Stock Magnum Intermediate Shaft w/Melling M72 Oil Pump?

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DirkHehman

67FSBarracuda
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So I'm buttoning up a 5.9 Magnum rebuild project and having trouble installing the stock intermediate shaft that came out of this engine. I replaced the original oil pump with a Melling M72 which I thought was a standard volume stock replacement. However, now when I try to install the intermediate shaft, it doesn't want to drop down to engage the camshaft gear.

I used my priming tool to measure the distance when it is seated in the oil pump to the intermediate shaft bushing. That measurement is about 1/2" shorter than the original intermediate shaft out of this engine. The measurement is 7".

What is the correct intermediate shaft for this application ? Thanks, appreciate any help in advance. This forum has been a great resource through this project.

Dirk
 
Stock intermediate shaft should have worked. Is the oil pan already installed?
Post a picture of the intermediate shaft you have, making sure we can see the shape of the tip that engages the oil pump.
 
I used the same new M72 oil pump and the original intermediate shaft when I built a 5.9. I can't remember having any difficulty getting it seated.
 
Attached is a photo of the intermediate shaft alongside the priming tool marked where it bottoms out.

Oil pan is on but you guys have confirmed what I was thinking. I'm gonna have to pull the pan and see what is happening at the pump. Was hoping maybe someone had run into this and I could avoid that but sounds like something is not right.

I have oil in it and used the priming shaft to prime it and confirm I had oil to the valve train. I did so I assumed all was good.

PXL_20220318_213109698.jpg
 
DirkHehman said:
Attached is a photo of the intermediate shaft alongside the priming tool marked where it bottoms out.

Oil pan is on but you guys have confirmed what I was thinking. I'm gonna have to pull the pan and see what is happening at the pump. Was hoping maybe someone had run into this and I could avoid that but sounds like something is not right.

I have oil in it and used the priming shaft to prime it and confirm I had oil to the valve train. I did so I assumed all was good.

View attachment 1715891641
Click to expand...
Was that a brand new priming shaft? By the little wear marks, it looks like only the very tip of it engaged the oil pump. I would venture a guess that something is inside that pump, keeping it from going in.
 
Yes, priming shaft was new. I'm going to drop the pan and see if I can determine what is happening at the pump. Thanks for the feedback!
 
Was the shaft bushing replaced? If so, how was it installed? If you just poke those in, they have to be sized. I have an old shaft that I use to install these so the I.d. doesn't deform from installation. Looks to me, from your pic, your issue is where it meets the bushing.
 
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