Need Help Quick - The 1947 - Present Chevrolet & GMC Truck Message Board Network

CT-Truckster · 01-09-2006, 06:37 PM

ok i got a 88 gmc with a 96 or 7 vortec 350 me and my dad put in it about 5 years ago. theres some kind of oil pressure sensor right above the oil filter on the side of the block, and i can't remeber what its for. the pressure sending unit is on top of the block behind the intake right? anyway the one above the filter has gone south and pouring out oil, can i just plug the hole for now to get this thing back on the road tonight or is this a vital piece the truck won't run without? Thanks in advance for any help.

bglad420 · 01-09-2006, 06:39 PM

Pretty sure you can just plug that one if your running another.....

chevyfan420 · 01-09-2006, 07:11 PM

maybe a mechanical tube, that got crimped or melted over time? either way you can plug it to get going again. you dont "have" to have a oil pressure gauge, but its advisable

CT-Truckster · 01-09-2006, 07:21 PM

i found this serching some past posts about the oil pressure sensor on the top of the block and the one down by the oil filter

"the reason behind a oil pressure switch, for the choke is very simple. When you press on the pedal, the choke closes. When you start the vehicle, the choke starts heating up, if the switch sees oil pressure. As long as the engine has oil pressure, it receives power. No pressure, as per the switch, no power. The reason is so the choke won't open unless the engine is running. If this switch wasn't used, all you would have to do to make the choke open is turn on the ignition. If this happened, the engine would still be cold, and the choke wouldn't work when you started it up.

Now, after TBI came into the picture, this switch is used to supply power to the fuel pump. Same sequence. After it starts, if oil pressure isn't sensed, it shuts off power to the fuel pump. This is a safety feature. Say you wreck and the engine dies, but the switch is still on. Without the switch, fuel would still be pumping and if a leak were to occur, well you see how this wouldn't be a good thing."

So mine is still got the tbi even with the vortec engine, so if this pressure swith controls the power to the fuel pump, then its not gonna run, so i'm gonna go plug it and find out.

pugs · 01-09-2006, 08:10 PM

im not familar w/ the later model V8's but i know on the early models what looks like a oil pressure switch on the side of the block was what they called a knock sensor again im not familar w/ later model engines

CT-Truckster · 01-09-2006, 08:36 PM

well, i plugged it and its still running just like always. must be for the oil pressure gauge, maybe that explains why the gauge never worked right, sometimes it would, and then finally just quit working at all. I replaced the oil pressure switch up behind the manifold but it still didn't work, so maybe the one up top is an oil pressure switch for something other than the oil gauge, maybe the fuel pump or something, I don't know. i'll pick a new one to replace the one i removed later in the week and see if my oil gauge starts working again.

01-09-2006, 06:37 PM	#1
CT-Truckster ? Join Date: Jul 2002 Location: Dyersburg, TN Posts: 471	Need Help Quick ok i got a 88 gmc with a 96 or 7 vortec 350 me and my dad put in it about 5 years ago. theres some kind of oil pressure sensor right above the oil filter on the side of the block, and i can't remeber what its for. the pressure sending unit is on top of the block behind the intake right? anyway the one above the filter has gone south and pouring out oil, can i just plug the hole for now to get this thing back on the road tonight or is this a vital piece the truck won't run without? Thanks in advance for any help.

01-09-2006, 06:39 PM	#2
bglad420 Registered User Join Date: Dec 2005 Location: Bellingham, WA Posts: 167	Re: Need Help Quick Pretty sure you can just plug that one if your running another.....

01-09-2006, 07:11 PM	#3
chevyfan420 Registered User Join Date: Nov 2003 Location: Ancaster, Ontario, Canada eh Posts: 95	Re: Need Help Quick maybe a mechanical tube, that got crimped or melted over time? either way you can plug it to get going again. you dont "have" to have a oil pressure gauge, but its advisable __________________ 80 Chevy K10 350/350turbo 86 Chevy 1/2 ton shorty project truck 79 Chevy 1/2ton 350/350turbo not much to look at... *Retired* 97 Chevy C1500 4.3/5 speed.....daily driver

01-09-2006, 07:21 PM	#4
CT-Truckster ? Join Date: Jul 2002 Location: Dyersburg, TN Posts: 471	Re: Need Help Quick i found this serching some past posts about the oil pressure sensor on the top of the block and the one down by the oil filter "the reason behind a oil pressure switch, for the choke is very simple. When you press on the pedal, the choke closes. When you start the vehicle, the choke starts heating up, if the switch sees oil pressure. As long as the engine has oil pressure, it receives power. No pressure, as per the switch, no power. The reason is so the choke won't open unless the engine is running. If this switch wasn't used, all you would have to do to make the choke open is turn on the ignition. If this happened, the engine would still be cold, and the choke wouldn't work when you started it up. Now, after TBI came into the picture, this switch is used to supply power to the fuel pump. Same sequence. After it starts, if oil pressure isn't sensed, it shuts off power to the fuel pump. This is a safety feature. Say you wreck and the engine dies, but the switch is still on. Without the switch, fuel would still be pumping and if a leak were to occur, well you see how this wouldn't be a good thing." So mine is still got the tbi even with the vortec engine, so if this pressure swith controls the power to the fuel pump, then its not gonna run, so i'm gonna go plug it and find out.

01-09-2006, 08:10 PM	#5
pugs Registered User Join Date: Mar 2003 Location: Hamburg Pa Posts: 1,153	Re: Need Help Quick im not familar w/ the later model V8's but i know on the early models what looks like a oil pressure switch on the side of the block was what they called a knock sensor again im not familar w/ later model engines __________________ I don't do thing cuz I can, I do it cuz someone told me it couldn't be done...

01-09-2006, 08:36 PM	#6
CT-Truckster ? Join Date: Jul 2002 Location: Dyersburg, TN Posts: 471	Re: Need Help Quick well, i plugged it and its still running just like always. must be for the oil pressure gauge, maybe that explains why the gauge never worked right, sometimes it would, and then finally just quit working at all. I replaced the oil pressure switch up behind the manifold but it still didn't work, so maybe the one up top is an oil pressure switch for something other than the oil gauge, maybe the fuel pump or something, I don't know. i'll pick a new one to replace the one i removed later in the week and see if my oil gauge starts working again.



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