N engine rebuilders

Dr.Bert

Member
I'm rebuilding the engine out of one of my 2N's. Plastigauged all bearings (all within acceptable tolerance) and spun the crank after torguing the mains and rods--turned easily. Then inserted the pistons with cast rings in the original sleeves ( honed and crosshatched) and now it takes a breaker bar on the front of the crank to turn it. Each piston was ribbon gauged for clearance and all were within recommended tolerances. The starter cannot turn it!! Other than pulling the tractor in gear or spinning it at the V belt pulley, what can I do to loosen the engine up? Also, checked the ring gaps.
 
Got a cap on backwards? Caps not back in original locations?

Even new rope seals can make them tight.

How did you install the rods on the crank, then install pistons???
 
JC: Put the pistons in without rings and torqued the caps (all 4 marked prior to removal) and spun the crank. Then, put on the rings and reinstalled each piston, then tried turning the crankshaft and it was very tight. I'm using mineral oil to lube each cylinder and that seems to be helping.
 
Ok. That sounds about right.

Still the only thing that comes to mind are the caps. Did you mark them to each rod and which direction they were facing? If you get one rotated 180* it will be very tight.

The last one I tore into last summer, not all caps faced the same way. Two logos were toward cam, two weren't.

If your unsure, try flipping them one at a time.

Since you checked ring end gap, torque, plastigauge that's about all that's left.
 
(quoted from post at 18:40:19 02/13/14) During teardown, each rod cap was indelibly marked with an electric grinder, both for position and direction.

Good deal. May try loosening the pan just to see if it's the seals.

Last one I did with new sleeves and rings was real tight. I just kept turning it over with a breaker bar and socket on the crank nut. That loosened it up considerably.

Another guaranteed lockup is if the pistons hit the head? Did you have either the head or block skimmed.

Is it on a stand or installed? Out of gear? Clutch not stuck? Just grasping at straws now without seeing it.
 
JC: Thanks for your input. Engine is still on the stand. After your replies, I think I will tear the engine down and start over. I have done a number of N engines and never had one like this. Very curious to know what is the cause. Probably "pilot error".
 
(quoted from post at 20:55:21 02/13/14) JC: Thanks for your input. Engine is still on the stand. After your replies, I think I will tear the engine down and start over. I have done a number of N engines and never had one like this. Very curious to know what is the cause. Probably "pilot error".

Sorry I couldn't have been more help.

I've gotten pretty good at rebuilding them. Not because I'm good, but because I always end up in your shoes and break them back down if they're not right. There's a poster at work..."If you don't have time to do it right, when will you have time to do it over."

Good luck and let us know what you find.
 
I measured over 45 ft-lbs to roll the crank over after installing the pan during my rebuild. I was shocked how much resistance the crank seals added.
 
JC: Your suggestions and input are more helpful than you know. Thanks. Loosened the pan this AM and the engine turned somewhat easier!!! Will remove the pan tomorrow and check each main and rod cap and bearing. Also--learned something that I will past along. Tried lubing with motor oil and that didn't help much, but bought some mineral oil and pour3d it in each cylinder--engine turned much easier--not great but better.
 
JC: You've been more helpful than you realize. Thank you. Loosened the pan this AM and the engine was somewhat easier to turn. Will remove same tomorrow and check each main and rod cap and bearing. Also, this may help you. On the next tight rebuild, try using mineral oil in each cylinder before another teardown. Mine turns easier after I started using it. Much easier than with plain motor oil
 
Dr.,

No problem, just glad to pass along anything I've learned over the years.

New rope seal will make them tight, but tight is a relative term. I've never had one TOO tight unless I missed a cap. It helps immensely to soak them in warm oil, or any oil for that matter, for a day or so.

With the pan off, check your caps. To see if it's the rope seals, loosen the mains a little. That'll take pressure of lf the upper seal. Don't forget to retorque...that could get ugly.
 

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