Would you run this oil pump?

[50MercMetalHead]

I’m rebuilding my 8CM after it started losing oil pressure. I found a considerable amount of sand in the engine, and I’m 99.9% sure the source of the pressure loss is the cam and rod bearings, cause they’re pretty bad. I’m unsure if this pump is still good to run though.

It was making about 5psi at slow idle, about 15-20 at fast idle, and I think I saw about 30-40 when I was driving the car in the shop, which got it up to like 1500-2000rpm if I had to guess (no tach). To me, if it had good bearings, I would expect to see normal pressures, but I don’t have a ton of experience with oil pumps so I want other opinions.

Shaft spins really nice, I see and feel no sand or grit anywhere. I’m not sure about the wear on the impellers, no gouges or chunks missing that I see, just wear. Here’s some pictures:




Hopefully I can get some input from you guys who have rebuilt a few of these things, would really appreciate it. Thanks in advance for any input.

[19Fordy]

Based on what your photos show, I would not "run it". The "pinned set screw gear" set up in first photo is not good. Lots of wear on gear cover plate by the gears. Time for a new oil pump, in my opinion. Also, be sure to check the oil pump drive gear located at the rear of the engine.
https://www.quartoknows.com/blog/qua...cting-oil-pump

Read thru all the oil pump related links here.
https://www.google.com/search?q=worn...hrome&ie=UTF-8

[Talkwrench]

Seems like theres not much wrong with your oil pressure if it was hot.. They quite often have very low oil pressure at idle, certainly when hot. but if it had oil pressure while driving and comes up with revs you probably wasted your time.

[bbrocksr]

Originally Posted by 50MercMetalHead

I’m rebuilding my 8CM after it started losing oil pressure. I found a considerable amount of sand in the engine, and I’m 99.9% sure the source of the pressure loss is the cam and rod bearings, cause they’re pretty bad. I’m unsure if this pump is still good to run though.

It was making about 5psi at slow idle, about 15-20 at fast idle, and I think I saw about 30-40 when I was driving the car in the shop, which got it up to like 1500-2000rpm if I had to guess (no tach). To me, if it had good bearings, I would expect to see normal pressures, but I don’t have a ton of experience with oil pumps so I want other opinions.

Shaft spins really nice, I see and feel no sand or grit anywhere. I’m not sure about the wear on the impellers, no gouges or chunks missing that I see, just wear. Here’s some pictures:[IMG]https://uploads.tapatalk-cdn.com/20210725/d70471c63a022d510c8183e612d39215.jpg[/I






Hopefully I can get some input from you guys who have rebuilt a few of these things, would really appreciate it. Thanks in advance for any input.

Gear teeth are worn through the hardening.
Bill

[UncleBill]

My opinion, for what it's worth, I would install a new pump. Better than tearing it apart again next month.

[DavidG]

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That's an unusual and unfriendly wear pattern on the two gears. Likely re-buidable, but a new pump may cost less than the parts requiring replacement.

[50MercMetalHead]

Originally Posted by Talkwrench

Seems like theres not much wrong with your oil pressure if it was hot.. They quite often have very low oil pressure at idle, certainly when hot. but if it had oil pressure while driving and comes up with revs you probably wasted your time.

Compared to the pressures I have been used to in this engine it was low. It would normally slow idle closer to 10 when warm. Here’s a couple rod bearings, they all looked about like these, mostly saw .0025-.003” all around with plastigauge on the rods, so they are on the looser side. The purplish discoloration is my biggest issue with them though. There’s a pic of one of the cam bearings as well, the marks that go side to side are from me pulling cam, but I’m pretty sure the rotational ones are from sand while running, because I didn’t rotate the cam anywhere near enough to make those myself. Mains looked good but were on the loose side at .003”.

[50MercMetalHead]

Originally Posted by 19Fordy

Based on what your photos show, I would not "run it". The "pinned set screw gear" set up in first photo is not good. Lots of wear on gear cover plate by the gears. Time for a new oil pump, in my opinion. Also, be sure to check the oil pump drive gear located at the rear of the engine.
https://www.quartoknows.com/blog/qua...cting-oil-pump

Read thru all the oil pump related links here.
https://www.google.com/search?q=worn...hrome&ie=UTF-8

I’ll read up there. Drive gear is really sloppy on its shaft so I will be doing something with that. That’s the last thing I need to get removed from the block, waiting to find time to run the block into town so I can borrow a slide hammer from the parts store without renting it.

[bbrocksr]

Originally Posted by 50MercMetalHead

I’ll read up there. Drive gear is really sloppy on its shaft so I will be doing something with that. That’s the last thing I need to get removed from the block, waiting to find time to run the block into town so I can borrow a slide hammer from the parts store without renting it.

That rod bearing has worn through the tin overlay bearing material into the copper underlay, time to replace it. How is the crank journal ?

Bill

[G.M.]

I would not put any oil pump, new or used in an engine without
testing it with the drive gear removed and using a half inch electric
drill and a pressure gauge to test it. The pump runs in the direction
of drilling a hole. A gauge and flexible plastic hose over the pump
output, bending the hose to make the pressure raise. This also tests
the bypass valve. G.M.

[19Fordy]

50Merc: Look thru this thread and you'll see you don't need a special tool to remove the oil pump drive gear.
Use a big socket , a bolt and a wrench.
https://www.fordbarn.com/forum/showthread.php?t=158008

[Ggmac]

Rod bearing is toast , anytime copper is visible, its a good time to replace .

[Tim Ayers]

For something as vital as an oil pump, I would suggest getting a good pump than you've either tested or is known to be good. They are very easy to find.

Why chance it?

As for the sand in the engine, that's not casting sand. Casting sand would be found in the water jackets. I'd really be concerned and figure out how the sand/grit got into the engine and oil passages. Cleaning this block is going to paramount so this does not happen again.

[Bill OH]

I would install a new oil pump. You have the engine torn down and the pump is accessible. A new pump is a good investment. I follow the rule if I have the oil pan removed a new pump goes in!!!!

[Kube]

Would I run that pump? Yep, directly to the trash can.