oil pressure questions. |
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Ryan_289
Member Joined: 17 Mar. 2013 Location: Russellville AR Status: Offline Points: 1299 |
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Posted: 26 May 2016 at 2:25am |
I posted several days back about my cheap oil pressure gauge reading low. I installed my other gauge with the small plastic oil line straight to the block and verified that I was getting over 30 at speed and 10 at idle. I ordered one of the US made gauges from Kaiser Willys and installed it today with the rubber line and the metal hard line setup. This one is doing the same thing that the old one was doing. It pulses at idle and bumps between 5-10 hot. If you shut it off and crank it back up it stays at 0 until you rev the engine and it will come up. It shows right at 28-30 at speed once hot. Ive had the oil pan off to replace the pan and there was almost no sludge in the engine and the pickup was clean. Is there something else I can check or is this fairly normal for an unrebuilt engine. Im running straight 30W oil right now, would swapping over to 15W40 oil help any?
On a positive note, I fixed my broken speedometer needle! I pulled a needle out of a parts speedometer. I checked it with my gps and it pretty accurate up to about 45 mph. It looses some speed after that but im ok with it. Edited by Ryan_289 - 26 May 2016 at 2:30am |
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pjensen641
Member Joined: 21 June 2014 Location: United States Status: Offline Points: 690 |
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I'd be checking the oil pressure relief in the oil pump I think. What does it read cold? I think the pulsing thing is likely normal. Whats the amplitude, 5 psi? Most people are use to current car gauges, which don't show reality. They are slowed down quite a bit so that they dont have people freaking out who wouldn't know any better. Its possible the pulsing is somewhat due to the pressure relief valve chattering from open to close.
Other than that, I would be checking oil clearances in the rods and mains, or maybe the oil pump is worn. I've also read about the cam gear lube jet that was changed from a larger to a smaller orifice, you could pull the cover and check what you have. I think there was also an orifice somewhere in the filter assembly. if that is missing it would bleed too much away from the system. The engine I pulled from my Jeep was near the same when warm :(
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Ryan_289
Member Joined: 17 Mar. 2013 Location: Russellville AR Status: Offline Points: 1299 |
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The cam oil jet has been replaced with the smaller jet. The pressure is higher when it's cold. Closer to 15-20 at idle. How would I check the pressure valve? The engine sounds good and feels like it's got good power. No smoke.
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pjensen641
Member Joined: 21 June 2014 Location: United States Status: Offline Points: 690 |
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I've never done it, but there is a plug on the outside of the oil pump. Behind it is a spring, possibly some shims and a poppet. If there is anything hanging it up from going closed or if the spring has relaxed it would be letting to much oil back to the sump. The spring can be shimmed tighter to increase oil pressure, but that only works if it is opening early. If its already held closed and your oil pressure issue is due to something else, it wouldnt help.
Figure 52 and 52 on page 43 of the universal manual has the photos. It also claims that 6psi at idle is the low limit, and 20 psi at 2000rpm.
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WorkInProgress
Member Joined: 13 Nov. 2013 Location: Kennewick, WA Status: Offline Points: 829 |
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your oil pressure seems to act the same way mine does. starting it it will stay at 0 psi for a few seconds and then you rev it it will then seem to act as it should . shows around 35 cold drops to about 10 at warm idle. my engine is also believed to have never been rebuilt but i did install a new oil pump from napa last year to try and get my oil pressure higher than it had been before which it did seem to increase it.
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Ryan_289
Member Joined: 17 Mar. 2013 Location: Russellville AR Status: Offline Points: 1299 |
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67charger
Member Joined: 27 Sep. 2011 Location: Kentucky Status: Offline Points: 1272 |
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Did you make sure the oil pick up tube is flush with the block where it bolts into the block? I guess they can leak just a little bit there where the gasket is if it isn't square.
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Ryan_289
Member Joined: 17 Mar. 2013 Location: Russellville AR Status: Offline Points: 1299 |
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Im pretty sure the pickup tube was good.
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pjensen641
Member Joined: 21 June 2014 Location: United States Status: Offline Points: 690 |
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Yeah, if your cold oil readings are that much better....that is likley bearing leakage flow. Bearing leakage should be laminar flow and laminar flow is more sensitive to temperature than flow through an orifice (like the cam lube jet or oil pump relief). Only other thing out could be is oil pump side clearance, which is also laminar. 15-40 diesel oil is a good oil for these engines anyway.
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Ryan_289
Member Joined: 17 Mar. 2013 Location: Russellville AR Status: Offline Points: 1299 |
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With the engine running well otherwise, do I just watch the oil pressure and live with it until it starts running under 5 at idle? Or would it be better to try replacing main bearings now? Can I change those with the engine in the vehicle?
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pjensen641
Member Joined: 21 June 2014 Location: United States Status: Offline Points: 690 |
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You're just getting it back on the road right? If I were you, I guess I would enjoy it for a little bit and drive it easy. Just don't lug it down and load it up at idle. Hydrodynamic bearings like oil flow and speed, so if you are pulling a hill or something, it easier on them to downshift and rev than to lug. I guess if the manual says 5 psi, that is likley enough to keep from spinning bearings and keep it in good rebuild-able shape. Leave the rebuilding for a winter day.
I'm not expert on the L134 and rebuilding, but I've seen a few threads with people replacing bearings in frame. Its a bit iffy on how long this will last, since the crank journals might need to be ground if they are in bad shape. An easier thing to try might be a new or NOS oil pump. If you are rebuilding at some point, you might need one anyway. That you could certainly do in frame. |
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Ryan_289
Member Joined: 17 Mar. 2013 Location: Russellville AR Status: Offline Points: 1299 |
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I changed the oil over to John Deere 15w40 oil last night. It was raining so I didnt get to take it out for a spin to see if the oil pressure changed.
I may go ahead and buy an NOS oil pump. It looks like Mullins Jeep parts has some. Ive never dealt with him before, anybody had any dealings? The listing states that the packaging fell apart and they already washed the cosmoline off so there is no way for me to know for sure if it is actually NOS.
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Carlsjeep
Member Joined: 15 Jan. 2011 Location: Taylorsville Ky Status: Offline Points: 2642 |
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When you buy a new pump tear it down and measure the distance the gears are below the surface of the oil pump housing and side clearance of gears to housing. There is a spec in the manuals and it MUST have that gap. If not the pump will lock up.
The manual says 8 psi at idle and 20 psi at 38 mph is spec. If you want it higher try shimming the relief spring with a washer or two.
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