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pls help: rod caps too loose?

hi anyone,

this is a troublesome problem. i got a 92 Chevy Corsica V6. i took off two of the rod caps to inspect the bearings. they have a perfectly normal pattern of wear. no problem.

oil and replace the bearings and caps, slip the rod caps over the rod studs and start to tighten the cap nuts. i tighter the nuts to 20 #s and the crank won't turn. its hopelessly wedged. the Haynes manual says 39 #s.

everything is right and in good shape. scratch my head. loosen the cap nuts and it cranks normally by hand with a wrench. tighten the cap nuts at half the rated torque and the crank is frozen solid. didn't touch any of the other rods.

so what the hell? no i didn't do the plastigage. but why should i? the wear pattern is perfect. and it was turning just fine before i started. i used the torque wrench on some of the other nuts and it seemed that they weren't torque as much as they should be, but then how much torque do they need?

thanks anyone, Louie

Reply to
Louie
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#1 did you replace the rod caps on the same rod they came off?

#2 are you sure you got the little divot in the bearing shell aligned with the cutout in the rod/rod cap?

Take everything off and look *closely* to make sure all is kosher.

Reply to
Mark Olson

OK i'm still working on this. i verified that the caps were not switched or reversed and the bearings are properly oriented. still hopelessly frozen with only one of the caps tighened down at half the rated torque.

any help would really be appreciated.

louie

Reply to
Louie

well it looks like there's just not gonna be any answer to my problem i've got it down to the absolute bottom line and it still doesn't make sense. i've done those things and everything checks out. thanks anyway

louie

Mark Ols>

Reply to
Louie

And the backs of the shells, and the bearing face of the cap is _clean_, right?

Reply to
Stephen Bigelow

yep. checked that too. louie

Reply to
Louie

If the rod caps are numbered, and the engine has had a rebuild, the numbers could be wrong as sometimes shops just mix and match caps and rod and regrind them true with a bearing to fit.

Are they upside down maybe, they are ground in place on the studs, so if upside down or sideways whatever way you are looking at it, they will jam the crank.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's

Louie wrote:

Reply to
Mike Romain

Reply to
Louie

Have you tried just doing ONE of them at a time?

Reply to
Hank

This is a totally off the wall idea but as you've seemily covered most other things...

I had a torque wrench a while back which was really off calibration. Could you actually be torquing these on tighter than your wrench is indicating? Maybe trying another torque wrench and/or calibrating yours would be in order??

Cameron

Reply to
Cameron

Yes it is off the wall and wouldn't make a scrap of difference to whether the crank turned or not.

The problem is clearly due to some misalignment of the shells or caps or damage to the shells if they got pinched between rod and cap at the first attempt and are now bent.

Dave Baker - Puma Race Engines

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Reply to
Dave Baker

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