OEM Headers: Crack & O2 Bung Repairs?

[~JM~]

Removed my headers & see the crack on the rear tube on the driver side header. Haven't really examined both very closely yet. What should I be looking for? I've heard mention of cutting the mounting flange & creating clearance for expansion & contraction. Also heard of an additional brace welded in. Are the heat shields typically cut off & then tacked back on after repairs/modifications? I have a spare set of heads to bolt up to.

O2 sensor bung repair? My O2 sensor has been cross threaded. I chased the threads, but I believe it has probably been done before. The O2 sensor will not thread in & seat flush. Any reason a new bung couldn't be positioned about 90 degrees away from the original one? I need to mock it up before selecting a final position, but I'm thinking there should be a spot available with better access for sensor replacement.

Thank you.

[Steve Wood]

my experience is that cutting the flange may make the problem worse, not better.  Some put a gusset between three and five to add more strength.  I'm not sure that helps either  Probably does not hurt is about the best I could say LOL  The tubes are old and thin and that adds to the problem.  

A good welding solution that uses tig and floods the inside of the pipe with gas to make the repair as clean as possible is probably the best solution and make sure the entire area is heated up so the cooling off is over a larger area rather than stressing along the weld helps.

the most effective solution is to replace the header in question...wel l, not effective in the cost for sure. smh.  The Chinese imports are cheap, fragile, thin, and may not fit.  Not much of an option at all from all the reviews I have read.

My first thought on the O2 bung is to heli-coil it if the correct threaded insert is available.  There is no reason you cannot add another bung, tho.  Just make sure it is in a place that the wire to it will not get burned.  I would keep it as close to the turbo as possible but a little lower should not hurt.  It needs enuf room to allow all six cylinders to be mixed so you get an average reading.

As long as it does not leak, it should not hurt to have a 1/16" of clearance between the base and the bung, imol.

[ULYCYC]

I wont offer and advice on repairing the header tubes other then good luck.  The O2 bung is easy.  Its a sparkplug thread so a sparkplug thread chaser like a    Lisle 20200 will do the job. If not a sparkplug repair kit with helicoil will work. I wouldn't try and drill holes and reweld a bung on 35 yr old shitty stainless steel.

[Steve Wood]

good advice

[~JM~]

This is what the old O2 sensor looked like when I removed it. The threads in the O2 bung are not "square" or "plumb" for lack of the correct term. The threads are angled into the bung causing the thread tap or chase to follow at an angle. I was able to clean up the threads to accept the new sensor, but the base of the sensor does not meet the shoulder evenly. It sits at an angle.

What type of cleaning process should be performed to prepare for a successful repair?

What replacement options are available. Prefer to avoid imported parts.

[~JM~]

Hmmm... The picture appears short & wide.

[ULYCYC]

I would just try and use the thread chaser and screw in a new O2 sensor with some high temp RTV on the threads.  Your only sealing exhaust gas  and not compression. It should hold and work. Even if it goes in a little off center, it won't effect the O2 readings.

[Steve Wood]

Hmmm... The picture appears short & wide.

Some windows rescaling programs seem to not reproduce accurately here.  I don't recall if Paint works okay or not, but I generally use an aftermarket routine with no problems.

[~JM~]

my experience is that cutting the flange may make the problem worse, not better.  Some put a gusset between three and five to add more strength.  I'm not sure that helps either  Probably does not hurt is about the best I could say LOL  The tubes are old and thin and that adds to the problem. 

A good welding solution that uses tig and floods the inside of the pipe with gas to make the repair as clean as possible is probably the best solution and make sure the entire area is heated up so the cooling off is over a larger area rather than stressing along the weld helps.

the most effective solution is to replace the header in question...wel l, not effective in the cost for sure. smh.  The Chinese imports are cheap, fragile, thin, and may not fit.  Not much of an option at all from all the reviews I have read.

My first thought on the O2 bung is to heli-coil it if the correct threaded insert is available.  There is no reason you cannot add another bung, tho.  Just make sure it is in a place that the wire to it will not get burned.  I would keep it as close to the turbo as possible but a little lower should not hurt.  It needs enuf room to allow all six cylinders to be mixed so you get an average reading.

As long as it does not leak, it should not hurt to have a 1/16" of clearance between the base and the bung, imol.

I have another dumb question... I can't remember which tubes the dipstick passes between. Need to verify clearance before welding a brace between tubes 3 & 5.  Thank you.

[Steve Wood]

comes between 3&5.  Bracket on the tube goes to the top bolt of number three

[~JM~]

comes between 3&5.  Bracket on the tube goes to the top bolt of number three

Thank you. I was thinking that was the case. Reinforcement bracket needs to be kept short. Any idea of height limit?

I'm in the midst of juggling the car details, contractors & painters. 

[Steve Wood]

Neither of my cars has a factory header on the drivers side so I cannot say for sure.  The crack is generally on the back side of the joint between the two pipes.  I think a gusset would have to be put as low as possible...dow n around the area where the heat shield is.

gnonxy has done a lot of work on his factory headers, you might send him a pm and see if he took any pics of whatever he has done

[Steve Wood]

probably the best advice I can give you is to buy a stock replacement header from TA Performance as they sell their version singly if so desired

http://www.taperformance.com/proddetail.asp?prod=TA%5FV2009D

[~JM~]

Local fabricator was able to weld driver side header & swap O2 bung. I asked him to add an extra O2 bung in a location that I think will provide easier access.

[~JM~]

The new O2 sensor bungs are a slightly taller profile. I'm hoping the O2 sensor will still function correctly. Might take a bit longer to warm up fully.