Hardened Oil Pump Identification

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Bodyperson

Bodyperson

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I am in the process of building a known to me good running 340. Upon disassembly, the engine reveled a high volume oil pump. I defaulted to a new hardened oil pump shaft because I do not know if the existing oil pump shaft is hardened as is required for a high volume oil pump. I am having second thoughts as to which of these 2 shafts may be better. I got a lead off of this site to a supposedly US built hardened shaft but I am having second thoughts as to if this a quality piece, Ya, the oil pump bushing is bragging about being made in the USA but the shaft has me perplexed.

The packaging has vague writing but the bushing is in a proud "made in USA" container. The new shaft has a heavier feel to it. I'll get some pics up with my phone.

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Bodyperson said:
I am in the process of building a known to me good running 340. Upon disassembly, the engine reveled a high volume oil pump. I defaulted to a new hardened oil pump shaft because I do not know if the existing oil pump shaft is hardened as is required for a high volume oil pump. I am having second thoughts as to which of these 2 shafts may be better. I got a lead off of this site to a supposedly US built hardened shaft but I am having second thoughts as to if this a quality piece, Ya, the oil pump bushing is bragging about being made in the USA but the shaft has me perplexed.

The packaging has vague writing but the bushing is in a proud "made in USA" container. The new shaft has a heavier feel to it. I'll get some pics up with my phone.

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Going on the same camshaft if that makes a difference.
 
The new pump shaft is definitely hardened, no question. Can you get a good picture of the transition to the hex on the old shaft like you did on the new one?
 
The new one is the one you want. Not sure that hardness is the issue. Look at them both. The one on the right has a built in stress point.

Right where the hex starts. That square edge is a failure point.

That said, I have never failed either type. And I always use a HV/HP pump.
 
4spdragtop said:
How can you tell? Curiosity...
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See the smooth transition going into the hex? None of the stock non hardened shafts are like that. They all have a machined square edge at the beginning of the hex and that's always the failure point. Stress cracks form there and will twist and or snap the hex off the end. That smooth transition eliminates the stress point. All hardened shafts have that smooth transition.
 
Thanks Rob, I'll chk the couple that I have.
RustyRatRod said:
See the smooth transition going into the hex? None of the stock non hardened shafts are like that. They all have a machined square edge at the beginning of the hex and that's always the failure point. Stress cracks form there and will twist and or snap the hex off the end. That smooth transition eliminates the stress point. All hardened shafts have that smooth transition.
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FWIW.....I took an OEM drive with the square transition point and mounted it in a vise. Laid a big *** pipe wrench on the gear and gave it a twist..... It took a **** load of torque before it snapped off. It seemed pretty sturdy.
 
CFD244 said:
FWIW.....I took an OEM drive with the square transition point and mounted it in a vise. Laid a big *** pipe wrench on the gear and gave it a twist..... It took a **** load of torque before it snapped off. It seemed pretty sturdy.
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Yes, but that was a one time incident, not loaded over a long period of time. You'd be surprised what hydraulics can do.
 
Best to be pinned to provide insurance to prevent the gear from spinning up top
 
Bodyperson said:
There is none.
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Not on the new one? Look real, real, REAL close. Sometimes manufacturers will lightly machine the surface where the pin goes through and it makes it almost impossible to see.
 
RustyRatRod said:
Not on the new one? Look real, real, REAL close. Sometimes manufacturers will lightly machine the surface where the pin goes through and it makes it almost impossible to see.
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I bought one that did not have a pin, the gear was just pressed on. I drilled it myself , and put one in, for peace of mind.
 
RustyRatRod said:
Not on the new one? Look real, real, REAL close. Sometimes manufacturers will lightly machine the surface where the pin goes through and it makes it almost impossible to see.
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There is a very, very, ,VERY faint quarter inch circle closer to the gear. Hard to even get a picture. It's only on one side.

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Bodyperson said:
There is a very, very, ,VERY faint quarter inch circle closer to the gear. Hard to even get a picture. It's only on one side.

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Man. That's a tough call. If I had to guess, I'd say it's not a roll pin. I think 1/4" would be way too big for that shaft anyway. I think a hole that big would weaken it to the point the roll pin didn't matter. I'm unsure it's something to worry about. Have any of yall ever seen a pressed on gear spin on the shaft? I have not.
 
RustyRatRod said:
Man. That's a tough call. If I had to guess, I'd say it's not a roll pin. I think 1/4" would be way too big for that shaft anyway. I think a hole that big would weaken it to the point the roll pin didn't matter. I'm unsure it's something to worry about. Have any of yall ever seen a pressed on gear spin on the shaft? I have not.
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The old one shows no sign of a pin and it had been spun up pretty good a time or two on the HV pump. Its not a roll pin for sure.
 
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