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What is involved in repairing a blown head gasket?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by midwest wheeler, Jan 23, 2004.

  1. midwest wheeler

    midwest wheeler Registered Member

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    I tried to search on this site and google, but couldn't find much. Anyway I am thinking of buying another K5. A 1989 Jimmy with 350 TBI, very little rust, and a great interior. Only problem is blown head gasket, it still runs and drives. How difficult would it be to fix and how do I fix it? I would consider myself fairly mechanically inclined, not a mechanic by any means but I can do a bit.
    Thanks for the help /forums/images/graemlins/thumb.gif
     
  2. Confedneck

    Confedneck 3/4 ton status

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    if it still runs and drives, and runs well.. then i would say its a leaky head gasket and not blown.. because were it blown, it could have serious damage to the engine..
     
  3. firefighter184

    firefighter184 1/2 ton status

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    I have an 89 as well, exact same thing going on. I'll be watching this post to see what comes up. I'd like to do it myself, but so far, all I've really learned (by doing) is a brake job, changing the oil, replacing drive shafts and u-joints. We'll have to wait and see what your post drums up. /forums/images/graemlins/1zhelp.gif
     
  4. zach78k5

    zach78k5 1/2 ton status

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    A head gasket on a 350 is not really a difficult task. You will have to remove the head. Make sure you know which head gasket is blown or leaking(left or right). To remove the head, just remove the carburetor, intake manifold, exhuast manifold and any hoses, spark plugs, etc. and then unbolt the head. make sure you unbolt the head by turning each bolt a few turns at a time, so the tension on the bolts is released equally between all the bolts. Then scrape the old gasket from the head and block and clean both. Then replace the gasket and put it back together. You dont want to use any gasket sealer, just the gasket. When you put it back together, use a torque wrench and tighten each bolt about 10 ft.-lbs at a time. I dont know the exact torque spec but someone on here will. Make sure you find that out and torque it properly. That is very important. You could also check autozone.com. They have online fix-it information for blazers and pretty much any car.
     
  5. zach78k5

    zach78k5 1/2 ton status

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  6. HarryH3

    HarryH3 1 ton status Author

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    Yep, the head has to come off. But there is no way that I would go that far into the engine and change only ONE headgasket. The effort to yank the other head isn't that great. I would go ahead and replace both head gaskets. It would suck to have to go back in a couple of months later and do it all over again because the other side started to leak.

    Also, before you even open the headgasket package, check the heads VERY closely for cracks. New gaskets won't fix a cracked head. /forums/images/graemlins/frown.gif If the heads look OK, then replace the head gaskets.

    And since you'll have so much of the engine apart anyway this would be a great time to drop in a hotter cam. /forums/images/graemlins/thumb.gif
     
  7. mudjunkie 82

    mudjunkie 82 1 ton status GMOTM Winner

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    Also you might want to take the head down to your local machine shop and have them check to see if it is totally flat on the gasket side. They might have to deck" it
     
  8. angrysnowplow

    angrysnowplow 1/2 ton status

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    I second doing both gaskets, guy I know replaced one, only to have the other side go less than a month later.
    I did mine...wasn't that bad of a job for a novice such as myself... [​IMG]
    Second time I've been through the job. I can't decide which I loved more- being IN my engine compartment for hours, or hurting my back leaning over Camaro fenders /forums/images/graemlins/rotfl.gif
    If you think you can handle it, go for it. /forums/images/graemlins/thumb.gif
     
  9. midwest wheeler

    midwest wheeler Registered Member

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    So I should have the heads magnafluxed as well? I will do both head gaskets, intake, water pump, and TBI gasket. Anything else I am missing?
    Thanks for all the good info
     
  10. angrysnowplow

    angrysnowplow 1/2 ton status

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    What I did was drop the heads off at the machine shop, and they did a complete valve job (needed it) and 'fluxed them looking for cracks.
    $225 later, I took home a set of horrible flowing TBI heads that looked brand new. /forums/images/graemlins/rotfl.gif
    Good luck with it. /forums/images/graemlins/thumb.gif
     
  11. Leadfoot

    Leadfoot 1/2 ton status Premium Member

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    When I picked up NoAngel's 88 K5 with a "bad head gasket" it ran fine (slight miss at idle). I loaded it on the trailer and brought it home. Pulled the TBI and intake off, removed exhaust manifolds (broke the A.I.R. Pipe $$$), pulled both heads (as if one gasket blew the other was not far behind). Turned out the head gasket blew, but it also caused one head to crack and the other to warp. I had to get one new head, and both machined down to match and have a straight edge. It bumped compression up a bit but not enough to notice. It's not a bad job, but it can take some time (especially if you have not done anything like this before which I had). It took about a week for me to do waiting on heads and whatnot, but it took me about 16 (broken up over the course of a week) hours start to finish with replacing all belts, hoses, waterpump, thermostat, plugs, wires, cap, rotor, etc, etc.

    The hardest part was dealing with the broken A.I.R. pipe and spreading the exhaust manifolds (without a spreader) for re-assembly as they "shrunk" from sitting.

    I think total cost with new head and machine work (including valve job), tune-up, etc. was around $500 (no labor costs).

    Hopefully you luck out with just a bad gasket, but regardless, I would have a machine shop magnaflux the heads and at the very least install new seals.
     
  12. detailer03

    detailer03 1/2 ton status

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    How many miles on the engine. Mine went with 225,000 on it. I opted to just replace the engine. Belive it or not, book time is the same labor. It is a real pain in the back side to do head gaskets. Just the cleaning alone is an almost endless task.

    When working on high mileage engines, sometimes you open up a real can of worms.
     
  13. midwest wheeler

    midwest wheeler Registered Member

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    Re: What is involved in repairing a blown head gasket?-UPDATED

    I found out that the blazer doesn't run, but the motor and trans are supposed to be in good shape. The motor has 120k on it. It is an 89 K5, pw and pl, with no rust and a great interior, all glass is good as well. You think it is worth $1300? It is a little dirty in the pictures, but not rusty
    [​IMG]
    [​IMG]
     
  14. HarryH3

    HarryH3 1 ton status Author

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    Re: What is involved in repairing a blown head gasket?-UPDATED

    Nice loooking rig! What part of Nebraska? If you don't want it at that price, then I may need to drive up and get it. /forums/images/graemlins/eek.gif
     
  15. midwest wheeler

    midwest wheeler Registered Member

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    Re: What is involved in repairing a blown head gasket?-UPDATED

    It's actually not in Nebraska, its a few hours away and I'm picking it up Sat. Sorry /forums/images/graemlins/thumb.gif
     
  16. Me89'Jimmy

    Me89'Jimmy 1/2 ton status

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    i bought my 89 in worse condition than that for 2250,and odly enough its currently out of commission due to a blown head gasket, go figure. ya but a no rust 89 1300 is a steal, grab that mofo before someone else does /forums/images/graemlins/deal.gif /forums/images/graemlins/thumb.gif
     
  17. midwest wheeler

    midwest wheeler Registered Member

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    I'll post some pics of it and I'm sure I'll have a few questions to ask when I need some info!
     

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