Oil pressure anomaly (1 Viewer)

[Godwin]

Just got a call from @cruiserinsanity regarding unusual oil pressure readings with the stock gauge on a 3FE. At idle the gauge is reading about 1/3 on the gauge, while at elevated rpm the needle is resting just above the lowest mark. This is opposite of how the gauge should be functioning which is a lower reading at idle and increased pressure at higher rpm.

While on the phone he looked over the engine. Oil volume is reading on the dipstick, no oil leakage at the sending unit, nor at the oil filter, plus there are no major oil leaks. Also pressure is not dependent upon volume until the amount of oil drops below 2 qts or so allowing the oil pickup to suck air. Then oil pressure will drop.

At the moment we think that the issue is a bad gauge, wiring, or sending unit.

Any input?

 

[cruiserinsanity]

Oil pressure at idle

And oil pressure under load

 

[1911]

I don't remember if the 62 gauges are better-grounded than 40 gauges, but a bad ground would be my first suspicion.

 

[Spook50]

Yep, grounding for the sender would be the first thing I'd check. Then failing that, pull the sender to give it a good cleaning with some throttle body cleaner. A few years ago my gauge started reading excessively low, and for some reason I had remembered recently (at that point) reading about cleaning out the sender. Mine wasn't too bad inside, thanks to a couple decades of running synthetic oil keeping sludge buildup to a minimum, but upon cleaning and reinstallation, my gauge was back to working normal again.

 

[cruiserinsanity]

Gauge resumed normal operation.

 

[1911]

Gauge resumed normal operation.

Intermittent ground or other open circuit.

 

[Rodger1957]

Put a mechanical gauge in

 

[CruiserTrash]

@Godwin @cruiserinsanity Glad it got working again - did you find a culprit? Bad ground? corroded sender wire? Gauge issue?

For what it's worth my oil pressure does drop at sustained high rpm/high speed highway driving. I assume that's because the oil gets hotter and thins out. Idle is at about the 2/3 mark, and highway driving is at about 1/2. It's interesting to me that the oil is a part of the engine cooling on these. I didn't have experience wrenching or thinking about this stuff prior to owning 60s, so maybe that's normal.

 

[Godwin]

@Godwin @cruiserinsanity Glad it got working again - did you find a culprit? Bad ground? corroded sender wire? Gauge issue?

For what it's worth my oil pressure does drop at sustained high rpm/high speed highway driving. I assume that's because the oil gets hotter and thins out. Idle is at about the 2/3 mark, and highway driving is at about 1/2. It's interesting to me that the oil is a part of the engine cooling on these. I didn't have experience wrenching or thinking about this stuff prior to owning 60s, so maybe that's normal.

It self-corrected. Oil gauge function returned to normal, so we haven't tried to troubleshoot.

 

[CruiserTrash]

It self-corrected. Oil gauge function returned to normal, so we haven't tried to troubleshoot.

Sometimes those are the best fixes.

 

[Godwin]

When I did the 3FE swap ca. 25 years ago I made the mistake of hooking the oil pressure sensor connector to the grounding tab and killed the oil pressure gauge. Having no oil pressure showing on the gauge I stopped by the local Toyota dealership and talked to one of the techs about the lack of pressure showing on the gauge. His response was don't worry about because he'd never seen a 2F or 3F with inadequate oil pressure. That's been my experience over the years, even with oil pumps with 300k + miles on them the oil pressure remains solid.

 

[Spook50]

When I did the 3FE swap ca. 25 years ago I made the mistake of hooking the oil pressure sensor connector to the grounding tab and killed the oil pressure gauge. Having no oil pressure showing on the gauge I stopped by the local Toyota dealership and talked to one of the techs about the lack of pressure showing on the gauge. His response was don't worry about because he'd never seen a 2F or 3F with inadequate oil pressure. That's been my experience over the years, even with oil pumps with 300k + miles on them the oil pressure remains solid.

350K+ miles on mine and the oil pressure gauge still shows good.

 

[AndersBror]

My first technical post...So driving home from work tonight I glance down and my oil pressure was zero....of course I freak out pull over and check oil ,which is fine. Started back up and oil pressure returns to the normal just below 1l2 way mark .The gauge has been working normal since I've had the 62 since August. The engine has 250K on it and runs good. Thoughts? Sending unit?...or something to be worried about?
Thanks!

 

[cruiserinsanity]

My first technical post...So driving home from work tonight I glance down and my oil pressure was zero....of course I freak out pull over and check oil ,which is fine. Started back up and oil pressure returns to the normal just below 1l2 way mark .The gauge has been working normal since I've had the 62 since August. The engine has 250K on it and runs good. Thoughts? Sending unit?...or something to be worried about?
Thanks!

If you are concerned about the possibility of oil pressure being low you should probably install a mechanical gauge and see what it reads.

I stated having the issue with my gauge two months and about 3000 miles ago. My oil pressure gauge sits at the L when I'm running and intermittently comes back to normal when at idle. I cleaned grounds and the sending unit wire with no change. I'm not worried about it.