Not sure where oil is leaking

[chengny]

2X Steve!

How can either the sender or switch start leaking at the threads? They are unable to rotate due to their associated harness connectors - they are essentially locked in place.

Unless pipe threads are intentionally backed out they rarely just start leaking - especially to the degree as shown in the image you posted.

I would take a very close look at the special pipe fitting that they screw into. And I don't mean those threads either. It may well be the case that the nipple that screws into the top of the block is cracked - either at the block surface or where it is joined to the horizontal 90.

Pull the sensors, remove the street/90/tee thing and inspect it closely.

As noted above, unless you are the type who scans his gauges every 10 seconds - if that fitting lets go, you are out an engine. Your oil pressure will drop to zero immediately and unless you catch it right then...that'll be all she wrote.

 

[Boone83K10]

Your oil pressure while at idle can be between 20 and 35 psi...with a leaky pressure switch, it will spew oil out quite fast. My first square was a 1978 and it leaked like crazy....and drove me nuts til I found it.

That seems low to me. My engine oil pressure at idle is near 40. 60 at cruise. Those are both when fully warm @ 195 deg. But i also know the old 10 psi for every 1k rpm

 

[MadOgre]

My oil pressure gauge still works. so I was thinking I'll take it out and put a little RTV on the threads as long as they look alright

The main reason why oil sending units leak is because Someone tightened it in by the top of the sender. This rotates the body separate from the threaded tube that threads into the block. Causing it to leak. Always tighten the oil sender to the block from the threaded tube that threads into the block!

If your current one is leaking you will have to purchase a new one that has not been rotated on its stem.

 

[smoothandlow84]

That seems low to me. My engine oil pressure at idle is near 40. 60 at cruise. Those are both when fully warm @ 195 deg. But i also know the old 10 psi for every 1k rpm

Lol...wasn't sure of the exact oil pressure at idle...my oil pressure is close to 45 normally when driving and as high as 60 when cold.

 

[83kid]

As noted above, unless you are the type who scans his gauges every 10 seconds - if that fitting lets go, you are out an engine. Your oil pressure will drop to zero immediately and unless you catch it right then...that'll be all she wrote.

Just a little fun thing to add here...

Ran a 350 with no oil in it once... motor was gonna be junked anyways, and it was on an engine stand (This was in school), so we drained the oil and ran it for a little, till it seized up. Waited a few hours, and it ran right again. Not saying youd be able to drive a vehicle that way after thatd be done to the motor, though

 

[smoothandlow84]

Sounds like the ol Castrol Syntec commercial.

 

[Georgeb]

Just a little fun thing to add here...

Ran a 350 with no oil in it once... motor was gonna be junked anyways, and it was on an engine stand (This was in school), so we drained the oil and ran it for a little, till it seized up. Waited a few hours, and it ran right again. Not saying youd be able to drive a vehicle that way after thatd be done to the motor, though

Funny, I just did about the same thing but on the interstate. it was full of oil just no pressure hot. It was not happy but after it cooled a bit....runs fine. I wouldnt make it a regular practice tho.