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Shop told me my motor is broke!

Discussion in 'The Garage' started by Robert D, Aug 9, 2006.

  1. Robert D

    Robert D 1/2 ton status

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    Well, the history of my problem has been hunting down an idle issue. This has now gotten much worse. What I have not replaced in the ignition system includes the coil and ICM. In the fuel injection system I have not replaced the pump, EGR, ...and thats pretty much it. Now to the problems I am having...

    The truck on a cold start takes about 3-4 secs to turn over, then it almost always dies right away. Turning it over again takes less than a second. Once started, the truck idles very very badly...low idle speed, truck misses, it seems to also hunt for the idle at first. When driving from a stop, I need to put the gas pedal down almost all of the way due to the engine missing in order to go anywhere. The severity of this missing goes away after 10-15mins of driving but it is still there once warmed up. Now, the truck has been burning oil, but once warmed up seems to run pretty well. The oil is going at about a quart every week or so with moderate highway/city driving.

    Having tried to hunt down this miss/idle issue for some months now I decided to drop the truck in at a shop to have them check the distributor coil, ignition system, and fuel system. Pep Boys is around the corner from work (yeah...I'm thinking about taking it to the dealer now), so I took it in for a diagnostic. After about 30mins, the guy tells me oil is collecting on the spark plugs and burns off after you drive for a bit. He says a new motor is the only way to fix this... WHAT? I asked for the feedback on testing the ignition/fuel system and he says there is no point in doing the tests. Needless, they charged me half price for their diagnostic.

    Now, about 5months ago I changed the plugs/wires and noticed on one plug a bit of oil. I didn't think much of this as the truck has ~150k miles on it (probably ~145k at the time, I don't drive much). So, today I am going to replace the plugs again and change out the ICM (it looked pretty corroded when I changed the cap/rotor recently). What do you guys think? In my experience with Porsches, writing off the motor at first sign of burning oil isn't the normal practice. We usually rebuild the head FIRST...I'm guessing this opinion from Pep Boys is pretty...bad? Help me out here.
     
  2. 1985_K5_Silverado

    1985_K5_Silverado 1/2 ton status

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    A friend had a great-running engine that developed a rough idle / ignition miss / reduced power problem, and it turned out that a spark plug wire had been burned through by heat from the header tube, so he was running on 7 cylinders. This isn't likely to be your problem, but I thought I'd mention it.

    As far as the oil thing goes, any compression or leakdown test yet? Stuck a vacuum gauge on it?
     
  3. Robert D

    Robert D 1/2 ton status

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    I'm going to try to limp the truck down to San Antonio this weekend to do a compression check at my father's. He has the tools. As for a leakdown, when I take it into the dealer to have them check the ignition system (assuming that the ICM/plugs change goes ok) I'll have them do a leakdown. It just doesn't seem right that the truck runs fine under power and doesn't blow a white cloud out the back but needs a new motor due to rough idle/stumble....

    Tonight I'll have the plugs/ICM changed out and I'll post my findings later tonight or tomorrow when I am back at work.
     
  4. diesel4me

    diesel4me 1 ton status Premium Member

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    its possible...

    It is a possibility the motor has a few bad intake valve giudes, or stem seals,that lets not only oil reach the plugs,and possibly cause them to foul and misfire after enough accumulates on them,but also AIR is being sucked into the loose intake guides,and that will affect idle quality and speed--it IS a vacuum leak!..

    I'd do a leakdown test or compression test to ensure the rings are not the cause of the oil consumption..be aware if you freshen the heads up,the rings might start blowing by..everything is worn,and when you tighten up one part,like the valves and heads,the compression will look for the easiest escape route,and thats usually the rings..I've done a lot of valve jobs on small blocks,and about 50% of the time,the motor starts smoking and using oil WORSE after a valve job!..sometimes its best to do it all,rather than half the job..:crazy:
     
  5. jekquistk5

    jekquistk5 Weld nekid Premium Member GMOTM Winner

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    personally, I would check your EGR valve make sure its workinig correctly, then replace the EGR solonoid, and the IAC motor. I wouldn't be surprised if those fixed your problem. Also you might want to run some seafoam through your tank, and throttle body to clean out carbon build up. The compression check should be the end all tell all though. Good luck, but dont call it quits before everything is done.
     
  6. Robert D

    Robert D 1/2 ton status

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    Dang. I cannot wait to pull the plugs today because I really don't believe it is burning oil that badly...if it was there would be a noticeable cloud from the exhaust....but from what I am seeing is faint puffs when I really get on the gas. I am going to put my money on ignition system.
     
  7. readymix

    readymix 3/4 ton status

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    Same thing on a truck I used to work on was caused by a broken tooth on the reluctor. It is what the pick-up coil uses to generate the pulses for the ignition module.

    I remember it being a real bitch to troubleshoot....mostly because I would have never thought that one would break.
     
  8. Robert D

    Robert D 1/2 ton status

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    Yeah, my thoughts are to replace the plugs and ignition module. Then depending on what I find on the plugs (how many appear to be burning oil or are coated with oil) decide what to have the dealer do: leakdown/compression and ignition/fuel system check.

    The guy at PepBoys thought that seeing oil on the plugs (who knows if he even looked) would mean the plugs are working when the truck heats up because they are burning the oil off of them........I should still see quite a bit of smoke....and there is an oil leak coming from the rear main seal I believe...so not all of the oil I am losing is burning up.
     
  9. 1985_K5_Silverado

    1985_K5_Silverado 1/2 ton status

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    By the way, for this particular problem, we also suspected the ignition module, because it had done a long trip while running like a top, and then gone rough and short of power as soon as he started the engine to go home (like an ignition module might do if it decided to go screwy). The engine was in super tune at the time it happened, which made the rough running very noticeable. He has true duals, and one pipe sounded normal (smoothly choppy at idle), but the other definitely had a miss.

    It turned out that the header tube heat had been slowly burning the insulation on the #5 plug wire, the heat from that last trip was just enough to finish burning all the way through, and so then it had a massive voltage leak from the wire to the header/head. It now has some wrap on the tubes and an insulated sleeve over the wire in that area. We had both thought it would be a screwy module for sure.
     
  10. Robert D

    Robert D 1/2 ton status

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    I'll be sure to check my wires while I am at it.
     
  11. fabjunkie

    fabjunkie 1/2 ton status

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    I can't add to what has already been said, but I would take anything that came out of anyone's mouth at Pepboys with a grain of salt. I would rather talk to my proctologist about engine problems.
     
  12. theperfectgarage

    theperfectgarage 1/2 ton status

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    My experience with gm modules has been that they either work or they dont.
    I smoked one about a week ago and it died like you killed the ignition. Diaged. a no spark, had 13Vt. at the dist.

    Popped the cap and I could smell burnt elec. Had a hole the size of a quarter burnt thru the housing of an accell module.

    As others have said, you need a leakdown test. You dont need a dealer, just a shop or mech. you trust. Best of luck.
     
  13. Robert D

    Robert D 1/2 ton status

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    That's the thing; I do not know any mechs I trust here in Austin. I'll have to post on the austin forum tonight. I bought this truck last Oct and have been doing everything myself so far. I guess I can wait on touching the ICM, but heard of people having issues relating to temperature with the ICM (they are fidgety). Perhaps I am wrong???
     
  14. Robert D

    Robert D 1/2 ton status

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    I am going to see what stepping up the timing will do...the truck seems to be idling pretty low even for it having a miss.
     
  15. Metrodps

    Metrodps Strange but nice guy Premium Member GMOTM Winner Author

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    1.Get a can of either and spray short burst around carb area see if idles up. If it does you have a vacuum leak.
    2.When was last time you replaced PVC on it that will cause it to use oil.
    3.Check the spark plug wires as stated you can use a *minds blank* volt tester thingy to see if wire is good.
    4. may be a computer problem too.
    Just based off my past experiences. Good luck
     
  16. Robert D

    Robert D 1/2 ton status

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    Well, found oil on one plug....it was ugly. It appears my head gasket has gone south around the front passenger cylinder and is leaking oil and water (don't know if water is going into the cyl, but it is leaking down the side of the block). I suspect the gasket was on its way out when I bought the truck a year ago; when I replaced the plugs in November I noticed a little bit of oil on this same plug. So now I need to find a good machine shop here in Austin to take both of the heads over to have them re-worked. I don't think there will be too big of an issue driving this thing for a few more weeks until I find a shop?? Won't any water turn to steam in the block...I wouldn't think a rod would be thrown for a little water...

    Good call on the spark plug wires. It looks like one of my new wires has a crack in the insulation as it was too close to the header. I'll have to either buy or make a new one. Thanks for the help guys I'll keep you posted. It looks like I'll have to fresh heads out of this! So much for a "blown motor"...freaking PepGirls.
     
  17. Russell

    Russell LB7 Tahoe Status Premium Member GMOTM Winner

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    Also check all your sensor readings. If your truck is dumping too much fuel in or something, that can cause some pretty crazy poor running.
     
  18. theperfectgarage

    theperfectgarage 1/2 ton status

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    Blown Engine

    Is there a more vague or misused term then "blown engine" in car talk? Those two words can make me grit my teeth when I'm talking with a bozo.
     
  19. 1985_K5_Silverado

    1985_K5_Silverado 1/2 ton status

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    We used a boneyard part off a Ford Explorer (a V6 I think, but I didn't do the pick and pull myself) to keep this from happening again. Apparently, they have a heat problem with at least one of their plug wires, so they have an insulated metal sleeve to protect the plug wire and boot in that area.
     
  20. diesel4me

    diesel4me 1 ton status Premium Member

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    not good!..

    I'd park it until you can fix it--any prestone in the crankcase will eat the babbit in the main and rod bearings!:eek: ..but if its been leaking for awhile,the damage may already be done..

    I'd do a complete rebuild,I've had too many engines with "just a blown head gasket" start rapping a few weeks later!,after all that work and $$..its cheaper to toss another decent running junkyard engine in it,in the long run,unless you plan on doing everything over at once.....

    I can get a decent running 350 motor around here for 300-400 bucks--having head work (a valve job) can easily cost that much by the time you buy gaskets,and labor--and the "bottom end" is still hurtin!:crazy: ..
     

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