Failure of oil pump

daveymc29

daveymc29

Well-known member
I had my engine rebuilt for touring, with counter weighted and balanced crank and such. Also inserted and full oiling. The engine ran beautifully until at about 1350 miles it suddenly had zero oil pressure, where it had been running at approximately 35 psi for 355 miles that morning. Fortunately I saw the zero soon and shut it off, coasted into my garage and pulled the engine and took it to the rebuilder, after I determined that it wasn't just a faulty gauge. I am told the power shaft broke and fortunately there is no other damage. Tomorrow I will retrieve my engine and begin the re-installation. So, what would cause the shaft to break? What questions should I be asking the rebuilder? Should it be a later model oil pump, such as for the V's or is that a question for another forum? Thanks for any clues you can pass on to me.
 
daveymc29 said:
I had my engine rebuilt for touring, with counter weighted and balanced crank and such. Also inserted and full oiling. The engine ran beautifully until at about 1350 miles it suddenly had zero oil pressure, where it had been running at approximately 35 psi for 355 miles that morning. Fortunately I saw the zero soon and shut it off, coasted into my garage and pulled the engine and took it to the rebuilder, after I determined that it wasn't just a faulty gauge. I am told the power shaft broke and fortunately there is no other damage. Tomorrow I will retrieve my engine and begin the re-installation. So, what would cause the shaft to break? What questions should I be asking the rebuilder? Should it be a later model oil pump, such as for the V's or is that a question for another forum? Thanks for any clues you can pass on to me.
Click to expand...

Hi Dave,

Unfortunately you will never know the facts having not inspected it prior to returning it. They must have a specific charge for the oil pump on your original invoice. What does it say? While I'm sure someone, somewhere has broken an oil pump I've never heard of one nor come up with a believable scenario where that would/could happen.

If the pressure plumbing was done internally (valve chamber) I would suspect a failure in the plumbing.

Maybe someone here can come up with a PLAUSIBLE scenario where the report could be true.
 
I wonder if the problem is the shaft at the driver. Was the shaft steel, or aluminium?
Was there galling? A misalignment?
Strange stuff.
Bob
 
The only failure even like this I have heard of was I guy who did a engine rebuild and fit a high volume oil pump but reused the old pump/distributor drive assembly because it looked ok and the tang broke off the drive assembly
I have seen the tangs worn very thin
As a new pump drive gear is not a big $ item compared to a engine I would install a new 1
 
Hi Dave,

Thanks for your sincere report on your keen & intelligent observation of your oil pump failing.

Not everybody is sincere enough to relate stories about Model A mishaps & failures.

In my opinion, some Model A Forum replies are centered around Model A owners wanting everybody to think their Model A's are perfect in every way ....... LOL.

I had only one oil pump break over 50 years ago -- it was devastating and enough to convince me to install an oil pressure gage ..... and to monitor same as you did.

Thanks for your reply and your letting us know that you are observant; and also have above average intelligence when it comes to mechanical preventative maintenance.

Lots of intelligent & kind folks on all of these Model A Forums ..... please keep posting actual experiences.
 
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The reason I didn't thoroughly inspect this mishap myself was that I didn't wish to somehow void the warranty by opening the engine. It had only approximately 1300 miles since the rebuild and I did discuss pulling the pan myself and we decided that might give the builder an out if the engine was toast, Thanks for all the replies. Three of us will enter into the conversation with the builder. I'll be back with the outcome of that tonight,
 
Just have him show you the broken part or parts and have a little discussion on the cause or possible causes. It will be interesting.
 
I've never seen a broken shaft in an oil pump. I have seen a sheared pin in a repro drive gear, but that disables the distributor at the same time. I have also seen failed or forgotten oil pump retainer springs, which allows the pump to drop below the drive gear tab. Forgotten springs are probably more common than other causes. If, in fact, the shaft "broke", it must have suffered from some binding of the gears or of the shaft due to mis-aligned bushings to put that much force on the slot at the top. I can't imagine it breaking at any other point.
 
Hey Dave,
If I were to bet on a 'broken' part causing you problem, I'd bet on the cam/oil pump drive gear. UNLESS...someone messed with/rebuilt the pump and did something that could cause the shaft to break....like modifying it by cutting down the shaft to change oil pressure. Fords cam/oil pump gear is robust and simple. I'd like to hear from ANYONE who has had such gear break, if the gear was in good condition when installed.
We will be following your findings closely, as they may reveal something beneficial to all of us !
 
FWIW: On my broken original oil pump years ago, the long cast iron part surrounding the steel shaft sheared near the bottom.

After it broke, oil exited at the shear line and was not pumped up into the valve chamber.

There was no problem with the steel shaft or gears below.
 
on mine the tang broke off the oil pump drive apparently because the oil pump locked up. you could spin the oil pump shaft and feel it lock up and have to turn it backward to get it to unlock. could not find anything inside it but it wiped out the rear main
 
What if: The engine was put together without the spring, and the builder just said the shaft was broken????? Better see the part.. I bet he pitched it already..
 
To tell the rest of this story, yes he did show three of us the broken part. The pump is Chevrolet 6, repo, I understand and the drive shaft if smaller just above the gear. This is where it broke. If someone could send me an email address, I will send them a picture of the parts if they will then put them on this forum. I do not know how to do it on here, but can send a photo with my iPad to someone more knowledgeable. Will that work? There is some peculiar wear on most of the teeth of the pump. I'll go make some photos and someone figure how to get them on here. The builder said, "Chinese metal." as his answer for why it failed. He said he fully expected to find something had jammed the gears, but they were free.
 
Hey Dave,
Appreciate the followup, as very informative. Also what not to use in out A FORDS, EH..i.e.-cheevee parts :)! Did the builder mention to you that he'd like to try chev oil pump :confused: !
FWIW...My new B long block has a AB59 Ford V8 modified oil pump, set for 45 lbs. Looks great and the old timer (4e4 gent) has been making them for race engines for decades. Hoping mine Is no exception to his great machinist skills;) ! Sorry for your problems and hope that you get satisfaction in this situation.
Q: if a guy feels that something is 'Chinese junk'....why would he use it ??
 
I had that question in my mind but didn't broach it. Should have I guess. Evidently both members of that rebuilding team felt the fault to be "Chinese Crap," but neither had the next obvious statement which should have been, "From here on out, only American made parts, or we'll make our own if we can't buy them. I'm thinking of pulling the pan and putting in a different oil pump. Seems the modified 59AB might be a better step, especially if it from an old source of parts. Any suggestions guys?
 
daveymc29 said:
I had that question in my mind but didn't broach it. Should have I guess. Evidently both members of that rebuilding team felt the fault to be "Chinese Crap," but neither had the next obvious statement which should have been, "From here on out, only American made parts, or we'll make our own if we can't buy them. I'm thinking of pulling the pan and putting in a different oil pump. Seems the modified 59AB might be a better step, especially if it from an old source of parts. Any suggestions guys?
Click to expand...

Dave, that's the reason I mentioned the "oil pump" on your original invoice question on my first post. They are the only ones MODIFYING these pumps for use on our engines. I've never been fond of this for may reasons. I suspect poor machining on their part to be the problem but not the only one.

Hopefully their "fix" will survive this time.

I'm not used to doing this from my phone (cable is out) so I hope this displays as intended!
 
The pump Stan and others are using is the modified 8BA, short body with low pressure relief. Seems like a good choice for a pressurized engine.

A's Always
Dave
 
daveymc29 said:
I had that question in my mind but didn't broach it. Should have I guess. Evidently both members of that rebuilding team felt the fault to be "Chinese Crap," but neither had the next obvious statement which should have been, "From here on out, only American made parts, or we'll make our own if we can't buy them. I'm thinking of pulling the pan and putting in a different oil pump. Seems the modified 59AB might be a better step, especially if it from an old source of parts. Any suggestions guys?
Click to expand...

Hey Dave,
This is a picture of two AB59 oil pumps, one modified and one original. This is the pump that I've installed in my new B engine. I also have a Stipe alum custom oil pump in my other B. That pump is like a jewel, but expensive !! I'm not sure if B. Stipe makes them anymore, but IMO worth the money, eh :) ! Expecting great service out of this 59 V8 pump.
 

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