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95 3.4L Main bearing replacement


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#1 EccoBlackfin

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Posted 15 May 2020 - 02:32 PM

So I hit a pothole here in Pothole, Michigan, and the car suddenly just stopped doing anything worthwhile.  I mean misfiring like crazy, no power, stalling, everything.  Thankfully there was a shop not even half a mile away, and they took a look at it for free.  The guy said that the main thrust bearing was shot on it, and literally just shoved the crankshaft back into place, fired up, and it ran fine..until it slipped forward again.  So despite the incredulity of it, pretty sure that's the issue (please correct me if I'm wrong).  Also, manual trans, and the previous owner sucked at driving a stick shift (first thing I replaced on the car was the clutch because it was slipping constantly), so banging that clutch into the crank didn't help I'm sure.

 

$800 to *hopefully* fix a fairly rusty car with more than 250k miles on the clock seems pretty steep to me.  Can the bearings be swapped out in-car?  If so, what would the steps be?

 

Should I just go with stock tolerances because it'll be good enough til the car dies for good, or oversize and risk them being too tight?  Any other tips?

 



#2 sea dog

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Posted 15 May 2020 - 03:06 PM

Changing main bearings with engine in car is not a job for the faint of heart. Transmission, clutch & flywheel must come out. All the pulleys on crankshaft have to come off. As well as timing cover, & timing set.

 

Anything blocking the removal of timing parts must come out also. This includes radiator & hoses, cooling fan, any belts, etc.

 

Then you have to remove oil pan. This usually requires engine to be raised off of motor mounts for working room. Oil pump must go. Then you can remove connecting rod caps, carefully push piston,& rod assembles up out of way.  Then rear seal carrier must be removed. Front seal should have come off with timing cover. Finally, you cam remove main bearing caps and carefully remove crank.

 

But because crank had way too much end play, crank, rods, & pistons could be damaged. And to take piston & rod assemblies out of engine, they must be removed from the top. Which requires removing heads, intake, exhaust, etc.

 

If you put oversize main bearings in an engine that hasn't had crankshaft ground for them, engine will probably lock up tighter than a drum. Even though crank is probably worn, cranks don't wear evenly around the bearing journals.



#3 EccoBlackfin

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Posted 16 May 2020 - 07:48 PM

Changing main bearings with engine in car is not a job for the faint of heart. Transmission, clutch & flywheel must come out. All the pulleys on crankshaft have to come off. As well as timing cover, & timing set.

 

Anything blocking the removal of timing parts must come out also. This includes radiator & hoses, cooling fan, any belts, etc.

 

Then you have to remove oil pan. This usually requires engine to be raised off of motor mounts for working room. Oil pump must go. Then you can remove connecting rod caps, carefully push piston,& rod assembles up out of way.  Then rear seal carrier must be removed. Front seal should have come off with timing cover. Finally, you cam remove main bearing caps and carefully remove crank.

 

But because crank had way too much end play, crank, rods, & pistons could be damaged. And to take piston & rod assemblies out of engine, they must be removed from the top. Which requires removing heads, intake, exhaust, etc.

 

If you put oversize main bearings in an engine that hasn't had crankshaft ground for them, engine will probably lock up tighter than a drum. Even though crank is probably worn, cranks don't wear evenly around the bearing journals.

Pretty much just what I was thinking.  I have heard of people doing in-place bearing replacements, doing it one bearing at a time, thought it might be doable.  Oh well..  Rest in peace, firechicken.  It was fun while I had ya.






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