Car dies & low oil pressure?

[tayter1021]

I recently bought a 94 300zx and for a day or two the car would die when I would slow down for intersections and such but it would start right back up. After doing this a couple of times it did as i took it for just a quit ride and it wouldnt start back up. I ended up having to jump it to get it started again and when it did i noticed it was making a knocking sound (it made a light knock before but it was much worse) and the oil pressure gauge was reading very low. I was thinking it could have something to do with my oil pump but im no mechanic for sure. Help me!!

[speedeast]

Well, I would start by checking your oil and then check for leaks if it's low. If it died when you let off the gas and needed a jump, then either your battery needs changing or your alternator is about to kick the bucket.

[tayter1021]

I checked the alternator and it was good i just charged the battery & it started right up but the oil pressure gauge is still down. Would the oil pressure sensor cause it to die? By the way i believe i found the reason for the battery dying in the first place. It had to do with some wiring in it to the sound system.

[speedeast]

How's the oil level though? Take the oil cap off and look down in there with a flashlight, does it look like it's a little dry?

[tayter1021]

I've checked the oil levels and it seemed good. Maybe i should change the oil just in case?

[robomatic12]

How was your oil pressure before? You should check with another gauge as the factory gauge is hard to trust and prone to clogging up.

[speedeast]

^That's true, but on the other hand he mentioned that his lifter tap was louder at the same time the light came on...

Change the oil, and use a good filter (Not FRAM!); capacity according to almost all sources is about 4qts including filter. Also, I don't know if you know oil change etiquette, but I'm going to throw some pointers out there just so I can say I told ya: dip your finger in the new oil and lube the little rubber ring seal on the new filter before installation. When installing, rattle the filter as you turn it, when it touches the surface and there is no more play --> 1/4 turn more and that is all! And don't over-tighten the oil pan drain plug bolt or you'll regret it. It should only take about 12lbs of force total to get it seated nicely. </rant> Good Luck!

Oh, and a nice trick to clean up your lifters and try to quiet them down. Before you do your oil change, add about a half quart of Automatic Transmission Fluid to your motor oil and run like 10 miles on it or something - than change. The detergents in the ATF clean up clogged, dirty lifters. Works great!

[evildky]

dieing when you clutch in on decel is most likely the common iacv issue (search)

[tayter1021]

Thanks for the input. By the way i tried starting it yesterday and it started right up but the oil pressure gauge was still down.

[es.biggs]

Do you get a lot of lifter ticking/tapping? That's a sign your pressure really is down, and you definitely shouldn't be driving it until you verify your oil pressure with an actual "oil pressure tester"

My pressure was fluctuating a lot (on the gauge in the instrument cluster) so I replaced my oil pressure sending unit. It's right above the oil filter. That didn't fix it and eventually my gauge quit working over a few weeks. It sits at 0 now all the time. As soon as I noticed that the new OPSU didn't fix the gauge problem, I got a pressure tester and checked it.

All you have to do is remove the OPSU and screw in the oil pressure tester. All it is is just a tube with a gauge on the end - much more accurate and dependable than the factory one in our cars. Removing the filter makes it easier to screw in the tester. After that I re-installed the oil filter and started up the car and checked my readings. My real oil pressure is about 20-25 psi when it's idling which is fine. Also verify that it climbs when you rev the engine. I can't remember the spec for that but if it goes up the higher the rpm, you should be good.

I used a $25 oil pressure testing kit from Harbor Freight and it worked fine. No reason to spend $100 on something I'll use 2 times a year lol