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Exhaust leak...how to tell where it's coming from?**Update**

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by UseYourBlinker, Mar 26, 2002.

  1. UseYourBlinker

    UseYourBlinker 1 ton status

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    Exhaust leak...how to tell where it\'s coming from?**Update**

    I'm having some problems with an exhaust leak. I first thought it was the EFE valve so I replaced the gasket,and also the collector gasket's (lead doughnuts).. The bolts on the manifolds are tight.I don't know what else to do? The leak sounds the worst when the tranny hits second gear while accelerating. Also is there a gasket between the manifolds and the block?
     
  2. Den

    Den 1/2 ton status

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    Re: Exhaust leak...how to tell where it\'s coming from?

    I used to own a muffler shop..and there are a few ways.. have a buddy almost plug the tailpipe.... then listen... or take a stray bottle of water and squiter all the joints..someone will tell you to put ATF in the carb and watch for smoke... will work...just dont like to suggest it....
     
  3. Sparky

    Sparky 1/2 ton status

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    Re: Exhaust leak...how to tell where it\'s coming from?

    Best way i have found is to get a piece of vacume tubeing or fuel tubing roughtly 3/8 in. diameter. Hold one end up to your ear and the other end up to the suspected exaust leak. You will be able to hear the exaust leak easily. Kinda like blowing on the top of a coke can. Only problem is it dosent work to well near the radiator fan.
     
  4. NoSmog73

    NoSmog73 1/2 ton status

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    Re: Exhaust leak...how to tell where it\'s coming from?

    Hey eric yes there is a gasket inbetween the block and the manifolds ( they are the ones that like to blow out on headers ).If you can take the heat use a mechanix glove and "feel" for the leak just be very carefull with the rest of your arm too(this was the only way to "see" where mine was)....You should also check for cracks in the manifold I found a crack on the underside of my manifold and now I have the headers in the box just waiting till I get money for the flows....mike
     
  5. 84_Chevy_K10

    84_Chevy_K10 Banned

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    Re: Exhaust leak...how to tell where it\'s coming from?

    Look where carbon spews out. That's where the leak is.

    The gasket is between the manifold and the cylinder head, not the block. There should be carbon all over your spark plugs if it's leaking. Just look for a black buildup around the suspected leak area.
     
  6. UseYourBlinker

    UseYourBlinker 1 ton status

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    Re: Exhaust leak...how to tell where it\'s coming from?

    Thanks for the info Mike. My other question now is if I do have a cracked manifold, is there a smog legal header that I can use? (That will pass smog in CA) I need to re-route my exhaust any way. The cross over (y-pipe) rubs agianst the front driveshaft.
     
  7. UseYourBlinker

    UseYourBlinker 1 ton status

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    Re: Exhaust leak...how to tell where it\'s coming from?

    Thanks for the info Tim.
     
  8. NoSmog73

    NoSmog73 1/2 ton status

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    Re: Exhaust leak...how to tell where it\'s coming from?

    Ya I know they have them just take a look at summit or jegs and what you need (if you have the smog pump and the air injection, is a header with the injection ports.) I know they have them just don't have the part # handy Or you can buy a used set and have a muff shop weld them in for ya but then you might as well buy them with it...mike
     
  9. BlazerGuy

    BlazerGuy 3/4 ton status

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    Re: Exhaust leak...how to tell where it\'s coming from?

    If it's cold out just stop up the pipe lightly(rag over the end) and watch for smoke along the system
     
  10. gotmud?

    gotmud? 1/2 ton status

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    Re: Exhaust leak...how to tell where it\'s coming from?

    someone will tell you to put ATF in the carb and watch for smoke... will work...just dont like to suggest it....


    We've used fogging spray oil for this. the stuff in a spray can that you shoot into carbs before storing an engine over the winter. might have to clean the plug's after this though.
     
  11. Zeus33rd

    Zeus33rd Smarter than you GMOTM Winner

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    Re: Exhaust leak...how to tell where it\'s coming from?

    II don't think most small blocks with manifolds have gaskets between the manifold and head. Mine doesn't, And all the others I've owned haven't. Headers obviously do, but I don't think manifolds need them.
     
  12. UseYourBlinker

    UseYourBlinker 1 ton status

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    Re: Exhaust leak...how to tell where it\'s coming from?

    I went down to a local auto parts store,and asked if they had manifold gaskets for a 350. Heres what a got. Should I use them?

    <a target="_blank" href=http://coloradok5.com/gallery/albuo96/aac>Click for Pic</a>
     
  13. Zeus33rd

    Zeus33rd Smarter than you GMOTM Winner

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    Re: Exhaust leak...how to tell where it\'s coming from?

    If your manifolds are warped and won't seal without them, Use'em. Won't hurt.
     
  14. Zeus33rd

    Zeus33rd Smarter than you GMOTM Winner

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    Re: Exhaust leak...how to tell where it\'s coming from?

    If your manifolds are warped and won't seal without them, Use'em. Won't hurt.
     
  15. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Re: Exhaust leak...how to tell where it\'s coming from?

    I use those gaskets with my headers...never had a leak at the head yet. They don't burn up or blow out and the nifty little tabs make em easy to install./forums/images/icons/smile.gif

    Rene
     
  16. 84_Chevy_K10

    84_Chevy_K10 Banned

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    Re: Exhaust leak...how to tell where it\'s coming from?

    Those are manifold gaskets. That's what our trucks came with from the factory.
     
  17. TX Mudder

    TX Mudder 1/2 ton status

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    Re: Exhaust leak...how to tell where it\'s coming from?

    When our trucks were new, the heads were perfectly straight and our exhaust manifolds were perfectly straight. There was no need for a gasket and the factory did not put one on.
    Now that our trucks are seasoned, the head mating surface maybe is slightly warped but more likely the manifold itself is warped. They all are with use.
    That's why there are exhaust manifold gaskets. Yes, you should use one. No, it didn't originaly come on the engine.
    -- Mike
     
  18. UseYourBlinker

    UseYourBlinker 1 ton status

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    Re: Exhaust leak...how to tell where it\'s coming from?**Update**

    Thanks for the knowledge guy's!!
     
  19. Leadfoot

    Leadfoot 1/2 ton status Premium Member

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    Re: Exhaust leak...how to tell where it\'s coming from?

    I second Rene,
    Putting those in place of the paper header gaskets was one of the cheapest fixes I've ever done. The expensive aluminum gaskets and/or copper ones would probably to the same or better job, but when I was still in high school and low on cash I installed a set of these (I think I got them for $9 a complete set) after replacing the paper ones several times (and I think I even paid more for the replacement paper ones) and never had any trouble. I did go with some aluminum ones which I think are better when I upgraded to the Hooker Super Comps, but this style probably would have worked too (or at least better than the paper ones).

    And yes most trucks did not come with those from the factory. I was told that if there was a leak detected before delivery they would be installed and that there was also a recall one year in which the "fix" was to install this style gasket to stop exhaust leaks. So some may have had them stock, but very few. Also if you remove an old set of manifolds, it is almost certain (I'm guessing about 90%) that you will have leaks without some sort of gasket due to the repeated heating and cooling cycles. A buddy of mine that works at a GM dealership says all the older motors (whether is was car, truck, van, etc.) when the heads were done or the manifolds removed for exhaust work, they always used these gaskets during re-assembly. For what it's worth.
     

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