Motor help, please

336wheeler

Well-Known Member
Joined
Sep 9, 2006
Location
Boone
I have a '95 4.0 in a YJ that should be working. Need some suggestions on what possibilities it could be. I put marvel mystery oil on top of the pistons on thursday, so I'm going to try rolling it over by hand tomorrow. The motor is more or less seized... my attempts at rolling it over by the crankshaft pulley have resulted in me either tightening or loosening the crankshaft pulley bolt. I believe that a cracked block, rolled bearing, or throwing a rod can be ruled out, but the motor isn't wanting to do anything. The motor has not been spun in two years. Suggestions please? If I can't free it up this coming week I'm just going to go ahead and put the tranny, t-case, and driveshafts in, then take it to someone for some motor work when the budget allows.
 
How did you rule out the bearings/rods/cracked block?

If its seized then it prolly needs major work. So you would be better off taking it back out because it will have to be out to do any work on it.

It could have gotten water in one of the cylinders and that has locked it up, you could pull the head to see if there is any water(or look inside if you have a borescope).
 
if it sat for 2 years it can be a bear to just spin.
And it wouldnt be the first one to have thee rings "bond" to the wall and snap the first time you turn it over.
 
Spray some WD-40 in the spark plug holes and let it soak for a while. I'm guessing the mystery oil may be something similar.

Don't forget to double check the stupid sh#t.. If it's a manual, makes sure the tranny is in neutral, removing belts helps, etc...

Like everyone said... only way to really know is pull the oil pan to look at the bottom end or pull the head to get a look at the top end....
 
If the MM Oil doesn't work, go to Wally World and get a can of PB Blaster penetrating oil with a rust dissolving additive. Yes, the rings are likely stuck to the walls but the PB will win but you must be patient. One to two days of a good soaking will get er done. WD 40 is fish oil and is poor at dissolving rust.
 
I figured I would have to use PB, but didn't know if PB would actually harm the rings or not. For pulling the pan, I haven't yet because its currently being used to keep the motor and transmission level (I found out the hard way that the motor was seized when I tried to start it with the starter). I'll get out the transmission jack and pull the pan sometime soon. The MM oil didn't work... it's still as seized as ever. Looks like PB's going in it.
 
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