GMC pickup help....

The sending unit is made up of a diaphragm and a linkage to a switch inside if it has an indicator light. If it has a gauge, it still has a diaphragm but the switch is a variable resistor. Point is, the diaphragm can split, crack, pinhole, etc., and it is under direct oil pressure. They are crimped closed at assembly, and not serviceable. But they can leak a lot of oil. Usually you can tell by looking at the crimp area, or where the stud/screw comes through the phenolic.

The PCV valve is suspect for being stuck closed. The design is to recirculate crankcase vapors (smoke) from ring blowby back into the intake and be burned. If it is stuck closed, pressure builds up in the crankcase and can force oil out in weakly sealed areas, or sometimes even pop seals out of place. If there is a leaky seal, a small leak becomes a large leak because of the increased pressure.
 
I'd start with the oil sending unit, it's a pretty easy fix, if it's not too hard to get to. Before anything, if it was mine, i would degrease the $h!t out of the motor and pressure wash the rear of it well, covering the distributor with a heavy plastic bag. Let it dry thoroughly, don't start it during that time. Once dry , get some light on it, start the motor and try to eyeball where the oil is coming from. It'll be easier to spot once the motor is cleaned and dry, because it'll shine if you can see it, or it'll be the only oil spot if you can feel it but not see it. Either way it'll be a lot more pleasant to work on when it's clean.
 
Chevy is one of the hardest to stop oil leaks, as a chevy owner and gmc i have banged my head against the wall many times, i think you will find it is the intake gasket in the back of the engine that is leaking, slite chance valve cover, if you do find out it is intake make sure you use threaded rods as dowl pins when reinstalling the intake, cause the slightest slip of the intake and wham oil leak, i have seen the small canister type oil sending units leak around the seam at bottom, thats why i always use the manuals oil pressure gage with the copper tubing even in my 2009 yukon, the 283 is one of chevys best engines made they have plenty of torque and with a nice shave of the heads will give you some eye opening adventure, good luck and more chevy power to you. lol
 
Thanks guys!!! It is a big leak in the back. Smaller leaks I don't really care about, but when it looks like the Valdez out there after work I'm a little worried lol. I'm going after work to get some degreaser, idk what kind though. Should I spray it on when the motor is hot?

The valve covers do have a small leak to them also. I will probably change them as well. I'm just a little worried about getting it back in time. I'm going to have to look for the torque specs also. Are they any different since it is an aluminum intake?

I will check out the sending unit tonight. As soon as I find it lol. I'm telling you I was under that thing and even the transmission cooler lines are soaked. It's a mess!!

Thanks,
Chris
 
Thanks guys!!! It is a big leak in the back. Smaller leaks I don't really care about, but when it looks like the Valdez out there after work I'm a little worried lol. I'm going after work to get some degreaser, idk what kind though. Should I spray it on when the motor is hot?

The valve covers do have a small leak to them also. I will probably change them as well. I'm just a little worried about getting it back in time. I'm going to have to look for the torque specs also. Are they any different since it is an aluminum intake?

I will check out the sending unit tonight. As soon as I find it lol. I'm telling you I was under that thing and even the transmission cooler lines are soaked. It's a mess!!

Thanks,
Chris
Chris let the engine cool a tad 20 min. before degreasing dont want no flames poping up or castiron poping, and yes aluminum intakes take a different torque setting which can be got from your intake website . Mac:))
 
Well I degreased it and still couldn't see anything. Oh well that's my luck lol. But I do believe I'm just going to put a new intake gasket, valve cover gasket, oil pressure sending unit and new gasket around the distributor. It will be like 40 bucks from Napa for it all. I couldn't see anything from the bottom of the motor. Now the fun begins.........

Thanks,
Chris
 
Well I degreased it and still couldn't see anything. Oh well that's my luck lol. But I do believe I'm just going to put a new intake gasket, valve cover gasket, oil pressure sending unit and new gasket around the distributor. It will be like 40 bucks from Napa for it all. I couldn't see anything from the bottom of the motor. Now the fun begins.........

Thanks,
Chris
Chris dont know how much mechanical experience you have, but when pulling the distributor make sure your harmonic balancer and pointer is lined up at top dead center then pop the distributor cap off and make sure the bug is pointing to number 1 plug wire if not rotate engine to make sure number 1 plug is correct with bug and pointer in top dead center, that way when you re install the distributor it will be in time, if any doubt pull number 1 plug piston will be up and pointer will be pointing at top dead center, if you have electronic ignition use the plug and pointer tecnique. Mac
:))
 
Thank you Mac. I hate pulling distributors, I would rather go to the dentist lol. But thank you!! I just hope it will go back together in time :rofl:

Thanks,
Chris
 
Well here's an update. Got it tore apart and I decided to take a break to get a cup of coffee and a smoke.
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Hopefully I can get it done today. Working midnights sucks!!!

Chris

16884A70-23F3-46D4-9E3C-6E04D05C7FA9-49786-00000F104D8F2D08.jpg
 
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