Oil Pressure Gauge Location

[adf5565]

I’m pretty sure this is a dumb question but I’m going to ask anyways, is oil pressure at the drivers side plug (above the oil cooler lines) an accurate place to verify oil pressure?

The reason I’m asking is all of a sudden my Autometer oil pressure gauge has been reading very low (0-10 psi), but according to a mechanical gauge temporarily hooked at the location specified above my oil pressure is fine (30 psi idle with the motor fairly warm). The Autometer sender is T’d off the stock indicator sender location. The oil pressure indicator light doesn’t come on, but I believe that’s only if there’s a total loss of pressure? Actually what is the pressure that comes on at for future reference at least?

Im assuming my Autometer gauge or sender has crapped out but as this is a brand new motor want to verify everything is in the clear. I

 

[cucvrus]

I was always told that the oil pressure sending unit is located the farthest from the oil pump and that is where you will get the most accurate oil pressure. That if I understand correctly is the end of the line for the oil galleys and would show that you have sufficient oil pressure thru the entire system if the reading you see is at the end of the oil cycle. I hope that makes sense. It always seemed accurate to me. The oil pressure in the oil cooler lines would not be the most accurate place to pick up that signal or tap the capillary for the oil gauge. I may be wrong.

 

[adf5565]

Interesting. Well sounds like the only way to know for sure if I have an issue is hooking up the mechanical gauge to the sending unit location. Not sure why I just didn’t do this in the first place. This morning I pulled my Autometer sender off and hooked in the gauge. After startup at idle the gauge was showing 52 psi.

It may be an apples to oranges comparison to the pressure I got last night at the cooler line location but at least I know now I’m still getting good pressure.

Does anyone know what pressure the indicator light comes on at?

 

[Barrman]

The stock idiot light is supposed to light up when oil pressure gets below 8-12 psi if I remember correctly. Pretty much just enough warning while driving down the highway to not get the engine turned off in time to save the bearings.

If you still have the stock block the stock oil psi spot and the plug above the oil filter are the only places to get a pressure reading. I think 1994 was when the blocks got an extra oil port on the front of the passenger side cylinder bank. Factory turbo oil feed port. I mention that because you never know what was done to your truck before you got it.

 

[adf5565]

The stock idiot light is supposed to light up when oil pressure gets below 8-12 psi if I remember correctly. Pretty much just enough warning while driving down the highway to not get the engine turned off in time to save the bearings.

If you still have the stock block the stock oil psi spot and the plug above the oil filter are the only places to get a pressure reading. I think 1994 was when the blocks got an extra oil port on the front of the passenger side cylinder bank. Factory turbo oil feed port. I mention that because you never know what was done to your truck before you got it.

Thanks for the info on the idiot light, I'm glad it comes on then vs at 0psi or almost 0.

I just swapped in a 6.5 Optimizer so the motor is brand new. It does have the additional oil feed port on the front of the passenger side head which is where I've tapped in for my turbo. It only has 250 miles on it so far so theoretically my bearings and everything are nice and tight (clearance wise) so i shouldn't be having oil pressure issues. The mechanical gauge shows proper readings so I'll swap the autometer sender tonight and see if that resolves my gauge issue.

 

[WWRD99]

Thanks for the info on the idiot light, I'm glad it comes on then vs at 0psi or almost 0.

I just swapped in a 6.5 Optimizer so the motor is brand new. It does have the additional oil feed port on the front of the passenger side head which is where I've tapped in for my turbo. It only has 250 miles on it so far so theoretically my bearings and everything are nice and tight (clearance wise) so i shouldn't be having oil pressure issues. The mechanical gauge shows proper readings so I'll swap the autometer sender tonight and see if that resolves my gauge issue.

I'd hook one up there at the head. One thing I've seen when doing that though is you pop a t in there and that can break over time so use the shortest extension coming out of it to the t so it won't fracture with all the vibration or get a short hydraulic hose made so the vibration won't matter and make some kind of holder so it won't move if possible. I'd bet your sender isn't working right though. I like mechanical gauges but can make a mess if that line blows too!! Never ends!

Sent from my SM-S906U using Tapatalk

 

[adf5565]

The new sender arrived today so I swapped that in. The gauge works better now, shows was seems to be a more accurate reading. It doesn’t exactly line up with my mechanical gauge (Autometer reading is lower) but it’s still is giving a realistic value.

I bought a full replacement gauge/sender, next time I have the dash apart I’ll swap the gauge itself.

 

[James Suitcoat]

Ive read this thread a few times now. And hope I can bump this thread with a question.

I am going to replace the sending unit with a new one but I would like to dummy proof it further and install a mechanical oil pressure gauge.

The oil cooler lines at the block seem to be a good place to create a T and tap in. I keep finding mixed beliefs which is the inlet and which is the oulet to the oil cooler, or which will provide a better representation of the oil pressure? Or is this just a bad idea?

pics for attention purposes only.

 

[Barrman]

Above the oil cooler lines is a little square headed set screw. It is blocking a pressurized oil gallery. That is probably the best place to put another gauge sender.

I use it for an oil temperature sender on one of my trucks.

You will look at the set screw and think a 1/4” socket extension will get it out. Probably not. There is a spec Snap-On tool that is needed to remove it.

 

[adf5565]

Agreed, and this should help with the plug removal.

Oil Plug Above Filter Removal

I am trying to remove the plug from the block (above the oil filter) to use as the oil supply source for my turbo but it is putting up quite the fight, even after soaking for a few days in penetrating oil. A 1/4” drive extension doesn’t fit snug enough to be able to put a lot of force on and I...

www.steelsoldiers.com

 

[James Suitcoat]

Above the oil cooler lines is a little square headed set screw. It is blocking a pressurized oil gallery. That is probably the best place to put another gauge sender.

I use it for an oil temperature sender on one of my trucks.

You will look at the set screw and think a 1/4” socket extension will get it out. Probably not. There is a spec Snap-On tool that is needed to remove it.

Thank you for this. What size is this opening so I can find the right sending unit. Or a link to what you think should work?

 

[adf5565]

I believe it was 1/4 npt but I don’t remember exactly. Could be 3/8. You can get an adapter from that to whatever your mechanical gauge needs. I’d guess that would be 1/8 npt.

 

[cucvrus]

I have put several oil pressure gauges on CUCV’s. I just T fitted the sending unit with brass fittings and used mechanical brass and plastic capillary’s to run to the gauge and this way it is short and high and tight out of harms way. I think the capillary is about 2 ft long and a straight shot to the drivers side gauge area. Good Luck. I think I have that special square socket in MAC tools from 40 years ago. Never used in over 40 years. I also have a Snap On socket for changing Cadillac North Star water pumps that I used lots back in the day. Only once since then in 35 years. Take Care.

 

[James Suitcoat]

I have put several oil pressure gauges on CUCV’s. I just T fitted the sending unit with brass fittings and used mechanical brass and plastic capillary’s to run to the gauge and this way it is short and high and tight out of harms way. I think the capillary is about 2 ft long and a straight shot to the drivers side gauge area. Good Luck. I think I have that special square socket in MAC tools from 40 years ago. Never used in over 40 years. I also have a Snap On socket for changing Cadillac North Star water pumps that I used lots back in the day. Only once since then in 35 years. Take Care.

Today I swapped the sending unit in the back of the block under the air filter housing with a new one and still got the intermittent “red oil pressure light” on the dash - once the truck was warmed up (and only at idle)

Do I trust the light? Well, this was the main reason it was sold. If I speed up the idle it may go away, but it might leave me stranded if indeed I have low oil pressure.

ill post on my personal thread where I go from here.

 

[87cr250r]

What is your oil pressure at hot idle?

 

[James Suitcoat]

What is your oil pressure at hot idle?

do not know - do not have read out gauge

 

[87cr250r]

Your oil pressure probably is low. It would be wise to check it. If the oil pressure is low, you may consider dropping the pan and rolling in new bearing inserts. If you can tolerate downtime, plastigauge each bearing and mix and match standard inserts with undersized to get the correct clearance. Start with one new standard rod and main.

With that said, on GM engines the front cam bearing wears out and causes low oil pressure. It is possible to replace the front cam bearing without completely tearing down the engine. You would need to pull heads and radiator.