2 months ago, I went to start up my new build and it cranked over a few times then locked up. I was able to turn the crank counter-clockwise about a 1/2" so I moved it back & forth and it wouldn't come loose. So I went to get some Marvel Mystery Oil to put on the piston rings for a day or so to see if that was the problem.

The next day I pulled off the head then turned the crank again and it had loosened up and was spinning all the way around yet still had a rough spot the 1st 5 or so turns in the same position as where it was locked. I put enough Mystery Oil in each cylinder to cover the pistons then everything spun freely.

While the head was off, I put in some new valves, fixed some manifold studs that were stripped and cleaned up the whole head.

A few weeks ago, I dropped the oil pan to put in some ARP main studs. The oil was clean and the rotating assembly looked good. I took out the oil pickup tube to check for any blockage and it's good as well. Put everything back together, filled up the oil and tried again.

Today, it cranked a few times then I heard the sound I've wanted to hear so bad the last 3 years, my Evo start up.....only for a second though. Cranked it again, same thing. The 3rd time, stopped cranking. The crank won't budge. I removed the spark plugs and a little smoke came out. Took off the starter and timing belt and it still won't move. I have some more Mystery Oil on the pistons now and will try again tomorrow.

The motor has:
4G64 crank
Eagle rods
Wiseco 9.0:1 85mm pistons
ACL bearings
ARP main & head studs and rod bolts
GSC S2 intake cam
Revolver exhaust cam

The car is sitting on jack stands on the front end sitting a little higher than the rear, no radiator or exhaust past the O2 housing. I want the car to run and idle before messing with putting the whole car back together as it's a PITA to take it back apart if a situation like this one comes up.

I'll add more info later but my question is,

What could cause the motor to lock like this???

 

Bump for help

 

Who built the engine? Having a 4G64 crank in there for a 2.3 build requires clearencing of the block for some parts of the crank.

 

when they built it did they use assembly lube ?

 

It was built by Top Level Performance in New York. Not using assembly lube has already crossed my mind. I might tear it down and do it myself if nothing else works. I received the motor last June and yesterday was the 1st time it was started.

 

I would say look at the ARP main studs man...they could be a little tight! Lube is key also!

 

^^^or the rod bolts/studs also may be a too tight!

 

If assembly lube was not used liberally enough, a near one year sit would cause it to be sticky if not properly sealed off from the elements. Sounds like you may have to tear it down and redo some things.

 

Looks like I'll be tearing it down. Even though it's been a pain getting the car together, it's been a great learning experience and I've learned more about the car the last few years than I did when it was running.

So pulling off the rod caps and crank girdle is all I should need to do to put the assembly lube on?

 

If your going to be tearing it apart, you might as well just go all the way and double check cylinder walls etc. Just to be sure.

 

Just rubbing on some assembly lube is not going to make the engine run. Theres obsessively a bigger problem causing the crank to bind and not want to spin easily. You say your running a 4g64 crank with eagle rods. Are you sure the rods are a stock length? Only stock length rods can be used with a 4g64 crank in a 4g63t block. You also stated that it did move when the head was removed but would not when the head was on and T-belt was off. Your combination of parts may be causing piston to valve issues. If your not 100% going into a tear down I'd bring it to a local known machine shop and have them check it over.

 

The crank is seized with the pistons midway in the cylinder. I'll pick up a ring compressor after work, pull the head and get everything checked out.

Thanks for the advice so far.

 

If i WAS to guess dude above is on the right track, our rods are hitting the bottom of the cylinder with the 100mm stroke crank in that block....Im doing the same thing 4G64 crank in my evo 8 except ams 2.3 pistons and manley rods

hopping my oil squirters still fit my block after the new setup

 

sounds like the rods are hitting the cylinder walls or the crank on the block could be both hard to tell. when you had the oil pan off you did not notice anyhting hitting(scraping on the block anywhere) its hard to believe this motor even made it out the shop i rotate the crank after every piston and rod assembly is put in to pin point problems like this one.

 

I didn't see any problems at all. I failed to mention before that I've cranked the motor over several times in the past to do a compression test and to get some old fuel out of the tank and never had this problem.