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No oil pressure 351M

21K views 31 replies 14 participants last post by  mgawat 
#1 ·
The quick version:
I have zero oil pressure. 0 when cold, 0 when warm. Needless to say I don't run it very long. I added a mechanical oil pressure gauge and it doesn't even push any oil up in to the tube.

The long version:
When I bought the Bronco the PO said it had a blown head gasket and that it was showing no oil pressure, and that he had just installed a high volume oil pump because it had no pressure. He said it still had no pressure after the new pump. I noticed the gauges didn't work at all so I was hoping once I got the gauges working it would show oil pressure. I never could get the gauges working so I hooked up a mechanical oil pressure and temp gauge yesterday, and as mentioned above it doesn't even push any oil up in to the tube for the gauge.

I'm looking for any advice or experience here. Are the 351M's bad about snapping oil pump drive shafts? Or stripping at the pump or distributor?

I did search, but all the serches came up low oil pressure rather than zero. :(

Thanks
Tyler
 
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#7 ·
It has been 22 years since I built a motor, a 302, and I can't remmeber what I used to prime the motor. All I remember is using a drill to do it.

What size fitting is the end of the pump shaft? Can you just buy a priming shaft?

Thanks
 
#3 ·
If i remember correctly the oil galley's are undersized and tend to clog up easy..... someone else could chime in and add to it but im pretty sure thats what it is. i had a 351M in a 76 F250 and it has about 5 lbs of oil pressure all the time
 
#10 ·
For one thing dont take the last owner word that he changed to oil pump. Does it look like the oil pan has been off? The pump might be locked up, the oil pump rod might be broke shit it even might not be in there. STOP starting it for one cause that is just KILLING the main and rod bearings.

If I was you I would pull the distributor and see if the rod is in there. And if it is see if you can rotate it.
 
#11 ·
Yea, the pan has fresh sealant around it evidencing recent removal. The old oil pump is sitting in the floor board so I feel pretty confident it got changed. I am suspicious of the work though.

The rod/main bearings already worry me. I drove it on/off the trailer, a couple times to check the gauges, and once after installing the mechanical gauges. :( I'm considering pulling it and going thru the whole thing including putting new bearings in it. I don't want to spend money on machine though. May change my mind once I get into it though.

Trying to keep this project very cheap. Into it for $303.49 as it sits.
 
#12 ·
Knocking....time for a 460 IMO:toothless

if you gotta keep the M-block, start with this:

Remove your distributor and check the oil pump shaft, it is a 5/16" hex shaft. If it is twisted, your pump is locked up.

If it is twisted, get a new oil pump and a new pickup tube. Always replace as a pair.

It is a good idea to also get new valve seals and a new timing set. These parts came from ford made of nylon, and after 30 years the nylon gets brittle and brekas into pieces. If one of these pieces is small enough it will get lodged in the pump rotor and lock up the pump.

good luck
 
#20 ·
Moroso makes the "oil pump primer" tool, part number 62210, cost me $35.00 and it's an 8 inch long round bar shaped tool and one end fits over the "intermediate oil pump shaft" that has an octagonal shape....the other end goes into the drill, distributor completely out you need to get the end of the tool on the intermediate oil pump shaft inside the little galley there, run the drill for approx 5 minutes so the oil circulates thru the oil pump and galleys etc......

I've heard of guys here making their own PRIMER TOOL with small mm sockets but be carefull if you do something like that, you don't want sockets coming off and dropping down inside the engine you know.....ain't no magnet gonna help there....lol lol

* This is the procedure for new or rebuilt engines before firing it up the first time.
Obviously it's easier if the engine is out of the vehicle on a stand so you can simply turn it upside down and perform this procedure...

Keep in mind there is a little round "CLIP or KEEPER" on the intermediate shaft which prevents it from droping out of the oil pump when upside down......ROYAL PITA to get that shaft with it's octagonal shape back into the pump thru the top distributor hole "galley".....EEHHH!

I'm assuming with the mechanical guage you don't need the oil
pressure sending unit...?


Good Luck ~ :thumbup
If I make my own primer I think I'll tack weld the socket to the extention to be safe. If I remember right it is easy to tell when the oil pressure is up as the torque on the drill becomes obvious.

I took the sending unit off when I added the mechanical gauge.
 
#18 ·
A Ford OP drive is designed to be removed from the pump side, not out the top. So what I wanna know is..... How are you guys pulling your OP drives without knocking off the drive-retainer and having it fall into the oil pan?

DGW
 
#21 ·
DGW1949: right Brother, the round little pump shaft retaining clip prevents it from coming out thru the little galley hole below the larger hole where the distributor goes in BUT that's why it's important to be carefull using the drill because the retinaing clip could MOVE up or down on the shaft if the primer tool gets stuck on the shaft when trying to pull the drill out where you might have enough play and the shaft comes out of the oil pump slot....trying to get it back in thru the top would be a PITA.....these things happen you know, long way a round the block but you get the idea....

If you make your own primer tool, make sure the "tack weld" is very smooth so it has enough clearance thru that little galley hole with out binding so it doesn't come off....

Fluid pressure will make the drill slow down etc.

Good Luck ~ :thumbup
 
#23 ·
if he ran it that long he has oil moving through the motor, just all the places to make pressure are all worn the fawk out.

I bet he pulled the pan to put a pump in it and dropped a main or rod cap to check the bearings and found well they are copper to crank and all the lead is gone from them.

if there was no oil moving the engine would have seized by now.
 
#25 ·
Ok i dont know my arse from my elbow but...... how about removing the pressure sender and connecting a fitting with an airline to it and try blowing out whatever obstruction may be there. Of course that nugget of stuff will then be free in your engine and your oil gallerys full of air meaning you need to reprime. Or... remove the sender from the block and connect the airline to that, to see if the sender works.
 
#30 ·
I appreciate all info and comments back and forth so keep them coming. It was dark before I got done working yesterday so no chance to tinker on the Bronco. It's looking like it will be the weekend now.

351w500,
Thanks for the comment about having the drill in reverse. I should know that from dizzy rotation, but probably wouldn't have thought of it.


Thanks to all,
Tyler
 
#31 ·
I pulled the distributor and used the drill with an extention & 8mm socket to turn the oil pump. Seemed to be building pressure good so I pulled the oil filter just to see. It pumped oil out strong. I'll pull where my gauge attached and pump again to see if it is clogged there. It may just be worn and starved. I'll post up with progress, but it probably will be next weekend before I get back on this.

Tyler
 
#32 ·
Just to lety you know, I've driving 351m since they were new and everyone I ever had eventually developed this no oil pressure problem. Everytime, I just replace the oil pump and it ran great till it the body's fell apart. In my experieince, it's just something the 351m's are know for.
 
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