Oil pressure gage help!

[87Hi-v15HND]

So I have an 87 GMC 4x4 pick-up. Just bought a remanufactured engine and got it in all hooked up ready to go finally. Oil pressure gage reads 30 with ignition OFF. Keyed on position it’s pegged all the way to the right in the 2 o’clock position.

I have he sensor plugged in right behind the distributor and I also have the sending unit on the bottom of the driver side of the block just above the oil pan In between the number 4 and 6 cylinder I believe. I know there is a set screw just above the oil filter but I’m not sure if it will fit there? I tried to put it there and only could get it on about one to two threads before it bottomed out, almost like it wouldn’t fit there.

I’m not a mechanic, just a backyard mechanic/do it yourselfer. Any advice would be awesome guys!

Also can I run my truck with out O2 sensor/un-capped headers hooked up and set the timing? Off topic but I’m getting my exhaust welded up at the moment but I’m pretty much ready to start and get the timing set...

 

[1987 GMC Jimmy]

Did your pressure wire get pinched or clipped? Your sender is supposed to thread in behind the distributor, and then you have your pressure switch by the filter for the fuel pump circuit.

 

[PrairieDrifter]

You also need to make sure you got the correct oil pressure sending unit. It needs to correlate with the year of your gauge cluster.

 

[HotRodPC]

It's normal for the guage to sit at 30 or so when it doesn't have power. It should go to zero when you turn to key to on though and it gets power. If it goes infinite, then the wire going to it is probably grounded or pinched somewhere.

 

[HotRodPC]

And you're sure you got a guage sending unit and not an Oil Light sensor?

 

[87Hi-v15HND]

And you're sure you got a guage sending unit and not an Oil Light sensor?

So the one behind the distributor is a brass fitting with a plug that screws into the side of the brass fitting. The one on the side of the block looks like a can with a one prong metal piece the plug slides over.

I figured one behind the dist. Was dummy light and the one on the side of the block was for the gauge...

 

[87Hi-v15HND]

You also need to make sure you got the correct oil pressure sending unit. It needs to correlate with the year of your gauge cluster.

Yea the one I got is for an 87 1/4” threads (coarse threaded I’m assuming).

 

[87Hi-v15HND]

Did your pressure wire get pinched or clipped? Your sender is supposed to thread in behind the distributor, and then you have your pressure switch by the filter for the fuel pump circuit.

The one behind my distributor has the brass fitting and then the sensor screws into the side of it. Looks like a 90 and the one on the block looks like a can with a metal prong the plug slides over

 

[1987 GMC Jimmy]

Okay, yeah. The one behind the distributor is the safety switch, and the canister by the filter is the sending unit. That’s how mine is set up, too, but normally it’d be the other way around.

 

[87Hi-v15HND]

Okay, yeah. The one behind the distributor is the safety switch, and the canister by the filter is the sending unit. That’s how mine is set up, too, but normally it’d be the other way around.

Well is the sending unit supposed to be by the filter or can it go in between the #4 and 6 cylinder in that other port? I don’t know if it matters or not but the canister is too big to fit in that corner where the filter is. I can only get it threaded in like two threads and then it bottoms out

 

[Rusty Nail]

Really great replies here. These dudes are gonna get you all fixed up pal!

 

[PrairieDrifter]

I’m not positive if that spot above the oil filter will function the same. The big can with the prong on the end goes into that brass fitting by the intake to clear the distributor, that’s just where I’ve always seen them go, that’s where the sending unit goes from the factory. The wire should have a spade connector and a rubber boot that covers it, should be a single wire.

 

[1987 GMC Jimmy]

Well is the sending unit supposed to be by the filter or can it go in between the #4 and 6 cylinder in that other port? I don’t know if it matters or not but the canister is too big to fit in that corner where the filter is. I can only get it threaded in like two threads and then it bottoms out

Can you post a picture of what you’re referring to? I’m only aware of two oil ports on an SBC.

 

[87Hi-v15HND]

Can you post a picture of what you’re referring to? I’m only aware of two oil ports on an SBC.

Will do as soon as I get home

 

[87Hi-v15HND]

Can you post a picture of what you’re referring to? I’m only aware of two oil ports on an SBC.

This is the sending unit on the side of the block. I couldn’t get a picture of the one behind the distributor but like I said it’s a brass fitting and the sensor threads into it and there is a plug that plugs into it. Started the truck and it is pegged all the way to the right passed 60psi.

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