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Discussion Starter · #61 · (Edited)
With the cam bearing do they normally have a Babbit layer over the Copper?
Apart from no layer there does not appear to be much sign of major wear, only a couple of wear points.
I would have assumed so but the product pictures shows copper. It should be here this week, will let you know.
As far as the wear Cummins inspection instructions shows that any heavy scoring the bearing should be replaced.
 

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With the 2 large freeze plugs you definitely have the early block. Yours would be bushing 3901306. As for the construction of that bushing it seems to vary depending on who makes it. Some are definitely babbitt coated and some appear to be a copper colored coating. Don't think it would be regular copper though. Probably a special alloy that has a copper tint. Clevite's bushing is one of the copper colored ones and is their part SH-1404. Prices on that part range all over the board. From about $5 to over $60. The ones in the genuine Cummins box range from about $30 to the $60+ range. Below are 2 photos, both of a Clevite SH-1404 and their surface appears to be totally different.
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Discussion Starter · #63 ·
With the 2 large freeze plugs you definitely have the early block. Yours would be bushing 3901306. As for the construction of that bushing it seems to vary depending on who makes it. Some are definitely babbitt coated and some appear to be a copper colored coating. Don't think it would be regular copper though. Probably a special alloy that has a copper tint. Clevite's bushing is one of the copper colored ones and is their part SH-1404. Prices on that part range all over the board. From about $5 to over $60. The ones in the genuine Cummins box range from about $30 to the $60+ range. Below are 2 photos, both of a Clevite SH-1404 and their surface appears to be totally different.
Thanks, I have the 3901306 bushing on order.
 

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The Cummins repair manual doesn't say any thing about the patterns on the cam lobe. Anyone seen this before? I still need to pull the lifters to see their condition.
bad tappets i would believe and likely bad tappet holes.. ... check the tappets and holes to make sure they are in spec. if the tappet holes are too larger the tappet can walk and do funny things to the cam ( think of them as orbital sanders.. )
 

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Discussion Starter · #65 · (Edited)
The tappets holes and tappets are with in spec.
But the "clown" that installed the cam bearing didn't get the 2 holes lined up. According to the Cummins spec that's a no-no. Almost half of the oil hole is covered by the bearing.
 

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Discussion Starter · #66 ·
The engine part number is behind the tappet cover.
 

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Yup, I'd found a photo that showed the part number there. Well, it may be a casting number but anyway it's a way to identify it. Incorrectly installed cam bushing would sure account for premature wear. Lucky you caught that before it damaged the cam. One thing that has me puzzled. You listed the cam as part 3924574. What little info I could find says this is a 6bt cam and Cummins shows it obsolete with no replacement number.
 

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The tappets holes and tappets are with in spec.
But the "clown" that installed the cam bearing didn't get the 2 holes lined up. According to the Cummins spec that's a no-no. Almost half of the oil hole is covered by the bearing.
Cam Wobble side to side could cause the tappet patterns... I would suspect..
 

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Discussion Starter · #69 ·
Yup, I'd found a photo that showed the part number there. Well, it may be a casting number but anyway it's a way to identify it. Incorrectly installed cam bushing would sure account for premature wear. Lucky you caught that before it damaged the cam. One thing that has me puzzled. You listed the cam as part 3924574. What little info I could find says this is a 6bt cam and Cummins shows it obsolete with no replacement number.
I guess it's A new number for the books:
 

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Discussion Starter · #70 ·

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Discussion Starter · #72 ·

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Discussion Starter · #73 · (Edited)
All of the bearing journals, rod and mains have no damage. Bearing inserts show wear but no scoring. Waiting for UPS to deliver the 2" to 3" micrometer, main bearing set, rod bearing set.
Decided to go with a micrometer for measureing the journals, the vernier calipers didn't work out very well and i didn't have a 2" to 3".
 

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Discussion Starter · #74 · (Edited)
The tappets holes and tappets are with in spec.
But the "clown" that installed the cam bearing didn't get the 2 holes lined up. According to the Cummins spec that's a no-no. Almost half of the oil hole is covered by the bearing.
Now was that so hard,,,
 

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Discussion Starter · #76 ·

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Not a very common thing on these engines for the cam bores to be worn. You certainly want to install new rod and main bearings since you've got it apart. Those bearings a very cheap. Also, put in new rod bolts. Cummins does not recommend reusing those. They aren't expensive either. If you desire an upgrade, you can use ARP rod bolts. They are ARP part 247-6304 for a set of 8. Cummins part is 3900919 for one.
 

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Discussion Starter · #78 ·
Not a very common thing on these engines for the cam bores to be worn. You certainly want to install new rod and main bearings since you've got it apart. Those bearings a very cheap. Also, put in new rod bolts. Cummins does not recommend reusing those. They aren't expensive either. If you desire an upgrade, you can use ARP rod bolts. They are ARP part 247-6304 for a set of 8. Cummins part is 3900919 for one.
Yes I have a complete set of Rod and Main bearings coming (standard) and have a set of Cummins rod bolts. The ARP rod bolts were out of stock.
 

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Discussion Starter · #79 · (Edited)
The good news, After a visual inspection of the bearing journals, they all appear in excellent shape, including the cam. The cam bearing showed a little wear, replaced it. All of the crankshaft and rod bearings showed minor wear, replaced them. I'm planning to measure the journals for wear anyway but the 2-3" micrometer I bought arrived broken. Using the 2" standard it read 1.9750, off my .0250". So the engine will sit for another week waiting for the next new micrometer to arrive before I can start putting the engine back together. Except for the injection pump. I'm having to send it up to Phoenix to get it repaired again. Who knows how that will go..
 

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Unless there's been some major problem in the past, the cam and crank journals don't wear much. Might need a bottle of valium if the pump has major issues. Nothing from Bosch is cheap on those pumps. I check one time to find out how much the 4bt P7100 costs new. Seems like it was something over $10,000. That particular pump was made in very small quantity compared to the 6 cylinder model.
 
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