High oil pressure

@tomkuester posted:

After finally getting a new ignition system working, I'm back to a previous oil pressure issue. I replaced the sending unit but still get the same reading of about 70lbs. Even when cranking the motor while starting it after sitting for a few weeks the gage climbed immediately, then went up to about 45 once the motor started and within a minute was up at 70lbs where it would stay. Could it be the gage? Low oil pressure I can understand. There are no obvious signs of distress with the motor. It doesn't burn oil. no blue smoke, no new leaks. Just a small leak at the front bearing seal that's been there for a long time. Are there any tests I can run? Thank you

Try putting a Separate Ground on the Oil Pressure Gauge.

Can you temporarily install a mechanical pressure gauge? That will tell you whether or not the stock gauge is working properly. Make sure the mechanical gauge is accurate.

I don't think that you have a problem.  I run mechanical gauges and show 70lbs at start up and while cruising until the oil gets up to temperature , 180 degrees plus.  Then it falls to 64lbs cruising and ~ 35lbs at idle.

You have good bearing clearances. Be thankful.

JT

I took your advice and ordered an oil pressure test kit. Not very expensive and easy to attach.

Hope you can attach it, is tricky with different thread sizes SAE/english stuff and DIN, self sealing or not etc.

I added a classical "mechanical"  Instrument via a T bridge at the sending unit location. Was a bit effort to find a braz bridge and adapters so that both are working in parallel electrical and plain "mechanical". Other forum fellows have done this as well. There are def some pictures as far I can remember. I was eager to have something NOT looking like a cristmas tree

Car is in winter sleep but if you need a picture happy to provide.

Matthias

that's not a bad idea. good oil pressure keeps the beast healthy.

First, where is your sender connected? If its at the back of a 351-C block, that's high unless the engine is stone cold. If the sender is over the fuel pump mount like a Windsor or some aftermarket blocks, it may be 'normal' at hot idle. Certainly it will be different. And we're all assuming a std, not a high pressure/hi volume pump, which is never needed on street (or most race) cars.

The sending unit sits in the back, 351 C style, and it's not a high pressure pump. Until about a month ago it read normal, 35 to 45lbs. I change oil yearly, and will do so before I start it up again. I cant imagine a clogged oil filter, and the oil level is correct.

That isn't too high a pressure. Leave it alone. It's fine.  As with all Fords, you need to consider more oil volume in the pan really to run consistently over 5,000 rpm. You can run the pan dry if using a stock pan with only 5 quarts under certain conditions.

It's been so long since I have run a stock oil pump I just don't remember what the pressure was with one? I think around 40-45 was what it would show stock?

Not to go off on a wild goose chase but I'd recommend that you run an Aviaid oil pan if you intend to fully exercise those Webers.

I've got 12 quarts in the system which uses the Aviaid but I'm also running an oil cooler, dual remote oil filters, along with the six feet or so of -10 lines that accounts for the additional quantity of 10 in the pan.

Over oiling is rarely a problem. Under oiling is.

I would add that if your sender is installed on the original factory provided oil port that even thought you have likely not installed restricter sleeves in the lifter bores and you have all of those corresponding oil losses through the lifter gallery, you STILL have more then adequate oil pressure in the system.

If you are running a hydraulic lifter camshaft then I wouldn't change anything. If it is a solid lifter cam, you need to use the Johnson oil restricter type that were originally designed by Ford for the Boss 351 solid lifter cam application.

Sleeving the lifter bores is a good idea but it is for the purpose of keeping oil in the 5 quart pan and to avoid running out of oil at high rpm use.

It isn't just the Clevelands that do this, the FE Fords particularly when the 428cj was introduced in the 68 model year with oil starvation warranty claims. Strange that it didn't show on the 427's to that extent but the documentation is there to show it was a lack of oil capacity and the engine was pumping the pan dry over only 5,000 rpm.

Shelby installed a larger capacity oil pan, the T-COBRA aluminum pan, on the 65 and 66 GT350's which were 289's. All Fords can pump the pan dry. I had a 76 Granada with a 302 that did it. There it actually siphoned the oil out of the valve covers into the intake through the pcv system.

That high oil pressure may be fine, but why did it start now after years of running at about 45lbs in the past. That change concerns me. I am getting a mechanical tester shortly. Hopefully it will tell me something. I'd rather know that something is wrong than be worried that something bigger will go wrong. Maybe it's nothing like you say. I keep my fingers crossed.

Oil pressure doesn't change like that overnight. Electrical connections and grounds can become loose and give you a different reading.

Senders also can fail.

Diagnosing over the Internet is problematic at best. If your foot falls off, I can just give you generic reasons why it could have happened.

You are the doctor there and the answer should be obvious.

The stock gauge is electric and as Doug said, odd things happen. You should have added your new sender with only one (1.0) wrap of pipe tape. More than one wrap is fine for home plumbing but can interfere with the sender's ground to the engine block. Try this: with the engine running at idle, touch a temporary ground wire to the sender body. If the gauge reading changes, remove the sender and excess pipe tape & try again.

Next, turn on the headlights. If the indicated oil pressure drops on your gauge, you likely have a circuit issue, not an oil pressure issue. Start trouble-shooting by first checking the oil pressure gauge ground, then by pulling one fuse at a time until the gauge reading is affected. Start with that circuit and check everything on it starting with the fuse. Somewhere, there's a poor connection or corrosion. Sometimes a separate ground between block and chassis fixes such things. There should be an OEM ground wire between the ZF & frame, but a second one from a cylinder head to frame can sometimes help.

as we all know DTs have an constant issue on electricity/wireing/fuses etc. The comment above are TOP to diagnose it.

Well I was more nervous on the INSTRUMET reading quality itself - after obejing the above instructions from the team . I love Italia..is just 450 km form here.
So as above (when you have found the issue on probably electrical nature) I recommend something like this "EXPERIMENTAL" set up.

readings at idle for brand new motor  app. 800/750 up/m
Cold 10/40 oil = 4..5 ATM
Hot                   = 2 ATM !!!

Use correct Temp and pressure material tube ok !  I will have the instument moved to the rear window or have a nice spot in the engine  bay.

If I cant figure out the oil pressure problem with all the diagnostic advice received, I shouldn't be driving an old car. A mechanical test kit has been ordered. I just hope I don't have to drop the pan and replace the oil pump. The pressure relief valve could be the culprit as well.  Thankfully I cut out the hand brake cross brace years ago. Funny thing, only once did I wish I had a functioning hand brake when I pulled too close to a building sitting on a downward slope. It took me a while to find a rock to keep me from rolling forward.

After some worry about sudden high oil pressure I ordered a mechanical oil pressure test kit. It shows 50 lbs of pressure with cold engine, not the +70 lbs readings the electrical gage was giving me. So, do I consider 70 lbs the old gage my new normal, or do I look for electrical influences. Some of you suggested things to find the electrical glitch. You don't have to answer that.

Thank you for your input.

...I Do NOT See what Your Problem Is!

What 'Weight' of Oil are You using?

There are NO 'High Pressure' Pumps!!

There ARE High FLOW Pumps!!

Pressure is Produced ONLY when there is Resistance to That Flow! I.E. a 'Brand-New' Re-Build with Tight Bearing Clearances...Very Thick Oil as in 50W, Clogged/Restricted Passages...Other. Last, Hydraulic Lifters, Pumping-Up, Relieving-Down, Can and Will Effect Gauge Readings.

As suggested, You may have a 'Sticking' relief Valve...Or You have a High Flow Pump Installed.

A Mechanical Gauge, Hook-Up should offer clues.

My Digital gauge will read 51 Lbs. Cold...41 Hot, (and the Engine is Well 'Broken-In', with Bearings 'Normally' 'Warn-In') Taken at the Oil Pump, while the Mechanical Gauge at the Rear of the Block reads 60+ Pounds, most of the time, and with a 'By-Pass' hose from the Pump to the 'T' Gauge Mount, in the Block Rear. I DO run a High-Flow Melidon Pump, using 10W-40 Weight Valvoline.

MJ

P.S. ...NOT 'Letting' the Crankcase 'Breathe', as in Breathers, or a PVC system, Will Drastically Effect the Efficiency of Every Pump!! ESPECIALY, When it is a Fuel Pump. pumping from a Tank with NO VENTING!! Pumps Do Not SUCK/SUCTION..."Pumps Provide/Create a VOID that is filled by 'Atmospheric Pressure". When the Atmospheric Pressure is Denied, there is NO filling of the Void, result, NO Pumping!! I'am Not saying THIS is in Your case, But to some who may read this, may realize their Problems.

Veglia electrical gauges are mixed here with Ford senders and as a result are not spot on.

I agree with Marlin. You don't have a problem. Now if you were ONLY showing 10 psi at idle, THEN you should be concerned.

You just calibrated the oil gauge by your test. Leave it all alone. It's ok.

Incidentally, the Veglia tachs are often off 300 to 600 rpm. There that actually is the tach, not a sender BUT you can have them calibrated as well.

Jon Haas also has a calabration adapter for the temp gauge, which I hate to mention this, but stock is off quite a bit. I don't think he's done anything for the oil pressure but you might want to ask him over at Pantera-electronics.com.

Apparently to many who visit here, he's a mystery? It isn't Jon who hides under a rock but apparently too many Pantera owners do? I could never figure that out? Most HAVE heard of electricity and the internal combustion engine but not much else?

Tom, I once had a friend at Autozone who let me borrow 10 different oil pressure senders. I plugged them into my engine one after another. I got eight (8) DIFFERENT readings with the same engine, gauge and wiring! All 10 read lower than a mechanical gauge.

I added a tee pipe fitting to the back of the block and permanently added both a mechanical gauge (which are 2% accuracy minimum in the U.S)  and the sender that read the closest to it. That was in 1981. The stock gauge is to tell me if I have ANY oil pressure. If I want to know within 2%, I open the deck lid and look at the far more accurate mechanical gauge.