GJB928

I'm 3 months deep into my exhaust project now. Over the summer I was getting exhaust fumes in the cabin. I had previously fixed a leak at the emissions test port in my crossover pipe so I thought that it may have been a bad sealing ring. I've burned my hands many times trying to isolate an exhaust leak before I learned a new trick on the forum.

I have a spare shop vac that I've thoroughly cleaned and installed a HEPA filter on. This vac allows me to switch ports so it can blow. I put the hose into my exhaust pipe and seal it and turn it on to the low setting. I immediately find my leak at the header y's. Both 1-4 & 2-3. They each had a crack right down the middle of the weld. I was able to see this because they are Speed Force Racing Headers, thus no heat shields. Let me say, the welds are absolutely beautiful compared to the factory porsche headers (I'll post some comparison pics). However for whatever reason they cracked right down the center of the welds.

I had the receipt from the previous owner for the headers and I called SFR and asked what my options were. Tim was very pleasant to deal with and offered to sell me a new set at a discounted price. The last set was 7 years old and the replacements were $1000+ with a 5 year warranty. I'm having a difficult time justifying another $1000+ after the last set failing and only getting a 5 year warranty.

So I started searching for a stock set. Lart had a set for a reasonable $199.00 I bought them and built a rig to test them before I put them on. The 1-4 was in perfect shape. Absolutely no leaks.

1-4 header pressurized to 20 psi
The 2-3 blew bubbles like a Jacuzzi.

2-3 major leaks
Lart sent me another 2-3 but it leaked also. Next I found a set at 944 Reanimation. I asked if they were leak/crack free before I bought. They assured me they were off a low miles car and were leak free. I anxiously awaited them and pressured them up within minutes after arrival. 2-3 was a no go. 944 reanimation then sent me 3 more 2-3 headers and they all leaked!

Next I posted on this forum and a member graciously offered up a 2-3 header to try (I paid shipping so he was not out any money in trying to help me). Again that one leaked also.

In the mean time, I took the SFR headers to a local fabrication shop that builds custom exhaust and they fixed the cracked welds in the SFR headers. Tested them and no leaks. But now I'm really wanting to return to stock headers with the heat shields. Here in CA, depending on the smog tech, aftermarket headers are an immediate fail. I'd rather not go through that again. So if anyone wants a set of SFR headers that have been repaired, for less than half the cost of new ones let me know. I'll be doing a separate post for those.

So now I'm curious, why are there so many cracked 2-3 headers and the 1-4s hold up? I'm going to find out. Stay tuned as I start dissecting them.

Also if anyone has a 2-3 header laying around, I would like to try to find a good one. I'll pay shipping and pay for the part if it's good.

GJB928

Here is my process for removing the heat shields. They are a clamshell design where the two halves are spot welded together then tack welded to each section. I started by using a thin cutoff wheel on my Dremel to cut the weld joining the sections at the 90 degree bend.


Next I used a 1/8 titanium single cut burr in my Dremel to cut out the top layer in the spot weld.

Its a very slow process, but I didn't want to mangle the heat shield because I will reuse them when I fix the crack.

Almost done.

Success!

The heat shield came off without any deformation or damage. They should go back on easily.
It looks like the insulation MIGHT be asbestos. I used a respirator while grinding and had soaked the header in water while testing for leaks. The insulation peeled off like wet toilet paper. I disposed of properly.

Next is to identify the source of the leak

MAGK944

GPA951s

Great Procedure… I shoved a regulated air hose in mine and Duct taped it shut and felt around for air. Im Tempted to light up a smoke bomb and then pressurize it.. LOL
Anyhow.. The Expansion rate of the alloy used on the header is different than the aluminum of the engine. The 1 and 4 have that accordion thing-a-ma-bob (expansion joint) on it allowing it to move freely. the 2 and 3 are hard mounted and when the engine gets heated up its like pulling on a wishbone.
Years ago I removed the heat shields on my 86 to find the cracks. I welded them up but I used filler rod and Purge welded them so I penetrated all the way through. That was ten years ago and no leaks. I welded the heat shields back on as well. There is some discussion as to what form of stainless the headers are made of but I will tell you, Stainless Moves with heat. I used to do sanitary welding for the food industry and worked with it daily for 5 years. It is Truly amazing how much it moves with heat. An old-timer said that if you took a 20 foot piece of 4" tube 2 foot off the ground and just poured boiling water into it so It flowed (heating just the bottom) that the other end would touch the floor, essentially making into a banana shape.

GJB928

I'm planning on using some of the lava header wrap. I think the 3" could be cut and formed into the heat shields with only one or two seams. It looked like that was the way it was done at the factory.

GJB928

Pretty well settled that they are made of Inconel.

elanman

Surprised you managed to get 1-4 to seal when of a car/engine .1-4 has a sleeve joint that works with expansion and the I guess the bellows seal any small leakage before it heats up
In my case the bellows do leak but the sleeve joint seals after a very short warm up period

GJB928

Interesting. I have two 1-4 and neither leak when cold and underwater.

divil

Same here. I have exactly the same test set up as you and have tested 2 1-4 pieces and they were fine, even though the bellows feels a little loose on both. As for getting them to fit on the car however...

From reading the archives it seems it's the 2-3 piece that cracks the most.