Odd Crank Question

[eagletalonjohn]

OK, so i was out driving the other day.I got on my car alil, and all the sudden i lost clutch peddle and the car started making a weird chattering noises. My first thiought was i blew the clutch again. But why the chattering? I tow the car back to my place. The following day i ripped the tranny to findout the clutch was fine. I went to jiggle the clutch,flywheel and it is wobbling pretty bad. So i took of the pp, flywheel to findout there was massive in and out play on the crank. At that time, i noticed while i was moving the crank in and out the crank pulley was not moving. My 1st thought is to turn the crank from the crank pulley side and see if the crank snapped.All 4 pistons go up and down like it should. So then i put 2 out of the 6 flywheel bolts in so can spinn the crank on the clutch side.and once again all 4 pistons move. it is so weird..

NOW, this is where i am so lost.. If the crank has in and out play on the flywheel side, and not on the timing belt side,and alll 4 pistons are moving? THEN WTF happened..

Little history on the engine. Its a g4cs crank in a 2.0 block. Which makes it a 2.3. .40 over eagle wiseco,acl bearing blah blah blah... The engine was built about a yr ago and has like 10k miles.

I am looking to pull the oil pan off today to take a glimpse. Any info for what i should look for would be very helpful.

THANKS...

 

[donniekak]

Pull the oil pan and let us know. Sometimes it's easier to see the flywheel move than the pulley. Or, the crank is broke between the center thrust and the flywheel. A broken crank can crack at an angle so it will still turn, but when a large load is put on it it seperates and grinds. The machine shop i go to say's most people put 4g strokers together without balancing, and blow up as a result.

 

[eagletalonjohn]

Ok i pulled the oil pan off. the crank snapped right on the side of where the flywheel bolts too. Now what would cause that?

 

[LiquidX]

You still using a harmonic dampner or under drive pulley? I know the aftermarket crank pulleys execpt fluidamper(?) can cause problems with cranks and will break them over time. Perhaps your flywheel bolts were pretty weak when the new clutch went in?

 

[ilco187]

ive seen a few people with the g4cs crank break and there is a few on these forums, here is a pic of a g4cs crank http://i171.photobucket.com/albums/u291/sixbolt/album_pic.jpg

 

[donniekak]

Coming from an extensive 3000gt/stealth background i've seen this kind of problem with hyuandai cranks. The forged 6g72 crank only came in 1993+ dohc 6g72's, kind of rare. The hyuandai 6 cylinder uses the same crank, and it's forged also. They break. I don't think mitsu actually produces the internals for the hyuandai engines, but has an agreement to let hyuandai manufacture the parts from mitsu designed tooling. I have also heard of a lot of g4cs cranks breaking, but not the more rare 6-bolt 4g64 crank out of the galants.

 

[eagletalonjohn]

You still using a harmonic dampner or under drive pulley? I know the aftermarket crank pulleys execpt fluidamper(?) can cause problems with cranks and will break them over time. Perhaps your flywheel bolts were pretty weak when the new clutch went in?

i was using my alloy crank pulley. i was kinda thinking that would cause all this... shit

 

[eagletalonjohn]

ive seen a few people with the g4cs crank break and there is a few on these forums, here is a pic of a g4cs crank http://i171.photobucket.com/albums/u291/sixbolt/album_pic.jpg

i just looked at the pic. my crank broke the same exact place.. hmmmm. probably just weak there. thats bullshit.