Oil 'Dummy light' vs. Oil Pressure gauge
 

Hello,

I'm currently looking at a 300ZX a neighbor has for sale - and was wondering if the oil pressure gauge (the circular one on the dash beside the voltage gauge) runs to a different sensor than the oil 'dummy' light on the dash instrument panal. I ask this because I started the car up today (the owner is very cool and is letting me check the car out over a few days) and the oil pressure gauge was recording a very scary "0" after a few minutes (I didn't think to check until then). The car's oil level is completly full, and it didn't make any horrible noises so I there was oil pressure in the engine and that the sending unit to the pressure gauge is faulty.

In my haste, I shut the car off before I took a look at the dash to see if the oil 'dummy' light was on as well.

So - does anybody know if the oil pressure sending unit supplys the info to both the dash oil dummy light and the oil pressure gauge?

The thought of no oil pressure in the engine scares the hell out of me. :)

Thanks!

Re: Oil 'Dummy light' vs. Oil Pressure gauge
 

sorry - forgot to mention... '84, 300ZX N/A Automatic 2+2.

Thanks!

Re: Oil 'Dummy light' vs. Oil Pressure gauge
 

I'm not 100% sure on this car but on previous cars I've owned the light basically just informs you when the oil level is low.Drive it around a bit,if there's no pressure it won't take long to find out.Better to know now than later ;) The gauge showing no pressure is probably a sensor.Try cleaning the contact point.

ZenArcher

Re: Oil 'Dummy light' vs. Oil Pressure gauge
 

Thanks for responding so quickly...

The light being a indicator of oil level does make sense if the gauge is for pressure - but then why when you put the key in and turn the car on (but not the engine on) does the dash oil light come on (because the oil level is full even if the engine is off...) and then it is suppose to go off after the car's been running for a few secs.

Also - how hard it is to try and clean the contacts of the oil pressure sending unit... one thing that could be the problem is that a power steering pump line broke and sprayed oil around everywhere on that side (passenger) of the motor. Will try to clean it next time I get to see the car.

Thanks guys - I really appreciate your help.

Re: Oil 'Dummy light' vs. Oil Pressure gauge
 

When you turn the key to the last click before starting the car, all the dash lights should be on - Not sure why this is (maybe so you can tell if a bulb is out??). but yes, it should go off after the car is running.

It's not hard to clean it, disconnect the battery, and spray it down with some brake parts cleaner. get a big old towel to catch any runoff of oily dirty stuff so you don't mess up his driveway and tick him off. Especially if you really want the car :). The hard part is getting to it. From what I have heard from others, the sending unit is one of those parts that commonly goes out. I haven't had this problem (yet) so I don't know how expensive they are or availability at autozone type places versus the dealer.

Re: Oil 'Dummy light' vs. Oil Pressure gauge
 

Oil pressure sending unit is bad. Very easy to fix. I'd only buy a Nissan sending unit though as the first 2 autozone units I bought never read accurately. And the light on the dash is the idiot light for low pressure as well. Mine sometimes is on for a second or two when I first start it up after it's been sitting for a while.

On replacing the sending unit... do it when you need to change the oil. Move the starter out of the way (2 bolts) and it will be really easy to get to. Total time should be about an hour, including oil change and clean-up.

...and from the ashes shall rise a new hope. And it shall be known as "Z". And it will be good.

Re: Oil 'Dummy light' vs. Oil Pressure gauge
 

Alrighty then Eliott! Welcome to the addiction,um,club.Have fun!

ZenArcher

Re: Oil 'Dummy light' vs. Oil Pressure gauge
 

Not to worry Elliot, my gauge has read zero for years! After replacing that damn sending unit twice in order to get it to work O.K., I decided to save my money the last time it went in '97 and just live with it reading the innaccurate zero.