Ok broken crank poll

[AL92]

I think have broken crank in my 2.4. Not 100% sure for awhile but my car sounds very bad and its parked until it gets torn down.

So lets hear if you have broken a crank, symptoms you noticed and what rpm you have your rev limiter at. If you polished or turned the crank. And how many miles this happened at .I have like 4500 miles on mine. Crank was low mileage polished only.

 

[Turbo Monk3y]

I have been gathering data for over a year on this very thing... This is for 6 bolt only cranks... So far the ratio of people with 2.3/2.4L running is larger than those with broken cranks.. Also of all 5-6 people I have found with broken cranks they all broke at the #4 rod journal bearing area. At first I thought this was only true of the G4CS hyundai cranks, until one of my friends and his brother broke 2 of the Mitsubishi STAMPED "64" cranks in the exact same place as the G4CS ones.

So with this infomation I began gathering their setup data.. Most people who broke either used a STOCK 4g63 crank pulley, with a combo of unbalanced cranks... So then I began to try and figure out why the #4 rod journal bearing is a weak spot. I went to my local race engine builder and he has balanced a few mitsu cranks in his day, he said that he noticed the cranks themselves are balanced damn well from mitsubishi, It was the Fidanza flywheel and ACT clutch that are crazy off from each other multiple grams off.. That was a good piece of info right there... So then I began to think maybe most G4CS/4g64 crank guys should buy a fluidamper or ATI equivelent.. I then came across your Post about having a Fluidampr on your car. This is where I think you dont have a broken crank, maybe just crankwalk or spun bearing of some sort... In any case I really want you to drop the oil pan so you can take pictures or tell us whats up... I have my motor about to be put together as we speak and I really want to stick with my G4CS crank as its STD. size and perfect as well as polished/balanced... But I also don't want to have to buy an eagle crank as they require Chamfered bearings and I don't know if my Calico Coated Ct-1 Acl's are Chamfered. They look to be but I have not had them checked by a professional.. In any case there are a few guys running on cut G4CS cranks trapping 140MPH for over a few years so........... thats what makes it hard... I still thinking about buying an eagle but I still cannot decide..........

 

[AL92]

Interesting stuff. I thought maybe being non turbo cranks they were inherently weaker than the turbo ones. So might break more at higher power levels. I figure was putting thru around 500 engine hp at 21psi with my mods. I did go to about 25psi a few times but very low timing.
I didn't track it and my mph was terrible measure on my tazzo /gtech type thing. Like 105mph at 21psi with my mods. It should have been more like 120mph! I have this slipping clutch type thing happening. Car revs but don't go anywhere really bad in like 1st and second. Not sure if new clutch is screwed .only got 3000 miles or whatever on it. But did have master go and slave go so that might have made it slip all the time.
Maybe have broke center diff, not sure if broken crank can cause that symptom.
The car knocks and bangs and don't run at all. Stalls pretty much instantly .It does start quick though. But not trying that anymore. I am just too damn busy right now to go messing with pulling the pan. I may do it in next few weeks. A month whatever.
I am working on my first love. MY 99 trans am twin turbo project. the turbos are not on the car yet ,likely next year.Building motor for that car big one..408 cubic inch or 427 cubic inch. Just put new twin disc in that car rated well over 1000 ft pounds. Now need stronger rear end. stronger trans. But less weak links I think and simpler than the dsms.

But anyway.I did not balance my engine. I put in the same crank that came in the block,crower rods and wiseco pistons. I use fluidampr you are correct.
I kept redline to 8000 and usually shifter in the 7000s but hit limiter here and tehre mostly in first.
I changed oil like 6 times in 4000 miles. I prelubed engine on the stand. I usually took out fuse and cranked it after oil changes. I did have three overheats from faulty mits therm. Each time car boiled over and shut it down right away and didn't drive it home and no apparent damage. Never saw any blue or white smoke. No coolant in oil.
I don't think detonated hell out of the engine either. I watched my knock warning lights on dsm and didnt' stay in it if saw it flashing at 2 degrees its set.
I used only 92 premium.
So what symptoms usually did the broken cranks exhibit. See spun bearings thought would knock but not stall car virtually instantly.
Anyway all conjecture. I didn't know that about the eagle and bearings. So might have to order the right ones. I thought acl coated were good ones they were not cheap that is what I am running. I have act flywheel and hd 4000 clutch. not balanced I don't think.
I had some buzz at idle and some at 4000 up . I have poly inserts in front and back.
Rubber mounts in sides. I have problems with bolts loosening up. Was always losing manifold bolts etc. Thought mabye timing tensioner had come off but belt is tight and on there.

I will keep you posted if take off pan. I am curious too over what killed it.

 

[JOEY A]

I know somone local that broke two cranks due to a miss fire each time.....If I see him ever ill get more info for you guys..

 

[JOEY A]

This was on a 2.0 liter if that matters..

 

[project_tsi]

I've been running a 2.3L 6 bolt now for about 6k miles or so. I drive the car every day, to and from the track, and it runs low 11's, shooting for 10's soon. Eagle rods, Wiseco pistons, G4CS uncut crank. I run 30 psi on pump gas and meth, daily. I do run a Fluidampr crank pulley. I have no balance shafts, no piston oil squirters, and the crank, pistons and rods were balanced as a rotating assembly also. Shit, I even blew a HG from excessive detonation from my own stupidity last year and its still been great.

 

[snox135]

This is atleast your 3rd thread about your engine. You seem to like to blame the crank. Why don't you just drop the oil pan and check it already. Making new threads will not fix your car. You need to go find out what is wrong with it.

 

[toddmeunier]

My brother had his V8 freshly built for his truck and it was sitting in his garage on some milk crates and it fell over onto the cement. Nothing visually wrong with the engine so he installed it anyways. A year later the crank blew. He was never sure if the impact had anything to do with it though. Blowing a crank just sucks. His crank was from another stock engine but he used forged pistons and upgraded rods.

 

[TimG]

My brother had his V8 freshly built for his truck and it was sitting in his garage on some milk crates and it fell over onto the cement. Nothing visually wrong with the engine so he installed it anyways. A year later the crank blew. He was never sure if the impact had anything to do with it though. Blowing a crank just sucks. His crank was from another stock engine but he used forged pistons and upgraded rods.

Me too. ####ing crank broke cause I used one from a non-turbo and the whole motor fell over. I got pictures if you want.

 

[PSI TSI]

I think I broke a crank once It was in a chrysler 2.2. I noticed a trail of oil behind my car as I drove down the road. When I got to work I noticed the drain plug was off. The car ran fine and all but I must have broken my crank from that right?
I just filled up the engine with lucas and drove it for another couple days untill I scared myself into thinkin "Man I must have broken my crank" But I was to affraid to pull the pan so I just parked the kcar. And stuck my head in the sand wishing the problem would go away. I never did pull the oil pan off just sold the car as a broken cranked POS the guy even drove it away.

 

[kiggly]

If anybody replies who has broken a crank, can you also state if you were running a main girdle on a 6-bolt or if it was a 7-bolt? Also please state if it was a 4G63 or G4CS block as the latter has less stiffness between the outer mains. I expect stiffening the bottom end would help crank life, but I have no proof of this or accumulated information.

Kevin

 

[BrokenTsi]

My crank is cut .010. 2 seasons and 10k miles on my engine. I have oil squirters, stock crank pulley, and I drive my car every day. I went 10.9 on a slipping act 2600 and also went 133mph. 110mph in the 1/8th. DSM link put me at 590whp, not sure how accurate that is, but I'm doing good. I forgot my crank was cut until I read this thread.

 

[slugsgomoo]

If anybody replies who has broken a crank, can you also state if you were running a main girdle on a 6-bolt or if it was a 7-bolt? Also please state if it was a 4G63 or G4CS block as the latter has less stiffness between the outer mains. I expect stiffening the bottom end would help crank life, but I have no proof of this or accumulated information.

Kevin

Kevin,

The block I have here that was in a friend's car when it snapped the crank is a 4G64 6 bolt, no girdle and while i'm pretty sure the #4 rod journal is where the crank broke, the #4 main is definitely tweaked to the point that the block is mostly an ornament.

When I finally get around to building mine i'm going to run the girdle, simply because I look at it as very cheap insurance/peace of mind.

 

[gsx951]

Reman G4CS crank with an underdrive pulley.....

http://i171.photobucket.com/albums/u291/sixbolt/album_pic.jpg

 

[Big Woo]

Balancing is always a good idea, but should be concidered a requirement if your using a crank from here, rods from there, flywheel from another place, well you get the idea.

Further more when balancing the crankshaft the harmonic balancer, flywheel and pressure plate should also be done, both kinetically, and dynamically. Remember that just a gram or two at or very near the centerline of rotation will have a relativly small effect on overall balance. However those same few grams 8 inches off from the centerline will turn into pounds in a big hurry.

A harmonic balancer dampens harmonic vibrations, it does not balance poorly matched components.

 

[AL92]

Well can't see magus for example balancing flywheels and pressure plates. That is stupid. Very likely you are going to be changing out flywheels and pressure plates and possibly brand of clutch thruout the cars life and you can't go back into the engine all the time. I have heard mostly to balance the crank and that most aftermarket rods and pistons are going to be pretty close.

 

[Big Woo]

Well since the flywheel and pressure plate are neutral balanced, one could have them balanced seperatly, and even have replacement ones balanced at a later time.

"Well can't see magus for example balancing flywheels and pressure plates. That is stupid."

Onces again stupidity rears its ugly head, Yes Lets olny balance have or part of the rotating mass, and then start threads asking why crap breaks!

So if your crankshaft is broken (in two pieces) and the timing belt is on cylinder #1 end of the motor, and the transmission connects to the #4 cylinder end of the motor, again rembember the crankshaft is now in two pieces. What part of the engine running and the car driving don't you get!

 

[gsx4g64]

My buddy broke his crank not once, but twice. Both in the same place.

 

[Boosted98gsx]

Sorry for bringing this back from the dead.

Just cracked my 4g64 6-bolt stroker crank at the #4 rod journal as well. My entire short block was completely balanced and harmonically damped. It lasted ~30k miles.

Has anyone figured out why this occurs?

 

[TSITurbo95]

What about eagle cranks? Anyone have any luck with them not breaking?

 

[Boosted98gsx]

Turns out it has to do with crank journal overlap. The stroker cranks have none, resulting in higher stresses across the journal. Couple that to the "right" angle machining of the rod journals amplified by the distance from the harmonic damper and you have a broken #4 rod journal.

 

[TSITurbo95]

^ Very good info!! Thanks!

 

[MichaelSuch]

Turns out it has to do with crank journal overlap. The stroker cranks have none, resulting in higher stresses across the journal. Couple that to the "right" angle machining of the rod journals amplified by the distance from the harmonic damper and you have a broken #4 rod journal.

So if you are running a 2.3L motor, you're guaranteed to break the OEM crank eventually?

 

[Deuce_three]

I had a crank break on me. Its not a stroker but I figure I'll just post it anyways.

http://www.dsmtuners.com/forums/art...reviews/403071-crankshaft-rebuilders-inc.html

 

[bryanwheat]

A good rule of thumb, have the crank magnafluxed before any machine work is done on it to verify that it isn't cracked.