I have a fairly simple/beginner question.

Shouldn't I be able to hand turn the crank both clockwise and counterclockwise with about the same amount of effort?

Which direction does the engine turn it when running?

What would it mean if one direction seemed to "jam".

The truck isn't running well and I'm trying to do some diagnostics.

 

I do not have enough practical experience to answer your question, so I would hope someone else will, but the first thing that comes to mind is that you are coming up to the compression stroke on one of the cylinders, or maybe one of the better cylinders if some are leaking.

 

Thanks for the advice. I didn't want to force it so I'm still not 100% sure. But I'm almost dead positive that its supposed to turn clockwise and thats the direction that jams on me (and by jam i mean a HUGE amount of force above what it takes for the other direction doesn't get it to move).

Theres a loud knock that developed on day on my way home, large lose of power and a vibration at idle. limped it the couple miles home, now I'm trying to figure out whats wrong.

Current theory is that i possible skipped a tooth on the timing and the piston is hitting the valve. Forward and reverse have a slightly different profile on the cam so I think I'm barely missing the problem bringing it around backwards, but if i go forward....

Time to tear down the top end take a look.

 

Pull the plugs and trun the engine by hand.....yes the effort should be the same and no feeling that something is touching

 

I forgot to mention, I had loosened the oil pan so air could escape while I did this. Should negate the compression stroke issue I believe. I will remove the plugs on the most noisy cylinders and feel around with a dowl. If it jams when they approach/reach TDC sounds like some valve issue.

Then comes the fun of tearing the top end down, and if I confirm it, probably the front to look a the timing pieces.

 

Loosening the pan won't help any. The compression is on top of the pistons (it's supposed to be on a non-broken engine). Maybe a cam follower fell of not letting exhaust out. The last engine that I had get rough with no power had broken a rod and had no compression in #2 cyl. and vibrated really bad from being out of balance.

 

Thanks for the advice. Took the valve cover off and both rocker arms for #1 where laying around.