exhaust gasket issue.

i 've got a 1990 b2600i with a shot exhaust system.  my first step is replacing the gasket at the manifold and down-pipe.  the one i got from autozone was a fel-pro # 60817 (manifold flange)  although it more resembled the fel-pro # 60831 which is designated for the converter.  the thing is a few weeks after install and a bit of driving it appears have begun to fail and leak. 

my question is:  why is this new gasket burning up?  the material it's made of is beginning to ash and one side is almost blown out.

should i get a beck/arnley one instead?  (# 039-6382)

thanks

did you tighten the bolts in sequence? i'd get another gasket. tighten it from the middle out and see how that works.

sorry let me clarify..

this is the gasket on the manifold flange to the downpipe, not at the head it self.  there's only two bolts on this flange.

as an update, i soon realized my mistake.  when i replaced the gasket i neglected to remove all of the remnants of the previous gasket.  the pieces left over were actually welded into the flange of the manifold.  making it difficult to realize they were there.  having not properly cleaned the flange allowed the gasket to burn prematurely and therefore leak.  to remedy the situation i removed the exhaust manifold (surprisingly easy) and used a dremel to remove the old gasket bits.  moral of the story, i'm an idiot and didn't do a thorough job the first time.

i do have another exhaust question though.  i'm looking to replace my muffler with a bosal unit. i soon realized they specify a different mufflers for the 2wd than the 4wd.  (2wd unit is $40 cheaper but looks identical, guess which one i'd like to use) this is in regard to the mid muffler not the one incorporated into the tailpipe.  i plan on using a tailpipe off a 2200.  apparently they were not burdened with a second muffler on their tailpipe.

my question is:  is there really any difference in the two units?  both are 1990 2600i long wheel base.


               bosal 171-541 4wd                                                         bosal 171-533 2wd

btw, the factory exhaust manifold on a 1990 b2600i weighs 21.2 lbs.

The second muffler in the tailpipe you describe is probably only a resonator and doesn't/shouldn't affect the backpressure, performance or mileage just mellow the tone a bit. 
 
From the pictures above it's hard to tell but it appears that the 2WD muff has a center outlet whereas the 4WD unit has a left side outlet...??  Also the front hanger looks shorter on the 4WD unit, perhaps because it hangs closer to the floor boards than the 2WD does??
 

hey, how much are you getting the bosal muffler for? a muffler shop here told me they would so a univ. muffler for me for $55, so i'm just wondering how much a bolt on one would be.
thanks.

i've been looking on-line at autohaus arizona.

they give a price of $126.60 shipped for the 4wd version and $94.39 for the 2wd version.

quote:

ORIGINAL: virgin1
The second muffler in the tailpipe you describe is probably only a resonator and doesn't/shouldn't affect the backpressure, performance or mileage just mellow the tone a bit. 

From the pictures above it's hard to tell but it appears that the 2WD muff has a center outlet whereas the 4WD unit has a left side outlet...??  Also the front hanger looks shorter on the 4WD unit, perhaps because it hangs closer to the floor boards than the 2WD does??

true enough regarding the resonator on the tailpipe but price-wise the difference is substantial.  $38.77 w/o versus $87.64 with.

regarding differences, i notice some of the same ones you mention.  however, i'm hoping for a confirmation because i think the pictures leave too much unanswered.

thanks though.