So tired of this problem...

[wallaka]

OK. Here's the rundown for those who might not remember: There is no oil pressure registering at the sensor hole when the engine is running. When it is running, no oil even comes out of the fitting even if it is left open, with no gauge or sender in. When I take the distributor out and spin the pump with a ratchet, pressure builds up on the mechanical gauge or squirts all over the place. It also comes up through the rocker arm like it is supposed to. There isn't any kind of lifter tap or anything when it is running.

I just put new main and rod bearings in, and plastigaged them. They were a little on the loose side but within spec. Also went thru with a brush and compressed air to try to clear out all of the oil passages. They seem clear.

The oil pump shaft looks good, and engages well in the dizzy. I have another dizzy, and put that in thinking it could be the problem. No oil pressure then either. It's a new stock replacement Melling pump. There are no visible problems with it. The pressure relief is moving like it should, and I used the gasket when putting the pickup back on. When I first put it in this summer, there was plenty of oil pressure. After a couple of months, though, I noticed that the pressure wasn't even registering. I was only a quarter mile away from home, so I went home quick. I tore the motor down and found a main bearing with a deep scratch all the way around it. This was the only visible damage.

Since then, I've put the motor back in twice. The first time I goofed up and didn't notice that the engine did not want to turn over. I had put all the rod caps on backwards. Figured that problem out, and just put the motor back in. It is a pain to do this by myself, let me tell you.

So, any suggestions? I was thinking about getting another oil pump, but that is 50 bucks I don't have right now. I'm starting to get real sick of dealing with this thing. I don't have the knowledge to blueprint the pump that I have to make damn sure it's within spec, but it does pump when I move it manually.

 

[wsa111]

Have you removed the sender from the block & run a drill or wire into the horizontal oil passage.
I don't have a bare block in front of me so i'm just stabbing for the right answer for you.
Looking at the shop manual the guage or sender seems to come from a passage from the rear camshaft journal bearing going to the head for oil to the rocker arms which you have.
Remove the sender & check the passage to this main artery. Is it blocked or is the rear camshaft journal bearing blocking one passage???? When you put the main bearings in did you have the groved part of the insert toward the top of the block??
Please let us know what you find. bill

 

[rbohm]

8) is the sending unit even good? i have had that problem on a few cars.

 

[addo]

There has to be either an odd internal leak, or a plug missing. Is the motor in the car, or out?

 

[BUZZ]

I agree with the other two post. Did you install a new pickup on the new pump? I'm sure you did but if you didn't it could have a blockage or small hole in it causeing it to lose prime. Also make sure your sending unit is not screwed to far in some times this can happen and hurt you oil flow.

 

[james singleton]

It could be that the oil pump is cavitating, or sucking air instead of oil. Also make sure that your oil level is correct; not too high or too low. I am assuming since you pulled the motor twice (and the pan twice) that there would not be anything clogging up the oil pick-up in the pan.??? I hate to admit to this, but when I put a new motor in last year there was a small cotton rag that was up in one of the piston cylinders that ended up being sucked up by the oil pick-up and causing practically zero oil pressure. Fortunately I caught it in time when I dropped the pan to check the oil pump, etc., and found the problem; and no damage to the engine! Good Luck! Jim

 

[The Plankster Prankster]

it seems the most likely option is a clogged oil gallery, as you said you have oil at the rockers but not at the sending unit, even with the sending unit removed. obviously, the pump is making pressure (the rockers are getting it), but something is preventing that from getting to the gage.
check that main oil gallery in the block, it may well be clogged somewhere. if it's like the big-block, there's a few 1/4"NPT plugs going into it from the side of the block, try pulling one of those and seeing if there's oil there. or IIRC you can pull a plug when it's disassembled and have on open view from the end of the gallery...

 

[Anonymous]

OK. Here's the rundown for those who might not remember: There is no oil pressure registering at the sensor hole when the engine is running. When it is running, no oil even comes out of the fitting even if it is left open, with no gauge or sender in. When I take the distributor out and spin the pump with a ratchet, pressure builds up on the mechanical gauge or squirts all over the place. It also comes up through the rocker arm like it is supposed to. There isn't any kind of lifter tap or anything when it is running.

So when its running no oil comes out of the hole and it registers 0 psi, but when you pull the dizzy and with a different shaft, spin it manually then it pumps oil out and will register pressure correct?

If thats true then it could be a bad oil pump drive shaft. The cam has a gear on it which meshes with the dizzy gear which in turn drives the dizzy and the oil pump through the shaft.

It could also be the hex on the bottom of the dizzy gear is stripped and is not engaging the shaft properly.

The problem has to be right there in either the dizzy gear, cam gear or shaft. It could also be the hex in the oil pump itself but being you can spin it manually and get pressure.....

Later,

Doug

 

[addo]

The oil pump is a simple device. Things to check are that the cover is flat, and that the gears are no more than 15 thou or so below the hosuing flange. Also confirm that the biggest feeler gauge possible between the rotors is 15 thou or less.

Make sure the pickup attaching bolts are not bottoming out, nor backing off loose. Inspect the pickup carefully for cracks, and confirm it is the right type.

The oil pump feeds into the filter via a drilled hole, and thence into the gallery by another.

The oil gallery - there really is only the one. It is above the cam tunnel, with a pipe plug in the rear and a freeze plug in the front. Your mains are drilled up into this gallery. The oil gallery intersects with the lifter bores; this is how the lifters are oiled, and why a hydraulic tappet may run with a solid tappet block. At the block rear is the oil feed riser to the head's recess.

This recess passes up the left rear head bolt hole, and is then diagonally drilled to exit under the rear rocker pedestal. The pedestal must be the correct one, and this is resolved by inspection. Some other pedestals may have oil bleed holes in the top - possibly capped by a washer. The rocker shaft has freeze plugs in each end.

For no oil to get pumped, look for massive deficiencies - missing gallery plugs, and a too-short hex shaft for starters.

 

[ludwig]

What addo said. Sounds like its pumping nothing when it's closed up and works fine when you drive it directly. I found that the pump shaft on my stock replacement pump was too short. There is a Melling casting that has a longer shank pump and there is a correspondingly longer shaft. The guy at my favorite stand-alone part shop gave me the longer shaft for nothing and it worked fine. There is also a little circular retaining spring thing that keeps the shank at the right level of insertion. Without this, the shank drops down and won't engage in the base of the dizz. Of course, I junked the old block and the shaft went with it.

 

[Nutz4mystang67]

There is also a galley plug behind the cam gear, if it is missing the normal spinning of the dizzy is not fast enough to preasurize the whole system and will all dump out the front hole. A drill will spin fast enough to get some oil to the sender hole and to the top . I wiped out 2 sets of cam bearings before I found that problem. I myself is a (3 times a charm)engine builder. .............Kelly

 

[wallaka]

OK. Here's the rundown for those who might not remember: There is no oil pressure registering at the sensor hole when the engine is running. When it is running, no oil even comes out of the fitting even if it is left open, with no gauge or sender in. When I take the distributor out and spin the pump with a ratchet, pressure builds up on the mechanical gauge or squirts all over the place. It also comes up through the rocker arm like it is supposed to. There isn't any kind of lifter tap or anything when it is running.

So when its running no oil comes out of the hole and it registers 0 psi, but when you pull the dizzy and with a different shaft, spin it manually then it pumps oil out and will register pressure correct?

If thats true then it could be a bad oil pump drive shaft. The cam has a gear on it which meshes with the dizzy gear which in turn drives the dizzy and the oil pump through the shaft.

It could also be the hex on the bottom of the dizzy gear is stripped and is not engaging the shaft properly.

The problem has to be right there in either the dizzy gear, cam gear or shaft. It could also be the hex in the oil pump itself but being you can spin it manually and get pressure.....

Later,

Doug

Even with the new dizzy it doesn't register any pressure. I spun the pump with a socket and ratchet. I inspected the pump pretty closely when I pulled the engine and it LOOKED fine. The dizzy spins like it's supposed to (obviously, the engine runs) so I don't think it is that part of it.

I might need the longer hex shaft like Ludwig said. I'll see what the local parts store has. There are two wear patterns on the shaft, one about an inch long and one about half an inch, but there is also a new, fainter wear pattern superimposed on the top of the originals (presumably from either switching the shaft upside down, or the new oil pump?). I originally got a pump that was for a four-main engine; it is about 1/2" too short for a 7-main (hits the main cap). This one fits fine, but I also don't remember the little retaining spring thingy. I suppose I'll drop the pan once again and see what I can see. Hooray.

If I have to pull the engine again, it will not be going back in. I'll get a new one before that happens.

 

[wallaka]

There is also a galley plug behind the cam gear, if it is missing the normal spinning of the dizzy is not fast enough to preasurize the whole system and will all dump out the front hole. A drill will spin fast enough to get some oil to the sender hole and to the top . I wiped out 2 sets of cam bearings before I found that problem. I myself is a (3 times a charm)engine builder. .............Kelly

This is a good tip, but I checked that already. And I didn't use a drill to spin the pump; I used a ratchet. Probably 30-60 rpm max. I'm not that strong, LOL.

 

[ludwig]

FYI, my original short shaft spun then dropped out, then came back up and reinserted itself. The shoulders of the shaft were rounded (more than out of the box) and the wear pattern of which you speak was a continuous surface.

There was no little ring clamp thingy to hold the original shaft it up into the end of the dist. You can do the shaft/shank business through the dizz hole. No need to drop the pan at this point. Maybe I just kept the little clamp ring that kept the shaft at the right height. The longer shank and the clamp ring are not available separately.

 

[BUZZ]

Being that you can spin the shaft at 30 rpm and get oil pressure but not get it at idle which is about 500 rpm makes me think not you might have a bearing clearance to tight or a blockage somewhere that is causing your oilpump to bypass, or like the others suggest your shaft is to short to connect.
when you wrote this. [/quote]The oil pump shaft looks good, and engages well in the dizzy. I have another dizzy, and put that in thinking it could be the problem. No oil pressure then either. It's a new stock replacement Melling pump. There are no visible problems with it. The pressure relief is moving like it should, and I used the gasket when putting the pickup back on. When I first put it in this summer, there was plenty of oil pressure. After a couple of months, though, I noticed that the pressure wasn't even registering. I was only a quarter mile away from home, so I went home quick. I tore the motor down and found a main bearing with a deep scratch all the way around it. This was the only visible damage.
Your saying that you had oil pressure but lost it.Right? Its just hard to figure out how the shaft could be slipping in the dizzy unless the oil pump shaft hole is to big on the oil pump it's self.
My other thought is what left that scratch and where is it now?

 

[Lazy JW]

A couple of thoughts: I would most definitely open that oil pump up and look inside. I read over at SpeedTalk that the new Melling oil pumps have powdered metal gears which really isn't a problem unless there is a problem :roll: They told of split gears, etc. but were mostly referring to high-speed engines. At any rate, it's worth a look and isn't expensive to do so.

Next, I would do some very careful measurements to verify the proper length of the drive rod. You may need to get creative to accomplish this but shouldn't really be too difficult.
Joe

 

[Bort62]

Alright, hold on a second....

If you can spin the pump manually and get pressure, but when you fire the engine you don't... the pump isnt spinning when you fire the engine.

KISS

Your distributor is not engaging the oil pump drive shaft for some reason. It is possible that the female hex on the end of the distributor is stripped, or that the oil pump drive shaft is not long enough.

Take the gear off your distributor and re-install it in the block. Put a drill on the distributor shaft where the rotor goes and spin that. See if you get oil pressure.

I bet you don't.

 

[wallaka]

Take the gear off your distributor and re-install it in the block. Put a drill on the distributor shaft where the rotor goes and spin that. See if you get oil pressure.

I bet you don't.

I need to get a punch to take the gear off first

I did think of that, though. I just don't have a punch small enough to get the roll pin out. Guess I need to go to Sears or HF.

I think that I'll try and see if the morons at the parts store can look up a longer oil pump shaft. I'm not too hopeful since we don't have a NAPA in town.

 

[CoupeBoy]

I thought you could use a length of a 'allen wrench' to make your own drive?

-ron

 

[addo]

It's an alloy steel - I suppose Allen stock would work, but where to get it in such lengths?

The more I chew on this one, the more I believe the "hex shaft too short" theory postulated above.

Not to sound sanctimonious, but to install an oil pump without looking inside merits flogging with (at the very least) wet celery. Many people pack it with moly grease because this provides great suction for initial startup.

Pressure filling or even gravity feed with a decent "head" of oil, would do fine for priming. The filter's anti-drainback valve will stop it all going south.