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Q: Found bad rod bearings in cylinder 4 but other seem fine. Should I replace all? on 2005 Ford Escape Hybrid

Should I replace all the rod bearings even if they feel tight? or should I use Plasigauge on each one to be sure?
What should the crankshaft diameter be where the rod bearings connect and what plasigauge reading is acceptible using standard bearings?
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Pull another rod cap off, if the journials (what the bearing runs on) if both crank throws dont look the same and that one that has the "bad" bearing is the least bit rough or scored,, the crankshaft will to have to be removed for machine work,,,,,you know what that means!! If you just install another bearing, it might run 10 minutes before it too is destroyed!!! Sorry, but without seeing it, wish i had better news.
the crank is smooth with no scoring. Does antone know the specifications for the crank at the rod bearing? I read 1.935 to 1.955. Is this within tolerance?
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The real question is, why did that bearing fail? The specification is 1.967-1.968" and production repair would be 1.957-1.958" which would require a .010 undersized bearing. Trying to use plastigage without resizing the rod and polishing the crankshaft on a machine which ensures that both are perfect circles is a miss-use of the product. You could easily line up a high spot and think your clearance is OK when in fact you have way too much 90 degrees of rotation away from that point.

The biggest problem is how sensitive the upper end of the engine is to oil quality and starvation. So I'll ask again, why did this bearing fail? You need a real good answer for that or else you are doing a lot of work in vain. Was there a service issue and the wrong oil used or service over extended? Was there a consumption issue? One of the other responses really does have the right answer, complete rebuild IMO. A machinist needs to polish the crankshaft, resize it and fit bearings if necessary. He should be checking the line bore of the block and resizing the rods, and honing the cylinders in prep for new rings at the minimum. Plus the cam bearing journals need inspected to see if the head is still serviceable or not.
Your point is well taken and I appreciate that you've taken the time to answer.I haven't had any service issues with the Escape. What began as a lifter type of sound developed into a knocking in the #4 cylinder.I am not working so lack of income and a despirate need for transportation has brought me to the place of educating myself in the repair. I think a more lateral way to determine the state of the cranks diameter for poor folk like me might be to use 4 plastigauge around the crank at the bearing and press them all at once. What do you think?
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" I think a more lateral way to determine the state of the cranks diameter for poor folk like me might be to use 4 plastigauge around the crank at the bearing and press them all at once. What do you think?"

Absolutely not. You cannot use 4 pieces of plastigage like that. Its only intended to confirm bearing clearance after proper reconditioning. Any use of plastigage to attempt to fit a bearing, while potentially successful is a misuse of the technology.
I like "potentially successful". I was told by Ford that access to the rod bearings was not possible from the Oil Pan and that the Uniframe construction of the Escape would not allow that kind of access. They where entirely wrong or prehaps deceptive. At worst, my efforts will be met with failure but then there's "potentially successful" starting me in the face. If the crank is accentric then the plastigauge will indicate that. Not to determine bearing tolerance as intended but accentricity. And who cares what a tools intent is, curiosity is the mother of invention. Who knows ...maybe we'll all be wiser for the effort....Maybe not...Thanks for your input though. I know you have a great deal of experience over me and I do respect that.
Go for it, how else will one ever know! Clean all bearing material that may have transferred to the crank, install the new bearing and see what happens. As i stated before, obviously without recognition by some, at this point what choice do you have unless you are going to pull the engine? Any further debate is moot! Good luck.
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Potentially successful means the plastigage MIGHT confirm that the bearing and journal are no longer serviceable and need to be correctly addressed, but it cannot tell you if they are OK. So if your going to go on a guess by not pulling the crank and having it polished, like PR says clean up the journal, slam a bearing in there and hope.
About the only thing missing with slamming a bearing like you are going to try to do is shouting "Hey y'all watch this".....
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