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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: hondarider188 on October 26, 2012, 09:06:00 pm
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i have a 1983 chevy k10 with a 5.7liter engine. My gauge says that it has about 10psi of oil pressure. it has always said that says i got it about a week ago. but none of the other gauges work besides the speedometer and the fuel gauge. The valve cover does have a small leak, would that be the cause? I did tighten all of the bolts on the valve covers since they were basically just sitting in there so i believe i may have fix the small leak. But back to the oil pressure I think the sending unit may be the problem, but is there anyway to test it?
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I forgot to add that the original engine in the truck was the 305 engine, then about 3 years ago the last owner swapped it for the 350 engine so could that possibly have something to do with the connection the original gauge?
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Remove the sending unit and check the oil pressure with a mechanical test gauge. That's the best way to determine if you have an issue. A leaking valve cover will not cause low oil pressure, unless it resulted in little-to-no oil left in the engine.
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for a mechanical test gauge do you mean a new gauge that is mechanical instead of a electrical system? Or is there a tester that you can you such as a compression gauge?
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An actual tool - similar to the following...
http://www.harborfreight.com/engine-oil-pressure-test-kit-98949.html (http://www.harborfreight.com/engine-oil-pressure-test-kit-98949.html)
(pictured below) or something equivalent. Check your local auto supply stores, Sears, Harbor Freight, etc. Look for a gauge that registers about 100 PSI.
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To comment on your other gauges not working... This is a weak spot IMO on our style trucks. A similar problem led me to this forum some 3500 posts later. There is a plastic printed circuit that is on back of the speedometer cluster that all the gauges/indicator lights except a clock if equipped and the speedometer if mechanical. It is common that circuits burn out causing some things to quit working. Also if previous work done to replace the speedometer cable it is easy to partially unplug it. Also verify that you have the right sending units for your trucks application since the engine was changed.
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I know for sure The coolest temp is not even hooked up because the last owner installed a sunpro gauge under the dash and didn't work either so I replaced it again and it works great now. The oil pressure gauge just seems weak or I have low pressure after all, but I don't believe the low pressure to be the issue, where I think the issue there is the sending unit.
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I finaly replaced the oil sending unit, but it didnt change anything that the gauge is reading. When i turn the key on the gauge does drop down to zero then once is start it jumps back up to about 10 pounds. This is at idle with a cold engine. So would that mean that the gauge is working properly? And my next question is where do i go next? I was thinking maybe the oil pump. I did find another sensor on the side of the block right below the right valve cover( if your facing the grill) and it was unplugged to i hooked it back up, but i havn't seen or noticed anything coming on. The wire for it is green. So does anyone know what it is?
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Green single wire is the temperature sensor.
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So do i have two temperature sensors, and wouldnt the temp. sensor want to be in the coolant system of the engine not the side of the block. My other sensor( the sunpro) is installed right next to the intake on the coolant for the engine. Any ideas on the oil pressure?
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Have you changed oil since you bought it? If so what did you put in it?
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Sorry about the long reply back. But in answer to your question I havn't changed the oil yet, but it is probably overdue and when i do it i am going to replace the filter as well. Is their any specific brand that seems to work best in the trucks and would just the 10W-40 be best. And sam questions for the filter. Thanks
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I would start with 10w30 so you have a benchmark for your oil pressure.
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I finally was able to test my oil pressure while i was at school( in case you didn't know i am still in high school) and the gauge was reading a good 25lbs when at idle. So i do have good oil pressure. So that just leaves me up to the gauges. I do believe that the oil gauge is just going bad or it has a bad connection at the back of it, or it may even be just barely arcing out somewhere. But i heard that the instrument light fuse is part of the gauges receiving power, and i am blowing that fuse for other reasons but cans someone verify this?
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I finally was able to test my oil pressure ... 25lbs when at idle. ... i heard that the instrument light fuse is part of the gauges receiving power ... can someone verify this?
The gauges are powered by the ignition circuit. The instrument lights and all running lights are powered off of battery. The gauges and lights are fused separately.
Why don't you ask your high school auto shop whether they have a universal gauge tester?
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Yeah thats why I took it into the shop was to test my oil pressure to make sure it was just something in the gauge. And not just having a bad engine.
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Restating my earlier post...
Since you've verified that engine oil pressure is good, perhaps your auto shop has a universal "electrical" tester that you can use to actually "test" the dash gauge and sending unit, to help you determine whether the low pressure reading on the dash gauge is a faulty sending unit, a faulty gauge, or wiring/connection problem. Look at the image for an example...
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sorry to jump on the thread, but isnīt 25ft lb a little low.... my truck is about 50ft lb on idle...
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sorry to jump on the thread, but isnīt 25ft lb a little low.... my truck is about 50ft lb on idle...
25 PSI at idle is not unusual for a stock engine.
http://forum.73-87chevytrucks.com/smforum/index.php/topic,22586.msg187645.html#msg187645 (http://forum.73-87chevytrucks.com/smforum/index.php/topic,22586.msg187645.html#msg187645)
The "low" idle pressure I experienced in the above thread was due to anti-cavitation grooves machined into the pump cover.
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sorry bd I thought you were talking about a universal gauge to test the oil pressure itself. I have already replaced the sending unit so I think its safe to say its in the wireing to the gauge or the gauge itself. And I will try to ask the shop tomorrow if they have one.