Oil pressure problem
 

Ok so my engine was rebuilt recently. I have an issue with low oil pressure. It only gives me low pressure after warm up 210° or so and on level ground. Let me elaborate. When the front end is elevated (as in on my driveway 8%grade) the idiot light will not turn on. I have had a gauge on it and it drops to 7PSI. At one point I noticed that the oil pressure would only drop when rpms dropped below 680 but when it is on my driveway the rpms drop but not the pressure. Weird , right? So, help me out. I figure that what ever is causing low pressure is being covered up by the oil when on my drive way. I have already taken out and cleaned throttle and IACV. ANY IDEAS???????

NOTE::::This engine has already had three rebuilt heads and two new Oil pumps.

Re: Oil pressure problem
 

Oil is at the full mark? Remove a quart or so of oil (maybe 1.5) and see if the pressure then is low enough to turn on the warning light at hot idle. It shouldn't be if there is no suction leak.


Possible sump pickup tube suction leak, maybe bad tube gasket (reused too many times) or cracked pickup tube

Stuck relief valve

Shop didn't actually plastigauge any of the bearings during the build, excessive oil clearance(s)
Pressurize the oil galleries with the pan off and look for a gusher that would indicate hydraulic loss

Re: Oil pressure problem
 

Yes, oil is full. New gaskket on pick up tube. I thought it was bearing clearance from beginning but that would mean that I would get low pressure all the time wouldn't it? The idiot light doesnt come on all the time and never when front end is higher than back end.
Will try thkse things see what happens.
I have seen how to raise pressure on you tube but I want to find the cause and fix it, though.

Re: Oil pressure problem
 

Re: Oil pressure problem
 

I did not notice any obstructions on the front drain holes but I will try that first. You never know.

Re: Oil pressure problem
 

No. Depends on how much clearance (abnormal leakage) there is. Depends on how viscous the oil is. And pump speed too.

You'll have decent pressure as long as the pump can move more fluid than there is leakage, and as long as the fluid is thick enough to give sufficient resistance. As those variables change, pressure changes accordingly.
Pressure decreases after the oil heats up and gets less viscous, that's normal.

This is really weird to me.
Put the gauge on it again and take pressure readings with the car in various positions?

Re: Oil pressure problem
 

Thanks will try that aswell

Re: Oil pressure problem
 

thicker oil?

Re: Oil pressure problem
 

Ok so I did not try my car at a downward angle because it did turn the idiot light on at an upward angle now. So scratch that angle off list. The only other cause would be the clearances. Like I told the owner from the beginning.
Anyways, I just tried some Lucas oil stabalizer and that stuff works. The idiot light did not turn on after an hour long test drive.
Now I have to see if owner will stiilll accept responsibility. If he does hopefully he gets someone else to work on it. Someone that can use a Mic and knows how to set correct timing.

Re: Oil pressure problem
 

The Lucas stuff just makes the oil thicker, which is usually not a good thing. You probably have excessive bearing clearance if the Lucas fixed it. That engine probably won't live long.

Re: Oil pressure problem
 

Yeah, I know. I just plastigauged the mains. Let me knkw what y'll think. Pics coming in a bit

Re: Oil pressure problem
 

Do you know what the factory spec is?




Same deal for the rod bearings too.

Re: Oil pressure problem
 

The only info I found states .0007 - .0014 for #s 1,5
And .0009 - .0017 for #s 2,3,4

I could be wrong though.

Re: Oil pressure problem
 

I didn' t do the rods. Didn't want to get so deep. Y'all think these two are enough to cause the low oil pressure??? I hear a small tick but that might be the valve lash (set to 8 and 10)

Re: Oil pressure problem
 

Sorry I forgot about this.

Looks like it's at the wide end of the spec range. Not ideal.

I'd say to check the rods.

Too many of these with clearances of 'almost too much' can add up to a total amount (I learned it as "stacking tolerances") that's just more than it should have, more than the pump can keep up with. You end up with low pressure.

Re: Oil pressure problem
 

Yeah, that is what I thought according to the specs I found. I took the car back and the owner has promised to fix it. So, I will let yall know how things turn out. Thanks for ideas and advise.

Re: Oil pressure problem
 

You're right. Great point!

Re: Oil pressure problem
 

?

not your car?

Re: Oil pressure problem
 

Yes it is my car.