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Connecting rod bearing 08 3.8 engine

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#21 ·
fuzzylogic_y2k said:
Wow that's grapes of wrath era... I have only 20 years experience in vehicles and rebuilding engines so you could be right.
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Honestly not even that far back but it doesn't matter much since all things are relative. It's amazing what some around the world are getting away with out of necessity even today.

Not that it matters but I've been building engines for nearly 50 years although very seldom lately. In the 70s when money was tight for most folks you'd be amazed at some of the things I saw. I even saw one ole boy with a Farmall tractor that had busted a piston drive a cedar post down into the cylinder. Cut off the rod eye and mounted the eye around the crank to maintain oil pressure. Put it all back together and used it to pull a brush hog for years after that. Necessity is the mother of invention. :drinks:
 
#24 ·
Geech08 said:
I am going to go with the .50mm .002 bearing and use thicker oil if needed. If it’s knocking I’ll then go back and put on the .75mm .003 bearing.

Any final thoughts? Speak now or forever hold your peace! Haha
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GOOD GOD MAN! The last time I heard that question it cost me 47 years of my life. I've learned my lesson and will not respond for that very reason. :censored:
 
#28 ·
If you have a bigger filter you spend less time in bypass and run cleaner oil longer that’s why over the road semi engines last longer bigger oil filters are better than small ones. The stock oil filter used on the Jeep 3.8 is the same filter that Kohler uses on their twin cylinder 24 horsepower riding mower engine. Why would anyone want the filter to be bypassed? Bigger filter housings also dissipate more heat, yet another reason for engine wear If your happy letting your engine oil filter run bypassed why not just spin on an empty can with no filter at all
 
#29 ·
Mopar jk said:
If you have a bigger filter you spend less time in bypass and run cleaner oil longer that’s why over the road semi engines last longer bigger oil filters are better than small ones. The stock oil filter used on the Jeep 3.8 is the same filter that Kohler uses on their twin cylinder 24 horsepower riding mower engine. Why would anyone want the filter to be bypassed? Bigger filter housings also dissipate more heat, yet another reason for engine wear If your happy letting your engine oil filter run bypassed why not just spin on an empty can with no filter at all
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If your filter is being bypassed it is because it has been contaminated beyond its capacity which means you have much more serious problems. You never want a filter to bypass. As to heat dissipation, you won't see even a single degree difference by doubling the size of the filter.
 
#30 ·
Yes you have made my point you don’t want your filter to be obstructed and bypass unfiltered oil thru the engine that’s why the larger filter will maintain filtered oil for a longer period of time then the smaller one change the oil and filter more frequently will be better than allowing a clogged filter to stay in service
 
#31 ·
Mopar jk said:
Yes you have made my point you don’t want your filter to be obstructed and bypass unfiltered oil thru the engine that’s why the larger filter will maintain filtered oil for a longer period of time then the smaller one change the oil and filter more frequently will be better than allowing a clogged filter to stay in service
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The point of my comment is the fact that there is never a need for a larger capacity filter than prescribed. If your stock filter is being bypassed within a reasonable amount of time there are internal problems that must be addressed that a larger filter cannot solve.
 
Discussion starter · #33 ·
Finally fired up the engine yesterday. I ended up going with the .50mm .002 undersize bearing on the bad journal that I sanded.

So far I’m cautiously optimistic. I have driven very slow for about 7 miles keeping the RPMs under 2k and speed under 30. Oil pressure light has not come on at any point. Temperature holds steady.

Jury is still out, but I am going to slowly ease into breaking it in and see what happens. Who knows....we shall see.
 
Discussion starter · #35 ·
It cranks and idles perfectly fine. Upon revving up to 2-2.2k it makes a “dieseling” sound which is probably a slight rod knock. Oil pressure light has stayed off and temperature is good.

I am wondering if that is a result of the .50/ .002 bearing being a little loose in the one rod/ journal that was the problem. I almost went went the .75 .003 but was afraid it was too tight at .001 clearance per the plastigauge. Next option is to drop the pan and try the .75 .003. One note is I did use 10w 40 thinking it would help if the gap in the rod was too big.

Thoughts? And yes I get the whole thing is a big shot in the dark, but I don’t mind spending a little money to see if I can pull it off.

Thanks in advance
 
Discussion starter · #38 ·
Mopar jk said:
When you had the rod disconnected did the wrist pin feel tight plastic gauge one of the undamaged rod bearings and use that clearance to fit the new bearing
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I pushed the piston up and down a couple of times as I removed and connected it to the crank and didn’t notice anything loose.

I did not plastigauge the undamaged rods. I did replace the bearings with a new standard set.

The noise isn’t bad, just a slight diesel chatter type sound. I’ll keep testing it slowly and if it gets worse shut it down and put in the tighter bearing. I’ll try 5w 20 to see if that matters at all.
 
Discussion starter · #39 ·
Is there any way for me to isolate the rod bearing that is the bad one I’ve been working on? In all likelihood I that is where the chatter is coming from, but to make sure, could I pull the plug wire on that cylinder so the piston doesn’t fire? If the sound lessens then it is likely where the problem continues to be.

I read this can be done. Thoughts?
 
#40 ·
Disconnecting the wire from the offending cylinder will change the tone to the trained ear. Oil viscosity isn't going to make a difference as to clearance issues. Your 10w40 will be fine in a worn engine. As you know nothing you're doing is going to actually fix this thing. It's really just a learning experience. Think of it as a game and have fun with it.
 
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