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In need of an oil pump shaft

2K views 28 replies 10 participants last post by  paul bell 
#1 ·
I have an older Melling pump that has uses a hex shaft instead of the standard slotted. It has a pickup on it that is sort of specific to my pan as well. I was sending a set of pistons to Line2Line to be coated and decided to get the pump gears coated as well and put it back in service. Well I got it back together,went to spin it with the shaft and noticed a lot of play. Looked inside the shaft and noticed there was a good amount of wear, didn't inspect it upon teardown. Apparently they only used them for a while and then went back to the standard, Melling said they haven't had any on the shelf for years. I was hoping one of you guys had one in good shape lying around that I could purchase before going to a whole new pump and pickup. Thank you very much
 
#3 ·
I understand where you're coming from Jeb. The reasons I want to use it is, it's not the standard M77 pump, it's the select anti-cavitaition version that is good shape, especially now with the coated gears that I have invested in. Plus I have a very unique pickup that fits my custom pan that is one with the pump. I have a local CNC guy that said he can make one but I'm just hoping by chance someone has one lying around first.
 
#6 ·
I mentioned that to Melling and they strongly advised against it because of the risk of losing the press fit. I'm thinking it would be ok, but also think it would be always be in the back of my mind.. I'm not sure of the cost on a new one yet, he said he needs to see it in person first and I haven't had a chance yet.
 
#5 ·
Josh,
Did Melling give you a part number for the shaft ? You would be amazed at how much old/discontinued stuff I have found on E-bay. I have some old Melling catalogs at the shop and could probably find the number for you Monday if you want.
 
#7 ·
I had a Melling dealer make some calls this week and no luck on part number, but if you have the time to look into Bill I would certainly appreciate it.
 
#9 ·
Yes the main shaft is pressed into the one gear. I'm sure what you are seeing is the driveshaft leaning because of the slotted style which is nice bug deal. The distributor gear centers it up.
 
#11 ·
Josh,
It looks like it is probably a 10778C pump. Can you measure the shaft length ? What size is the hex ? Maybe 3/8" ? The catalog I have has a list of shafts with lengths and hex sizes etc. Picture would be nice also.
 
#12 ·
Yeah that's it Bill. I dont have the shaft with me but can get a pic of it later. I know the hex on the pump is .340 so an 11/32" broach is used to make the shaft.
 
#21 ·
I am finding that an 11/32" broach is is very uncommon size. I have one guy that thinks he can maybe modify a 3/8 but not sure.
 
#19 ·
If anyone has an old Hoof Products catalog, or any Hoof NOS products, you might find the pump driveshaft there. Hoof was located in Maquoketa, Iowa and their product offering was much the same as Melling's. Hoof actually developed the hex drive SBC oil pump before Melling did, around 1985 or thereabouts. You might also contact Egge Machine Co., in Santa Fe Springs, CA. They buy and stock huge quantities of NOS engine parts from manufacturers, distributors, jobbers, etc. and they might have the needed part.
Otherwise, a good machine shop will be able to manufacture a new pump shaft for you.
 
#29 ·
Well I got it back together,went to spin it with the shaft and noticed a lot of play. Looked inside the shaft and noticed there was a good amount of wear, didn't inspect it upon teardown.

A quality socket is high hardened tool steel and it certainly won't wear like the original did.
 
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