Caution UOA - PP 10W30 6881m on 2001 Jeep 4.0

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Originally Posted By: Donald
One knowledgeable person told me that in a straight 6 you need to have the crank better balanced than a 4 cyl or V8 due to its physical long length. I am thinking that the engine was just not reman as well as it could/should have been.
I don't know that you "need to have the crank better balanced," since its supported by a main bearing every other throw, although good balance is always important. However, the engine not being assembled well is a possibility. Also could be cam bearings. A Jeep shop that I use told me that a lot of 4.0 low oil pressure issues come down to cam bearing wear and clearances allowing a lot of oil discharge at the cam bearings, and nobody thinks to look for it since its relatively uncommon in other engines. If this was a mass production reman, I betcha they didn't check the cam for straightness before installing it. The last one I put in a v8 needed a few 10-thousandths of truing up before it would spin freely in the bearings. None of this is to say it won't run 300,000 miles just like it sits.
 
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Originally Posted By: Ramblejam
Originally Posted By: 440Magnum
You know my solution for Jeep 4.0s... Rotella T6 and an Ultra or RoyalPurple filter makes 'em last forever.
What have you observed with T6 that makes it superior? What size filter do you run?
I've never seen a Jeep 4.0 UOA series that consistently looked bad on RT6, and there's a lot of anecdotal evidence that they hold up really well with it. They're not normally that picky, but there are a few of them that are 'problem children' like this one and they seem to respond decently to HDEOs. I run a full-size XG-8A (or equivalent) filter on mine. Sometimes you need to throw the UOA away and just drive. The numbers can be scary and the engine still live WAY past your desire to use the vehicle.
 
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Originally Posted By: 440Magnum
Originally Posted By: Donald
One knowledgeable person told me that in a straight 6 you need to have the crank better balanced than a 4 cyl or V8 due to its physical long length. I am thinking that the engine was just not reman as well as it could/should have been.
I don't know that you "need to have the crank better balanced," since its supported by a main bearing every other throw, although good balance is always important. However, the engine not being assembled well is a possibility. Also could be cam bearings. A Jeep shop that I use told me that a lot of 4.0 low oil pressure issues come down to cam bearing wear and clearances allowing a lot of oil discharge at the cam bearings, and nobody thinks to look for it since its relatively uncommon in other engines. If this was a mass production reman, I betcha they didn't check the cam for straightness before installing it. The last one I put in a v8 needed a few 10-thousandths of truing up before it would spin freely in the bearings. None of this is to say it won't run 300,000 miles just like it sits.
Looking back at the trends, its clear that there are some lead "events" going on. Makes one want to look closer at filtration, or maybe something happened in the usage cycle during those two OCIs that caused it? Any lead-containing additives (fuel or otherwise) sneak in there somehow?
 
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Originally Posted By: DoubleWasp
Sodium definitely jumped up pretty good on this one too. What could be responsible for that, if not coolant?
Different lab doing the test? The fact that the last test is a different lab kinda negates any trending going on, IMO. But you're right, I guess it could be coolant- especially since the remanufacturer might have used a "331" head casting.
 
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