The Stovebolt Site Forums The Shop Area Engine Shop NO OIL PRESSURE

Rebuilt my '61 261 last year and did a very successful break-in run on an engine dolly. Ran the engine 20 hrs in 1 hr increments under no load conditions varying the speed between 1500 and 2400 rpm. Was very pleased with the oil pressure, and vacuum readings throughout the test cycle and the compression check at the end. Drained the oil, stored the engine over the winter and installed it in the vehicle last week. Filled with new oil, got it started at low rpm, checked the instrument panel oil pressure gauge and there was no reading on the gauge!!!!! Put the manual pressure gauge on that was used during break-in, removed the valve cover, restarted the engine, still no pressure, AND no oil to the rockers. Shut the engine down again and just about cryed. What should I do to find the cause of this problem short of dropping the pan. Many thanks in advance for any advise.

I would pull the distributer and use a drill and shaft to spin up the oil pressure. That way you won't put any wear on the motor while you are trouble shooting. About all I can think of is something to do with the pickup or the pump. Maybe have a look see at them.

Dennis

I pulled the end cover off the pump during rebuild and everything looked good, screen was clean, and pickup tube was solidly in place so I reused it. Got good pump performance during the 20 hr break-in 20psi @ 1500rpm, 38psi @ 2400rpm.

Try forcing some oil into the oil pressure port with a hand pump or a low-pressure pump driven by a drill motor. It's possible you've got an air lock in the pump gears and you need to get them a little wet before they will develop enough suction to pull oil up out of the pan. It's also possible, but not likely, that the pump pickup tube has gotten dislodged in the process of installing the engine.
Jerry

I would go with Hotrod Lincoln.
If that doesn't work, Check the pressure relief valve. I don't know if a 261 has it in the block or in the pump like the 235's.
I had one that broke a spring. The first shot of oil when the engine fired up pushed the valve open and it stayed. Most of the oil went back into the pan and not enough pressure to get to the top of the engine or gauge.

Do you have an oil filter on your engine? If so, take the filter off and see if you have oil in it. I agree with Hotrod's advise.

Just connect the inlet and outlet 1/2 inch ports to each other with a temporary clear tube line. If oil flows through the line and shows up on your valvetrain, than it's the wrong oil filter likely. If it doesn't show oil to the valvetrain, than follow Jerry's advice.

Pulled the dizzy and spun the oil pump for about 10 minutes in both directions and still no pressure or flow to the rockers. The drill didnt seem to have a load on it during this spin, unlike the first time I primed the system when I could tell the drill was laboring to pump the oil. Am using a new oil filter of the same type I used for break-in and even filled the cartridge with oil before starting the engine this time. Will try to backflow the system per hot rod lincoln, but would like a couple of more ideas before I ¨bite the bullet¨ and drop the pan.

I have heard of people overfilling the crank case to submerge the oil pump to get it to prime.
BTW the drill should spin clock ways.

Adding another 2-3 quarts of oil can't hurt, and it just might help the pump clear an air lock. It's beginning to sound like you need to drop the oil pan and start doing some in-depth diagnosis, however.
Jerry

Every oil pump which I have primed needed a 1/2 inch plug-in drill to turn it fast enough to turn the pump. Takes a lot of torque to do it.
Sounds like there is something wrong in the vicinity of the pump. I wonder how much torque it takes to turn a dry pump. If not much is needed, you might just have a pickup problem. Still have to open her up to find out.
Carl

Are you sure that the pump is actually turning? Maybe the shaft is turning and not the gears? If adding extra oil to the pan would allow the pump to prime I would be nervous that it would loose its prime again. The cost of a pan gasket is nothing compared to scoring all the bearings or worse yet wrecking the engine. I'd drop the pan and see whats going on.

Don't want you fellow bolters losing any sleep over my demise (LOL) so I'll tell you I bit the bullet today- dropped the pan and pulled the pump. Holding the pump I submerged the the screen to about the same depth of oil as is in the pan, put my thumb over the discharge pipe that connects to the block, and spun the pump with a drill. To my suprise I was able to hold back any flow of oil out the pipe with my thumb. Thought there would be more pressure than that. More interesting though was as I lifted my thumb to bleed some oil during pumping, the oil was creamy white!!!!!! (and I"m guessing) indicating there is an air leak on the suction side somewhere, suction pipe, cracked casting, gear cover gasket, or something else? Next week I'll rig up a gauge to the discharge and progressively submerge the pump in oil to see where the leak is exactly. Ok, sleep well my friends!!

That is a cool test procedure. I won't be sleeping well until you get back to us with what a good pump setup does with your procedure. BTW, I never sleep well, generally speaking.
Carl

Bought a new Melling oil pump, bench tested it ok, installed it, and spun it, again NO OIL PRESSURE""". Finally after about a half dozen tries over a three day period, it finally started developing pressure to the engine, and is now consistently doing so. Still don't know the why of this whole episode 'cuz an oil pump is not rocket science, but I'll take'em as they come. Thanks for all the input, and I hope this "case is closed"

I always pack a new oil pump with Vaseline before I install it. It helps the gears develop suction to pull the oil through the inlet screen, and petroleum jelly dissolves completely as soon as oil hits it, unlike some types of grease which contain fiber material that can find its way into places it can cause problems.
Jerry

You reminded me of the 66 Buick V8 I used to have. The oil pump was external, and if you did not pack every crevice with petroleum jelly, you were hosed (high tech Canadian vernacular, eh?).
Carl

I have been having the same problem with the 292 I rebuilt for my 66 c10. It has been racking my brain for over 6 months now. I am going to pull the pump and pack it with Vaseline, as suggested to you, and see if it does the trick. Fingers crossed because I am ready for my green monster to be back on the road.

If your going to remove the oil pump from the engine it would be a good idea to get a pan of clean oil and connect your drill and see if you can get it to pump. If it still doesn't prime and pump then you can pack it with vaseline and see if that works. Its easier doing it on the bench than installing it back in the truck only to find out you have to take it back apart.

I have bench tested it twice and out works great out of the truck. As noted in some of the other post replies, it seems to lose its prime when back in the truck do to lack of suction between the gears, I assume because the oil is no longer surrounding it or being direct fed. Will try priming for a while before I pull it while it is still in the truck and hopefully it will save me from dropping the pan.

Sounds like a leaky pickup tube. Can you test it out of the engine with the pickup attached?
Carl

I have tested it before when I did the rebuild and again after I pulled the pump back out to retest it. I just ran the drill on the pump through the distributor port and finally started getting oil up to all 12 valves. It is slow, but better than before.

I wouldn't mess with a questionable oil pump. Rock Auto has one listed for 40.00.

I'm with Don. My 261 registers 60#,at cold idle,and stays 60#,at 2500 RPM,(warmed-up).

So that no one gets concerned about having lower oil pressure on a 261, the 1958-61 261 spec is 30 psi at about 1200 RPM on a warmed engine.