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  1. #1
    Bald Tire
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    H3 Exhaust Manifold

    The title many of you would love to ignore (from research)

    Anyways, at startup the truck sounds like a diesel. At operating temperatures, you can hear the ticking on the passenger side front during acceleration (ruled out anything drivetrain). Im assuming a bolt sheared off or I have a crack in the manifold. I will be taking the heat shield off soon to see if my assumptions hold true. Plan on replacing it with a Dorman part# 674-989, mainly because it has a lifetime warranty along with getting it discounted for under 400$ through Autozone.

    What are your guys' experiences? Im willing to take it to a shop since i know its a pretty big job, especially if a bold sheared, and also because she's my daily driver.

  2. #2
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    You should be able to see if the bolts are gone, especially in the front. You will need an 02 sensor removal tool also which is not expensive. Try to tweak the bolt heads to see if they are cracked inside the head. If one of your front bolts are bad, there is a good chance that the rear is also bad but not always the case. If the front bolts need replacement, is not too bad.
    Two years ago, I purchased my exhaust manifold on ebay. It was $276 shipped. I also purchased better bolts even though the manifold came with replacement bolts.
    Soak the bolts with penetrating oil the night before, even if you take it to a shop to have it done.

    Here is the seller's current listing. Perfect fit and two years later, no issues.
    https://www.ebay.com/itm/Catalytic-C....c100005.m1851
    Last edited by Paranormal; 10-07-2018 at 12:42 PM.
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    2006 Blue H3

  3. #3
    Mud Terrain
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    Avoid Doorman. I'm not a Doorman fan period. Specific to exhaust manifold, I bough one for the Jeep since it's a beater toy anyway. It was crap. Holes were not drilled correctly. Was noticably less stout than the Jeep part it replaced. On the H3, replacement is a job. You don't want to do it any more than necessary. Get the GM part.

    Sent from my HTC U11 using Tapatalk

  4. #4
    Street Tire
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    The gm part cost more, but look how long the one you're replacing lasted .The same with ball joint control arms and wheel bearings. I have 150000 miles on my H3 and all ball joints and control arms ar original.

  5. #5
    Bald Tire
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    Thanks all for the suggestions. Here is a video I took this morning. Cold startup https://youtu.be/z0AZPUCeq0o

    To my knowledge, this manifold is the original and I currently have 160,000 miles on the h3. The car ran in the family. However I know that warranty work was done for the head issue, but I donít know know if the manifold was replaced at that time.

    Defiantly steering clear of dorman now, considering doing what whatwoodwardsh3 said and just replacing with the original but Iíll have to see on the price tag and how much I can get it for. The eBay listing is very tempting as well, especially with no issues.

    If the bolts are sheared should I just take it to a shop to take care of it? Never had to remove a sheared bolt before.

  6. #6
    Bald Tire
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    Do you recall the part# or the brand of bolts you went with?

  7. #7
    Bald Tire
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    Quote Originally Posted by Paranormal View Post
    I also purchased better bolts even though the manifold came with replacement bolts.

    Do you recall the part# or the brand of bolts you went with?

  8. #8
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    Quote Originally Posted by EndeavoredH3 View Post
    Do you recall the part# or the brand of bolts you went with?
    9 Piece M8 x 1.25mm x 45mm High Tensile Alloy Steel Exhaust Manifold Stud Kit. Search On Ebay
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    2002 Black HMCS
    2006 Blue H3

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    EndeavoredH3 (10-17-2018)

  10. #9
    Bald Tire
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    I have a 08, with the 3.7 I bought from my bank as a repo last year. While deer hunting last winter I developed an exhaust leak. It gradually got louder. My son in law, Jody & I tore it down last weekend. The base of the air injection check valve was broken and had a sizable exhaust leak. We pulled the exhaust manifold and 4 of the 9 bolts were broken. 3 were extended or flush so we welded nuts on and removed them. The last one at the rear was broken off inside the hole. We drilled it and broke an extractor off, rather than pull the head we bolted on the manifold with new bolts and gaskets. We fabricated a block off plate and eliminated the valve for now. I drove it 80 miles home and didn't get a hint of any exhaust leak. It did loose a lot of powder due to catalytic converter blockage. Tomorrow I will go to the exhaust shop an have the rear one eliminated. The next weekend Jody has off we'll get the front converter and reinstall the air injection check valve that Jody welded up at work. I'll give you an update upon completion. My advice at this point is exhaust leak should be checked out ASAP. The manifold bolts only torque to 15 lbs. That's not much an they are small bolts.

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    Korby7 (10-10-2018)

  12. #10
    Bald Tire
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    I have a 08, with the 3.7 I bought from my bank as a repo last year. While deer hunting last winter I developed an exhaust leak. It gradually got louder. My son in law, Jody & I tore it down last weekend. The base of the air injection check valve was broken and had a sizable exhaust leak. We pulled the exhaust manifold and 4 of the 9 bolts were broken. 3 were extended or flush so we welded nuts on and removed them. The last one at the rear was broken off inside the hole. We drilled it and broke an extractor off, rather than pull the head we bolted on the manifold with new bolts and gaskets. We fabricated a block off plate and eliminated the valve for now. I drove it 80 miles home and didn't get a hint of any exhaust leak. It did loose a lot of powder due to catalytic converter blockage. Tomorrow I will go to the exhaust shop an have the rear one eliminated. The next weekend Jody has off we'll get the front converter and reinstall the air injection check valve that Jody welded up at work. I'll give you an update upon completion. My advice at this point is exhaust leak should be checked out ASAP. The manifold bolts only torque to 15 lbs. That's not much an they are small bolts.

  13. #11
    Bald Tire
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    Last week I was going to take the H3 to work and get the rear Cat replaced with a piece of pipe. It lost power decreased to a maximum speed of 17 mph. I turned around and brought it home and took my truck. That evening I unbolted the main exhaust pipe from the manifold. It ran like a raped ape. I took it in the next day and had the Cat replaced. It still runs the same only quiter. In the year and seven months I've owned it, it's never ran better. It cruzes at 70 easily and passes with power to spare. I've had it up to 85 so far. I'll take it back to my son-in-laws and reinstall the air injection value Jody welded up. Clear the codes and post an update.
    I ordered a new gasket and reinstalled the air injection pump after milling the base to insure everything was correct. Everything is working fine with over 1200 miles, no leaks.
    Last edited by Niteowl1; 12-15-2018 at 07:21 PM.

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    EndeavoredH3 (10-17-2018)

  15. #12
    Bald Tire
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    Duplicate post

  16. #13
    Bald Tire
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    Quote Originally Posted by Niteowl1 View Post
    I have a 08, with the 3.7 I bought from my bank as a repo last year. While deer hunting last winter I developed an exhaust leak. It gradually got louder. My son in law, Jody & I tore it down last weekend. The base of the air injection check valve was broken and had a sizable exhaust leak. We pulled the exhaust manifold and 4 of the 9 bolts were broken. 3 were extended or flush so we welded nuts on and removed them. The last one at the rear was broken off inside the hole. We drilled it and broke an extractor off, rather than pull the head we bolted on the manifold with new bolts and gaskets. We fabricated a block off plate and eliminated the valve for now. I drove it 80 miles home and didn't get a hint of any exhaust leak. It did loose a lot of powder due to catalytic converter blockage. Tomorrow I will go to the exhaust shop an have the rear one eliminated. The next weekend Jody has off we'll get the front converter and reinstall the air injection check valve that Jody welded up at work. I'll give you an update upon completion. My advice at this point is exhaust leak should be checked out ASAP. The manifold bolts only torque to 15 lbs. That's not much an they are small bolts.

    I too had a leak in the area of the secondary air injection valve that ended up being a bad gasket that mated the valve to the block. At the time, I was about to send in my computer to PCM For Less (still have to write an amazing review for that tune...), so I decided to also have them delete that A.I.R system while they had it. I then purchased another gasket along with a block off plate from Gm themselves for 20$ ish. I have part numbers if anyone wants them.

  17. #14
    Street Tire
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    Before you bolt your secondary air valve back on put a straight edge across the mating surface. If it is slightly off run a long file across and make it flat. Most crack if slightly off when reinstalling. Also always use new gasket. Old gaskets get compressed. Again, they will crack or break at base if slightly off.


 

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