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| Cracked header repair (Page 1/2) |
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Rsvl-Rider
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OCT 11, 09:51 PM
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As you can see by the pictures I have two cracks in the trunk side header of my 3.4 V6. The cracks have been there for quite some time and although I don't think they go clear through although they may have expanded over time. As far as I can tell there are no cracks in the firewall side header. I have not driven the car in some time because I'm sure the headers would fail the smog inspection.
I think these may be Sprint headers but I don't really know anything about them or what they are made of. They came on the car when I bought it several years ago. Is it possible to do a repair with some kind of high heat JB Weld type stuff or does it need to be welded? I'm afraid to remove it to have it welded and then find that it won't fit correctly upon re-installation.
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pmbrunelle
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OCT 11, 10:33 PM
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The header should be welded while bolted to a spare head, to avoid fitment problems on the car.
I use countersink head screws to make sure the bolt holes in the flanges are well-centered with respect to the threaded holes in the head.
If you don't have a spare head laying around, you can buy:
http://rodneydickman.com/pr....php?products_id=434
JB Weld is great... but not for exhaust.
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Rsvl-Rider
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OCT 11, 11:25 PM
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pmbrunelle
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OCT 11, 11:42 PM
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When metal reaches 2400 °F, it's glowing white-hot. I can't imagine the stuff sticking to white-hot metal; the 2400 °F claim sounds like a load of marketing bollocks.
Exhaust doesn't get that hot, but I'd expect it to unstick and be blown out of the crack.
The JB Weld might work for a short-term half-assed fix if you're absolutely desperate to get the car working right now, but welding is the long-term quality repair.
If you did want to try the JB Weld route, you should drill out the ends of the cracks, so they don't continue to propagate. But I would avoid the JB Weld altogether; any remnants of it may contaminate the weld job.
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Honest Don
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OCT 12, 12:09 AM
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The jig would probably work, but I’d rather do it bolted to a spare head.
Forget the JB. Taking a welding class at the local CC is the best “car money” I’ve ever spent.
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Dennis LaGrua
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OCT 12, 06:45 PM
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Mig or Tig welding is the only solution to fixing those cracks in the exhaust. Preventing them in the future involves keeping cold water from dripping on the hot exhaust when the deck lid is opened. ------------------
" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "
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Patrick
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OCT 12, 06:54 PM
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| quote | Originally posted by Dennis LaGrua:
Preventing them in the future involves keeping cold water from dripping on the hot exhaust when the deck lid is opened.
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The weird thing is... it appears to be on the other side. 
| quote | Originally posted by Rsvl-Rider:
As you can see by the pictures I have two cracks in the trunk side header of my 3.4 V6.
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pmbrunelle
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OCT 12, 08:11 PM
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| quote | Originally posted by Patrick:
The weird thing is... it appears to be on the other side.
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It would seem that the exhaust heat alone (without water) is enough to cause cracks.
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theogre
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OCT 12, 08:36 PM
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Very likely have engine problems on top of crack exhaust.
Engines running lean or wrong base timing can cause glowing exhaust and this overheating will make broken headers and even cast manifolds.
GM has several TSB for Fiero and other models just for this.
Weld to repair crack line above often won't help for long. More so w/ above issue.
Yes you can, often will, Fail E-test w/ crack exhaust. Worse cracks upstream of O2 sensor can suck air into the pipe and make O2 sensor output bogus data and screw up the ECM even w/o setting any codes.
Running too lean or rich can also cause Cat overheating problems and even destroy it.------------------
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)
The Ogre's Fiero Cave
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Dennis LaGrua
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OCT 13, 10:27 AM
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On second thought this crack could be the result of a leaking EGR tube. I saw that quite a while back on a V6 Fiero that I was repairing.
The manifolds glowed bright red until the tube was replaced. Probably the result of an overly lean mixture
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