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Edelbrock TES Header repair


Schurkey
10-11-2015, 09:11 PM
Thousands of years ago, Edelbrock sold Tubular Exhaust System (TES) "headers" that were smog-legal having the appropriate EPA and/or CARB certifications. While not equal-length headers, they sure were more streamlined that the OEM iron manifolds.

I bought the Edelbrock P/N 6667. Edelbrock was still selling TES in "Stainless Steel", which I thought was a wonderful idea. They were NOT inexpensive. They did seem to be nicely made, though. They included gaskets, hardware, the two "headers", plus a Y-pipe which would connect to the OEM catalyst. The part number I bought also has provision for the AIR injection plumbing.

http://hbassociates.us/K1500_TES_Instructions.pdf

In my case, I had just popped an engine at 230K miles; and the existing exhaust system was pretty-well toast. I bought the TES, a new high-flow catalyst, and an aluminized mild-steel Flowmaster cat-back system, in about 2000 or perhaps 2001. The Flowmaster system developed rust holes big enough to push a puppy through within a dozen years. I replaced that with a stainless steel muffler and tailpipe, keeping the previous catalyst and about a foot of Flowmaster pipe. And all was well for about two or three years.

Over the summer, I've had a very annoying exhaust rattle, and lately the exhaust noise level has gone completely obnoxious. I clearly had more exhausting work ahead of me. The rattle was simple: The welded-on heat shield for the catalytic converter had broken a weld. The heat shield was vibrating with the exhaust pulses. I wasn't willing to re-weld the shield, so I wrapped a huge-long clamp around it. I tighten the clamp, the clamp holds the shield--and no more rattle.

This is the story of how the Edelbrock "Stainless Steel" TES let me down.

True enough, the header flanges at the engine, and the header pipes--including the Y-pipe--are in fact stainless steel. The friggin' hardware was NOT, however, and that includes the "permanently-attached" flanges that hold the Y-pipe to each of the header collectors. These flanges are the securing method to keep the exhaust "donut" gaskets in place. When the flange rots away, the donut gets loose, and the exhaust gas leaking past a donut will cook it in short order.

My quest was to not only replace the leaking donut gasket on the right side, but to figure out a way to secure that side of the Y-pipe, since both flanges were horribly corroded. The first challenge is that Edelbrock has discontinued the p/n 6936 donut gaskets. As it turns out, I own a set of the disco'd parts--but I wanted a replacement number in case I'm not the only person on Earth that still has one of these systems.
Fel-Pro 9998 is readily available and dirt-cheap. I think they're about three dollars each at my local NAPA.
http://hbassociates.us/K1500_Exhaust_Donut_01.jpg

Replacement flanges (Walker part number 36130, 2 1/2" nominal size) are made with a split design. The original one-piece flanges are installed over the pipe, then the pipe end is flared. Because I can't un-flare the pipe to install inexpensive one-piece flanges I have to install these expensive two-piece replacement flanges. The remains of the original flanges are cut off, and the split-flange bolts on in the same area of both the "header" and the Y-pipe (since both original flanges are totaled.) I got mine at NAPA, they're p/n EXH 36130, $26.49 each.
http://hbassociates.us/K1500_Exhaust_Donut_02.jpg

The "header" (on top, in this photo) and the Y-pipe (lower) come together to sandwich the donut gasket in a formed seat. The rotted flanges have already been cut off.
http://hbassociates.us/K1500_Exhaust_Donut_03.jpg

Dead, leaking donut on the Y-pipe seat. The donut is a metal-reinforced high-temperature fiber.
http://hbassociates.us/K1500_Exhaust_Donut_04.jpg

Donut seat cleaned-up and ready. Removing the old donut was no fun at all. I spent plenty of time with a hammer and custom-sharpened chisel to get the biggest pieces out, and then cleaned-up the rest with a variety of picks. Eventually, I wire-brushed the last of the donut from the formed seat.
http://hbassociates.us/K1500_Exhaust_Donut_05.jpg

Fresh Walker flange and fresh Fel-Pro donut in place
http://hbassociates.us/K1500_Exhaust_Donut_06.jpg

Upper and lower flanges in place, donut tightened. Steel nuts supplied with split flanges were replaced with brass for ease of disassembly the next time this disaster happens. Also brass nuts on the vertical bolts, holding the two flanges together, sealing the donut. Bolts were too long (all I had handy) so I threw on some oversized steel nuts as spacers to take up the extra bolt length. I've got anti-seize on all the threads even though that shouldn't be needed with the brass nuts. Make no mistake--I LOVE brass nuts when doing exhaust work! They're expensive and somewhat hard-to-find, but they're worth the trouble. I will allow this to "season" for fifty or a hundred miles, then re-tighten the vertical bolts that secure the donut.
http://hbassociates.us/K1500_Exhaust_Donut_07.jpg

NO, I was NOT brave enough to disassemble the non-leaking left donut! It seemed solid 'n' secure, and that's good enough for now! I am not eager to discover the only thing holding those flanges together is the rust; and I'm not eager to drop ANOTHER sixty dollars in replacement flanges and brass nuts. I did shine a flashlight down the neck of the converter, which appears to be just fine--not melted, not cracked, not plugged with carbon/antifreeze residue/oil residue/squirrel carcasses. The Y-pipe was sealed to the converter neck with a fresh 3" formed-stainless-steel band clamp; one of the wonders of the exhaust world. NAPA p/n BK 73 33222, $11. The previous clamp was starting to crack. Band clamps can sometimes be re-used; but not always. My old one was as bad as the flanges.

I am considering buying some one-piece flanges, welding some tubing to the side, and then putting 'em through the band-saw to make my own split flanges. I bet I could build split flanges similar to the ready-made Walker parts for ten dollars instead of $26.49 each, plus tax.

Blue Bowtie
10-12-2015, 06:06 AM
Well done, and a very informative and useful post (I'm recording the part numbers).

Not to defend anyone, but the manufacturer didn't necessarily mislead you. Not all stainless steel is high nickel. 400-series SS will eventually rust, albeit more slowly, and is extensively used in exhaust systems because of its reasonable corrosion resistance and superior strength to 300-series SS. High nickel SS will also corrode eventually, is by far weaker, and suffers crevice corrosion and stress cracking far worse than 400.

Schurkey
10-12-2015, 03:12 PM
Yep, I intended the part numbers to go down in posterity, and I try to itemize part cost, also. Some poor bastard is going to need those donut numbers; I hope he finds this thread to show that even with the flanges rusted to nothing, the headers and Y-pipe are probably still usable.

The "header" and the Y-pipe are stainless of some sort--there's no real rust on them, after close to a hundred thousand miles, although there's some staining from oil and road splash. However, the flanges that rotted out were plain ol' mild steel.

Schurkey
11-04-2015, 11:36 PM
The rattle was simple: The welded-on heat shield for the catalytic converter had broken a weld. The heat shield was vibrating with the exhaust pulses. I wasn't willing to re-weld the shield, so I wrapped a huge-long clamp around it. I tighten the clamp, the clamp holds the shield--and no more rattle.
...For a week. The rattle came back as the clamp "seasoned". Instead of the shield rattling, the loose "tail" of the clamp was vibrating. I tightened the clamp several more turns, and cut the tail shorter--and bent the stub away from the rest of the exhaust system--to resolve this...again.

I will allow this to "season" for fifty or a hundred miles, then re-tighten the vertical bolts that secure the donut...

...NO, I was NOT brave enough to disassemble the non-leaking left donut! It seemed solid 'n' secure, and that's good enough for now!
"Seasoned" for a month, and much more than a hundred miles. Gave the vertical fasteners a quick tighten, (less than one full turn) although they may not have needed it. The left donut continues to be secure and quiet.

I'm satisfied--Job completed.

j cAT
11-05-2015, 09:56 AM
I don't agree with the brass nuts. brass is soft and will loosen over time esp. with the heat/vibs working on it. I use SS on my exhaust bolts / nuts , for many years and once these are installed I can re-use them again . years ago with a rusting steel pipe system I re-used the ss hardware clamps/bolts/nuts , and installed the new system every 3yrs. I got 6 replacement exhaust systems under warranty on my 1983 no cost. the ss hardware is very expensive compared to the steel crap. Brass nuts of the larger sizes are a tough find. mixing metal parts does cause problems with salt . nuts can get eaten ... the bolts that are on my 2000 silverado are ss. looks still real good factory hardware. I can see cleaning the old ss pipes on your exhaust was was not easy , when you have to be careful not to damage the joint . felpro donut is a good product. I had to do this back on my 1983 20 yrs ago.

j cAT
11-05-2015, 10:09 AM
I did use the split flanges a few times. with ss hardware they lasted as long I owned it. used them on my 83 and my current 96 impala. so far my 2000 silverado has had no exhaust work done . at least GM did that properly. on the cat converter heat shields I do not use clamps. I use ss wire. using .050 dia this stuff is great and will never fail to keep the ss shield for rattles. cheaper than steel clamps , looks better never loosen or rust up..

Schurkey
12-30-2017, 11:52 PM
I replaced that with a stainless steel muffler and tailpipe, keeping the previous catalyst and about a foot of Flowmaster pipe.
Well, OK, it was more like two feet. Guess what failed next...

The aluminized Flowmaster pipe is history, replaced with Stainless Flowmaster pipe. God bless band clamps. This was simple and easy...



...and while I was underneath the vehicle, I looked over my previous flange-and-donut work. It's holding together nicely.

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