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Discussion Starter #1
Hey gang, what would cause oil pressure to drop 5-10 psi at random. Sometimes it does it other times it doesn't. Might be once in a short trip or it may be 5 times in a short trip. It kind of makes me worried. I took off the fram oil filter and put a motorcraft on after first oil change after being ridiculed for having the orange filter LOL. It is a high volume meling pump and either a canton or milodon oil pan but I don't know how much it holds. I have 7 quarts in it now but even when I had 6 in it did it. It just started doing it yesterday at least as far as me noticing it. It will do it at any time, whether you are cruising or idling or coming to a stop. Could it be air in the gauge tubing?

Oil pressure at idle in neutral is 30 psi, in gear it is 22-25 psi. Cruising it was close to 60 psi but it seems to stay around 52-53 now.
 

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Factory gauge? The sending units act like that when they go bad. Still, you are correct in feeling uneasy about it.

Irregardless, I suggest first testing with another gauge--preferably a mechanical one. I have one installed under the hood in order to remove all doubt.
 

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Discussion Starter #3
It is an autometer pro comp liquid filled mechanical gauge. I don't know if they can go bad? Could it also be some break in lube still in the motor or shouldn't that have an affect? I am keeping an eye on it the whole time so I can shut her down just in case. When it does drop it comes right back up. I would think that if it were something wrong motor wise that it would be constant.
 

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Discussion Starter #4
I am going to get another filter and change the oil again tonight and see if that helps aslo. I was planning on taking it for a nice drive and cruise tomorrow but I don't know if I want to until I know for sure it is going to be alright.
 

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Yes kinked tubing will affect the gauge reading.

Hopefully you are not running a Fram oil filter.

Did you cut open the any of the old oil filters? Might try that and check for debris.
 

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Discussion Starter #6
I have the fram filter I took off but didn't cut it open yet. We double checked and torqued the pick up tube. Maybe the pressure relief on the pump is acting up? I am going to double check the line because now that I think about it I did put a wire loom over it and the water temp gauge line to make it look nicer and protect it, maybe I have it bound somewhere.

The other thing I was wondering is the only time I have noticed it is when I am off the gas so I am wondering if maybe the torque converter might be letting it come more to an idle or something. It would be nice if it was consistent it would be alot easier to diagnose. It is so random and it is only a 5psi drop and it comes right back.
 

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Fram has got to be one of worse filters out there. I either use Amsoil's EO filters or Napa Gold oil filters. They do a far better job.
 

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Discussion Starter #8
Ya the fram was only on there for about 10 mile. I had it already and just used it. It has a motorcraft on it now. I might swing by napa on the way home and get a filter.
 

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Fram, motorcraft napa, autozone Wix..... THey ALL filter the oil, some have anti drain back some do not. None of them effect eh oil pressure like that. Ever...

Failing Gauge or Failing pressure releif valve in teh oil pump get's my vote...

Kinked hose isn't likely unless the oil pressure drops 5 lbs every time you hit a bump... no Bump no reason for hose to kink...

THat's my logic, maybe it's not logical at all...
 

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Discussion Starter #10
I am going to change the oil and filter tonight just to rule that out and see how it does. It wouldn't surprise me if it is the gauge because of it sitting around for 3 years and chances of it getting knocked around were pretty good. I would think that if the pressure relief in the pump was taking a dump it would have done it when the motor was first started.

The motor doesn't use oil and it doesn't even have more then maybe 60 mile on it since it has been put together.

I have a header evac setup, could this be causing any of the symptoms? I was thinking about switching to it a regular filter/pcv setup since I'm not up in the rpms all the time. I know the valve covers do condensate because when I pulled them off to check the valve clearances there was a decent amount of moisture on them. I am using 10w30 oil so I don't think that it is too thick or too thin.

Like I said before i just wish it was consistent so it would make finding the problem easier.
 

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Discussion Starter #12
I found something else that sparked my interest. I found a pinhole in my one heater hose, it doesn't leak but if you squeeze the hose you can see if bubble. The last two days I have had the heater on. Could it be sucking air and causing air pockets in the cooling system and causing different areas of the oil to be warmer then others? Maybe pockets of hotter oil and causes the pressure to drop for a second and come back.
 

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Discussion Starter #16
Well on the drive home it was perfectly fine, sat right at 52-55 psi fully warm above 2,000 rpm. Idle was at 25-30 psi. If the temp is at 180 or below it is at 60 psi at 2,000 rpm. Seems like 180 is the magical number. I will just keep an eye on it and see how she does. I have to pick up a headlight switch tomorrow and will get a new filter and some more oil anyway.
 

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Discussion Starter #18
I don't know what the op is at that rpm, usually have to hang on to much or can't take your eyes off the road long enough to look but I am guessing that it is up to 60 at 6,000. The rev limiter is set at 7,000 and she would pull past it if I let it but I would like to keep it for a while. It hits 6,000 too fast and peak is supposed to be at 6,500.
 

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Discussion Starter #20
I don't know what the correct psi #'s are. I always figured 15 at idle and 40 at cruise, at least that seemed to be the normal pressures in the cars I have owned over the years.

We took a cruise last night for ice cream and once she is warmed up to 180 the cruise psi is still a steady 52-53 psi. I am still going to keep an eye on it and make sure nothing happens and I am still going to change the oil today.
 
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