[SleekGT]

How can I tell if my oil pressure is ok? My needle sits nearly on the low mark or just past it. If I split the guage into quarters I'd say that the needle usually sits just below the 1/4 mark on a good day.
If it's not ok what is usually the common symptoms and fixes?

Most of this stuff is new to me so I'm learning as I go.
Engine is a 289 4 barrel.

 

[PaulS]

The ONLY way to tell what your oil pressure is (and to know if it is good or not) is to put a master gauge on it that reads 0-100 psi. You want to see a minimum of not less than 15 psi at idle and around 60-70 psi at 3000 with a stock 289 in like new condition.
The 289 can survive on as little as 10 psi at idle and 30-35 psi at 3000.
The rule of thumb is for every 1000 rpm you want at least 10 psi. (3000 - 30 psi; 5000 - 50 psi) but as you get above 5000 rpm you need more pressure to get the oil to the back rod journals so it all depends on your rpm.

 

[v8only]

my stock guage I read 3/4 ...or 35 idle 65 freeway

 

[Ivy66GT]

The stock sender combined with the stock gauge can indicate almost anything on one of these 289s. A major change is the thing to watch for. Another gauge reading in actual psi is the only way to tell if the pressures are reasonable.

The oil pump pressure regulator on a '66 Ford oil pump is set to delivery 55 psi at 2000 RPM although the official spec allows for 35-55 psi. The stock gauge needles on my two '66s read much differently but both of them are 55 psi.

 

[SleekGT]

So basically I should just go down to my local auto parts store and get an oil pressure tester? How do you work one of those?

 

[RagHead]

It could just be your oil pressure sending unit or the wrong sending unit, check it to see if its leaking or in fact the correct unit. I agree with all of the above comments, the only way to tell true pressure is to hook up a manual pressure gauge and compare the two. I have a t tied into my block and run both the manual gauge and the original.

 

[PaulS]

So basically I should just go down to my local auto parts store and get an oil pressure tester? How do you work one of those?

To hook it up you remove your sender and screw in the gauge. Start the engine and read it. Rev the engine to 3000 rpm on the tach and read the pressure again.
Write down the results and then you know about where your dash gauge reads.
Be sure to re-install the sender and hook it up after removing the gauge.

 

[jdstefan22]

Sleek GT, I am in the same exact boat as you, mine reads tops, to the 1/4 mark and mostly stays at the L side of the gauge, lower than that at idle.

It was so low, that I questioned as you, the same things. I replaced the oil pressure sending unit, which did not change things too much.

I then went and bought a fairly inexpensive oil pressure tester, at the local flea mkt, cheap.

My psi at was at 50psi when I started it and raised to 55 psi when I got the rpm's higher.

At that point, I know the old calibration on the gauge must be off, or I somehow may have tweaked the needle when I repainted it during my instrument cluster refresh.

Either way, the mechanical oil pressure test gauge gave me reason to not worry about low pressure readings, if anything I am worried about it being borderline high, as it read on the accurate mechanical gauge.

Get the oil pressure tester, it will give you peace of mind or just borrow someones, it takes all of five minutes to check it out.

 

[SleekGT]

Thanks guys, I appriciate all your help! I'll get a tester this weekend and try it out.

 

[Ivy66GT]

If you want details about the oil pressure senders read my earlier thread: http://www.allfordmustangs.com/forums/classic-tech/158024-oil-gauge-senders-v8-what-expect.html

For about $10 you can buy a 2" diameter, mechanical gauge that reads from 0-100 psi. Buy one at the hardware store or wherever; its not really a car part. It will almost always have the same thread on it as the oil sender on your car. Screw off the sender, screw on the gauge - REAL numbers. The only problem is you can only read it with the hood open. Once you know the real pressure then you can remove the gauge and screw the sender back on in about a minute. As the above thread will tell you, don't expect a new sender to work as well as your original one. The new ones are not only CHEAP but fortunately also relatively inexpensive. Since they are all the same internally buy the cheap ones: I paid $8 at AutoZone for the one I hacked open for the pictures.

 

[SleekGT]

Thanks for the info! Curious, when you install a new sender do you use anti-seize or the picures show what looks like pipe tape.

Also I wish it would swap senders out in a minute! I have a automatic fluid canister that sits next to it which makes access to the sender a pain. lol

 

[Ivy66GT]

Curious, when you install a new sender do you use anti-seize or the picures show what looks like pipe tape.

If the threads were bare I would use teflon tape for leak prevention. The one pictured had a white compound on the threads when new. It was not tape although its probably a similar sprayed on teflon. That sender was screwed on an engine for about 10 minutes, ONCE, and to my test gauge setup for a similar time. What you see is the compound remaining after those tests. When the senders are boxed for various retailers the details such as thread compound, exterior color (gold or silver), etc, differ although, from what I can learn the internals are all the same. Both gold and silver ones tested equally poorly.