Dixie Posted February 22, 2019 Share Posted February 22, 2019 Apologies on reviving an old thread. A month ago I took the oil pan off to replace the gasket and RMS. Doing so, I took the oil pump off to fully remove the oil pan from under the truck. Putting everything back together and starting the truck, I noticed the oil pressure gauge now sits at zero regardless of how long I’ve been driving it. I’ve replaced the sending unit. I’ve disconnected the wire, and the needle went far right, grounded the wire, and the needle went far left (0). I also took the sending unit off and stuck a zip-tie in to see if there was sludge build up, but nothing but clean, cold oil (after running it for 5 minutes). Could it be a bad oil pump? Just wanted to confirm and get input. Link to comment Share on other sites More sharing options...
Ωhm Posted February 23, 2019 Share Posted February 23, 2019 Disconnect wire at sending unit and connect ohmmeter from sending unit to ground. Start vehicle, check to see if sending unit is reading ohms between 0Ω and 88Ω's. Link to comment Share on other sites More sharing options...
Eagle Posted February 23, 2019 Share Posted February 23, 2019 On 4/28/2018 at 7:31 PM, ratty said: I tried it, but nothing changed. When the engine is turning over, the gauge goes to zero. So when it's off, it rests at 40, when I start it, it hits zero, and when I'm idling, its at 50. It doesn't matter what it reads when the engine is off. What counts is what it reads when the engine is running. The older oil pressure gauges didn't return to zero when you switched off the ignition, and I don't know what year they changed that. You may not have anything to worry about. 50 psi is a bit high for idle, but ... what weight oil are you running, and what's the air temperature? Colt oil is a LOT thicke/heavier than hot oil. Do the pressure readings change when the engine gets up to full operating temperature? Link to comment Share on other sites More sharing options...
Dixie Posted February 23, 2019 Author Share Posted February 23, 2019 Disconnect wire at sending unit and connect ohmmeter from sending unit to ground. Start vehicle, check to see if sending unit is reading ohms between 0Ω and 88Ω's. Reads 0 ohms before and when I started the truckSent from my iPhone using Tapatalk Link to comment Share on other sites More sharing options...
Dixie Posted February 23, 2019 Author Share Posted February 23, 2019 It doesn't matter what it reads when the engine is off. What counts is what it reads when the engine is running. The older oil pressure gauges didn't return to zero when you switched off the ignition, and I don't know what year they changed that. You may not have anything to worry about. 50 psi is a bit high for idle, but ... what weight oil are you running, and what's the air temperature? Colt oil is a LOT thicke/heavier than hot oil. Do the pressure readings change when the engine gets up to full operating temperature? I’m running 5-30 for oil at 70 degrees in humid South Carolina. As for the readings at operating temperature, still 0 on the oil pressure gauge Sent from my iPhone using Tapatalk Link to comment Share on other sites More sharing options...
Ωhm Posted February 23, 2019 Share Posted February 23, 2019 12 minutes ago, Dixie said: Reads 0 ohms before and when I started the truck Suggest renting/borrowing known good oil pressure gauge. Link to comment Share on other sites More sharing options...
Dixie Posted February 23, 2019 Author Share Posted February 23, 2019 Suggest renting/borrowing known good oil pressure gauge. C will report back when complete. Sent from my iPhone using Tapatalk Link to comment Share on other sites More sharing options...
Dixie Posted February 23, 2019 Author Share Posted February 23, 2019 And just because the devil’s in the details, the truck hasn’t overheated throughout all this. Sent from my iPhone using Tapatalk Link to comment Share on other sites More sharing options...
Eagle Posted February 23, 2019 Share Posted February 23, 2019 4 hours ago, Dixie said: As for the readings at operating temperature, still 0 on the oil pressure gauge ??? With the engine running? We need to reboot this discussion. Begin at the beginning. You're going to make a cold start. Engine cold, ignition off. Gauge reads 40? Always? Every single time? Ignition turned on -- what does gauge read? Engine started, at idle speed -- what does gauge read? Run engine up to 2000 RPM -- what does gauge read? Allow engine to warm up to normal operating temperature ... Idle speed -- what does gauge read? Run engine up to 2000 RPM -- what does gauge read? By the way -- since you had the oil pump out, did you prime it when you reinstalled it? Link to comment Share on other sites More sharing options...
Dixie Posted February 24, 2019 Author Share Posted February 24, 2019 21 hours ago, Eagle said: ??? With the engine running? We need to reboot this discussion. Begin at the beginning. You're going to make a cold start. Engine cold, ignition off. Gauge reads 40? Always? Every single time? Ignition turned on -- what does gauge read? Engine started, at idle speed -- what does gauge read? Run engine up to 2000 RPM -- what does gauge read? Allow engine to warm up to normal operating temperature ... Idle speed -- what does gauge read? Run engine up to 2000 RPM -- what does gauge read? By the way -- since you had the oil pump out, did you prime it when you reinstalled it? Engine cold, ignition off: 0 ignition turned on: 0 engine started at idle speed: 0 engine 2k RPM idle speed: 0 at operating temp... idle speed: 0 run engine up to 2k RPM: flickered to 40 then back to zero once, haven’t seen it happen again yes, I primed at reinstall. My gramps told me to take the sending unit off and start the engine to verify if the oil pump was even pumping, and it was. So I guess we can eliminate the oil pump failure? still haven’t attached a manual oil pressure gauge for verification. Will report back once done. Link to comment Share on other sites More sharing options...
Eagle Posted February 24, 2019 Share Posted February 24, 2019 I suspect it's the sensor, but there's a quick and dirty check for the gauge. With the ignition on (engine does not need to be running): Disconnect the wire from the sensor, and don't let it touch anything. The gauge should go to 80 psi. Ground the sensor wire directly to the engine block or chassis -- the gauge should swing all the way to zero. If it passes this test, and you have oil pumping out with the sender removed, it's probably the sender. Link to comment Share on other sites More sharing options...
Dixie Posted March 3, 2019 Author Share Posted March 3, 2019 I suspect it's the sensor, but there's a quick and dirty check for the gauge. With the ignition on (engine does not need to be running): Disconnect the wire from the sensor, and don't let it touch anything. The gauge should go to 80 psi. Ground the sensor wire directly to the engine block or chassis -- the gauge should swing all the way to zero. If it passes this test, and you have oil pumping out with the sender removed, it's probably the sender. Welp, hooked it up to a manual gauge and it read 0 psi and the highest being 5 psi. Wanted to make sure there was still oil being pumped so I, again, took the sending unit off and out came a strong, solid stream of oil. And just to double tap on the pressure reading, I hooked up another oil pressure gauge and same readings, but the highest was 10 psi. And it passed the test that you recommend I do. Any suggestions? Diagnosis? I do plan on getting a new sender (part # PS133 or PS155?)Sent from my iPhone using Tapatalk Link to comment Share on other sites More sharing options...
Ωhm Posted March 3, 2019 Share Posted March 3, 2019 PS155 is for the idiot light. Link to comment Share on other sites More sharing options...
Eagle Posted March 3, 2019 Share Posted March 3, 2019 If the gauge is good and a mechanical (manual) gauge shows no pressure, the sender isn't the problem. Drop the pan and replace the oil pump. Double check your work from when you were in there before -- be sure there isn't a spun bearing. Link to comment Share on other sites More sharing options...
Dixie Posted March 3, 2019 Author Share Posted March 3, 2019 Ok, will do. Thanks, all!Sent from my iPhone using Tapatalk Link to comment Share on other sites More sharing options...
Dixie Posted March 16, 2019 Author Share Posted March 16, 2019 Bought a new oil pump, Melling high volume. Would you guys happen to have any tips on how to get the pickup tube onto the pump? I read it’s supposed to be a tight fit but I can’t seem to get any bit of the pickup tube onto the pump Link to comment Share on other sites More sharing options...
Eagle Posted March 16, 2019 Share Posted March 16, 2019 1 hour ago, Dixie said: Bought a new oil pump, Melling high volume. Would you guys happen to have any tips on how to get the pickup tube onto the pump? I read it’s supposed to be a tight fit but I can’t seem to get any bit of the pickup tube onto the pump Put the pickup tube in the freezer overnight. Put the pump body in the oven for an hour or so at about 250 degrees. Link to comment Share on other sites More sharing options...
Dixie Posted March 17, 2019 Author Share Posted March 17, 2019 On 3/15/2019 at 11:45 PM, Eagle said: Put the pickup tube in the freezer overnight. Put the pump body in the oven for an hour or so at about 250 degrees. Worked like a charm! Thanks, Eagle! Link to comment Share on other sites More sharing options...
1989commanche Posted March 20, 2019 Share Posted March 20, 2019 On 3/15/2019 at 8:45 PM, Eagle said: Put the pickup tube in the freezer overnight. Put the pump body in the oven for an hour or so at about 250 degrees. Or just freeze the pickup tube with some dry ice. That will shrink it up right away at -109 degrees. Liquid nitrogen is even better but if you don’t have access to a dewar to haul it it’s not worth the hassle great for pilot bearing/ bushings too Link to comment Share on other sites More sharing options...
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