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Broke II

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    Senior Member holorinhal's Avatar
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    Default Broke II

    I posted this over in the jets section, for all that were curious, as to what happened at the river a couple of weeks ago.
    I am posting over here because now I need some opinions.

    Two weeks ago, I was making a pass on the river. At 5100 rpm, the engine abrubtly shut down. Tried to refire and it would not turn over.
    Got a tow back to the beach, and pulled the dip stick and oil looked fine, pulled all the plugs, and plugs were fine, no wetness to any of them. Tried to turn the engine and would not move.
    When I got home I pulled the motor, drained the oil, and imediately, I could see the rod cap, lying in the pan.
    I pulled the pan, and what a mess. Rod and piston parts laying in the pan, along with some block material.
    I put it on the stand and fliped it over to see the carnage. I took pictures and this is the results.

    Pulled thew valve covers, and every thing looks normal to the naked eye, nothing appears bent.

    #8 rod was broke and wedged between the crank and block.
    #8 piston was broke and the wrist pin boss on one side was partia;lly broke out.
    #8 cylinder has a chip out at the bottom of the cylinder
    rod journal on the crank looks pretty bad
    #7 piston is banged up prety bad
    #7 cylinder has a gouge in it

    I pulled the heads, and that is when I saw what I didnt like!
    Looks like all the exhaust valves, have had light contact with the pistons.
    #8 exhaust valve has a heavy contact mark, and #8piston and #8 combustion chamber have a contact scar scar in the same place.

    The engine has less than 10 hours on it. I have never been able to spin over 5200, with an aluminum Berk AA.
    To my Knowlege, I have never had the pump unload and over rev.
    I have been out 3 times this year, and twice before the other boat got wrecked,and have not ran the boat much, either time.
    The weekend that it broke was the hardest I have ran it since it was built.

    I took the shortblock and heads over to the builder, so that he could have a look at what seems to me to be a valve/piston clearance issue.
    The builder is of the opinion that all the exhaust valves had to have cotacted when it broke and that there is no way that they could have touched other wise or in the event of being over reved.

    The engine was built, shooting for 11:1, but realisticly is probobly a little under. I run 100 0ctane in it and have mixed 100 and 93, once. I dont think two full side tanks have even been ran thru the engine!

    Here are the pics of the carnage.
    What I am looking for is truth about the statement of the exhaust valve contact.
    Could it have been Detonation?
    Could piston/ valve contact have wiped the bearing and the the rod failed?




















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  3. #2
    Senior Member holorinhal's Avatar
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    I'm not here for a long time, I'm just here for a good time!
    If your not on the edge.......your taking up too much room......Drive it like you stole it!

    73 KONA Restoration http://www.performanceboats.com//showthread.php?t=10678
    '81 Spectra 20 Facelift http://www.performanceboats.com/user...-facelift.html

    18' Advantage http://www.performanceboats.com/jet-...k-project.html

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    Senior Member holorinhal's Avatar
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    I'm not here for a long time, I'm just here for a good time!
    If your not on the edge.......your taking up too much room......Drive it like you stole it!

    73 KONA Restoration http://www.performanceboats.com//showthread.php?t=10678
    '81 Spectra 20 Facelift http://www.performanceboats.com/user...-facelift.html

    18' Advantage http://www.performanceboats.com/jet-...k-project.html

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    Senior Member holorinhal's Avatar
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    I'm not here for a long time, I'm just here for a good time!
    If your not on the edge.......your taking up too much room......Drive it like you stole it!

    73 KONA Restoration http://www.performanceboats.com//showthread.php?t=10678
    '81 Spectra 20 Facelift http://www.performanceboats.com/user...-facelift.html

    18' Advantage http://www.performanceboats.com/jet-...k-project.html

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    Lack of oil in the bearing, bearing grabs the crank, carnage begins !

    Just a guess here !

  8. #6
    gn7
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    First, your builder is full of shit. You can't contact every exhaust with what happened. Its virtually impossible to contact ALL the exhausts with a broken T chain. YOU HAVE/HAD a piston-valve clearance issue, plain and simple. I MAY have contributed to the problem but think they are independent of each other.
    JMO, like Wizbang said, the thing became oil starved and grabbed the bearing on #7, over heated the journal and #8 was along for the ride. All the piston damage is probably a result of the rod seizing on the journal. Once the pivot is gone on the low end of the rod, the piston is going to get trashed.
    Clearances? To heavy of oil for the clearances? Lack of oil flow/pressure? Who knows. Considering the builder over looked the PV clearances, anything is possible. That's a basic check on any build.

    I know I don't like the forged 90* fitting on the oil filter bypass adaptor. #10 lines?? With that fitting? Not the best arrangement
    From the looks of the windage tray in the pan, that thing was cooking that bearing for a little while. Not my favorite oil pan, or the best pickup on the market. It all adds up to problems



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    Last edited by gn7; 10-25-2013 at 06:37 PM.

  9. #7
    Senior Member holorinhal's Avatar
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    Quote Originally Posted by gn7 View Post
    First, your builder is full of shit. You can't contact every exhaust with what happened. Its virtually impossible to contact ALL the exhausts with a broken T chain. YOU HAVE/HAD a piston-valve clearance issue, plain and simple. I MAY have contributed to the problem but think they are independent of each other.
    JMO, like Wizbang said, the thing became oil starved and grabbed the bearing on #7, over heated the journal and #8 was along for the ride. All the piston damage is probably a result of the rod seizing on the journal. Once the pivot is gone on the low end of the rod, the piston is going to get trashed.
    Clearances? To heavy of oil for the clearances? Lack of oil flow/pressure? Who knows. Considering the builder over looked the PV clearances, anything is possible. That's a basic check on any build.

    I know I don't like the forged 90* fitting on the oil filter bypass adaptor. #10 lines?? With that fitting? Not the best arrangement
    From the looks of the windage tray in the pan, that thing was cooking that bearing for a little while. Not my favorite oil pan, or the best pickup on the market. It all adds up to problems
    Bob, The oil pressure has allways been between 70-75 psi on wot and around 50-55 on idle.
    The black on the widage tray is dark oil. The oil surprised me, due to the fact that it was only one trip old. with really no hard passes on it.
    on the 90* fitting, yes it is -10. Should I switch to -12 and a straight, like the black one?
    I had been chasing a tinging noise since day one, and was pretty sure it was in My pump, Now not so sure.
    The noise would come on , when I was gassing, not hammering, but comming on to plane,normally and then it would go away after on plane.
    If the P/V were contacting, would the sound be intermitent, or constant?
    Builder said that if there was clearance issue, the engine would not have been running good or right from the start?
    Is #7 and#8 journal, more prone to oil starvation than the rest, on a BBC?
    Oil I was using is Valvoline VR1 50wt. Was that a mistake?
    Last edited by holorinhal; 10-25-2013 at 07:06 PM.

    I'm not here for a long time, I'm just here for a good time!
    If your not on the edge.......your taking up too much room......Drive it like you stole it!

    73 KONA Restoration http://www.performanceboats.com//showthread.php?t=10678
    '81 Spectra 20 Facelift http://www.performanceboats.com/user...-facelift.html

    18' Advantage http://www.performanceboats.com/jet-...k-project.html

  10. #8
    gn7
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    Pressure is a measure of resistance to flow. You can have zero flow, and have 100psi on the gauge. Not saying that exact thing happened, saying it is an extreme example that pressure does not mean flow.
    Nothing wrong with the VR1, but when you use straight 50wt, you better be damn sure the oil is hot before you stuff your foot in it, and that means more than idling thru the no wake zone! 50wt and clearances to tight for it is worse than 10-30 and loose clearances.
    I'd rather have 50 psi with 10/30 good flow thru loose bearings than 75psi and bad flow thru tight bearings.
    Just so you know, 75 is the relief pressure of your pump. It might have made much more if the relief was higher. It only means you probably weren't moving the oil the pump was pumping thru engine, just bypassing it back to the pump. You had 75 in the oil passages, but was it moving enough volume to meet the needs. It takes some serious pressure to move molasses thru a cold engine. The relief limits that pressure.

    As for the exhaust valves, how it ran would depend on how badly they are bent. They may have just touched the pistons enough to leave witness marks in the carbon. Remember, they are HOT, and when they land back on the seat they can tend to straighten back out if not tweeked too badly. But they will fail in short time. NO matter how lightly the touched the pistons, any is too much. But that DID NOT HAPPEN when the engine failed. It had been doing that from the moment you lit it off.



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    For what its worth
    I saw this in the jet boat section...man you need to clay those pistions,check valve to piston...any engine!!!
    and put a bronze gear on the dist. when running a roller cam...

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    gn7
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    Quote Originally Posted by Gone Green View Post
    For what its worth
    I saw this in the jet boat section...man you need to clay those pistions,check valve to piston...any engine!!!
    and put a bronze gear on the dist. when running a roller cam...
    SRPs and many other "sportaman" pistons have horrible exhaust side clearances. They really should lower the dome on the exhaust side down to the pistons deck level.
    As for the bronze gear, it could be a melonite gear, or the cam could have an iron gear option. Just sayin.



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    Quote Originally Posted by gn7 View Post
    SRPs and many other "sportaman" pistons have horrible exhaust side clearances. They really should lower the dome on the exhaust side down to the pistons deck level.
    As for the bronze gear, it could be a melonite gear, or the cam could have an iron gear option. Just sayin.
    The cam has the gear.
    I did not assymble the engine. I know the P/V clearance has to be clayed, and I know the builder knows, but I can not say 100% what the builder actually did.

    Bob, I was having trouble building heat in the engine, on the river. At first I had thought it was a faulty gauge or sender, but I checked both and They checked out good.
    The first three times i had ran the engine, on the trailer, and two hour to two hour outings, were on the lake, where the water temps were alot warmer, the engine made heat fine. I am guessing the cold water temps of the Colorado River, could be a contributing factor also?

    One other thing. This engine was a survivor of a wreck! Comming back from the lake, on the second outing on this freshly built engine and the freshly built boat, A drunk driver hit us and consequently, the boat was ejected off the trailer and hit a steel pole and richoced off into the middle of the street. The boat landed upright on its keel, but the impact had to have been a hard one.
    Is there any chance the bottom end could have been hurt, thru the impact.
    After the wreck, I posted here and ask, before firing it off again, and was told it would be fine. Idk, just asking?

    I'm not here for a long time, I'm just here for a good time!
    If your not on the edge.......your taking up too much room......Drive it like you stole it!

    73 KONA Restoration http://www.performanceboats.com//showthread.php?t=10678
    '81 Spectra 20 Facelift http://www.performanceboats.com/user...-facelift.html

    18' Advantage http://www.performanceboats.com/jet-...k-project.html

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    My 2 cents; Valve contact didn't happen with the blowup. No excuse for piston to valve not being checked. All of this is conjecture but when a chevy loses the rear rods a lot of the time its from aeriation. These pans will be listed as a 10 qt pan but we always prefill them with water and count the qts to keep the oil below the tray. Weve found that a lot of the time the pans are getting overfilled. The longer the stroke the more critical this becomes. If the oil gets whipped up by the windage or contact with the crank it will turn to a milk shake and the first rods inline will pay the price. Again all of the ideas above are also possible, but there is a lot of things going on in that pan that need to be addressed. Now back to my Cave....

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    gn7
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    I remember that accident. As I remember you caught some unnecessary heat for mentioning the driver's country of origin in that thread.
    As GN29 said, its oil related, whether its aeration, starvation, clearances verses oil viscosity verses temperature, what ever, it needs to be addressed because it will happen again. Something needs to change. It didn't "just happen"



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    Quote Originally Posted by gn7 View Post
    I remember that accident. As I remember you caught some unnecessary heat for mentioning the driver's country of origin in that thread.
    As GN29 said, its oil related, whether its aeration, starvation, clearances verses oil viscosity verses temperature, what ever, it needs to be addressed because it will happen again. Something needs to change. It didn't "just happen"
    Yea i did catch some flack over that!

    I'm not here for a long time, I'm just here for a good time!
    If your not on the edge.......your taking up too much room......Drive it like you stole it!

    73 KONA Restoration http://www.performanceboats.com//showthread.php?t=10678
    '81 Spectra 20 Facelift http://www.performanceboats.com/user...-facelift.html

    18' Advantage http://www.performanceboats.com/jet-...k-project.html

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