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Thread: 6g75 bearing failure

  1. #1
    turbo addict
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    6g75 bearing failure

    http://www.thegalantcenter.org/showt...ngine-failures


    thoughts?


    ooo and if someone knows where to look for a running g75: hit me up

  2. #2
    Garrett booster
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    Re: 6g75 bearing failure

    This is the first I have heard about this. I can say that when I dissembled mine the crank bearings had some scuff marks but nothing I would call worthy of failure. the only thing I have heard of with the 74 blowing up is a few rods going but as you know in our hobby that can be from just beating on the motor to much.

  3. #3
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    Re: 6g75 bearing failure

    Never know do you, could be that someone can't tune, or can't use a torque wrench, or that stuck a 200 shot of nitrous in the weekend prior "just to see"
    '88 Voyager 3.0, Auto with shift kit, timing advance, walker sound FX muffler on 15" pumpers wrapped in 215/65/R15 H rated Nexens.... and a '95 phord escort wagon PnP head.

    I like 3.0s ... so??? ... stop looking at me like I've got two heads!

  4. #4
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    Re: 6g75 bearing failure

    yes but i think its safe to say that dsm headbolts that brent and i have tried are worth using or even the arp hardware should be given a chance.

  5. #5
    Supporting Member Turbo Mopar Contributor Ondonti's Avatar
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    Re: 6g75 bearing failure

    75 crank is not drilled the same as 74 crank. As far as fasteners, 4 bolt has different requirements so maybe the only option is ARP. Mitsu went cheap and "easy" in the modern years. Most manufacturers had already gone that route. The good old 6g72 is built tough from the junkyard.
    Last edited by Ondonti; 01-18-2013 at 11:15 PM.
    Brent
    GREAT DEPRESSION RACING
    1992 Duster 3.0 - 11.5@125 22psi $90 Stock 3.0 Junk Motor - 516whp 519wtq 20psi 91 oct built 3.0 stock n/a computer
    Currently Megasquirt II/Extra. Stock 10:1 3.0 naturally aspirated
    1994 Spirit 3.0 - 13.85@108.8 10 psi - Daily Holset He341 280whp 304ft/lb
    1994 Spirit 3.0 A670 - Wife's
    1981 Starlet KP61 Parts
    1983 Starlet KP61 Parked

  6. #6
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    Re: 6g75 bearing failure

    yep. like the guy in the link says, he claimes the mains actually stretched. if they did stretch over time then there is no denying that a stronger fastener is needed. arp is not too pricy and they work great.

  7. #7
    Supporting Member Turbo Mopar Contributor Ondonti's Avatar
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    Re: 6g75 bearing failure

    I am with RW that there is probably a little bit of stupid involved in what might be assumed to be near stock motors having crankshaft problems... Like I ran a bit low on oil while spraying nitrous with no fuel enrichment and good thing my high compression piston or pencil thin rod didn't fail first. :P

    The difference in drilling of crankshafts is something I worry about for high performance applications. The 74 crank is cross drilled, the 75 is not.
    Brent
    GREAT DEPRESSION RACING
    1992 Duster 3.0 - 11.5@125 22psi $90 Stock 3.0 Junk Motor - 516whp 519wtq 20psi 91 oct built 3.0 stock n/a computer
    Currently Megasquirt II/Extra. Stock 10:1 3.0 naturally aspirated
    1994 Spirit 3.0 - 13.85@108.8 10 psi - Daily Holset He341 280whp 304ft/lb
    1994 Spirit 3.0 A670 - Wife's
    1981 Starlet KP61 Parts
    1983 Starlet KP61 Parked

  8. #8
    Mitsu booster
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    Re: 6g75 bearing failure

    Quote Originally Posted by Ondonti View Post
    I am with RW that there is probably a little bit of stupid involved in what might be assumed to be near stock motors having crankshaft problems... Like I ran a bit low on oil while spraying nitrous with no fuel enrichment and good thing my high compression piston or pencil thin rod didn't fail first. :P

    .
    Stock 6G75 motors, fully forged 6G75 motors all have failed with the same symptoms...stretched main bolts...about 15 thou.

    Oh well...

    (you can lead a horse to water but you can't make him drink)


    cya

  9. #9
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    Re: 6g75 bearing failure

    you cant not think something else was involved.. just go on club 3g and look at how misimformed 90% of them are.


    but, if they measured the mains and they are longer than they should be.. regaurdless of what caused it, they should be replaced with something better befote it happens. arp and dsm headbolts sound pretty good when you know your crank is going to wiggle around without them.

  10. #10
    Garrett booster
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    Re: 6g75 bearing failure

    Quote Originally Posted by redblower View Post
    Stock 6G75 motors, fully forged 6G75 motors all have failed with the same symptoms...stretched main bolts...about 15 thou.

    Oh well...

    (you can lead a horse to water but you can't make him drink)


    cya
    wow did you join here just to post that lol still with ondonti here lol

  11. #11
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    Re: 6g75 bearing failure

    Quote Originally Posted by paduster View Post
    wow did you join here just to post that lol still with ondonti here lol

    yep...when someone is a dickhead I enjoy telling them to their face.

  12. #12
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    Re: 6g75 bearing failure

    Quote Originally Posted by redblower View Post
    yep...when someone is a dickhead I enjoy telling them to their face.
    why are you getting so butt hurt? Do you even know who he is?

    He was just poking fun at the whole 24valve sohc community because it seems ALOT of them cut corners on fueling/timing or crazy high intake temps from their superchargers and blow their block apart at 300whp and then go on to claim that the blocks require forged everything before you can push it... so much misinformation out there. Yeah maybe the the main bolts stretch over time, thats why i posted it here because we have a couple of people messing with the 3.5/3.8 and we like to do things the right way and make real power.

  13. #13
    Buy my stuff!!!!!!!!!!! :O) Turbo Mopar Vendor turbovanmanČ's Avatar
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    Re: 6g75 bearing failure

    Quote Originally Posted by redblower View Post
    yep...when someone is a dickhead I enjoy telling them to their face.
    Not to get into an internet war here but you do realize telling someone something on a computer isn't telling them to their face?
    1989 FWD Turbo Caravan-2.5 TIII, GT35R, auto, a/c, cruise, pwr windows/locks, fully loaded with interior and ran with full exhaust. RETIRED FOR A FEW YEARS! 12.57@104 :O)
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  14. #14
    Supporting Member Turbo Mopar Contributor Ondonti's Avatar
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    Re: 6g75 bearing failure

    Quote Originally Posted by turbovanman View Post
    Not to get into an internet war here but you do realize telling someone something on a computer isn't telling them to their face?
    The 3g and 4g eclipse forums are a lot like this.
    I don't even understand what the person is offended about unless he has a broken motor and feels Mitsubishi is to blame. "built motor" means nothing as far as longevity or reliability as they are more likely built wrong then from the factory!
    I think my exact words were "there is probably some stupid involved in stock motors failing," and that is not a statement of fact for all cases. Probably can mean as little as 2% if there are 98 other possibilities that are 1% likely. Turbovanman is a professional mechanic and I am sure many major meltdowns he sees are caused by abuse or lack of PREVENTATIVE maintenance. I blame myself for every single one of my engine failures. I have never had one of my motors fail because of of something Mitsubishi decided to do. If I do something that I know will break the motor I can't blame Mitsubishi for letting that happen. If I break the top of the piston off, I know its my fault because I know what the ring gaps are and that they are not acceptable at a certain level of abuse. The moment you think your main bolts can't handle abuse, you don't abuse them or you fix the situation.

    The oiling weakness I am talking about happened on a motor with upgraded fasteners....but was most likely assembled wrong by the machine shop. Factually, 6g75 cranks are not drilled the same as 6g74 crankshafts but Italo just did 1168awhp on his 6g75 crankshaft on twin 67's.

    We all know those broken motors were pushed by their owners. Stupid can be as simple as running low on oil. That seems to be a common mistake even for people who love cars. Drive a mitsubishi and you should learn to check the oil at least every 5 minutes of driving lol.

    I find crankshaft oiling differences fascinating, I have no interest in talking about some TTY fasteners that a 'built' engine has. 4 bolt main engine stretching main bolts on a boring drive to work car sounds like quite a poor quality fastener or improper assembly or poor torque callout.
    Last edited by Ondonti; 02-03-2013 at 09:08 AM.
    Brent
    GREAT DEPRESSION RACING
    1992 Duster 3.0 - 11.5@125 22psi $90 Stock 3.0 Junk Motor - 516whp 519wtq 20psi 91 oct built 3.0 stock n/a computer
    Currently Megasquirt II/Extra. Stock 10:1 3.0 naturally aspirated
    1994 Spirit 3.0 - 13.85@108.8 10 psi - Daily Holset He341 280whp 304ft/lb
    1994 Spirit 3.0 A670 - Wife's
    1981 Starlet KP61 Parts
    1983 Starlet KP61 Parked

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