Exhaust problems..... - The 1947 - Present Chevrolet & GMC Truck Message Board Network

JVictor75 · 12-05-2002, 04:23 AM

Hey guys.....

It's been a looooooong while since I visited the board. Not cuz I don't like you guys, but because I've been having money problems and it's just too depressing to read about you all doing what you love with your trucks....

Enough whinin' on my part though, I've got a couple of questions...

I went out and found a good condition right exhaust manifold to replace my cracked one with (we're talking the passenger side of a small block here). I went ahead and installed it then drove to Austin Texas for the holidays.

Thats about a 110 to 120 mile trip for me.

When I got to Austin, my new exhaust manifold was cracked just like my old one was.... do you all have any idea what the deal is? It's cracking right above where the studs screw into the manifold, you know the "neck" of the manifold where all of the tubes meet. The collector if you will.... Yeah it's cracking right at the bottom of that area.

Is this normal and I'll just have to patch it until I can afford to put a set of headers on the truck or what? And if I do have to wait, what should I be looking at for cost to install the headers. The truck already has an aftermarket dual exhaust with flowmaster 40's and 2 1/2" tubing.

(I'd do it myself but my apartment complex has Nazis for caretaking staff and I cant do much more then change my air filter.)

HotRod929 · 12-05-2002, 04:45 AM

I dont know but could you possibly be torqueing the bolts down too tight? Or the exhaust ports on the heads are not all even so there is space so when u crank down the bolts to seal it it just cracks shortly under the pressure of the bolts.

HotRod

Project1970 · 12-05-2002, 05:10 AM

From his description, I think he means down away from the mounts, closer to the exhaust pipe itself...my passenger side manifold is cracked there too (but not through yet...) and from what I can tell it's a very common problem.

It's probably got something to do with the fact that they're 30 to 35 years old and I bet a lot of heat gathers right in that area quickly, seeing as it's the first spot where the exhaust gas from all cylinders on the side comes together...

Headers aren't looking cheap...I want to get some myself...coated headers look to run $180 minimum...add to that good gaskets, good mounting hardware, an A/C adapter bracket, and a new exhaust system (in my case...you could get away with the minimum of mods to hook the headers to the exhaust, from the sound of it) and I'm looking in the $600 to $700 range.

**jerry moss** · 12-05-2002, 07:54 AM

sounds to me as if your exhaust system is either in a bind some way, not enough hangers installed or is being hit by the rear differential when you hit bumps.

JimKshortstep4x4 · 12-05-2002, 08:41 AM

This may be a long shot, but what you are describing sounds like a heat problem. I would suggest checking the initial timing setting and the mechanical advance. If the timing is retarded it will cause more heat to go into the manifold causing it to grow especially at the spot where the cracks are occurring.

Jim

Crank · 12-05-2002, 10:23 AM

Possibly you could have too much weight on the manifold from your exhaust system at the neck of the manifold. Possibly when you fix the problem go back and wire up something to hold up the exhaust from falling and putting excess weight on the manifold. Also maybe try the heat issue, it could be due to excess heat at the collector.
Brandon

12-05-2002, 04:23 AM	#1
JVictor75 Maintenance Man Join Date: May 2002 Location: Phoenix, AZ US Posts: 213	Exhaust problems..... Hey guys..... It's been a looooooong while since I visited the board. Not cuz I don't like you guys, but because I've been having money problems and it's just too depressing to read about you all doing what you love with your trucks.... Enough whinin' on my part though, I've got a couple of questions... I went out and found a good condition right exhaust manifold to replace my cracked one with (we're talking the passenger side of a small block here). I went ahead and installed it then drove to Austin Texas for the holidays. Thats about a 110 to 120 mile trip for me. When I got to Austin, my new exhaust manifold was cracked just like my old one was.... do you all have any idea what the deal is? It's cracking right above where the studs screw into the manifold, you know the "neck" of the manifold where all of the tubes meet. The collector if you will.... Yeah it's cracking right at the bottom of that area. Is this normal and I'll just have to patch it until I can afford to put a set of headers on the truck or what? And if I do have to wait, what should I be looking at for cost to install the headers. The truck already has an aftermarket dual exhaust with flowmaster 40's and 2 1/2" tubing. (I'd do it myself but my apartment complex has Nazis for caretaking staff and I cant do much more then change my air filter.)

12-05-2002, 04:45 AM	#2
HotRod929 Registered User Join Date: Mar 2002 Location: Bondurant, IA but in Worcester, MA for school Posts: 767	I dont know but could you possibly be torqueing the bolts down too tight? Or the exhaust ports on the heads are not all even so there is space so when u crank down the bolts to seal it it just cracks shortly under the pressure of the bolts. HotRod __________________ 1970 Chevy C-20 350 V-8 Turbo 350 w/ shift kit Dana 60 w/ 4.10 gears AND Powr-Loc POSI New Additions: Summit Headers 135amp alternator Proform HEI Edelbrock 1406 600cfm carb Sunpro Tach Powr-Loc POSI Edelbrock Performer RPM Intake MSD 6A Ignition Box AIM: HotRod929 Visit My Site: http://1970chevy.netfirms.com/

12-05-2002, 05:10 AM	#3
Project1970 14.1 @ 96MPH Join Date: Jul 2001 Location: Mesa, AZ Posts: 2,811	From his description, I think he means down away from the mounts, closer to the exhaust pipe itself...my passenger side manifold is cracked there too (but not through yet...) and from what I can tell it's a very common problem. It's probably got something to do with the fact that they're 30 to 35 years old and I bet a lot of heat gathers right in that area quickly, seeing as it's the first spot where the exhaust gas from all cylinders on the side comes together... Headers aren't looking cheap...I want to get some myself...coated headers look to run $180 minimum...add to that good gaskets, good mounting hardware, an A/C adapter bracket, and a new exhaust system (in my case...you could get away with the minimum of mods to hook the headers to the exhaust, from the sound of it) and I'm looking in the $600 to $700 range. __________________ Project1970 - LS1 Swap Complete!

12-05-2002, 07:54 AM	#4
jerry moss Born Psycho Join Date: Feb 2001 Location: brentwood,cal,usa Posts: 4,936	sounds to me as if your exhaust system is either in a bind some way, not enough hangers installed or is being hit by the rear differential when you hit bumps. __________________ jerry moss 72 cheyenne super K20- tilt,tach,vacuum,speedwarning,buckets,shoulder belts,am/fm,tow hooks,bumper guards,toolbox,aux. fuel tank,posi front and rear,plus other goodies!!! SOLD 69 suburban K20-tilt,tach,vacuum,speedwarning,buckets,shoulder belts,am/fm,4 inch all spring lift,4 speed, 14 bolt full floater, dana 44 HD,warn winch,posi front and rear,tow hooks,plus other goodies. 73/80 chevy/gmc K20 SB400,turbo 400,205,tilt,a-c,gas hog. 77 K/5 cheyenne blazer-daily driver/beater. SON HAS IT NOW BRENTWOOD,CALIFORNIA

12-05-2002, 08:41 AM	#5
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	This may be a long shot, but what you are describing sounds like a heat problem. I would suggest checking the initial timing setting and the mechanical advance. If the timing is retarded it will cause more heat to go into the manifold causing it to grow especially at the spot where the cracks are occurring. Jim

12-05-2002, 10:23 AM	#6
Crank Registered User Join Date: Aug 2002 Location: Crittenden, KY Posts: 1,965	Possibly you could have too much weight on the manifold from your exhaust system at the neck of the manifold. Possibly when you fix the problem go back and wire up something to hold up the exhaust from falling and putting excess weight on the manifold. Also maybe try the heat issue, it could be due to excess heat at the collector. Brandon



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