Rebuilt 340 really difficult to turn over

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ESP47

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I had the engine rebuilt in September but I'm just now getting this thing in the car. About two months ago I set the timing on it and was able to turn the engine fairly easily with the crank bolt and a breaker bar.

Fast forward to today, I wanted to prime the engine right before I put it in so I went to turn it with the crank bolt and I couldn't get the engine to turn. The bolt felt real soft in there like something was going to strip out or break. I tried another bolt and same thing. So then I decided to just press down on the fan belt and turn the fan. Well that ended up snapping the fan belt and I was only able to turn it 1/4 of the way before I got worn out. The thing was so tight I was lifting one leg of the engine stand off the ground while trying to turn the fan.

Finally I took the engine off the stand with the cherry picker and ran two bolts into the backside of the crank where it connects to the tranny. I used a metal bar to then turn the crank over and it finally started turning, albeit with a ton of pressure. I'm going to need to turn it while it's in the car to line up the flex plate to the flywheel and I feel like I'm going to tear the threads out of the harmonic balancer if I run a couple bolts through it and use a bar to turn the thing over. What do you guys think is going on here? I don't have the spark plugs in. I was able to get it turned a couple times to prime both sides but it never really got any easier to turn over at any point.
 
There is something wrong. One hand on a 1/2" ratchet should turn over an engine with no plugs.
 
At this point it could be anything. I'd almost consider getting a gasket and taking it apart to find out what it is. You certainly don't want to put it in the car this way.
 
The starter can turn it to line up flex plate bolts after the trans is bolted up.
A remote starter switch is a good thing to have if you don't already.

You may want to shoot a little oil in those cylinders before it gets turned any more, just in case they dried out from sitting. (I know, oil doesn't dry) it was just a phrase to explain it.
 
25 - 30 foot pounds should turn it with plugs out.
 
The cylinders are rusted. Tear it apart.
 
plugs out, it should turn easy.
mine 318 turned about 30 fb w/o plugs
 
how does his cylinder walls become so rusted that its this hard to turn over? sitting on a stand in his garage in 6-8 months???
 
Did you have the plugs out while it was sitting? They can draw moisture like a sponge.
 
If there was light oil on the cylinders only and it has sat since September, it could very easily draw enough moisture to rust the cylinder walls. Ever see how fast nice clean raw metal rusts up? A day or two is all it takes for it to start.
 
I would check the cylinders for rust as stated above.

Then I would also take the oil pan off and look at the crank and bearings. Make sure that they are not scored and are clean.

I've seen a speck of dirt behind or in a bearing lock up a crank. Check all of your main and rod bearings. Maybe remove one piston at a time from the crank to see if the engine starts to turn over easier. Then with all of the pistons removed from the crank see if it turns over and how easily. the crank should spin and keep spinning on an engine without any pistons attached to it. You don't have to remove the pistons, just push them to the top of the cylinder, but that may keep you from testing the crank turning resistance.

As you 'release' some of the pistons from the crank, see if one in particular makes more difference than the others.

If you have a rusty bore, remove the pistons and get a 4" wire wheel for a drill and use it to remove the rust on the bores. Then clean all of the debris out before reinstalling the pistons. I like to lube the bores with Casite Motor Honey or STP. That will keep the bores and bearings lubed enough for the engine to start and oil pressure to come up.

For the engine to not turn over, the bores are rusty, or the crank has some interference with the bearings.
 
Tbone416 said:
did you get the tq con all the way in the trans first? it mite have you bound up!
Click to expand...
The engine isn't in the car, it was still on the stand, so no torque convertor yet.

Something is wrong. Tear it down or risk destroying it, then you will tear it down anyway.

Dennis
 
This is what i would do:
Buy yourself a gasket kit and tear it down. At least pop off the heads , intake, and pan.
If the bores are rusty, it has to come apart and the bores properly cleaned and reinstall the pistons etc. after they are cleaned up too. Pay attention to the bores if they are rusty, and look closely for pits.
The crank should turn freely with the pistons out, if not, take the thing apart and check all clearances and correct where needed.
Don't forget to check the valves for being stuck especially if the bores are rusty.
Years ago, i had a good running 340 i bought off a friend that ha 10,000 miles on it and i stored it in a shed for about a year sealed and covered.
When i went to use it, it was stuck.
I ended up pulling it apart to find #4 cylinder was rusty. Long story short, i ended up having to sleeve the cylinder and had the heads redone with new rings and a clean up hone job on the cylinders to clean all of the crap and rust out.
 
Thanks guys looks like I probably screwed up big time. Had a bag over the engine most of the time but the last month or so I left it off because I had all the accessories hooked up and it wouldn't fit. Didn't have the spark plugs in either so it's probably rusted. I'm just going to take it back to the machine shop because I can pretty much guarantee I'll screw it up if I try and mess with it myself.
 
I have my Hemi under a sheet. No plugs. But I go out about twice a week and turn it. I also used Motor Honey to assemble it.....which is about the same consistency as bar and chain oil, so it HAS lube. You just have to stay in front of the rust.
 
If you're having problems getting your car to turn over, here's what you do:

Get your car out on the highway and drive between 70 - 90 MPH. Then slam on the brakes and turn the wheel all the way to one side. Your car will turn over, no problem....

LOL!


Seriously, I also use motor honey when I build an engine. If no motor honey available, then STP.
 
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