge and it fixed the exact same problem you have, so it must have been the gauge's voltage regulator, not the one by the alternator. Quote Link to comment Share on other sites More sharing options...
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