Just finished changing the oil pan gasket on my 1991 F-250 5.8L 351W. Side-note: never doing that again without pulling the motor. Anyways, I started the truck up again and I have no oil pressure at the gauge. Ran for maybe 15s to see if it would build, but no luck. I did fill it with enough oil Checked the sender unit and it was never disconnected (yes I re-secured the connection anyway). Pulled the new oil filter and it was dry *gasp. Searching around the forums, it seems that the oil pump is no longer primed, which makes sense since I removed it during the procedure. I've read that some people have primed the system by pulling the distributor and spinning the pump drive shaft with a drill.
Any recommendations on how to proceed? If the answer is to pull the dizzy and spin with a drill, any tips on getting the distributor bolt out without snapping it? Mine seems well stuck in there and there's gasket material in the vicinity so Im hesitant to blast it with the torch (it is currently soaking in PB)
Tangential question - is it safe to crank the starter with the coil wire pulled? I know I shouldn't run the motor, but is it also bad to crank with the started to try and prime it?

 

May be a crazy question, but are you sure you got the pump drive shaft back in place when you re installed the pump?

 

That's a great question I think.

For the distributor bolt, penetrating oil is good. You could hit the bolt head with the torch, torch doesn't mean you have to cook everything in sight.. a little heat could be all that's needed. Have you tried turning it yet?

Good idea to scribe some marks for the distributor position before pulling it, and have a timing light handy to reset ignition timing.

For actually priming, if I remember right, the driveshaft is a 5/16" hex. I used a socket and extensions, taped together (so you don't drop anything) on a cordless drill to spin the oil pump.

 

This was my first thought also.

 

^^^all good suggestions.

A dry/unprimed oil pump will NOT prime with an oil filter on that has a good check valve. Simply loosen the filter or remove it and crank the engine on the stater for a few seconds, it will prime right up as long as it's full of oil and the pump drive is installed and turning.

However, if you simply removed the pump and reinstalled it without turning it/pumping oil out, it should have enough residual oil left to prime. Removing the filter and cranking it over on the starter will let you also know if the drive is installed if or if not you get oil coming out of the block.

 

Theres a reason I repack my oil pumps with vaseline or assembly lube before reinstalling them, whether they're new, or used, and prime the engine before attempting to use the starter. It's a good general practice.

 

No reason to go through all that and pump a bunch of muck into the filter causing the filter to possibly bypass until the oil is hot enough to melt the muck.

ALL engines I do are primed with an electric drill and have good oil pressure for at least one minute to purge all air before they get turned over. New engines are rotated by hand with no spark plugs or pushrods after the system has been primed for five minutes, to prime the crankshaft as they do not continuously oil the rod bearings unless full groove main bearings are installed. No matter the crankshaft position, there will always be an oil hole that is in the non grooved cap part of the bearing, not sending oil to a connecting rod bearing.

This guy is in a pickle with his dizzy and if he gets the bolt out without snapping it, there is a good chance the dizzy will be seized and not come out without being destroyed.....if he can even get it out. He already ran it for 15 seconds or more without oil pressure so a few seconds on the starter isn't going to make or break him.

We ALL crank and start up our engines every day without oil pressure. A cold DIZZY driven oil pump engine requires around 15 engine revolutions or more before there is oil pressure.

A CRANK driven oil pump engine will not have oil pressure until it's running...that's right...you cannot spin one on the starter fast enough to ever get oil pressure. A pressurized oil tank is required to prime or some sort of external pump.

We rely on a good check valve in the filter if the filter is not mounted vertically, and residual oil on the bearings and other parts to keep our engines alive on cold starts. Oil coolers increase longevity mostly because the oil is cooler when we shut a hot engine off, and the thicker oil clings to parts better. An oil accumulator with an electric valve or hand valve is the only way to have oil pressure before the engine is turned over.

 

Well this is just bulls*&t. I can disprove it with a $15 mechanical oil pressure gauge plumbed into any oil passage I might be able to get access to. You're absolutely correct that the engine is going to have zero oil pressure on cold start, but I can pull the coil wire, and spin the motor over on just the starter, without getting it up to RPM, and it will generate oil pressure fairly quickly, will it generate operating pressure, like it will if the engine is running? Probably not, but to say it's not going to generate any pressure on the starter alone is just incorrect. 15 revolutions sounds reasonable enough. An engine that has been running previously will also have residual oil left on the bearing surfaces, which is why the bearings don't eat themselves on cold start, unless they've been sitting a *long* time.

 

I said a CRANK driven oil pump engine will not have any oil pressure on just the starter....which is most of the late model stuff 4.6 5.4 5.0 Coyote ect....other makes as well.

I referenced both types of oil pumps....crank driven and dizzy driven.

 

Right, which is relevant for a discussion about a 351W how?

 

I think we both have better things to do today than bicker back and forth. We are both here to share our knowledge in effort to help someone.

But to answer your question....it has nothing to do with a 351w, but has a lot to do with other cars and trucks that people on here own besides a 351w. Now they and other readers will know about both of the common oil systems that vehicles have, and that what works on a 351w oiling system, will not work on there 4.6 Lincoln, Powerstroke, 5.4 pickup, Toyota minivan etc.

 

As above, pull the oil filter off, crank a little, see if it makes a mess, repeat.

Don't let it start.

If it's not priming, pull the plugs, crank a little more.

After that, if it's still not primed, start looking around for the drive rod...

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