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Oil pressure sending unit ??


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Hi all .. My oil pressure shows low on the guage. I dont think the oil pressure is actualy low. The oil level is fine. I have replaced the sending unit and (70$ latter) it made no difference. Should I put in thicker oil and see if that makes a difference. Is there a oil pressure tester I could try to see what the pressure actualy is? I know these motore have a very good oil pump. I dont really know the milege of this motor as the speedo has been changed. It does not burn oil and runs very well. It pulls hard up hills and sounds great .. no lifter noise even.

Any help or comment would be great

Thanks and Cheers Bruce Ü

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Did you buy a new factory unit? Aftermarket units are notoriously crappy, and you can grab a factory unit from CoutesyNissan for like $55 US.

You might also have a faulty new unit. Disconnect the lead from the sender and ground it to the chassis. Turn the key to ON and the gauge might rise to the top slowly. This indicates a faulty sender.

Could also be a broken gauge. It's been known to happen.

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Are you sure there is a problem? I mean my oil pressure reads fairly low (just above lower mark) when at idle and V low speeds, and will only go to the high mark when I'm really giving it the boot.

Does the guage move at all? Also check sender as earlier described.

Good luck

Luke

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10W30 is also what I use. I think thicker oil is a mistake in my opinion if you live in cooler weather. Some use that 20W50 weight which is way over kill in cooler climates. The 10W30 will reach the upper half of the motor faster and will provide much better lubrication. Now if you live in areas with 100+ degree heat than 20W50 is a must.

It is normal to have higher pressure when cold and when your reving the motor. It will always read lower at idle. Sounds like it's working correctly to me.

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My 240z had low oil pressure when running and almost no oil pressure at idle. Everything was running fine, but I switched the oil pump to a higher pressure/volume turbo unit for the 280z turbo engines. This change over brought the oil pressure to the 10psi/1000rpm level that is within my comfort level and it didn't take a lot of time or money.

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  • 2 weeks later...

I know that these electrical units do not react very quickly to pressure changes. If you have access to a mechanical guage, try plumbing it into the block and check the pressure. As long as you have 30#-40# pressure, your engine will run forever. Now if you tweak the engine and have high rpm needs, now that is another question. 25# oil pressure on the freeway is plenty of pressure to maintain oil viscosity.

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I have been told that to solve the gauge problem, use a sender from a fairlady roadster. Supposedly MSA sells it and they will know what you need if you call them.

Well, that depends on your definition of "solve".

I heard that story and I bought the roadster sender & installed it on my L24. Now, when I turn on the ignition (key turned to the first detent) I can observe the oil pressure gauge needle rise to well above the "0" mark on the gauge long before I engage the starter to "start" the engine.

Yes, at idle the oil pressure gauge needle shows a more positive reading; but my common sense (and the observation of the needle rising to above "0" before the engine is even running) tells me that the actual pressure has not been changed one iota by the substitution of a different sender than the gauge was intended to pair up with.

So ya, if the appearance of the needle being higher on the gauge scale makes you feel better, then the roadster sender is a miracle fix for this issue. On the other hand, if you want more (real) oil pressure, get a high pressure/high volume oil pump.

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Well, that depends on your definition of "solve".

I heard that story and I bought the roadster sender & installed it on my L24. Now, when I turn on the ignition (key turned to the first detent) I can observe the oil pressure gauge needle rise to well above the "0" mark on the gauge long before I engage the starter to "start" the engine.

Yes, at idle the oil pressure gauge needle shows a more positive reading; but my common sense (and the observation of the needle rising to above "0" before the engine is even running) tells me that the actual pressure has not been changed one iota by the substitution of a different sender than the gauge was intended to pair up with.

So ya, if the appearance of the needle being higher on the gauge scale makes you feel better, then the roadster sender is a miracle fix for this issue. On the other hand, if you want more (real) oil pressure, get a high pressure/high volume oil pump.

thats what I figured, its more for peace of mind. But the real question is, with the stock sender, is the oil pressure really low, or is it fine? Could just be that corrosion on 30-35year old wire has built up enough resistance to lower the signal. I'm pretty sure that all of us with the indications don't have low oil pressure.
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Its not just corrosion or resistance, as this was a common issue when these cars (240Z's) were new.

my opinion (and that is all that it is) is that it's a poor design or quality issue with the manufacture of the gauge or sender.

I am also sure that we all don't have really low oil pressure.

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I have a turbo pump and my running, hot pressure with an "all new" engine is 50#. What I was concerned about was the volumn. I do not care about high pressure. I DO care about volumn with my P90A head. I agree that we do not have low pressure. We have serviceable pressure that makes these engines run forever. As long as the needle still moves when I start it, all is well!

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There were 2 different "models" of oil sender as well.

These needed to be matched up to the correct gauge or as you have found there is little indication of oil pressure.

I believe the early model [the one you need] is no longer available and the only solution is to use a compatible gauge from an older zed...

FWIW

MOM

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just remember the oil gage is just that a gage If you really are concerned buy a cheep mchanical gage and connect it to the same port the present sender is mounted . This will tell you exactly what is going on. My gage on my Z with ZX engine and a turbo pump , after warm up hardly shows any pressure at idle and mid area while driving. The gage shows 25 psi at idle and 50 ,which is the relief setting , at 2 K . And I agree with the 10w30 for all season , at least here on the LEFT coast. Gary

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