LS swap lost oil pressure

[Camar068]

First things first, check your wiring to your gauges and sender (including grounds). Once known good, if you've not replaced the sender.....do that next. After that, get another gauge.

Don't really see how this has gone to 2 pages. To verify flow (last resort), unscrew the plug below cylinder #1 OR take out the sender and run it for about 10 seconds. If your showing oil leaking out of either of these holes.....you've got Some flow/pressure.

Peace out

 

[iamtherealJayy]

How to I check the ground for the sensor? It just screws in behind the intake? If I didn’t get it tight enough could that cause this issue?

 

[Ricko1966]

@Camar068 I hit like because I don't see how it's gone 2 pages either. I'm going to kick back and see if we can make it to 7.

 

[Camar068]

How to I check the ground for the sensor? It just screws in behind the intake? If I didn’t get it tight enough could that cause this issue?

disconnect positive just in case. ohm meter with leads from battery negative to the engine block. Should read close to zero.

 

[iamtherealJayy]

Disconnected positive, checked various locations on the engine with red lead, black lead on neg at battery, ohms 200 and the highest value I got was 7.8 at the top of the throttle body. Everywhere else shows 00.0 and if it showed anything higher I could move it a little and get 0. I went directly to the block beside oil pressure sensor and directly on the sensor both showed 00.0.

 

[iamtherealJayy]

The tab on top of the gauge showed 9.6 for resistance, after some reasearch 0 is 0 psi and 90ohms is 60psi? (For ‘78 and newer style sensors?) could I check directly off the sensor and see what it reads? The sensor isn’t super accessible I really don’t know how I’m going to get it out later.

 

[rusted nuts]

The tab on top of the gauge showed 9.6 for resistance, after some reasearch 0 is 0 psi and 90ohms is 60psi? (For ‘78 and newer style sensors?) could I check directly off the sensor and see what it reads? The sensor isn’t super accessible I really don’t know how I’m going to get it out later.

You just unscrew it to get it out.

 

[Bextreme04]

Your 40 year old oil pressure gauge is offset by a few PSI on the low side... the end. No fault found. Move on.

Rule of thumb is the engine needs AT LEAST 10 PSI per 1000rpm. That would mean it needs 5psi at idle. The show checked and it had 20psi at idle. Your gauge reads above 20psi while driving... so you are fine. Most oil pressure gauges don't actually have the bottom line as 0 psi.

 

[Buck69]

Sounds like you have a bad sender. Maybe crap in it from the last failed engine or just age.
Also, not sure what you are using for a meter? A lot of digital meters auto range. You have to pay close attention to which range they are in to know what they are actually giving for a reading. Just a FYI. Have seen that mistake made more than a few times when checking resistance.

 

[iamtherealJayy]

I finally found an affordable mechanical gauge locally. Whenever I finally get time to install it I will. For now I’m driving the 87 again.

 

[JACK34]

You better know your oil pressure. Today I just installed a mechanical gauge with copper tubing on my 1973. The only stock gauge that works is the oil pressure gauge and speedometer. So I have 2 mechanical gauges, one for for Temp in the head and one for oil behind the distributor. I didn't believe the stock gauge it read 60. New gauge in to today it reads 60 as well hot a little lower at idle but not much. It's just a stock rebuilt 350 nothing special 10W40 oil. Good luck!!

 

[rusted nuts]

Copper lines have a habit of breaking. Just saying.

 

[SquareRoot]

Eeeeegads......

 

[JACK34]

Copper lines have a habit of breaking. Just saying.

What would you suggest instead of the copper? I'm definitely open for any help I can get. Thank you.

 

[Ricko1966]

What would you suggest instead of the copper? I'm definitely open for any help I can get. Thank you.

They all break,steel cracks,nylon gets old,hard,and breaks,copper breaks,wires break or get chewed up by mice senders go bad so the only real bulletproof option is screw a mechanical gauge,directly into the galley port,you can't see it but nothing will break.Use whatever tubingbyou want,use common sense routing it,hard line put a coil in it for movement,when it breaks repair it. Same as everything else on these trucks when the brakes go out change them when the gas tank rusts out,change it. Do you see a pattern?