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Oil pump gear failures
https://www.slantsix.org/forum/viewtopic.php?t=49606		 Page 1 of 1
Author:  Rick Covalt [ Sat Aug 18, 2012 5:09 pm ]
Post subject:  Oil pump gear failures
As I mentioned in the other thread, I found another MP cam with the oil pump gear worn almost in half. But I did not tell you the rest of the story.

The reason we were changing the engine was that the original had lost its oil pressure and it locked up. So I pulled the oil pump off of it and guess what? The oil pump gear was completely gone on that one as well. This was the first one that I have seen on an original engine like this. 1985 truck with @ 135,000 miles. I'll post some pictures later.

Wow, 2 in one day! Maybe I will get some sort of prize or something! :lol: :lol:
Rick
Author:  Rick Covalt [ Sun Aug 19, 2012 3:05 pm ]
Post subject:  Picture
Here is the original 130,000 mile gear failure

Image

Image
Author:  Jeb [ Sun Aug 19, 2012 3:19 pm ]
Post subject: 
Wow, that's kind of unnerving. Had the cam or oil pump ever been changed on this truck?

I'm getting my original cam reground and I sent my oil pump off to Doc.
Author:  Rick Covalt [ Sun Aug 19, 2012 4:17 pm ]
Post subject: 
As far as I know it was the stock 85 hydro engine. We have only had it for about 3 years and it came from out west, so I don't know the history.

If you have a good cam and gear I would get it reground and keep the same gear that had run on that cam and have it put on the new pump. Just my 2 cents. And no it is not a good feeling!

Rick
Author:  tyb525 [ Sat Aug 25, 2012 8:14 pm ]
Post subject: 
Yikes, I have an '85 ram slant 6 with at least 194k and all I can say is I sure hope that doesn't happen! I have 30psi idle/50 highway pressure right now so far so good.
Author:  FrankRaso [ Sat Aug 25, 2012 8:46 pm ]
Post subject: 
Do you have any idea what grade of engine oil was used in this engine?
Author:  CNC-Dude [ Sat Aug 25, 2012 9:08 pm ]
Post subject: 
Did the timing chain show signs of excessive slop.
Author:  tyb525 [ Sun Aug 26, 2012 7:28 pm ]
Post subject: 
Seems that when racers have used high-output oil pumps they tend to strip those gears. So it has been determined that it is better to use the stock oil pump.
Author:  Rick Covalt [ Mon Aug 27, 2012 2:35 pm ]
Post subject: 
Quote:
Do you have any idea what grade of engine oil was used in this engine?
No idea what was used in it, before Ryan bought it.


Quote:
Did the timing chain show signs of excessive slop.
Honestly, I did not even look up inside the original engine to check the slop in the chain.

The engine that we are putting in with the MP cam that is stripped as well did have a good bit of slop. It is a double roller set-up.

Can someone tell me what a normal amount of play would be on an engine with less than 10,000 miles on it? Just wondering.
Author:  CNC-Dude [ Mon Aug 27, 2012 11:54 pm ]
Post subject: 
You'd be surprised how much a new timing chain stretches almost immediately when you first crank the engine. Its not uncommon to be able to rotate the cam gear 2-3° degrees in either direction after just a few hundred miles.
Author:  62hypapak [ Tue Aug 28, 2012 6:49 am ]
Post subject: 
In the pic it looks to me as if the oil pump gear is pressed on too far onto the shaft. Maybe?? What clearance do you have between the body and the gear?
Author:  terrylittlejohn [ Tue Aug 28, 2012 3:52 pm ]
Post subject: 
i don`t know what would have caused this to happen after such a long time running, but i do know that with dougs positive gear oiling modifications and harder gear, laped to the cam, it`s hardly going to happen again.
after doing these mods to my race engine, which see 6500rpms, after 3yrs. there is a normal wear pattern on the mating surface of the cam/oil pump gear. :wink: :D
Author:  Rick Covalt [ Mon Sep 10, 2012 4:23 pm ]
Post subject: 
Quote:
In the pic it looks to me as if the oil pump gear is pressed on too far onto the shaft. Maybe?? What clearance do you have between the body and the gear?
The original 100,000 plus gear that looks like it is pressed on to far is tight against the body. I cant even get a .002 feeler gauge between the gear and the body.


The other pump has .018 between the gear and the body. I also found out this evening that this engine had maybe 15000 miles on it.

Can someone tell what the clearance should be between the pump gear and the body? I have a new pump and one of Doc's hardened gears that I will be pressing on soon.

Thanks , Rick
Author:  Doc [ Mon Sep 10, 2012 4:35 pm ]
Post subject: 
I shoot for .010 of clearance between the gear and the pump housing.
(I insert a "U" shaped piece of shim stock around the shaft, install the gear and then pull out the shim)
DD
Author:  Rick Covalt [ Mon Sep 10, 2012 6:00 pm ]
Post subject: 
Thanks Doc. I sent you a PM.

Rick
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