DS Header is finally starting to crack!

[d0n_3d]

Just when my car was doing great performance wise, it's about to change because the other night after checking my motor for any problems, i happened to notice that the stock heat shield on the DS header had came loose...i moved it around and noticed some very faint, short white cracks on the header in the all famous spot...this header is factory and has never been welded...i think it's starting to crack now because when i bought the car it had never been driven hard and my car was kept stock until last summer...i have turned up the boost on the stock turbo since then and now have added a te-44 and lots of other mods...is this why the header is starting to crack now at 90k miles? what is the car going to do now with a slightly cracked header? and i do want to fix this...i don't HAVE to take this thing off do i? can't i just take it in a shop and have them weld it by taking my wheel off? it's fairly easy to get to from underneath...i can't weld it myself though...any suggestions?

 

[1970gsx]

Take it off. It's much easier than you think. I just did my ps header today. Took it off, welded the crack, and had it back on in an hour and a half.

 

[tom h]

Don,

yes, headers are surprisingly easy to take off... when I first looked inside my 87GN, my initial reaction was "I'll have to take the engine apart to get at them!" , but not true. (mine isn't cracked but I took it apart for other reasons).

In summary,

-- raise front end of car on jackstands.
-- remove driver side wheel.
-- spray header bolts (D/S only) and crossover pipe bolts (D/S and P/S) with "liquid Wrench" or equivalent. Let it soak as long as possible.
-- remove oil dipstick
-- remove crossover exhaust pipe, by loosening bolts at P/S and D/S ends.
-- remove alternator brackets etc, that are mounted to D/S header.
-- remove all bolts on D/S header.
-- remove header from bottom, not top.

I may have forgotten a couple minor things, but this is the main work.

You'll note there are no gaskets used between header and cyl head, or between header & crossover pipe. None needed, nor recommended in most cases.

Do a "header crack" search on the Forum, you will see it's mandatory the header be bolted to an old cyl head before welding to prevent warping of header.

The headers are 409 stainless, I've read it's possible to use 309 filler rod for maximum ductility (more flexible, somewhat less likely to crack again).

make sure all sealing surfaces are clean and free of rust & crud before re-assembling.

When re-assembling, use antiseize compound on all bolt threads.

I don't recall the correct bolt torques, off hand, but could look it up if you need to know.

{ADDED: it may not be necessary to remove driver side wheel, but I found it helpful to be able to reach thru the wheel well to access some of the bolts.}

 

[Dan Thompson]

tom h,

Did you leave the bolts the same or did you cut off the treads on the fender side?

When I changes plug #6 I could have used the extra space.

 

[salvageV6]

Don't take it off until you have proven it leaks a bit.

They all stress crack first sometimes without leaking.

Look for black carbon tracks and feel for air leaks or use the paper test.

Use a mirror too gotta look everywhere. Take the heat shield off it has to come off to weld it anyway and can be tacked back on afterwards.

If you can't see or hear it you may have a year or two left.

A poly. drivers side motor mount might help with the stressing of the thing.

It's about 1-2 hours to get it off without a lift I would say for your first time.

 

[d0n_3d]

well like i said...the cracks are very small and there's white residue in them which is carbon i believe??? i've heard that if you have enough carbon buildup around the cracks it tends to seal them...right now i don't hear any loud ticking and my boost doesn't fluctuate (yet)...it goes up at a steady pace

but i am afraid once i turned the wick up on the te-44 past 10 lbs i am gonna see the header get way worse...i havent pushed the te-44 turbo past 10 lbs yet because i am still waiting for my 50 lb injectors!!!

 

[tim87tr]

Originally posted by d0n_3d
well like i said...the cracks are very small and there's white residue in them which is carbon i believe??? i've heard that if you have enough carbon buildup around the cracks it tends to seal them...right now i don't hear any loud ticking and my boost doesn't fluctuate (yet)...it goes up at a steady pace

Good repair info by tom h...should put that on gnttype since I don't think they have all that. To follow up what salvage said, I would just leave it on until you hear the ticking noise and have slower spoolup. I did not fix mine until I heard the loud ticking sound at idle and the car still ran pretty good. Tim

 

[tom h]

Originally posted by Dan Thompson
tom h,

Did you leave the bolts the same or did you cut off the treads on the fender side?

When I changes plug #6 I could have used the extra space.

I replaced with new factory studs on the D/S, but only in those locations where an accessory bracket must bolt to it.

All other header bolts, I replaced with appropriate lengths hex-head, flanged cap bolt (not stud), black oxide finish. Under the flanged bolt heads, I put a Belleville style spring washer (stainless). IMO, these "lock" better than an ordinary split ring lock washer.

Overall it looks "stock-like". I would have preferred stainless flanged cap bolts, but couldn't locate any.

I don't yet know if this setup will lock as tightly as the special factory stud, which has a unique 1-way, ratcheting type of washer on it.

If my replacement bolts work themselves loose, I'll go back to the factory studs, but cut off the protruding stud (ugh, PITA).

On some of my bolts (especially #6 cyl), a normal socket & torque wrench will not fit in. I used a "torque adapter" on end of torque wrench to reach those bolts, from the underside of car I think. For those of you unfamiliar with a "torque adapter" , it's a flat tool 2" long, with a box end wrench on one end and a 3/8 square drive opposite end. It gives the torque wrench a bit more reach, when its head won't fit in. MORE torque gets applied with the adapter than is indicated on the wrench (since it lengthens the overall wrench length), but this can "usually" be ignored unless the application is super-critical.
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