Magnum oil pump

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elvaliant66

elvaliant66

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I tried replacing the oil pump with a new one .melling #m-72 . When installed the oil pan would not sit flush and kinda hits the oil pick up tube . It’s on at the tightest and sitting leveled. When the original pump is on it sits flush . I cross referenced the Oil pump (M-72) and it pretty much is the same oil pump for small blocks . Anyone else have issues when replacing the oil pump? I suspect the original pump is still good still have yet to open it up and check tolerances. I had a new oil pump laying around from a previous build that didn’t workout just hate to have a fresh part just laying on the shelf. Any feedback / suggestions/experiences are appreciated thanks in advance.
 
A couple of things to check.
There have been instances of new pumps not sitting tight to the main cap, especially when using ARP fasteners. A little clearance grinding on the pump housing or thinning of the bolt head may be needed.
A bit of tweaking to the pickup tube is also not uncommon at all. Heat the tube and carefully bend it so the pickup sits correctly.
 
elvaliant66 said:
I tried replacing the oil pump with a new one .melling #m-72 . When installed the oil pan would not sit flush and kinda hits the oil pick up tube . It’s on at the tightest and sitting leveled. When the original pump is on it sits flush . I cross referenced the Oil pump (M-72) and it pretty much is the same oil pump for small blocks . Anyone else have issues when replacing the oil pump? I suspect the original pump is still good still have yet to open it up and check tolerances. I had a new oil pump laying around from a previous build that didn’t workout just hate to have a fresh part just laying on the shelf. Any feedback / suggestions/experiences are appreciated thanks in advance.
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Are you using the the same pick up tube with the two different pumps? Are you sure you don’t have an M-72HV version pump?

I hope they didn’t change these, or outsource them. Post a picture of the pump showing the part number.

One last thought; where did you buy the pump? Wondering if it’s an eBay or Amazon counterfeit. Summit and other big box stores should have real ones from Melling.
 
I did a fitment test with the new pump and original pick up tube that came with the magnum and I also tried the old pump with original pick up tube it still hits the pan just barley right before all the bolt hole rails mate to the block. I also tried the new oil pump and old pick up tube off of a ‘72 LA block and it still hit . The difference between the original set up and the new oil pump set up is about .250”. I bought the oil pump about 3 years ago from rock auto. It’s a Melling pump . I have a picture of the pump but will post a picture of the block/ oil pump once I get home from work .

F6A95FDD-615D-41BB-ADA2-AA497A812FC6.jpeg
 
Old used original pan or a replacement? Either way bending the tube while heated or pounding out the bottom of the pan a little is fine.
 
I believe the oil pan is a replacement . The previous guy that I bought the engine from had it in his 68 barracuda .I matched the oil pan to another 72 LA block from a Dart and the oil pans are essentially the same . I was able to get the new pump on and used the pick up tube that game with the magnum as it was cleaner .

0D1EA02F-A7F6-4EED-8DB3-C4CBCCD3F3CC.jpeg
 
Did you end up finding a combination that worked or did you have to clearance the pan or pickup? Just wondering for closure.
 
I used the new melling oil pump with the original pick up tube it came with and will be using the a body oil pan it came with as well.
 
elvaliant66 said:
I did a fitment test with the new pump and original pick up tube that came with the magnum and I also tried the old pump with original pick up tube it still hits the pan just barley right before all the bolt hole rails mate to the block. I also tried the new oil pump and old pick up tube off of a ‘72 LA block and it still hit . The difference between the original set up and the new oil pump set up is about .250”. I bought the oil pump about 3 years ago from rock auto. It’s a Melling pump . I have a picture of the pump but will post a picture of the block/ oil pump once I get home from work .

View attachment 1716049294
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That is the correct way it assembles. With the pan touching the pickup screen. It is designed to work like that.
 
RustyRatRod said:
That is the correct way it assembles. With the pan touching the pickup screen. It is designed to work like that.
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Yep! It should be touching . My issue was the pick up tube was screwed on the tightest while still being orientated the way it should be on the pan but the pan rails were about .5 inch away from mating to the block hence why I bent the goose neck on the pick up tube. Now the P.U tube sits flush in the pan and the pan rails touch the block all around evenly .
 
elvaliant66 said:
Yep! It should be touching . My issue was the pick up tube was screwed on the tightest while still being orientated the way it should be on the pan but the pan rails were about .5 inch away from mating to the block hence why I bent the goose neck on the pick up tube. Now the P.U tube sits flush in the pan and the pan rails touch the block all around evenly .
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Yeah, that wouldda been a little tight. lol
 
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