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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: 1979C20 on March 12, 2014, 05:35:09 am

Title: Cracked exhaust manifold
Post by: 1979C20 on March 12, 2014, 05:35:09 am: 89 GMC V2500 burb. My passenger exhaust manifold where the #2 cylinder comes down to join the rest is completely broken inside of the heat shield for the thermostatic controller in the air cleaner. It has a very prominent exhaust tick from first start up until warm. It sometimes backfires when slowing down, but other than that I was curious of how harmful this could be to my engine until I can buy a set of headers?
Title: Re: Cracked exhaust manifold
Post by: Irish_Alley on March 12, 2014, 06:17:16 am: may not be too bad now, but since it heats up and cools down every time you run the engine the cast will expand and contrast and the crack will get worse and worse. you can try to get someone to weld it shut, but with cast it might not hold.
Title: Re: Cracked exhaust manifold
Post by: rich weyand on March 12, 2014, 10:22:35 am: If you buy headers, get Hooker headers for that 4x4. People have had problems with other headers not having enough clearance for the front drive shaft and universal joints. No problems with Hooker headers on my K10.
Title: Re: Cracked exhaust manifold
Post by: 1979C20 on March 13, 2014, 04:35:21 am: Ive noticed it getting worse over the year and a half ive owned it. I thought it was the manifold gaskets.
Rich, thanks for the advice. Ill be looking for Hookers then.
Title: Re: Cracked exhaust manifold
Post by: Irish_Alley on March 13, 2014, 04:36:55 am: Quote from: 1979C20 on March 13, 2014, 04:35:21 am
Ill be looking for Hookers then.
this son, will get you in trouble with the law ;)
Title: Re: Cracked exhaust manifold
Post by: 1979C20 on March 13, 2014, 04:38:14 am: dang automotive innuendos. Haha.
Title: Re: Cracked exhaust manifold
Post by: rich weyand on March 13, 2014, 08:46:18 am: Quote from: 1979C20 on March 13, 2014, 04:35:21 am
Ive noticed it getting worse over the year and a half ive owned it. I thought it was the manifold gaskets.
Rich, thanks for the advice. Ill be looking for Hookers then.

Get the header bolts that have the hex socket in the head. They are hex heads like a regular bolt, but also have the hex socket ("Allen wrench") as well. They come with a hex drive allen key for your socket wrench set. Much easier to torque, and to occasionally check the torque.

Header bolts can work loose due to temperature cycling. Checking torque on them should be part of regular routine at oil change time. Same with TH350 pan bolts, BTW.
Title: Re: Cracked exhaust manifold
Post by: bobcooter on March 13, 2014, 02:43:10 pm: I couldnt help but laugh when I noticed Rich is recommending Hookers and his truck is named "Working Girl". Too funny!
Title: Re: Cracked exhaust manifold
Post by: rich weyand on March 13, 2014, 09:00:04 pm: Quote from: bobcooter on March 13, 2014, 02:43:10 pm
I couldnt help but laugh when I noticed Rich is recommending Hookers and his truck is named "Working Girl". Too funny!

hehehe.
Title: Re: Cracked exhaust manifold
Post by: 1979C20 on March 14, 2014, 04:04:51 am: Ive got headers on my 79, and I know they are a decent bit of work to keep sealed. Ive found the best gasket to use on headers is factory exhaust manifold gaskets.
Title: Re: Cracked exhaust manifold
Post by: Irish_Alley on March 14, 2014, 04:41:02 am: i picked up a set of aluminum ones from the parts store was years ago but i think they were $30. You can reuse them and if a bolt backs out you don’t blow the gasket, just retighten the bold and move on.