Oil pressure

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Maybe the electric gauge's signal wire is getting some weird interference from another wire? Like maybe its near an ignition wire or something? Just throwing ideas out....

Get ready for the snow....

-Matt
Thanks Matt, but it’s really not near anything and the wire as well as the connection seems fine. I think it’s just a cheap ass sender. I actually noticed that the bottom of it discolored somewhat. Maybe the heat was messing it up? 

Ya I know, It’s been snowing off and on most of the day. Supposed to set a record low in the city of 27 tonight. Probably lower here. Brrrr

 

Capeman1954

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72 Mach1 351CJ 4sp, Glamour Gold Glow, Black interior, Magnum 500,
Bought new in May 1972
I am having some weird oil pressure readings on my newly built 351 Cleveland. At cold start I get 75-80 psi with the fast idle. Then hot idle is 25 and cruising around town around 50 psi. That’s all good as far as I know, but after engine is at operating temp my gauge sometimes starts jumping around some. It goes way down and the back to 50 pretty fast. It never does this at cold or hot idle, only when cruising around.

I have an aftermarket set of gauges that I replaced the original 3 gauges with. They are Classic Instruments and they are made in USA, so I figured they were a good brand to get. The oil pressure gauge is electric, so maybe the sender is going bad already? I have probably only put about 1500 miles on my new engine and I put these in not to long after that. If it’s not the gauge, can my oil pump be messed up? It’s a Melling std. volume and of course brand new with the engine build.

Thanks in advance for any suggestions!
I had similar issues w my 428 CJ. switched to a heavier weight oil helped.
 
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I have an aftermarket electric gauge. It’s supposed to be a good one made by Classic Gauge. Anyway it was doing the same thing, normal readings when cold but was getting weird when at normal operating temp. I have a very newly rebuilt engine so I put a mechanical gauge in and it reads like it should. No more weird fluctuations and I am confident it’s accurate.
 
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Jpaz, The factory gauges were marginal when new. 50 years on and coupled with wildly inaccurate sending units, they are of less than zero value. I have found the Autometer electrical gauges and seders to be of acceptable accuracy. I put them in my Cougar as I got tired of ruptured oil pressure lines and failed coolant temp bulbs. Just my opinion. Chuck
 
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Jpaz, The factory gauges were marginal when new. 50 years on and coupled with wildly inaccurate sending units, they are of less than zero value. I have found the Autometer electrical gauges and seders to be of acceptable accuracy. I put them in my Cougar as I got tired of ruptured oil pressure lines and failed coolant temp bulbs. Just my opinion. Chuck
Ya I couldn’t trust the factory gauges, so I changed them when I got my engine rebuilt. I used the sending unit that came with the new Classic gauge. Got rid of the ammeter, switched to a voltmeter and new temp gauge. Those seem fine, except for the oil pressure gauge. I got a good Stewart Warner mechanical oil pressure gauge and ran a copper line to it.
 
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Ya I couldn’t trust the factory gauges, so I changed them when I got my engine rebuilt. I used the sending unit that came with the new Classic gauge. Got rid of the ammeter, switched to a voltmeter and new temp gauge. Those seem fine, except for the oil pressure gauge. I got a good Stewart Warner mechanical oil pressure gauge and ran a copper line to it.
John, I've posted a lot on my gauge install as I know you've seen. My car had no gauges, so it was a clean slate. I bought Bosch mechanical oil and temp with the volt meter. A b**ch to find a place to run the copper oil line and the very delicate water temp sensor tube, but I'm so glad I went mechanical from the get-go, especially for the oil pressure.
Good luck with it, hope it solves your issue.
 
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John, I've posted a lot on my gauge install as I know you've seen. My car had no gauges, so it was a clean slate. I bought Bosch mechanical oil and temp with the volt meter. A b**ch to find a place to run the copper oil line and the very delicate water temp sensor tube, but I'm so glad I went mechanical from the get-go, especially for the oil pressure.
Good luck with it, hope it solves your issue.
I actually installed a Bosh mechanical oil gauge and I couldn’t get it to not leak. Was a bit annoying so I changed it to the Stewart Warner gauge. I am getting about a 5 psi increase in pressure, and I believe this one is more accurate.
 
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I actually installed a Bosh mechanical oil gauge and I couldn’t get it to not leak. Was a bit annoying so I changed it to the Stewart Warner gauge. I am getting about a 5 psi increase in pressure, and I believe this one is more accurate.
Strange. Was that gauge leaking from around the feral or elsewhere? Using copper is more difficult for sure to seal, but I had no problem on mine. Fortunately, I had the presence of mind to test for leaks before putting it in the dash.
I do find with the Bosch, it seems to 'flicker' a bit, but it's in there now and unless it fails, it's all good.
 
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Strange. Was that gauge leaking from around the feral or elsewhere? Using copper is more difficult for sure to seal, but I had no problem on mine. Fortunately, I had the presence of mind to test for leaks before putting it in the dash.
I do find with the Bosch, it seems to 'flicker' a bit, but it's in there now and unless it fails, it's all good.
I think the gauge was faulty. No matter how tight I got the fitting it still leaked. It was a cheap 20 dollar gauge, so you get what you pay for I guess. I just added the mechanical gauge under my dash and left the electrical one in the cluster. I didn’t feel like redoing it again, but I will someday.
 
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I think the gauge was faulty. No matter how tight I got the fitting it still leaked. It was a cheap 20 dollar gauge, so you get what you pay for I guess. I just added the mechanical gauge under my dash and left the electrical one in the cluster. I didn’t feel like redoing it again, but I will someday.
Yeah, that happens. I forget what I paid for my gauges as a set. Maybe I got lucky then.
 
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