Oil pressure gauge fluctuating - 3b turbo

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BigRedBJ

BigRedBJ

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My oil pressure gauge is moving randomly while driving my 1982 60 series 3b turbo. At constant RPM the gauge will drop to the bottom for 10-15 minutes and then move back to normal, no change in engine temp or sound, no exhaust color or temp changes. Adding throttle doesn't change the reading low speed or high speed nothing moves the needle.
I recently added an 80 amp alternator and that is my only guess at what might be going on.

Any thoughts?
Thanks team.
 
duncanrm

duncanrm

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I'd want a test gauge on it as soon as possible to determine if you really have an oil pressure issue, or just an intermittently faulty sender (or wiring, or gauge)..
 
roscoFJ73

roscoFJ73

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The bad scenario is when the oil pressure is sky high when cold and then drops away to nothing when warm. I think you have bad sensor or gauge. And sometimes fluctuating output in the electrical system can make gauges go haywire, so I would test the alternator output to dismiss that problem.
 
BigRedBJ

BigRedBJ

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Thank you, I will see if I can source a new sender locally before adding a second mechanical gauge
 
Radd Cruisers

Radd Cruisers

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If you are using the factory Toyota gauge as your reference point for oil pressure, then that is your problem. The Toyota oil pressure gauges in particular are extremely unreliable and often do not read well or respond to changes in oil pressure.

It is important to add a good quality brand name gauge that preferably is a gauge plus idiot light to warn of oil pressure problems.

3Bs are low oil pressure engines. A hot 3B at idle is happy with even as little as 8-10 PSI.


~John
 
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BigRedBJ

BigRedBJ

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Thanks guys. My worry was that over the last few years it hasn't ever dropped to zero while running and now it does and then pops back to normal.
It turns out that my hunch of electrical was correct, the wire to the oil pressure sender was severed in the loom near the exit, I've replaced the sender with a new one for a $100 and fixed the wire, it seems to be fine now.
20211104 134342
 
BreckenridgeCruiser

BreckenridgeCruiser

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The good thing is that your 3B should have two oil pressure sensors with one sending a shutdown signal to the EDIC when pressure is too low. If you haven't modded that system, then at least you know you're okay if you're main gauge goes out.
 

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