i recently bought a 95 that had 90% of the wires under the hood unhooked, the oil pressure and temp guages were among those unhooked. i have my dash out now, but befor i pulled it i hooked up the oil pressure sending unit and the guage was still pegged on the 0 end with no movement when cycling the key. seems like many people have issues with the sending unit so i planed on changing it while i have the drivers side battery tray out chasing other wiring/vacuum issues.
i bought a oil pressure sending unit socket and turned it down in the lathe so it would clear a bracket on the bottom of the injection pump, but it still wont go onto the sending unit. my new sending unit fits the socket fine, but i cant tell if the old sending unit is bottoming out in the socket or if it has a different size nut.
has anybody else run into this issue? i really need some advice on getting this old sending unit out, i am at a loss here.
also does anybody know what wires in the cluster conector i can check for continuity with the pigtail for the oil pressure sending unit? and is there a way i can test the guage in the cluster? i found in the fsm where it says that one wire goes to the lamp and the other to the guage, but i didnt see anything about the plug on the back of the cluster.
well, i got the oil pressure sending unit replaced, i had to use a 1-1/16 open end wrench. i got the wrench to bite just enough to turn, then i had to flip the wrench and do it again. i got at it from the bottom of the truck.
my socket is a evercraft brand from napa and the way the corners are designed is the reason the socket wouldnt go on. it works on the new unit though. a 1-1/16 deep socket is not deep enough.
i am still interested in the wiring for the back of the cluster. even though my dash is out i hooked up my cluster and my oil pressure guage works as it should, but i let the truck run long enough to get up to running temp and the temp guage never moved.
i wasnt going to mess with it while hot, but if i ground the wire to the temp sender it should peg the gauge, correct?
Something I am curious about is what your factory oil pressure gauge reads. 0 psi (actual) oil pressure has the needle sitting on the lowest white line. 70 psi (actual) oil pressure is a needle-width north of the "40" line. Is this consistent with yours?
I checked actual pressures using a mechanical gauge in the plugged port on the oil filter housing, next to the turbo feed line.
There is a pressure relief valve prior to the oil passage where the factory gauge sender is installed. The plugged port on top of the filter housing is not regulated. I can peg my 100 psi gauge easily when the oil is cold and I rev to 1500-2000 rpm measured from that port while the stock gauge is reading about 50.
I haven't checked with a mechanical gauge, and my truck isn't drivable at the moment, but when i was warming it up yesterday to check the temp gauge it was just above 40 and once warm was about 30ish maybe a little less at idle.
I could be wrong, but when I had my oil filter housing off, I'm 99% sure that both ports on top of the housing get oil from the same galley, which would mean the turbo is unregulated. The above diagram seems to show that.
It does seem like a lot of pressure for something that needs to spin so freely... but I've been surprised by more outrageous things. I'm not sure how the seals in the turbo are set up, but on the hydraulic saw motors I repair at work, case pressure behind the main shaft seal well exceeds 100 psi. Normal (generic) high-pressure seals seep instantly, but the correct (OEM) seals will last a good long while. The OEM seals have a ton more surface area and a different lip design than the cheapos.
I'm not going to pull my oil filter housing off again just to check, but I remember that whole upper "horn" feature being hollow, and the ports are just threaded into the wall of it. There could have been a divider in there, but nothing was visible from either port, the filter mounting stud, or any other holes on the block side of the housing. :confused013:
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