Motor broke...time for a new
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Motor broke...time for a new

  1. #1
    Sit N' Spin Jetaholic's Avatar
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    Default Motor broke...time for a new

    Well as some of you here know my motor broke at the DLB Hookie Day run halfway to Windmill Cove.

    Motor is now at the machine shop for teardown and inspection to find the cause of the failure. So far, we have a broken camshaft, 4 broken lifters and 1 pushrod down in the pan along with a couple of the lifters. The cam broke in two places...1 break right at the #8 exhaust lobe and the 2nd break at the #4 cam journal...and is wedged between the #7 connecting rod and the crank counterweight.

    Basically the story goes...out at the delta Danny and I (DELTA~HOLIC) were running from Orwood to Windmill Cove and he kept dropping fuel pressure and kept having to stop. He got so far behind I stopped the boat to allow him to catch up. He caught up and I fired it back up. Motor fired up, sounded great, had 50psi of oil pressure, motor temp at 140*. I bring the RPMs up to 4000 to get going and motor ran great for one second, heard a bad sounding noise and she was done. Nearest marina was Tiki Lagun so Danny towed me there. On the way there I tried to crank the motor. Motor cranked but kinda sounded very weak, then locked up.

    Well upon pulling the headers off I see that the #8 exhaust valve broke right in the middle of the stem. My theory is that the valve broke, causing the spring to relax against the rocker, which applied a ton of pressure to the pushrod/lifter and jammed the camshaft on the exhaust lobe, causing it to break there initially. Then while I was being towed, when I tried to crank the motor over, that section of the cam no longer being supported by the #5 journal was trying to push valves open, and broke in the second spot due to the rear of the cam not being supported.

    Theory #2 is that the cam broke for whatever reason, which stopped the #8 exhaust valve mid travel. Upon trying to crank the motor over the piston came up and hit the valve and broke the valve.

    In any event, the machine shop will be tearing it down early in the week and hopefully by Tuesday he'll know what caused it and we'll know what all is damaged and will know where to go from here.



    Quote Originally Posted by HammerDown
    Kendall L-427 Super Blu...extreme-pressure (ep) lithium complex keeps my thrusting balls happy
    Quote Originally Posted by back2k5 View Post
    Well I am putting in a nice stereo system in the Carrera...maybe Ill put on some rap and turn the scoop sideways

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  3. #2
    Senior Member GT Jets's Avatar
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    Dumb question, Chevy or Ford?, if a Chevy, the egg came before the chicken, the cam breaks the engine dies, or backfires then dies, one of the smartest things about the Bowties, so something bigtime let go in the lifter, pushrod, valve area, almost sounds like a stuck guide or bent valve started it...


    If its a Ford, the camshaft can break in half and the engine could potentially stay running, breaking bigger and better things for a while, I have seen the 460's actually stick a lifter in the bore at speed and break a cam like it was made of balsa...

    Just curious...


    GT
    GT


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    Put a 300 on the back of it, Flywheel it and a nosecone. $15,000 later you'll have a 65 mph pile of shit......

  4. #3

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    Damn john that sucks. Ive got a stock 454 sittin here if you need parts. Didnt Danny's boat break down also?

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    Choking my ....... beerjet's Avatar
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    Just curious Jon . If it's all lookin like mash potatoes in there , whats to figure out . It's broken . Just build a new one .

  7. #5
    E-7 Sheepdog (ret) SmokinLowriderSS's Avatar
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    It is always nice to figure out exactly what happned to cause the failure.

    Too bad sometimes it just isn't possible.
    "As democracy is perfected, the office of president represents, more and more closely, the inner soul of the people. On some great and glorious day the plain folks of the land will reach their heart's desire at last and the White House will be adorned by a downright moron."
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    OBAMA: Some people deserve this.
    The rest of us are being dragged along kicking and screaming.

  8. #6
    Sit N' Spin Jetaholic's Avatar
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    Well the block was magnafluxed and she checked good. A couple of minor dings in the cylinder wall from the broke valve...0.060 overbore should take them right out.

    Something else unrelated to the failure that killed it...the machinist that got me the studs failed to tell me that when going from a main bolt to a stud that the block would need to be align bored due to the fact that studs clamp the caps differently than bolts do, putting the main journal hole slightly out of round. Because of this, there was very uneven wear on the bearings and had this failure not have happened, it was due to spin a bearing any day. So this time the block will be getting align bored, along with the 0.060" overbore. I'm also having him check the cam bore and lifter bore alignment as well.

    We'll be replacing the #7 and #8 rods along with the crank. Crank will be a stock GM cast turned 0.010/0.010 and mag checked. Probe 9.5:1 pistons, rings, Federal Mogul main, rod and cam bearings.

    One of the heads is now junk since the broke valve got the intake seat pretty damn good. Also, both the heads had been milled at some point in their life. Throw in the fact that TRW L2465F pistons are relieved for stock valve sizes on a motor with larger valves (2.19" intake, 1.88" exhaust) and you have a real piston-valve clearance disaster recipe. Unfortunately these pistons don't have enough metal in them to relieve the pistons for the larger valves so we'll be going with a different set of pistons.

    Don't get me wrong, the L2465F piston is a great piston if you're running stock valve sizes. But if you're running bigger valves on open chamber heads don't even think about running them...you will not have enough piston-valve clearance. Also the reliefs in them are cut for stock valves and do not have enough material in them to cut them any bigger.

    Also, we're going with a SLIGHTLY different cam for this build. The original cam was an Isky 280H Mega. Single pattern cam, 280 seat-seat, 232 @ .050, 0.549 lift, 60* overlap seat-seat, 12* overlap 0.050, 110LSA, 110 lobe center installed at 106. The cam we'll be running for this build will be the Comp Cams Xtreme Marine XM278H. 278 @ 0.006" intake, 292 @ 0.006" exhaust, [email protected]" intake, [email protected]" exhaust, 112LSA, 110 intake centerline (will be installed straight up this time), 0.564" lift intake, 0.566" lift exhaust, 61* overlap seat-seat.

    Everything clearancewise will be getting checked and written down for this build and cam degreeing will be triple checked as well. Hopefullly this motor will live a long life and make the same power she made before.
    Last edited by Jetaholic; 10-23-2008 at 02:25 PM.



    Quote Originally Posted by HammerDown
    Kendall L-427 Super Blu...extreme-pressure (ep) lithium complex keeps my thrusting balls happy
    Quote Originally Posted by back2k5 View Post
    Well I am putting in a nice stereo system in the Carrera...maybe Ill put on some rap and turn the scoop sideways

  9. #7
    One Free Call Does it All CP Performance's Avatar
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    Quote Originally Posted by Jetaholic View Post
    Well the block was magnafluxed and she checked good. A couple of minor dings in the cylinder wall from the broke valve...0.060 overbore should take them right out.

    Something else unrelated to the failure that killed it...the machinist that got me the studs failed to tell me that when going from a main bolt to a stud that the block would need to be align bored due to the fact that studs clamp the caps differently than bolts do, putting the main journal hole slightly out of round. Because of this, there was very uneven wear on the bearings and had this failure not have happened, it was due to spin a bearing any day. So this time the block will be getting align bored, along with the 0.060" overbore. I'm also having him check the cam bore and lifter bore alignment as well.

    We'll be replacing the #7 and #8 rods along with the crank. Crank will be a stock GM cast turned 0.010/0.010 and mag checked. Probe 9.5:1 pistons, rings, Federal Mogul main, rod and cam bearings.

    One of the heads is now junk since the broke valve got the intake seat pretty damn good. Also, both the heads had been milled at some point in their life. Throw in the fact that TRW L2465F pistons are relieved for stock valve sizes on a motor with larger valves (2.19" intake, 1.88" exhaust) and you have a real piston-valve clearance disaster recipe. Unfortunately these pistons don't have enough metal in them to relieve the pistons for the larger valves so we'll be going with a different set of pistons.

    Don't get me wrong, the L2465F piston is a great piston if you're running stock valve sizes. But if you're running bigger valves on open chamber heads don't even think about running them...you will not have enough piston-valve clearance. Also the reliefs in them are cut for stock valves and do not have enough material in them to cut them any bigger.

    Also, we're going with a SLIGHTLY different cam for this build. The original cam was an Isky 280H Mega. Single pattern cam, 280 seat-seat, 232 @ .050, 0.549 lift, 60* overlap seat-seat, 12* overlap 0.050, 110LSA, 110 lobe center installed at 106. The cam we'll be running for this build will be the Comp Cams Xtreme Marine XM278H. 278 @ 0.006" intake, 292 @ 0.006" exhaust, [email protected]" intake, [email protected]" exhaust, 112LSA, 110 intake centerline (will be installed straight up this time), 0.564" lift intake, 0.566" lift exhaust, 61* overlap seat-seat.

    Everything clearancewise will be getting checked and written down for this build and cam degreeing will be triple checked as well. Hopefullly this motor will live a long life and make the same power she made before.
    Sounds good John, I've got the cam in stock if ya need it asap. Let me know if I can help. What HP are you shootin for?
    Brian
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  10. #8
    21 Daytona Outlaw's Avatar
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    $20 bucks says the #8 exhaust valve broke causing the mess,

    when you shut down after a long run, water from reversion spashed on the HOT exhaust valve
    and cracked it, fired it up and the spring pressure finished the job.

    do yourself a favor and buy inconel exhaust valves IMO
    #55

  11. #9
    Super Moderator HammerDown's Avatar
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    Quote Originally Posted by Outlaw View Post
    $20 bucks says the #8 exhaust valve broke causing the mess,

    when you shut down after a long run, water from reversion spashed on the HOT exhaust valve
    and cracked it, fired it up and the spring pressure finished the job.

    do yourself a favor and buy inconel exhaust valves IMO
    Yep been there broke that!
    Ferrari Inconel exhaust all the way now.
    <img src=http://www.performanceboats.com/gallery/data/500/medium/06-30-11_1234.jpg border=0 alt= />

  12. #10
    Sit N' Spin Jetaholic's Avatar
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    Quote Originally Posted by Outlaw View Post
    $20 bucks says the #8 exhaust valve broke causing the mess,

    when you shut down after a long run, water from reversion spashed on the HOT exhaust valve
    and cracked it, fired it up and the spring pressure finished the job.

    do yourself a favor and buy inconel exhaust valves IMO

    This is exactly what I'm thinking as well. And when the spring relaxed under the rocker it forced the pushrod into the lifter, which forced the lifter into the cam lobe, causing the cam to bind right up on that lobe which broke the camshaft.

    We are doing Ferrea valves on this next build as well.

    Brian...I'll give you a call or stop by the shop.



    Quote Originally Posted by HammerDown
    Kendall L-427 Super Blu...extreme-pressure (ep) lithium complex keeps my thrusting balls happy
    Quote Originally Posted by back2k5 View Post
    Well I am putting in a nice stereo system in the Carrera...maybe Ill put on some rap and turn the scoop sideways

  13. #11
    One Free Call Does it All CP Performance's Avatar
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    Quote Originally Posted by Jetaholic View Post
    This is exactly what I'm thinking as well. And when the spring relaxed under the rocker it forced the pushrod into the lifter, which forced the lifter into the cam lobe, causing the cam to bind right up on that lobe which broke the camshaft.

    We are doing Ferrea valves on this next build as well.

    Brian...I'll give you a call or stop by the shop.
    Cool, good choice in valves.
    CP Performance
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  14. #12
    Choking my ....... beerjet's Avatar
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    Is spending extra money somewhere where damage occured really a solution versus just pulling your valve covers before you take it out to make sure your valvetrain isn't takin a crap really the solution . My fairly mild/stockish motor ran forever with tons of preventative maintanance (of course). Wouldnt maintanance play a bigger part in engine life rather than (not knowing what "X" brand valves cost) spending more money on parts that were only "MAYBE" the cause of said damage ? After all , it's not like you actually saw it happen .

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