zx_drift Posted February 5, 2009 Share Posted February 5, 2009 I have an '82 280zx (NA) and my oil pressure is pretty strange. My oil pressure wavers a lot. When I come to a stop, the pressure drops to zero then comes back up. When I floor it, it stays pretty steady at around 80 psi (K&N oil filter) but sometimes it drops pretty low, but the oil light never comes on, even when the gauge reads 0. The car also burns lots of oil, so its time for a rebuild, but I have good compression (180 all around). Just wondering if anyone has any ideas. Quote Link to comment Share on other sites More sharing options...
woldson Posted February 5, 2009 Share Posted February 5, 2009 Odd and tough to say, could just be a bad gauge. If pressure drops to much the oil pressure kill will stop the engine. Quote Link to comment Share on other sites More sharing options...
wrxand280z Posted February 5, 2009 Share Posted February 5, 2009 Have you checked to see how much oil was in it? If its low it will act that way. Quote Link to comment Share on other sites More sharing options...
nismopick Posted February 5, 2009 Share Posted February 5, 2009 ^^^ Ditto... did you check the oil level? Also... the oil pressure sender has a tendency to go faulty. Replacing it will likely solve the prob (if the motor does have proper oil levels). Quote Link to comment Share on other sites More sharing options...
FlatBlack Posted February 5, 2009 Share Posted February 5, 2009 I was driving home the other day and noticed a slightly lower oil pressure, checked my levels when I arrived and everything was ok. I came outside a couple of hours later to head over to a friends, the oil pressure came up then dropped to Zero. I popped the hood, got out, and the connector had come of the sending unit. Maybe check to see if its loose? Quote Link to comment Share on other sites More sharing options...
zx_drift Posted February 5, 2009 Author Share Posted February 5, 2009 I've replaced the sender, and cleaned the connectors. The oil level is good, although it does do it more when it is low. Other info... it drops when I shift then comes back up as soon as I give it gas. sometimes at a little throttle it stays zero until I stomp on it. Oil is 20w50 (so it will burn less) Quote Link to comment Share on other sites More sharing options...
280zx 2by2 Posted February 6, 2009 Share Posted February 6, 2009 whens the last time you changed the oil? old thin oil or oil of the wrong viscosity will give you low oil pressure too... try that if you havent recently and see what happens... Quote Link to comment Share on other sites More sharing options...
zx_drift Posted February 6, 2009 Author Share Posted February 6, 2009 Just did one, problem is still the same. Is it possible the oil pump is bad, and its just churning the oil instead of pumping it through the system? Quote Link to comment Share on other sites More sharing options...
islanddozer Posted February 6, 2009 Share Posted February 6, 2009 I've replaced the sender, and cleaned the connectors. The oil level is good, although it does do it more when it is low. Other info... it drops when I shift then comes back up as soon as I give it gas. sometimes at a little throttle it stays zero until I stomp on it. Oil is 20w50 (so it will burn less) You don't run a l28 with 20 - 50 unless you have a diesel Z. Just kidding. If you are burning oil you know you have a limited time on that motor. Running your motor with 20-50 starves your engine of proper oil pressure at crucial times (start-up, heavy on the throtle) Go to 10-30 and if you want add a oil treatment but you are ovoiding the inevidable Quote Link to comment Share on other sites More sharing options...
Mayolives Posted February 6, 2009 Share Posted February 6, 2009 If you are using lots of oil, as you have stated, and you have good compression on all the cylinders and are not leaking oil, the you are probably in need of some head work. While you at it, drop the oil pan, clean it and the oil pickup. Check and replace sender unit and oil gauge as needed and you should be good to go without spending a fortune. By the way, you need to filter the "type of oil" information above, especially the 20/50 myth. While I'm not recommending what oil for you to use in your car, I will tell you that I have driven z cars for many miles and years using 20/50 castroil. Is it the best? There is no best! It's what works for you. Get the picture? Quote Link to comment Share on other sites More sharing options...
zxtman Posted February 6, 2009 Share Posted February 6, 2009 if none of the above suggestions help, check the oil pump. the springs may be weak or the pump itself may need to be replaced due to wear. how many miles on that motor? Quote Link to comment Share on other sites More sharing options...
zx_drift Posted February 6, 2009 Author Share Posted February 6, 2009 yeah, I know I need a rebuild, just been avoiding it for a while. I put a catch can in to see how much blow-by I'm getting to see if it could be the rings.. I also need to do a leak-down test, just haven't gotten around to it. Quote Link to comment Share on other sites More sharing options...
woldson Posted February 7, 2009 Share Posted February 7, 2009 if none of the above suggestions help, check the oil pump. the springs may be weak or the pump itself may need to be replaced due to wear. how many miles on that motor? I've really never have heard of a failing oil pump on this forum. I did a quick search and did not see anything. Outside of low oil, partially cloged pick up screen or electronics, it is tough to imagine a pump behaving the way he has described. HOWEVER, anything is possible. My money is on electrical. Quote Link to comment Share on other sites More sharing options...
slownrusty Posted February 7, 2009 Share Posted February 7, 2009 Do yourself and buy an auxiliary oil pressure gauge and hook it up at the block oil pressure sender and take the guess work out. I HIGHLY doubt its the oil pump. Yasin Quote Link to comment Share on other sites More sharing options...
ckolander Posted February 9, 2009 Share Posted February 9, 2009 this is a good one, cause my 79 is almost doin the same thing. Difference is, it never drops to 0, and I'm runnin with Castrol GTX 5w-30 high mileage. It seems to just be slight fluctuation and doesn't affect performance.....I don't think. Quote Link to comment Share on other sites More sharing options...
zx_drift Posted February 11, 2009 Author Share Posted February 11, 2009 Do I get an electric type or mechanical type gauge? and if it turns out to not be the gauge, what else could it be? Quote Link to comment Share on other sites More sharing options...
dan5138 Posted February 11, 2009 Share Posted February 11, 2009 Check it with a mechanical guage. Screw out the electrical sender and plum in the mechanical guage there. It's 1/8th in NPT. Quote Link to comment Share on other sites More sharing options...
zx_drift Posted February 11, 2009 Author Share Posted February 11, 2009 What's wrong with an electric type gauge? It is a brand new oil pressure sender. Quote Link to comment Share on other sites More sharing options...
dan5138 Posted February 11, 2009 Share Posted February 11, 2009 Ive bought electrical parts and returned them the same day . A mechanical guage is handy because you dont have to fiddle with any wires, and eliminates all the guess work. The in dash guages are kinda tempermental. I changed my sender, and as soon as I turn on the key with the engine off, the needle goes up to 90 and just sits there -.-. Quote Link to comment Share on other sites More sharing options...
RigilKent Posted February 14, 2009 Share Posted February 14, 2009 i seem to be noticing a similar problem it bounces around but i dont think its effecting much. a least as far as i can tell. I have about 100,000 miles and replace oil frequently. IDK I would just do everything mentioned and maybe the screen on the pump is fouled. best of luck Quote Link to comment Share on other sites More sharing options...
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