[tdowney135]

so I recently bought a 94 dodge dakota 5.2 auto 4x4. The truck supposedly drove into the barn it was sitting in 5 years ago. The truck has 94000 original miles. The starter wouldn't turn the engine so I pulled the spark plugs and turned it with a breaker bar on the harmonic balancer. The engine will turn one full rotation in either direction before it stops. No movement past a full rotation of the balancer. I pulled the valve covers and all rockers are tight. Oil was old but clean(no glitter or metal). This has me stumped. Any advice for what to look for would be appreciated.

 

[ImperialCrown]

Welcome to Allpar. Possibly rusted cylinder walls? This could be exacerbated by a damp environment. Proper storage would have been a shot of motor oil in each spark plug hole before sitting.
A boroscope (auto parts store tool loan?) could take a look through the spark plg hole.

 

[tdowney135]

I have let it sit the past 2 days with marvel mystery oil in the cylinders, Occasionally rolling it from stop to stop trying not to use to much force. Still stuck both directions. I've gotten a few other engines unseized but none of them ever made a full rotation either way before completely jamming.

 

[ImperialCrown]

Is it possible that a valve is stuck rusted open? This could stop a piston as it approached TDC in either direction.

 

[tdowney135]

Is it possible that a valve is stuck rusted open? This could stop a piston as it approached TDC.

If so how would I approach fixing it? All my rockers are working valves up and down when I push on or tap them with a brass hammer. Should I pull the heads? Or is there a better way to go about it?

 

[djsamuel]

Before getting into the internals of the engine, I'd make sure there wasn't something external blocking the rotation; such as something near the torque converter/flex plate.

 

[bguy]

How far from TDC does it stop each way? Could it be a rust ring?

 

[tdowney135]

How far from TDC does it stop each way? Could it be a rust ring?

I've let it sit in marvel oil the past 2 days with no change and number 1 cylinder is at top dead center with it turned all the way to the right.

 

[GoManGo0406]

Try shooting a liberal amount of WD40 or PB Blaster near the valve guides and slowly rotating the engine, while gently tapping on the tops of each valve with a rubber mallet. Then leave some to soak overnight. If still not freed up, I would pull the head to get a better look at what is going on. Chances are it's time for at least a valve job refresh and some new gaskets. If you do find catastrophic damage, then you can decide course of action from there before spending any more time or $.

 

[bguy]

Can you see the valves moving as the crank rotates or are you on compression stroke? Remove the rocker assy and see if one of the valves sits low using a strait edge. Since you are making it to TDC I agree that the issue may be in the power output.

 

[tdowney135]

Can you see the valves moving as the crank rotates or are you on compression stroke? Remove the rocker assy and see if one of the valves sits low using a strait edge. Since you are making it to TDC I agree that the issue may be in the power output.

When I rotate the full rotation cylinder 8 and 4 rockers go up and down and cylinder 1 and 3 on the other side do the same. The other four move when tapped on like they should. I've had all 8 cylinders doused in marvel mystery oil for the last few days. Gonna try and work it some more tomorrow to definitely rule out rusted cylinders. Just don't want to put more into it than necessary since I can get a good engine for around $600.

 

[tdowney135]

Before getting into the internals of the engine, I'd make sure there wasn't something external blocking the rotation; such as something near the torque converter/flex plate.

Pulled the inspection plate and everything seems normal.

 

[bguy]

Pulled the inspection plate and everything seems normal.

Only 4 bolts to set the converter free.

 

[tdowney135]

Only 4 bolts to set the converter free.

Ya ill probably take it lose tomorrow and make 100% sure its not trans related.

 

[ImperialCrown]

If a torque converter bolt has backed itself out, it can hit the back of the block.

 

[djsamuel]

Ya ill probably take it lose tomorrow and make 100% sure its not trans related.

Would probably be worth it just to confirm the issue is in the engine.

 

[tdowney135]

Would probably be worth it just to confirm the issue is in the engine.

 

[tdowney135]

UDATE:
I believe its a combination of a stuck open intake valve and multiple rusted cylinder walls/rings. It now turns but seems to catch and get stuck every other rotation. I think if I keep putting oil down the cylinders and rotating it more and more this ole 318 might just come back to life for me. Thanks for the tips everyone.