A drop in oil pressure on a newly rebuilt engine is a very serious thing. It seems that everyone has gotten off topic talking about oil pressure gauges. I would start by trouble shooting the gauge but it sounds to me like the pressure in the engine is dropping and the mechanic does not want to deal with it. Sounds like maybe the bearings have a problem. I hope this is not the case because it means pulling the engine back out.
I don't see where he doesn't want to deal with it. He told me he would have to check a lot of things including the gauge, the sending unit, and a lot of other things I can't remember. That's why I have to bring it back and leave it so he can diagnose the problem.
It dropped 20% but stayed there and I drove it for an hour on a warm day. It hasn't dipped below that spot. It also goes up a little bit when I rev the engine (properly).
You have to remember he tells me all this technical stuff and while I do pay attention, engines are not my area of expertise so I don't remember everything he's told me. When he's done with the car, he'll take the time to point things out to me, patiently explain things to me and make sure I know what was done or still needs to be done.
A drop in oil pressure on a newly rebuilt engine is a very serious thing. It seems that everyone has gotten off topic talking about oil pressure gauges. I would start by trouble shooting the gauge but it sounds to me like the pressure in the engine is dropping and the mechanic does not want to deal with it. Sounds like maybe the bearings have a problem. I hope this is not the case because it means pulling the engine back out.
Yes it is. And, I agree that the mechanic doesn't want to deal with it. If it were my engine, I would change mechanics.
If someone else has suggested this, forgive me but if it were mine, I'd install a good quality MECHANICAL gauge right at the block and see what's going on. Your mechanic is right, the fact that the pressure goes up when reved is a good sign. Did you mention what weight oil you are using?
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Joined: 10/10/2005 From: brunstank ga Status: online
ias stated before get it checked with a mechanical guage.if its low thens its an internal problem the mechanicla guauge will rule out the sending units as problems. if its fine i would replace the voltage regulator on the back of the instrument cluster along with the oil prssure sending unit to rule out those possibilities i would bet its the regulator though but oil pressure drops a little after a rebuild and the engine has broken in a good rule of thumb is 10p.s.i. for every 1000rpm the engine turn ex: idle should be at about 750-1000rpm so 10psi min
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If someone else has suggested this, forgive me but if it were mine, I'd install a good quality MECHANICAL gauge right at the block and see what's going on. Your mechanic is right, the fact that the pressure goes up when reved is a good sign. Did you mention what weight oil you are using?
Very first thing he did was start it up and rev it to see if it went up, and it did, and he said it was a good thing, and I repeated I was worried about the pressure and had checked the oil and it was full -- and that's when he said he'd be more worried about no oil than a lowered oil pressure.
I bought a bottle of 10/30 oil in case I had to add it, but didn't need to.
ias stated before get it checked with a mechanical guage.if its low thens its an internal problem the mechanicla guauge will rule out the sending units as problems. if its fine i would replace the voltage regulator on the back of the instrument cluster along with the oil prssure sending unit to rule out those possibilities i would bet its the regulator though but oil pressure drops a little after a rebuild and the engine has broken in a good rule of thumb is 10p.s.i. for every 1000rpm the engine turn ex: idle should be at about 750-1000rpm so 10psi min
My mechanic did say that to me, that the engine was being broken in so I'd be noticing little things here and there, and he praised me for watching my gauges so carefully.
I've put on probably 1,000 miles since the rebuild, but the car wasn't running right for the first 500 or so until they adjusted, rebuilt (again) and fixed the carb.
I'm taking it out in a little while to go look at 1955 truck I want to buy so will see how it does, see where the pressure indicator is today, etc.
I think I would go back to your mechanic and ask them to replace the "oil pressure sending unit" and see if that helps your problem.
If the oil level is full, and you do not hear any abnormal engine noise, I would assume you either have a faulty oil pressure gauge in the dashboard (which is rare), or you have a faulty oil pressure sending unit, which tells the gauge inside the car how much pressure the oil pump is producing.
The sending unit is cheap and easy to replace as a guess, and would be the first thing I would do. If that did not change things, I would manually check the oil pressure with a gauge AT THE ENGINE. This would tell me if there truly was a low pressure problem coming straight from the oil pump inside the motor.
At the bottom of your motor is the oil pump, and on the pump is a screen that acts as a filter. If the screen becomes clogged with dirt it will restrict the flow of oil to the pump, thus low oil pressure. If you truly do have a restriction or low oil pressure coming out of the oil pump you will usually hear noises in the engine because of lack of lubrication. Since you did not mention that, I would assume you have a sending unit issue.
ORIGINAL: Soaring The sending unit is cheap and easy to replace as a guess, and would be the first thing I would do. If that did not change things, I would manually check the oil pressure with a gauge AT THE ENGINE. This would tell me if there truly was a low pressure problem coming straight from the oil pump inside the motor.
At least it's just a gauge thing. Hopefully the sender...
He showed it to me, said they're a POS and often have issues in Fords (his opinion).
He suggested another gauge so I ordered a liquid display (so the needle does not bounce around) mechanical gauge with copper tubing (for under the hood) and I'll have it later today and hopefully get it installed tomorrow.
He left the meter on to show me that it was clearly at 50 after the car was good and hot. I drove it for about 2 hours after that and even took it out on the highway for a bit and it never went below the level on the photo above -- about 20% of the way up.
He did suggest I change the oil again and I'll do that.
I have run into an interesting problem with liquid filled gauges. They can become inaccurate in temperature extremes. My liquid filled fuel pressure gauge will read '0' after it gets hot, while the actual pressure is 6psi (the gauge is on the engine). Six psi isn't much for oil pressure, but it is something to keep in mind.
I have run into an interesting problem with liquid filled gauges. They can become inaccurate in temperature extremes. My liquid filled fuel pressure gauge will read '0' after it gets hot, while the actual pressure is 6psi (the gauge is on the engine). Six psi isn't much for oil pressure, but it is something to keep in mind.
Hm ... well, it was just $100 (plus installation) so if I have to replace it with a needle gauge, I will. I don't think I'll be in such extreme temperatures, though .... plus I'll now have a dual check.
Honestly, my mind is totally at ease now that the pressure has been tested properly. More and more people I speak to tell me it's normal for the pressure to drop after the engine has been broken in.
If I could reach I'd just get my own tester and test it myself.
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RE: Oil pressure gauge - 
