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Not again! motor issues can you help?..update!

Discussion in 'The Garage' started by supersize75, Jan 8, 2004.

  1. supersize75

    supersize75 1/2 ton status

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    Ok here are the symptoms, see if you can figure it out..

    motor is a 454 milage is unshure but likly 150,000 I think, carb is a 5 month old holly 670 truck avenger.

    truck has been bogging at higher speeds for the last couple weeks,

    I changed the spark plugs that where only a month old out and a couple were fouled out. Plug wires are newer too.

    Last couple days carb has been popping and kind of back firing, "I also did some manual back firing for fun before this started" if that helps. /forums/images/graemlins/ignore.gif

    then now its really bad, but a couple of short drives it acted normal and didn't do it at all /forums/images/graemlins/confused.gif

    I thought a bent valve but wouldn't it act the same rather than change how it acts?

    What about the accelerator pump? but the gas flow also looks inconsistant but would that have anything to do with back firing?


    Today I will pull the valve covers and see if the lifters are all acting the same or if I have some being inconsistant or different.


    thoughts? ideas recomendations? /forums/images/graemlins/1zhelp.gif

    also I noticed I am blazer of the month= ..thanks!
     
  2. jjlaughner

    jjlaughner 3/4 ton status

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    Re: Not again! motor issues can you help?

    if I had to take a stab considering some of the things are new... maybe timing chain? /forums/images/graemlins/confused.gif
     
  3. supersize75

    supersize75 1/2 ton status

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    Re: Not again! motor issues can you help?

    /forums/images/graemlins/thumb.gif that would makes since if it jumped the chain! /forums/images/graemlins/thinking.gif Would this result in the backfiring? Would hard use make a chain jump? /forums/images/graemlins/ears.gif

    that would throw everything off too, also my driving style has been nutty latly, been coasting in 3rd then slamming down a gear and flooring it...the acceleration is cool! Also multiple nutral drops a day, but the tranny is a surviver so far... "KNOCK ON WOOD"

    onlive my t-400


    thanks too /forums/images/graemlins/thumb.gif
     
  4. jjlaughner

    jjlaughner 3/4 ton status

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    Re: Not again! motor issues can you help?

    I thought mine jumped too but it didn't it was just really worn, sometimes it was fine and sometimes it would idle up and then down, back fires and big pops coming off high rpms (I thought I had a diff problem at first)
    It may not be the problem but a motor with 150K miles and hit and miss running it kind of sounds like it

    tension 1
    tension 2
    no chain
    New chain
     
  5. jjlaughner

    jjlaughner 3/4 ton status

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    Re: Not again! motor issues can you help?

    [ QUOTE ]

    tension 1
    tension 2

    [/ QUOTE ]

    since links open in new windows open 1 and 2 then flip back and forth between the two windows /forums/images/graemlins/thumb.gif
     
  6. southernspeed

    southernspeed 1/2 ton status GMOTM Winner

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    Re: Not again! motor issues can you help?

    May sound a bit obvious but have you check the distributer terminals in side and the cap for cracks. Also check the adv/ret action. May be worth having a look at your valve springs and make sure you don't have a broken one or two!Just a few thoughts from across the 'pond'!
     
  7. lukebaby1

    lukebaby1 1/2 ton status

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    Re: Not again! motor issues can you help?

    Those "for fun" backfire's may have damaged the powervalve located in the metering block on your holley. /forums/images/graemlins/crazy.gif
     
  8. y5mgisi

    y5mgisi 1 ton status

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    Re: Not again! motor issues can you help?

    My step dad (a mechanic) Says that you can identify a flat cam by if when you floor it it pops and stuff. /forums/images/graemlins/thinking.gif
     
  9. stretch67

    stretch67 1/2 ton status

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    Re: Not again! motor issues can you help?

    when does it pop or backfire? on acceleration or when you let off? i had a bad cam in a 350 that started as a pop as i gave it gas, the more gas you gave it the more it backfired back through the carb i finally pulled cam to find 2 round lobes the popping was compression coming back into intake because valves weren't closing at the right time you might be able to see by watching rocker arms if you have a bad lobe
     
  10. stretch67

    stretch67 1/2 ton status

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    Re: Not again! motor issues can you help? *DELETED*

    Post deleted by stretch67
     
  11. 84_Chevy_K10

    84_Chevy_K10 Banned

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    Re: Not again! motor issues can you help?

    [ QUOTE ]
    I thought mine jumped too but it didn't it was just really worn, sometimes it was fine and sometimes it would idle up and then down, back fires and big pops coming off high rpms (I thought I had a diff problem at first)
    It may not be the problem but a motor with 150K miles and hit and miss running it kind of sounds like it

    tension 1
    tension 2
    no chain
    New chain

    [/ QUOTE ]

    You usually change timing chains without removing the oil pan? I've thought about it in the past, but I've always been sure it'd leak if I did so (I have the worst luck with oil leaks. So in the past two years or so, I've always taken the oil pan off too.
     
  12. supersize75

    supersize75 1/2 ton status

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    Re: Not again! motor issues can you help?

    yep the more gas the more it pops, but it didn't pop for a couple of drives though, wouldn't a flat spot be a consistant problem? I am going to go pull the valve cover when I feel better to see whats up /forums/images/graemlins/thinking.gif
     
  13. stretch67

    stretch67 1/2 ton status

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    Re: Not again! motor issues can you help?

    i would think it would be consistent. it's been 5 years since i had the problem. so i forget a few details but i do know it got worse as time went along i drove it for about 3-4 weeks with the problem and as long as i did not get on the gas it would not pop much!
     
  14. jjlaughner

    jjlaughner 3/4 ton status

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    Re: Not again! motor issues can you help?

    [ QUOTE ]
    You usually change timing chains without removing the oil pan? I've thought about it in the past, but I've always been sure it'd leak if I did so (I have the worst luck with oil leaks. So in the past two years or so, I've always taken the oil pan off too.

    [/ QUOTE ]

    No idea this was the first time I have had to change a timing chain. It would have been easier without the oil pan on. I popped out the front two bolts and yanked the cover out after I wedged a screwdriver in front for some room to move. I took the new rubber piece from the timing kit and held it up to the old and trimmed it out then filled in the gaps with RTV and pulled the screwdriver back out and so far no leaks with about 3400 miles and one oil change.

    Honestly the gasket I cut out was very soft no cuts and I probley could have stuck the front cover back on with a little gasket maker to make a seal again, I figured if I did it would leak so I trimmed it and put the new one on the timing cover the stuffed it back in. so far so good... I need a little smiley icon knocking on wood /forums/images/graemlins/thumb.gif
     
  15. Mudzer

    Mudzer 1/2 ton status Author

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    Re: Not again! motor issues can you help?

    Try a new Powervalve.
     
  16. big k5

    big k5 Registered Member

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    Re: Not again! motor issues can you help?

    it may not be the same problem,but i have a holley truck avenger also & i HATE it,my old worn out quadrajet ran better than the brand new holley.it's finally starting to act right,but it was doing all the same things you mentioned.my choke was giving me problems,& the mixture was set too low when i got it.you could try changing the springs in the choke mine came with extra ones that were color coded for heavier vehicles.the same as you i suspected valves or worse,but it turns out it was just the carb. i hooked a vaccum gauge to the engine & my valves are fine.my dad bought a holley avenger for his el camino & had all the same problems. i have never tweeked on a brand new carb so much in my life ! lets just say I would never purchase another one. good luck i hope you get it running right. remember keep it simple,it may not be that big of a problem.
     
  17. cybrfire

    cybrfire 1 ton status Vendor GMOTM Winner

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    Re: Not again! motor issues can you help?

    check your advance and the weights inside the dist. I've had one stick on me and it would only do it once in a while. grease them up with some dielectric grease.
     
  18. supersize75

    supersize75 1/2 ton status

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    Re: Not again! motor issues can you help?

    well I pulled the valve covers and saw a push rod missing /forums/images/graemlins/eek.gif then I realized it was hiding isn the guide hole, and is bent and off the lifter.

    soooo


    looks like new ..
    lifters
    push rods
    water and power steering pump while I am at it
    put in the billit msd dist
    put on the alluminum intake fianlly and new msd wires
    new t-stat and head, valve covers, oil pan and other gaskets while I am at it.

    oh..and a power valve for the carb.

    Not as bad as I thought though /forums/images/graemlins/thumb.gif But I also just got a line up on another 454 /forums/images/graemlins/thinking.gif so that would be easier but 3 motor swaps in 5 months is gonna make me look crazy /forums/images/graemlins/crazy.gif

    well any way I look at it that means no buying my locker for the 14 bolt this month.= /forums/images/graemlins/frown.gif

    life is fun /forums/images/graemlins/smirk.gif

    thanks for all the help guys, I wish I could add a serpintine set up while I am at it, but I doubt I can get that by saterday /forums/images/graemlins/rolleyes.gif
     
  19. Mudzer

    Mudzer 1/2 ton status Author

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    Re: Not again! motor issues can you help?

    [ QUOTE ]
    well any way I look at it that means no buying my locker for the 14 bolt this month.= /forums/images/graemlins/frown.gif

    [/ QUOTE ]

    Now I have serious concerns about you. You broke a 14 bolt shaft, and don't have a Detroit in the rear? Is it welded? How could you drive around without a shaft? Lucy... you have sooom s'plainin to dooo.... /forums/images/graemlins/rotfl.gif
     
  20. 84_Chevy_K10

    84_Chevy_K10 Banned

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    Re: Not again! motor issues can you help?

    [ QUOTE ]
    [ QUOTE ]
    well any way I look at it that means no buying my locker for the 14 bolt this month.= /forums/images/graemlins/frown.gif

    [/ QUOTE ]

    Now I have serious concerns about you. You broke a 14 bolt shaft, and don't have a Detroit in the rear? Is it welded? How could you drive around without a shaft? Lucy... you have sooom s'plainin to dooo.... /forums/images/graemlins/rotfl.gif

    [/ QUOTE ]

    Would it be safer, and you'd have less concerns, if his rig just sat?
     

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