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Turning Crank Manual but does not move 360 degrees?


blbzeckhart

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I'll give you the back story after I present the problem:
1994 4.0L OHV VIN X (overheated, milky oil)
Replacement engine from junkyard, out of the vehicle does not crank a full 360 when turning crankshaft with a socket and wrench. "Junkyard states is a good engine, 6 month warranty, and supposedely started before removal?
I didnt try to manually turn engine over via crankshaft prior to install.
So, uninstalling failed motor because of overheat, wont run condition. ON UNINSTALL, no problem manually turning crank to remove 4 torque converter nuts from studs, through starter hole.
Install Junkyard replacement Motor, cannot rotate crank all the way to get all torque converter nuts on. Initially thinking torque converter not in all the way, somehow engine to trans cock-eyed?, or engine has bent valves?
Unbolted engine to trans. Torque Converter seems in all the way? While separated, Engine will not crank 360, with flywheel attached? Is my junkyard motor bad, bent valves? with all 8 bolts in and tight with engine to trans, cannot get all 4 torque converter nuts on bolts. Now separated. Engine will not rotate 360?? I think bad engine from junkyard! Thoughts?
 


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franklin2

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I agree. Go ahead and separate it from the trans, lift it up a little bit so it's hanging in the engine bay, and then try to turn it. If it won't turn, I suspect a bad engine from the junkyard also. Did you have the intake assembly off? Maybe a bolt fell down into the intake?
 

RonD

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The 4.0l OHV engine is a non-interference engine so at no time can valves and pistons touch

So either there is something inside a cylinder that is preventing a piston from going all the way up, or a connecting rod has broken and preventing crank from turning past a certain point
 

Elutheros

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I bought a 5.0 like that once. Found water in a couple cylinders--which won't compress and that stops it from rotating.
 

ericbphoto

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Pull the spark plugs and see if it rotates all the way.
 

blbzeckhart

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Yeah so I separated it, pulled the plugs, the engine just won't rotate all the way around. While installed I could never get the 4th bolt on torque converter because it locks up. Tried going both ways.
Never had intake or valve covers off. Just supposed to be an easy swap, lol.
Also, since I unbolted and separated this junkyard engine I double checked the torque converter again. It is all the way in and rotates all the way around. Problem seems to be engine. Before calling the junkyard, on a 4.0 ohv should you be able to rotate the crank all the way around in either direction?
What else could prevent being able to install all 4 torque converter nuts on while bolted together?
If the engine won't turn all the way out of the vehicle, surely something in the engine must be bad. No?
 

RonD

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Yes, always was some problem in the engine preventing it from turning
I would call the seller and ask them what they want you to do, pull it or investigate it
 

franklin2

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I bet they will exchange it if they have another one available. They seem to lay all the testing on you, since you are doing all the work. Most have a 30 day warranty. Who knows how many you will have to try before you get a good one.

I went to get a radiator at a junkyard, they led me back to a old school bus full of them. Everything was labeled. He found one and was going to pull it out, but I looked down in the throat and it was full of white corrosion. I told him I didn't want it because of that. He gave me a disgusted look, put it back in the rack and pulled another one. It looked good inside, so I took it. I bet someone else got the other radiator.
 

Shran

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Have you tried pulling the flex plate/flywheel off and turning it? Perhaps someone dropped a bolt or nut between the block and flex plate?
 

blbzeckhart

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Not sure if I updated on this issue, but here is what happened. So I called the junkyard and they suggested that their was carbon build up in the cylinders from sitting (possibly) and that is why the engine would not rotate 360 degrees? The junkyard owner had said he had seen this issue at least a dozen times and would be willing to bet is what the issue is. Skeptical, I thought this was really far fetched because I am rotating the engine by the crank pulley bolt with a breaker bar and it only spins 3/4 turns one way and the same the other and locks up. Many people in this forum suggested wrong flywheel bolts, could be hitting. Take plugs out, to much compression, bent valves, ect. Anyway, after I installed motor and bolted to trans I could never rotate the Engine all the way to put on all 4 torque converter nuts. So I ended up pulling engine back out. Removed plugs, removed flywheel, still no crank 360. I was ready to return motor, something internal wrong or bent/broke. So, as suggested by the junkyard......blow compressed air into each spark plug hole. When I did loose carbon and debris shot out everywhere. I also decided to use brake clean a very small amount in each hole to loosen up some more. Continued to rotate Crank pulley and also blowing out more carbon deposits and finally it freed it up. I was eventually able to crank by hand the engine 360 degrees in both directions. The reason I decided to use brake clean is because it lubricates and cleans and also dries out fast. I figured while using compressed air also, it would definatley dry it out. Either way, I would NEVER have imagined carbon build up, dried up soot, burt oil deposits would lock up a motor? I re-installed motor and had no problem installing all 4 converter nuts.
 


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