connecting rod bearing difficulties

[gatorgut_16]

when i rebuilt the engine i ordered a crankshaft kit, it is a remanfactured crank with all bearings included.... heres the problem. as i was putting the connecting rod bearings in the engine would get tighter and tighter and more difficult to rotate. to the point of me breaking a rubber mallet trying to rotate the crank. and i broke 2 good size bolts in the harmonic balancer with an open end wrench trying to turn the crank. i looked into it, the crank kit came with .040 bearings, and apparently they were to big or thick. i dont know.... so i ordered .030 bearings and put them in.... all is good. i thnink.

 

[mkast]

Re: connecting rod bearing difficulties

when i rebuilt the engine i ordered a crankshaft kit, it is a remanfactured crank with all bearings included.... heres the problem. as i was putting the connecting rod bearings in the engine would get tighter and tighter and more difficult to rotate. to the point of me breaking a rubber mallet trying to rotate the crank. and i broke 2 good size bolts in the harmonic balancer with an open end wrench trying to turn the crank. i looked into it, the crank kit came with .040 bearings, and apparently they were to big or thick. i dont know.... so i ordered .030 bearings and put them in.... all is good. i thnink.

Using a micrometer, measure the journals.

 

[Bt Doctur]

Re: connecting rod bearing difficulties

did this kit come with connecting rods sized to the crank?You cannot guess on bearing clearance. To be sure: install the cap on the rod, torque to spec, measure the ID ,them measure crank journal dia. The difference is the clearance.Another way is to obtain "Plasti-Gauge" to measure the clearance.

 

[jtybt]

Re: connecting rod bearing difficulties

.030" under/.040" under? That crank has been around. Just what company are you getting your parts?

Was this a rare engine you're rebuilding? It better not be a 5.7

 

[Fishermark]

Re: connecting rod bearing difficulties

all is good. i think.

I think all is not good. But the only way to tell is to measure as pointed out above. Do not just put in a different set and size of bearings hoping they simply sent you the wrong size. It could be you had them slightly off center or in a bind somehow. You should never need to force the crank around. It should turn fairly easily - even with the pistons attached.

 

[gatorgut_16]

Re: connecting rod bearing difficulties

the engine is a 1973 mercrusier 165 chevrolet l6. i got the crank kit from oreily auto parts. the kit only came with the crank, main bearings, and connecting rod bearings. and i used the connecting rods that i had. they werent bad. i spun a bearing on the number 4 cylender, that was the whole reason for the rebuild. the old crank was scarred up so i found the kit for $164. but its turning out to not be such a great deal.

 

[Paul Ryan]

Re: connecting rod bearing difficulties

When a engine is that hard to turn, STOP trying! It will never get better. Something isnt right! Found that out on my over head cam. Had the caps on backwards and locked the engine. Turn the caps around and engine spun like it should. Love "Plasti-Gauge". I know how to use mic's but the Plasti-Guage allows you to put the parts together. I would use plasti-guage, make sure caps are installed correct and torque down. DONT turn engine. Undo the cap and conpare the width of the plasti on the bearing/crank with the scale on the gauge wrapper. If you find 0.003/0.005 run with it!!! Knowing the spec from a manual would be ideal.

 

[HT32BSX115]

Re: connecting rod bearing difficulties

when i rebuilt the engine i ordered a crankshaft kit, it is a remanfactured crank with all bearings included.... heres the problem. as i was putting the connecting rod bearings in the engine would get tighter and tighter and more difficult to rotate. to the point of me breaking a rubber mallet trying to rotate the crank. and i broke 2 good size bolts in the harmonic balancer with an open end wrench trying to turn the crank. i looked into it, the crank kit came with .040 bearings, and apparently they were to big or thick. i dont know.... so i ordered .030 bearings and put them in.... all is good. i thnink.

Um......you did measure the crank and rod journals and use Plastigage to determine clearances after all this, didn't you?

If not, it needs to come apart. This ain't no Erector set!

 

[a70eliminator]

Re: connecting rod bearing difficulties

If you didn't know any better than to break off bolts trying to turn the crank and not measure anything than you may not have known not to mix up rod and main caps either? Not trying to be ficiecios but not everyone is a mechanic but know your limitations. You did the right thing by asking for help.

 

[gatorgut_16]

Re: connecting rod bearing difficulties

well this isnt the first engine ive rebuilt or worked on. as i was taking the engine apart i labeled everthing and the place it came from. so there is no mixing up parts. this is just the first time ive ran into this problem. my problem is i figured a company that sells crankshaft kits and other misc. car parts would send the the bearings that correspond to the crank. but i suppose this isnt the case. and i didnt acctually break the bolts... i just bent them... badly

 

[Bt Doctur]

Re: connecting rod bearing difficulties

Lets backtrack a bit
When you installed the crankshaft and torqued the main caps, did the crank spin freely?
Yes-No
Did you measure the rod vs crankshaft diameter?
Yes-No
Did you use PlastiGauge or micrometer
Yes-No
Yes to all 3 and motor will turn over by hand with the pistons installed.
And "YES" you can reverse a rod bearing and have it bind up.

 

[gatorgut_16]

Re: connecting rod bearing difficulties

installed main caps, spun great. measure rod crankshaft diameter no, and no to plastiguage.... im at work at the moment and i get off in the morning hopefully.... im going to go check the .040 bearings

 

[gatorgut_16]

Re: connecting rod bearing difficulties

ok i think i know what my problem was, i think i put the caps on backwards.... my part time dyslexia must have kicked in...

 

[Paul Ryan]

Re: connecting rod bearing difficulties

Yeah, I have built a few hundred engines. I mark and layout everything and still got my cam caps on backwards. It happens. Your not alone with the dyslexia It's so sweet when they spin but if they don't try not to force the issue. It never gets better and other problems can quickly become a issue if things get forced. As you very well know...lol...If the mfg hadn't marked the parts I would make punch marks to keep everything in order, but I never liked the idea I was smacking a part with a sharp tool I now use Paint Pens. You can pick the up anywhere and the work great. Just get all the oil/grease of the area. Glad you found it!!! Time to make HP