73-87chevytrucks.com
73-87 Chevy _ GMC Trucks => Interior & Equipment => Instrumentation => Topic started by: Skunksmash on January 27, 2012, 05:39:27 PM
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I've been grubbing around under the hood looking for my oil pressure sending unit on my 87 5.7L. Only thing is it looks like somehow there are two of them? How to tell which one is which? Where is it supposed to be located?
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If it's TBI, the 2-wire switch at the back of the intake next to the distributor is for your fuel pump. See subsequent post below.
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it could be on an extension, looking down at your distributor, it will be just to the right. It looks like a 2 or 3" bulb.
with my distributor out.....
(http://www.delbridge.net/oilsender2.jpg)
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If it's carb'd, the one at the back of the intake next to the distributor is the oil pressure sensor. At least that's the way it is on my '84 305.
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It is the one by the dist. w/ one wire. The other is an oil pressure switch for your choke.
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This image of the 'fuel pump oil pressure switch' on an '87 5.7K TBI engine shows the switch at the back of the intake. See SgtDel's image for best picture of location. It has one orange and one tan/white stripe wires connected to it.
The sender for the 'oil pressure gauge' may share the same fitting, but has only one tan wire attached. An alternate location for the 'oil gauge sender' is down by the oil filter. I hope one of us answered your question.
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Yes the one tan wire will help me locate the proper one. Apparently they just look the same. My truck isn't carb'd though.
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what do you mean theres two of them?
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Yes there are 2 oil sensors on the 87's. The one by the filter feeds the gauge (typical of the normal non TBI) the one at the back of the intake goes to the ECM.
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knew of both locations. just wasnt sure if he knew that there's a difference in the gauge one and light one, so it could be one of the three
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Do yall think a bad oil pressure sending unit could be responsible for the battery running down? Since its EFI, I think the computer may just sit there and run the fuel pump until the battery runs down if the oil pressure sending unit is dead.
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With no power to the system there is nothing to close the oil pressure switch to power the pump, this is just a backup for the fuel pump relay. It will keep the truck running with key on if the relay goes bad.
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Yeah I just saw this but its for a 94 not 87.
http://www.youtube.com/watch?v=c2igtCvCNwA&list=FL3j_kt41naUWZJ6cNG7II_g&feature=mh_lolz
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Yes there are 2 oil sensors on the 87's. The one by the filter feeds the gauge (typical of the normal non TBI) the one at the back of the intake goes to the ECM.
Wait there is another fuel filter? I only replaced the one that is at the back of the truck. I think it was on the frame rail, can't remember. There are two of them fuel filters?
I have the oil pressure sending unit that looks like the one in the pics, but I'm having trouble locating it. Probly need to look in the daytime lol. It seems to be buried under there, under all that mess of plugwires and stuff. I might have to pull the coil so that I can get at it easier.
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oil filter
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2 oil sensors, on fuel filter on the frame rail, and a sock filter in the tank.
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Well now I'm screwed. In my attempt to remove the oil pressure sending unit, I broke off its connection to the manifold. It would be that brass looking thing at the bottom left of the pic that bd posted. The thing the sender screws into. I had my wrench on the sender itself, trying to unscrew it. It broke off in the manifold. I'm afraid at this point, I'm at a loss as to what I should do.
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EZ out it.
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Guess I spoke too soon. Yeah the easeout worked. I feel like I got lucky on that one. Although after all this, I'm starting to think that it must be nice (if something has to go bad) when something goes bad on the FRONT of the motor. heh
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Yes there are 2 oil sensors on the 87's. The one by the filter feeds the gauge (typical of the normal non TBI) the one at the back of the intake goes to the ECM.
Are they both the exact same part? Are they interchangeable?
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They are not the same.
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Well thanks for all the help. But I do of course have another question. In your opinion, what is the best way to get that lower sending unit off? I have big hands and even after removing the oil filter, and the oxygen sensor, I'm still having trouble. There really isn't enough room to get a good enough pair of channel locks in there. And since its round, no kind of wrench will work either. What I am thinking would be perfect, would be a miniature oil filter wrench, if such a thing existed.
Maybe whoever changed it last just put it on too tight.
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There is a square at the base of the bell, just use the appropriate sized wrench or crescent wrench.
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Ok now back to the other topic lol. This thing has been fighting me tooth and nail against getting that top oil pressure sending unit fixed. I finally found a specialty tool at Oriellys that is made for the job, and it won't fit on because there is some kind of metal... tab sticking up to just below the sensor itself. The specialty tool is just a perfectly sized socket that fits over the sensor with just enough room between the firewall. But of course with that little tab sticking up, it can't slide on all the way. It just hangs.
So I guess I'm going to have to do something I'm not really comfortable with, which is pulling the distributor. I don't feel like I can get it back in exactly the way it came out. Never had good luck with doing it. So now that I'm done rambling, I'll ask my question.
What is the best way to actually make a mark on the distributor so you can line it back up, when you are reinstalling it? Given the very limited space and visibility that you know is there.
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Can you post a pic of the issue? Are you using the correct elbow fitting with the proper offset?
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No that was the problem it was a little bit different. But it was the only one they had at the junkyard. I got it on there though.
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2 ways
a)pull the cap (leaving the spark plug wires connected) and mark the location of where the rotor is pointing, unbolt it
b) put the motor on TDC, pull the distributor and then put it back where the the #1 terminal is supposed to go.
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Well try as I might, I could not get the factory sending unit off. The one for the gauge. So I cut it out with a die grinder. Once I did that, I was able to get the fitting itself (that the sending unit screws into) out of the block. Now only the threaded part of the sending unit remains. That thing is so corroded in there, that I couldn't even get it out with the use of a vice. Nor could I get it out with an ease out. So I'm looking for a new fitting.
I'm having to make a new fitting out of brass fittings screwed together, that I got at Oreillys. Not exactly the same, but I hope it will work.
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Yall don't think that the new brass fittings will give me trouble do you? They have bigger openings on the ends, than the factory fittings did. I'd say about half-again as big. Maybe it won't matter pressure-wise.
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Not really following what you mean by bigger? You got the broken piece out right?
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Yeah I got the broken piece out, and the new pieces in. But the new pieces are not stock GM replacements or anything, they're just brass fittings that fit. I got them at home depot. My only local junkyard for many miles did not have any replacements for me, and neither did anyone else. So I ended up just getting a 90 degree brass elbow, and like a 2 inch tube. Put everything all together with thread tape. The openings for the oil to flow through the new fittings, are bigger than the stock ones were on the stock piece. Probly half again as big. So much more oil can now flow through the fittings, and get to the sending unit. But the sending unit does have its own little reducer hole, so I don't know.