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Oil pump: reuse/refresh/rebuild or replace?

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Agas46cj View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Agas46cj Quote  Post ReplyReply Direct Link To This Post Topic: Oil pump: reuse/refresh/rebuild or replace?
    Posted: 10 Aug. 2022 at 8:49pm
Dropped my supersonic off for machining today. As I prepare for it’s return in 2 weeks my mind turns to other components of the rebuild. The oil pump on it was good.15 20psi at idle.  I’m curious as to what’s recommended for my rebuild since it was good, probably has some crud in it.  Should I clean it and regasket it? It didn’t leak, or is it better to replace the internal components or replace the whole thing? I don’t question it’s abilities but I’m hoping to build a lasting engine. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Ron D Quote  Post ReplyReply Direct Link To This Post Posted: 10 Aug. 2022 at 8:52pm
Do you have a copy of the Willys Service Manual?
I can look up the page numbers for oil pump inspection and servicing if you like.

Good luck!
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Agas46cj View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Agas46cj Quote  Post ReplyReply Direct Link To This Post Posted: 10 Aug. 2022 at 8:56pm
I do, I can look at that when I get home. 

Since I’m on the topic of what can be reused and what need’s replaced, what are some other things I should consider replacing? Aside from low compression due to worn rings and cylinders it was a running engine. Should I consider replacing things like cam and tappets? They don’t look bad, and the engine didn’t run bad, actually ran great for the wet compression test. I’m replacing pistons, bearings, valves and springs so far. I’ve reused cams in the past for other engines, and replaced for performance upgrades as well. I’m on the fence for this one. Don’t want an omix and don’t trust eBay. 


Edited by Agas46cj - 10 Aug. 2022 at 9:20pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Oldpappy Quote  Post ReplyReply Direct Link To This Post Posted: 10 Aug. 2022 at 11:02pm
The machine shop can, and should, check your tappets and either recommend replacement, or resurface.
They can also check your cam. NOS tappets, and cams are out there, I agree you need to avoid Omix-Ada on this. 

When you took it to the machine shop I hope you took the block, head, and crank. You should also take the cam to them. 

As already said, the manual outlines checking the oil pump to determine if it is within spec. They can be rebuilt, or you can probably still find a quality (Melling?) replacement. 


Edited by Oldpappy - 10 Aug. 2022 at 11:05pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Ron D Quote  Post ReplyReply Direct Link To This Post Posted: 10 Aug. 2022 at 11:23pm
Yup, the same Willys Service Manual that has the poop for inspecting oil pumps also has all the specs for the engine and everything else that should be inspected and checked for a complete rebuild.

Or --- you could just rely on what "looks bad".

You should ask your machine shop if they have a copy of the Willys Service Manual.
Unless they just remember all those inspections and dimensions from memory.

How will you ever know what they inspected and measured --- or didn't --- if they don't write it down on your bill?
How will they even know what you want them to do if you don't tell them?
Good luck with telling them to "look it over and tell me what you think."

You should try to minimize "hoping" from the equation.
Just my 2 cents.

I can look up those page numbers if you like.

Good luck!


Edited by Ron D - 10 Aug. 2022 at 11:55pm
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Agas46cj View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Agas46cj Quote  Post ReplyReply Direct Link To This Post Posted: 11 Aug. 2022 at 7:16am
I should have been a little clearer. I did check the specs for the camshaft journals in the manual and mic’d them. They are within 2 thou of spec. The tappets in the sleeve have about 3 thousand with a feeler gauge. Some a little tighter than others. The lobes visually look ok. The tappets are smooth on the bottom. The tappet adjusters are dished from contact with the valves. I’ll check the oil pump next. I ask because when I search the page I see info in both ways about replacing or not, some louder than others. The machine shop has everything but the tappets and I’ll drop them off with the valves and spring when they show up. 

Just checked the pump. I have 5 thou on the case to outer lobe ring and 6 thou on the inner lobes
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Joe DeYoung Quote  Post ReplyReply Direct Link To This Post Posted: 11 Aug. 2022 at 8:01am
If your cam is in question, Berry Cam Service in Minnesota can regrind it for around $100 or so. They can also resurface the tappets as well. If your tappet adjusting screws are dished then replace them. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote dasvis Quote  Post ReplyReply Direct Link To This Post Posted: 11 Aug. 2022 at 8:05am
Originally posted by Agas46cj Agas46cj wrote:

The tappet adjusters are dished from contact with the valves.  The machine shop has everything but the tappets and I’ll drop them off with the valves and spring when they show up. 

 I would suggest just buying new adjusters. When I did my engine last year I looked around & found a set that were NOS & very reasonable. If the shop is doing your valve job, they can re-face the end of the valve stem so it's flat again - assuming it's not worn so badly that it is thru the hardened surface.
 If reusing your old cam & tappets, be sure to keep the tappets in order so they go back on the same lobes. They have a wear pattern & if mixed up will wear out much faster.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote CMCSSeabee Quote  Post ReplyReply Direct Link To This Post Posted: 11 Aug. 2022 at 11:46am
I would normally say buy a new oil pump. It does sound like yours must be in good shape, given your hot idle oil pressure readings. They will be better with new bearings/tighter clearances.
All that said, I clearanced a used oil pump by the book for mine and had crap hot idle readings on a fresh rebuild. I had another pump off a very low mileage engine and it produced great numbers. In most cases, a used oil pump is a crap shoot. That said, they are VERY proud of the new ones!!
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