connecting rod bearing clearance issue

[quasi]

I am rebuilding my 1984  1.6 turbo diesel engine.  It is a 1984 CY engine. Here is my issue:

Local machineshop/speed shop checked all measuremeants,  and told me everything was perfectly with in standard replacement parts.  They then honed the bores for me, and also installed the intermediate shaft bearings.

So now I installed new main bearings used plastiguaged and all was well withing limits.  Cleaned them back up and applied assembly lube.  Torqued them to Bentley specifications.  Crankshaft turned very nicely.

Installed new pistons and new rings.  Then installed new connecting rod bearings.  Again like I did with the main bearings I plastiguaged them and torqued to 26 lbs.   Bentley calls for the following.  0.028mm to 0.083mm.  My readings are 0.051mm.  So I am almost dead center in the measurement for clearance.  So I should be totally fine.  I clean off the plastiguage, just like I did with the Main beaings.  I now have all 4 pistons and connectng rods installed with assembly lube.  Engine crank turns by hand freely with all pistons moving. 

So I torque them down per Bentley book 33ft pounds.  Crank wont move even with a socket and breaker bar attached.  So I back off all the nuts.  I then snugly tighten them up.  Crank still turns freely.  Now as a test I torque just one connectng rod to just only 26 lbs.  Crank wont turn.  I then loosen the connecting rod nuts to that individual piston.  I dissasemble the cap, and clean it dry.  I use the green plastiguage and again torque it, take it apart and get the same reading of 0.051mm. 

So i clean it again and use the red plastiguage strips and come up with 0.051mm.   So my clearance is perfect. I clean it up again, apply assembly lube, tighten it till the socket becomes snug.  Crank spins freely with all 4 pistons attached snuggly.  I again torque just one cponnecting rod to just 26 pounds and i cant move the crank even with a socket and ratchet.  It doesnt matter which individual piston I torque down. My crank is round.  the bearings that were originally removed show very little signs of wear. 

What is wrong?  any suggestions?  Why can't I turn my crank freely with the connecting rods torqued down?

[Vincent Waldon]

The most classic reason for this is that bottom ends of the connecting rods no longer are paired with their corresponding top... did you keep them the two halves of each connecting rod together as you tore the engine down and then rebuilt it?

[Baron VonZeppelin]

The only sensible guess i have, is just exactly what Vincent said.

So if that is your case, at least there are only 4 to go through, and not 8 of them. Supposed to stamp/mark the rod and its cap before disassembly.

If you can't get them back in order, take them to your machine shop and they can find the mates with an inside micrometer or out-of-round gauge.

[quasi]

They are stamped and matched up.

im wondering if for some odd reason.. perhps the bearings are not mnade correctly say at the ends...   I  am totally lsot on this

[Vincent Waldon]

They are stamped and matched up.

Yeah, it was a total long shot... you certainly sound like you've done this before.

I suppose the next suspect is the new rod bearings.... even if they plastigauge ok in one spot? 

[quasi]

I have rebuilt other engines in the past.  I am not a expert, but can hold my own.    I am thinking of taking the plastiguage and running it diagonaly from one end of the journal to the other end then put the cap on, to see if their is any variations.   If i cant figure this out, yes i will just have to order new rod bearings.

[kevinm]

Look for wear marks/scratches on the machined flats on the sides of the rod and end cap to help match them up if they are in fact mixed up. Also the chamfers on the inside of the bore by the bearing shells will be a good way to check as they run out a tad...

[Vincent Waldon]

If i cant figure this out, yes i will just have to order new rod bearings.

We've heard of reports of mis-sized bearings before... so it's a possibility at least.

[Baron VonZeppelin]

Mock them up (uninstalled in engine) with bearings in place, and take them to the machine shop to check for out of round maybe ?

What type/brand bearings are they ?
Purchased from where ?

[quasi]

sadly purchased from Prothe last year

[Vincent Waldon]

So why didn't you tell us you had a wheelbarrow when you listed your assets in the first place...  

http://www.youtube.com/watch?v=vjegMCMewtk

[quasi]

lol @ the wheelbarrow

The more i'm reading other threads, the more I am seeing a pattern with products from Prothe.  So I guess I need to just order new bearings...

[Baron VonZeppelin]

sadly purchased from Prothe last year

Somehow, i kinda saw that one coming.

. . So I guess I need to just order new bearings...

Yeh, thats going to be easiest/best thing to do now.
I'd try another supplier

[rabbitman]

Too bad, it sure sounds like that's the problem though.

[LC]

make sure tangs are togerher on rods. try to radious the rod bearing.