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AM I THROWING A ROD?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by foxman, Mar 11, 2002.

  1. foxman

    foxman 1/2 ton status

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    I cant believe this is happening... O.K. I was drining along one day after replacing the belt tensioner and when I came to a stop along my normal route, the idle was rough and she was shakin' all over. It feels like a dead cylinder, with a major loss of power, and the exhaust smells like sulfur. I took out all of the plugs, and the #1 cylinder plug is the only dirty one, and I mean dirty. It looks as if it is covered in unburnt fuel, yet there is spark in that cylinder, and the comperssion is just a couple of lbs higher than the rest of the cylinders. The knocking noise I'm hearing is faint and it is hard to tell where it is coming from, and it only happens after the engine is warmed up and at an idle. If in drive and foot on the gas, it does not have a knocking sound. Some have suggested a spark knock or valve related problems, yet I took off a valve cover and the valves don't seem to be sticking throughout complete rotation. I ran the codes on it and it says the MAP sensor has high or low voltage. I'll try replacing it, yet I've been told by a pretty reliable source that the journal bearing is probably where the clearance/noise/problems are coming from.

    My Question to all you guys is this, What does it sound like to you? If it is a rod knock how long can I let it go for driving 30 miles a day under 45 MPH? Can I just drop the oil pan and slide in a new stock bearing on the # 1 cylinder to stop this?

    Thanks for your reply.... I hope for the better, not the worse...
     
  2. Pugsley

    Pugsley 1/2 ton status

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    Sounds like the problem to me - You can replace just the one from underneath, but it's really a "Band-Aid" fix. While it will solve the immediate problem, your engine probably needs major surgery to determine and eliminate the source of the problem.
     
  3. txbluethunder

    txbluethunder 1/2 ton status

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    the smell of sulfer make me think that maybe your cat is dead and plugging up the exhaust???
     
  4. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    <blockquote><font class="small">In reply to:</font><hr>

    exhaust smells like sulfur.

    <hr></blockquote>
    I'd suspect a bad catalytic convertor. As for the plug, you may have a weak plug or spark plug wire to that cylinder. Unless you ran it dry or very low on oil, or tryed to see if 7000 rpm was possible I doubt you'd get spontaneous bearing knock. Get it running good again then see how it is. I've had some sucess chasing odd noises using an automotive stethoscope...

    Rene
     
  5. CaptCrunch

    CaptCrunch 1/2 ton status

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    Before you jump to conclusions I would do a compression test and a leakdown test. You may have a valve related problem on that cylinder. It is hard to say without actually hearing your "knock". I have heard that term a lot and seen everything from lifter problems, to valve adjustments or a broken rocker arm/stud being the cause. It is far easier to take a valve cover off and take a look at things then to deal with a rod problem. That or if you don't have access to the equipmenty or know how I'd take it to a neighborhood trusted shop. My shop will usually check a problem like that out and have an answer for under 100 bucks. At least then you know the problem for sure and aren't misdiagnoising it.

    There is no quick fix fpor the knock most likely. You could take out the bearing and take a look, but I think it is pointless cause knocks start up for a reason. Even if there isn't an oiling issue or oil contamination issue you will most likely have some wear on the crank itself that will cause early failure and/or noise. Plus it will only be a matter of time before the others go. You can pickup short and longblocks cheap... aftermarkets for as little as 800 bucks for a long block. GM's replacement is only about 12 or 1300. I'd do it once and never have to worry about the motor bottom again the band-aid a piss tired motor. That's my $.02
     
  6. ChevyCaGal

    ChevyCaGal 3/4 ton status

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    It does sound like your cat converter is clogged by the smell.... you should consider getting something like this or this from these guys or see if a local parts place carries it... <a target="_blank" href=http://qcpp.aol.com/jcwhitney.com__C/www.jcwhitney.com/productnoitem.jhtml?CATID=71197&amp;BQ=jcw2>CATALYTIC CONVERTER CLEANER/DEODORIZER</a>
     
  7. laketex

    laketex 3/4 ton status

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    or better yet, rod that cat out!!!
     
  8. bigmack

    bigmack 1/2 ton status

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    I say check the catalytic converter, it is probably where the smell is coming from. When these things are at the end of their life span they smell like hell. You can imagine how it is not letting the exhaust out of your engine, &amp; that will make an engine run like crap &amp; do alot of weird stuff.
     
  9. Anteak

    Anteak 1/2 ton status

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    First, I'm nowhere close to being a mechanic. From what you said, I would work my way back from the #1 plug. A knock should not foul a plug. Do you have adequate spark to that cylinder? Check plug, wire, and cap. Maybe a leaky valve seal is fouling your plug. Just could be a tune-up. Again, look at my fist sentence.
     

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