Exhaust Flange Retro Fit


    If there's one thing that bugs me more than just about anything, it's got to be those pesky exhaust leaks at the heater box area where it leaks around those pathetic doughnut gaskets!!  I'm sorry folks, but that has got to be the stupidest and all-time cheapest designs the engineers at Wolfsburg ever used.  For the life of me, I can't figure out why they didn't just flange them at the factory and stop the years of frustration by the owners and mechanics alike.  Nothing makes a nice running engine sound like a piece of junk old clunker, than an exhaust leak!!  

exhaust-stock.jpg (31466 bytes)

   Well I'm putting a stop to all my frustration once and for all.  I'm going to add flanges to my heater boxes as well as my new header.  Some folks will just have a muffler shop weld the header right to the heater boxes or "J" tubes, but that will ruin your expensive heater box and make removing the exhaust pipe a real pain.  Flanging is the only way to go!!  If you're thinking of doing this to your exhaust system, give your heater boxes a good looking over.  If they are full of holes and need to be replaced, replace them prior to modifying them as this is a modification that will last the life of the exhaust system.

   I start by cutting off the flared edge of the new header.  Welding requires a very clean surface for quality welds so next I use a wire wheel on the stub ends of my heater boxes and header in order to clean and prepare this surface to be welded.

heaterboxes-prepped.jpg (40181 bytes)             header-prepped.jpg (28092 bytes)

    Exhaust flanges are readily available for pipes with out-side diameters (OD) of 1 1/2" and larger usually increasing in size by 1/8" increments.  For your basic, cheap header, you will need two 1 1/2" for the header and another two 1` 1/2" flanges for the "J" tubes.  But if you are planning to use stock heater boxes, you will need two flanges with 1 3/8" inside diameter (ID) holes.  Gene Berg sells these, or you can make your own.  As usual, I made my own :-)

exhaust-flanges.jpg (40312 bytes) 

    Since you had to cut off the flared part of the header, you were left with a 1" stub that has been expanded to 1 1/2" from 1 3/8"  Since you won't be needing the entire 1"+ of this stub, carefully cut a thin slice with a hack saw that's just wide enough to fit inside the flange.  Trim each side this way and you will have two thin sleeves that you can tap into the 1 1/2" ID flanges which will size them down to approx. 1 3/8" ID.  Don't worry about the fact that they are only loosely pressed in.  When your welder welds the flanges into place during the final assembly, they will be fused together along with everything else.

 exhaust-flange-sleeved.jpg (47878 bytes)             flange-test-fit.jpg (43915 bytes)             flange-test-fit2.jpg (39956 bytes)

   Ideally, you should be able to bolt the header and heater boxes to the engine with the loose flanges bolted together and fitted in their proper locations.  Then tack them all in place.  Remove the header and heater boxes and finish welding everything.

   Here's a few shots of the finished welds on the newly flange modified heater boxes and header. 

header-flanged.jpg (29630 bytes)             header-flanged2.jpg (32803 bytes)             heaterbox-flanged.jpg (34285 bytes)             heaterbox-flanged2.jpg (39728 bytes)

    During the final assembly on the engine, you will use a standard exhaust flange gasket between the flanges to get a tight and leak-free seal.

 flange-gasket.jpg (35647 bytes)

    Here's a couple of shots of the completed and installed flanged exhaust header.

flanged-exhaust.jpg (28782 bytes)             flanged-exhaust2.jpg (37910 bytes)

UPDATE (01/15/01) - BUYER BEWARE. . .  I'm totally disappointed with the factory finish on the EMPI header and dual quiet pack muffler system.  The factory paint on both completely burned off within about 2 weeks and now I am left with a "new " exhaust system that looks like it's 5 years old.  I would HIGHLY recommend paying the extra $$$ and getting either a ceramic or jet coated system.  Nothing makes a car look bad like a rusty old muffler out back.  Also even though I purchased a "bus" system, I had to make a spacer for the muffler flange that would lower the mufflers slightly when installed.  Without this modification, I couldn't get my stock bumper on.  Not a good fit OR finish with the EMPI product this time!!  Next time, I'll take my money elsewhere :-(  Here's the "NEW" system after only 500 - 700 miles on it!!  And I effectively live in the desert where it almost never rains.

crappy-exhaust.jpg (43420 bytes)

    I ended up having to bead blast the entire thing down to bare metal and then apply some ceramic header paint to it.  To cure it, I heated it in an oven for about 4 hours @ 250 degrees F.  I'll let you know how this lasts.  The exhaust saga continues. . .


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