Oil pump intermediate shaft breaking

-
Newbomb Turk said:
Well damn. That’s a pretty thing. Maybe the new drives aren’t worth a crap.

Like I said earlier, I’ve run 125 psi on those drives and never failed one.

Unless some focknoid found its way into the pump and locked it up I’ve got nothing.
Click to expand...
Nothing in the pump, pulled it and opened it up. Clearances still look new. Pressure is ~50 psi
 
Rocket said:
In addition to what has been said above, if it is snapping, make sure the pump is seated flush and the shaft is straight . If the shaft engagement to the pump is not straight, there will be excess stress applied to the shaft.

Also be sure there is the right clearance between the shaft and the bronze bushing as well as the mesh with the cam gear to avoid binding and excess heat build up for lack of clearance and oiling.

Also be sure the shaft length is correct. For example if the block and china wall has been machined, you may have to shim the distributed or shorten the distributor tang that engages the oil pump drive to be sure the engagement and mesh of the gears is correct.

See discussion in this recent thread starting at post #146.

[/URL]
Click to expand...
Thank you Rocket, I will double check all of those
 
Bubbacuda68 said:
Nothing in the pump, pulled it and opened it up. Clearances still look new. Pressure is ~50 psi
Click to expand...
Are you 100% SURE. Does it possibly look like this? Look at the transition. It's a squared off step. Much weaker than the shaft in post #12.

PUMP SHAFT.jpg
 
Newbomb Turk said:
I should have asked RRR too (he can read this and answer too) how many of these failures have you seen at the drive gear end?

I know I’ve run as high as 125 pounds of oil pressure and never failed a drive.

I also gave a theory about bronze gear wear. IMO most of the bronze gear failures are because cam thrust is not verified and corrected.

If it’s not corrected the cam can move enough that rapid gear wear occurs.

I can’t count the number of times I’ve had to machine a cam gear to tighten up cam thrust. Almost half of the builds have the thrust too loose.
Click to expand...
Honestly I've never seen a oil pump drive fail, I've seen the gear beening wore out.
 
I was thinking;
the oil pressure is measured at the top of the main line. It is not measured at the pump.
So; what if the pump was running super high pressure, and dumping at the bypass, because there was a restriction up the line. But as soon as the oil got thru the restriction, now the system is regulated by bearing leakages and so on. Boy-O-boy that pump could be working overtime.
The only place I can see such a restriction occurring is at that diverter/separator cup-plug that is driven vertically up the main line to divert oil to the filter. Unfortunately, the oil-pump has to come off to inspect that cup.
 
AJ/FormS said:
I was thinking;
the oil pressure is measured at the top of the main line. It is not measured at the pump.
So; what if the pump was running super high pressure, and dumping at the bypass, because there was a restriction up the line. But as soon as the oil got thru the restriction, now the system is regulated by bearing leakages and so on. Boy-O-boy that pump could be working overtime.
The only place I can see such a restriction occurring is at that diverter/separator cup-plug that is driven vertically up the main line to divert oil to the filter. Unfortunately, the oil-pump has to come off to inspect that cup.
Click to expand...
I have the oil pump off, in fact, I pulled the whole engine back out because I wanted to check the oil passages just for the reason you are saying. Rocket had some good advice that i had not thought of, the length of the shaft and the distance between the distributor and the slot that it rides in. I will check all of these when i get the (3rd) new shaft. Thank you
 
Bubbacuda68 said:
I have tried both, the tapered and squared off. I did switch to a roller cam and I am hearing that there is a difference in the shaft/gear on the roller cams. Checking into that now
Click to expand...
Depends on what the camshaft gear is made of. If it's billet, the intermediate shaft gear needs to be bronze or melonized, I believe.
 
Bubbacuda68 said:
I have tried both, the tapered and squared off. I did switch to a roller cam and I am hearing that there is a difference in the shaft/gear on the roller cams. Checking into that now
Click to expand...
At this point post a picture of your broken intermediate shafts.

It does not take much in the oil pump to jam it up and cause the intermediate shaft to twist the tip off. There is a lot of stress there when the pump stops and the camshaft is still turning. It can be a tiny but of trash easily missed during inspection that gets stuck between the rotors of the pump. If you don't find anything wrong with the depth of the distributor revisit the oil pump and the pickup. Look carefully in the bottom of the oil pan for anything that feels gritty.
 
Wonder where the pump drives are made now?

I can tell you this. I bought the upgraded Direct Connection pump drive in the 70s when DC started. It was made of Moly 4XXX steel. This steel is hard steel....but not hardened like the stock piece. The Moly can absorb some twisting & not break; the stock piece has no give, like steel used in gears. I tried cutting the stock piece with a hacksaw....just blunted the blade. The Moly piece can be cut with a hacksaw.
I also found the DC piece was wearing against the bronze bush. I got another DC piece & used it with an alum bush, no more wear. It is just another indication of the difference hardness of the two pieces.

To continually break the aftermarket piece, I can only think of two reasons:
- poor quality metal
- something in the pump is locking up or extreme pressure is being applied to the shaft, eg binding relief valve.
 
Just to add to what has been said;
the Drive, and the HV pump, in my 367 came out of the DC catalog, and were new in 1999.. They now have over 100,000 miles on them. The last time I inspected them was 2005.
---------------------------------------------------------
My Barracuda only runs the factory gauges, so, IDK what my oil-pressure truly is, except to say that; one time,
I installed some 15W40 in the sump, and the first time I revved it up a lil, she promptly blew the oil filter off the block and pissed oil all over the header.
I fixed that by adding a second plate for stiffness, and doubled the number of holes in the plate, and installing a plate retaining fitting that had the hex on the outside and a round hole inside, which I drilled bigger. But after that, I never ran 15W40 again. and she never leaked there again either.
The point, I think, is that, the HV pump is a pretty good pump.
------------------------------------------------
To take advantage of the higher volume,
I ported the passages from pump to the main gallery, drilled all the passages in the block bigger, and supplied more oil to the top-end. I think there is an oil-mod sticky back on the opening page. I did all that except the oil-crossover, cuz I was never planning to go over 6000 rpm. That only started after I missed a few shifts and learned that the engine didn't seem to mind 7000. After that it was game on!
-------------------------------------------------------------------------------
The more oil to the top end was for lubing the aluminum rockers on the steel shafts/no bushings, and for cooling the springs, which are robust enough to run 7200 or more, without losing control.
 
Look very closely at the rotors, there should be a witness mark, divot, or some blemish on the gears, where it swallowed a chunk., 2 broken shafts, 2 divots.
Take the used oil pick-up over to the bench, and bang it really hard on the bench, numerous times, pound it, shake it, listen for debris, anything at all come out?

That's what I would do, jmo.

Then buy a new pick-up .

Be aware, some outer pump rotors have one chamfer edge, and if installed upside-down, may bind and jam the rotors.
Make sure the pump turns before install.
You know how I know . That was one shaft .
 
Last edited:
Bubbacuda68 said:
That is where both of my failures were, at the neck down where it goes to hex.
Click to expand...
I had one break on the hex, but at the pump. I think the pump had a bind in it and froze up. Replace pump and stock drive and never had a problem after that. Sometimes, there is no one answer to an issue.
 
I have found brand X guy's assemble a mopar roller cam engine with gallery restricters where
they don't belong and cause a mess.
Another is pickup to pan gap. Had one so tight to bottom of pan it acted like a seal. Did'nt
break the drive but would overheat a 3/8 120v drill attempting to prime in short order.
You all remember those, wall pluggers:)
 
You must log in or register to reply here.
-

Back
Top