What can the problem Be?

[2boats@hm]

I am putting a motor back together that just had the cylinders honed.(flash rust from a bad intake manifold) Everything was going great until I torque the conntecting rod nut to Jug 3 and or 4. When either of these pistons are torqued to to anything over 20ftlbs the crankshaft wont move.
The motor has less than 3hrs on it. 5.7 GM that I got from Ebasic 2 years ago.. The main bearings and the other pistons are torqued to spec.

 

[Don S]

Re: What can the problem Be?

Sure you got the bearings in the proper notches? Right caps on the rods? caps on the right direction?

 

[bomar76]

Re: What can the problem Be?

Plastigauge the rod bearings....

 

[Coors]

Re: What can the problem Be?

three words cancel message

 

[Don S]

Re: What can the problem Be?

And, are the caps not turned 90 degrees?

Cross ways???? How do you do that????

 

[Coors]

Re: What can the problem Be?

end for end; oil squirt hole on wrong side, not squirting cylinder wall, was machined to fit one way; you know..

 

[Coors]

Re: What can the problem Be?

Had to reboot.
Let me try to get through my southern terminology;
As "the Dude" said (hehe, that is funny);
The piston has a front and rear; The rod cap will fit on either way, but it was machined to fit only in one direction, related to the rod.
You did mark everything before taking it apart?

 

[Don S]

Re: What can the problem Be?

Had to reboot.
Let me try to get through my southern terminology;
As "the Dude" said (hehe, that is funny);
The piston has a front and rear; The rod cap will fit on either way, but it was machined to fit only in one direction, related to the rod.
You did mark everything before taking it apart?

It's called 180?, not 90?
90? is a quarter of a turn. Never work on a rod cap, half turn will be wrong, but a quarter turn is impossible.

And no, "the dude" isn't funny. The guy doesn't even know what the parts are called, let alone how to fix it, and I meant exactly what I said.
Sometimes ya just have to read between the lines of internet and reality.

 

[Coors]

Re: What can the problem Be?

Don, that's why it's funny; that "dude" has no clue, been working on his powertrain for 4 years- no factory manual; and he called you dude, and insulted you.
Calm down and see the humor. I had tears in my eyes.

 

[Don S]

Re: What can the problem Be?

2boats, not talking about you. Sorry about the intrusion.

 

[2boats@hm]

Re: What can the problem Be?

I removed all the pistons from the crank, and put the #3 piston in all by its self torqued it to spec....and the darn crank would not move.LOL My next boat is going to be brand new...

 

[Ed R]

Re: What can the problem Be?

just for kicks, put #1 and #2 pistions in #3 and #4 cylinders to see if it still locks up .

 

[Don S]

Re: What can the problem Be?

Swapping pistons is not going to find the problem nor answer the question of why that one is tight. He has a problem with #3, time to focus on #3.
First of all, make sure the end rod cap is on the proper way with the notches for the bearings on the same side. And make sure the number on the cap is the same as on the rod.
IF that checks out, put the bearing in and torque it down, then measure (with inside micrometer) the opening and measure the crankshaft throw.

 

[mkast]

Re: What can the problem Be?

Look at the back of the bearings, any of them +.010 oversize?
Wrong bearing in the right size box.

 

[brunolund]

Re: What can the problem Be?

something stupid like a hair in there? it doesn't take much to lock it up.

 

[Coors]

Re: What can the problem Be?

The rod bearing tang/groove in the rod and rod cap face away from the cam.
that will orient the piston. The rod does swing easily on the piston pin?

 

[Coors]

Re: What can the problem Be?

If both rods are not installed on that crank throw, you could have that rod cocked. take the wood end of the hammer and tap it toward the crank counterweight on all sides. while not fully tightened.