I have checked everything I can,,,almost and can't, so far, find the cause of low oil pressure at idle speed when at running temperature. Can any of you FE guys help? ISSUE: When I first installed the rebuilt engine the oil pressure was: COLD: 45 at speed and 25 at idle Running temp (180): 30 at speed and 5 to 7 at idle I replaced the oil pump with a new blue printed Melling HV pump, installed one of the stronger pump drive rods, checked the mains and some of the rod bearings, all perfect, changed the oil to 10w40 and started her up. Now: COLD: 75 at speed and 45 at idle Running temp (180): 45 at speed and 15 at idle To me this is still too low, especially at idle. I have no oil leaks (externally). The engine has screw in oil passage plugs so the rebuilder did the right thng there. Now, I am familiar enough with the FE's & MEL's to understand where all the passage plugs are in the engine. I think I can assume that if any of them were missing (not installed) I would have one of two possibilities. 1) a massive external leak or 2) a massive internal leak. I have zero external leaks, none, NADA. Now, if I had an internal leak from any missing passage plug in any of the main passages, I would have extremely low or no oil pressure at all I would'nt think. Especially once at running temperature. Except for those 4 passage plugs at each end of the lifter galley passages that run the length of the block, if any were missing, I would think that the oil pressure would be almost nil to zero. If the two lifter passages at the back of the block were missing, I would have a major external leak. I don't. To me this narrows things down to the front two plugs in the lifter galley passages. Since the rebuilder installed screw in plugs, I feel almost sure he likely installed all the ones he could readily see. He did an excellent job on everything else. Now this leads me to that sneaky little shit passage plug that resides deep in the block and hides behind the distributor. Since you don't normally put a screw in plug in that one, I am think maybe it was left out by accident. Maybe. Now my question to you FE dudes out there is this. If this one plug was missing (the one behind the distributor) and all the others were in place, couldn't this cause low oil pressure, but not seriously low? After all, this plug is not in a "main" passage. It only holds the oil back that has pressurized the lifters. What do you think? Also, how the fuck to check it out without pulling the engine down?
I don't know shit about FEs but just some other thoughts...are you using an oil pressure gauge that is known to be accurate? What filter are you using? Rumor has it, Frams can cause a drop in pressure.
The pressure in my 352 in my '69 F-100 is about 10 lbs idling, and 35-40 hot, it has been this way for 15 years and tens of thousands of miles.
My brothers 428 Super Cobra Jet had oil pressure like that. His engine was built by a internationally known engine builder friend of our Fathers. He said that was normal.
Ive run across a similar problem with a rebuilt FE. On break in it had good oil pressure and it started to go away. It had like 8#s at idle. I trouble shot it down to a internal leak. Turns out the builder left out one of the plugs inside. I found this out by pulling the intake and running the pre-oiler to see what was going on. Right up front cam passage.
Is there a pressure relief or bypass valve at the oil filter? If this is not functioning properly then this is a possible cause. 15lbs at idle is not too bad, but I would prefer at least 20psi.
You could remove the dizzy then pressurize the system with a long pre-lub shaft and drill motor. You would see the evidence if that plug has been left out right quick. That oil pressure is not to bad for an FE however? Two things that I have found that have a big impact on FE oil pressure is 1. If you change out hydraulic lifters some brands appear to let more oil pass through or around them. I stopped using Edelbrock lifters because of this. 2. If you have changed to some type of after market push rod/rocker arm/rocker arm shaft assembly and did not restrict the passage to the rocker shaft you can get low pressure readings. I usually just stick a .090 Holley jet in each passage or just to experiment to see what would happen you can sometimes just replace the rocker shaft bolt for the oil passage with a standard bolt. Just don't run it to long like that? Scott...
I have three 64 FE powered cars and once they are hot, it seems they don't have oil pressure much higher than 12-15 at idle either. Never had a problem with that.
I have had several FEs and all but of them except a 427 had oil pressure like that.It bothered me too for a while but I got used to it.Must be the design.
Loose rockers on their shafts can kill oil pressure. I bought a new set of adjustavle rockers and shafts from TRW and found them way too loose. If you pulled a valve cover and started it, they would drool 3 qts out in 30 seconds over the valve cover rail, but no spray on the valve springs, it was just dumping around the rockers. I got some oversized shafts from Doug Garifo, and used baffles that spill excess oil into the valley. I added an HV pump, its a rear sump 4X4, and restricted the top oil down with a 612 Holley jet on each feed hole, and I have 85 lbs of pressure at start up, and 70 at speed hot with 30 at idle. It will pull 100 at 7500 rpms. Something to check. Mine were .0045 over on the rockers, the new shafts tightened it up to .0025. It also stopped sucking oil down the guides, and it mists the valvesprings. That little booger behind the distributor has been left out on FE's alot and it can cause your symptoms too. I pulled the dizzy and used a mirrorand pen light to verify mine, but a preoil spin will tell you real quick.
the rocker arm shafts( both or just 1) are upside down...rotate them 180 degrees.....there are holes in them that feed the rocker arms...
OK guys, thanks for all the input. My plan from this point is: 1) Pull the dizzy and do the pressure check. I have the technolgy. 2) If #1 doesn't prove to be the problem...I will pull and check the rocker shafts. These ar not stock Ford. They ar Sharp stands, shafts and roller rockers and spacers. 3) If this isn't the culprit, I'll check to see if the oil holes leading to the rockers are restricted and if not, I'll restrict them. However, I have run it without the valve covers and too much oil up top is not an issue. 4) I'll check the oil filter adapter to see if there is a by-pass. 5) Stop worrying about it. I'll let you know what I find.
I had one of those little internal oil galley plugs pop out once, the oil pressure went from 40psi at idle when hot to 5psi at idle when hot.
What oil filter are you using? I always used regular Motorcraft oil filters on all my FE's in the past. Several years ago my Dad tried another brand and wound up with lower oil pressure on his FE. He changed back to a Motorcraft and the oil pressure picked right back up.
i had a 514 stroker build by an engine builder and had the same issue, low oil pressure. double checked anything and contacted the guy's on the forum and they said that it was normal. also the old geesers said the same. truck is running fenomenal puttung about 625 hp at the rear and is still running fast and hard. so i see no problem. see ya
I have a 390 and the same thing cold idle about 30 and hot about 5 lbs. rev up around 40 or 50 lbs. I have 2 gauges on it one stock F-100 and one aftermarket cheep one. if it aint banging or claddering it's good to go.. I hope.
The Jalopy Journal
