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| Durango_Boy | Pesky Header Leak...Seeking Creative Alternatives !!! | ||
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Elite Guru
 
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Okay so I have a SBC, 405, aluminum Vortec heads...in my 1977 Corvette, and a new set of Hooker side mount headers and side pipes. By new, I mean I installed them winter before last when I put the 405 in the car.
  Right from the start up I had leaking at every primary. I tried a new set of gaskets. Leaked. I tried a set of dead soft aluminum gaskets. Leaked. At this point I was stumped. I had checked them for square surfaces and the heads were new and I've had many sets of Hooker headers and never once had such a condition. So, I got ambitious and I pulled the headers out of the car so I could see what was going on. Using a Sharpie I colored the ends of the primaries and ran a file across in several directions and I found gaps on all four sides of each primary tip. Sooooo...I spent about three hours per set of headers hand filing the tips until all the Sharpie was filed off in a flat even square pattern. I was confident I solved the gap issue. While I was doing all of that work I also cut the flange apart so each was separate.  I put the headers back in with another new set of gaskets and it started up with no leaks. I was sooooo happy... ...until I started hearing that tell tale popping again. Man, the leak was back. However, this time it was JUST the center set on both sides. #3/#5 and #4/#6. I started realizing I just wasn't getting the torque I needed on the fasteners with the open end wrenches. They were separating and slipping off before I could get them tight enough. This is where I carefully dimpled the primaries between the fasteners and the tubes and beat in a socket wall until I could get a socket on them and with an extension...use a ratchet to tighten the bolts. I did this to both center sets. All was well for a few days of driving but now I have VERY SLIGHT puffs from both center sets again, and while I know I'm super close to solving this I'm still not quite there yet. I still have my set of dead soft aluminum gaskets and I have an evil plot... ...I want to take apart the dead soft metal gaskets and use a layer or two, along with a new set of standard gaskets. I like the double gasket idea but maybe not two standard gaskets together. I'm thinking two of the metal gasket layers, with the gaskets, and maybe with a bit of that high temp copper sealer between the two. Does anyone agree that extra layer might help me squish and seal and finally lick this leak? |
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Posted on: 2012/4/26 1:55
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| 76Nordic | Re: Pesky Header Leak...Seeking Creative Alternatives !!! | ||
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Dumbass
 
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I never had any luck doubling up gaskets of any kind. Did ya try the soaking in water trick with the gaskets??
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Posted on: 2012/4/26 2:22
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The Definition of insanity; Doing the same thing over and over again, and expecting different results.....Einstein 
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| 1Fast04Vert | Re: Pesky Header Leak...Seeking Creative Alternatives !!! | ||
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Elite Guru
 
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"While I was doing all of that work I also cut the flange apart so each was separate."
Sure that was a good idea?? Seems to me that would cause a leak. |
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Posted on: 2012/4/26 2:39
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2004 Vert. 475hp. Built by Vengeance Racing |
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| pianoguy | Re: Pesky Header Leak...Seeking Creative Alternatives !!! | ||
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Guru Emeritus
 
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I've read about guys running a bead of high-temp RTV around the ports, but I've never tried it. I may just do that myself if I ever get around to putting my headers back on - I always had problems with leaks.
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Posted on: 2012/4/26 3:04
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1996 LT4 �Before you criticize someone, you should walk a mile in their shoes. That way when you criticize them, you are a mile away from them and you have their shoes.�- Jack Handey |
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| Matatk | Re: Pesky Header Leak...Seeking Creative Alternatives !!! | ||
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Webmaster
 
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I used stainless steel allen cap bolts with locking washers. No leaks here.
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Posted on: 2012/4/26 3:26
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2002 EBM convertible, Magnusson supercharger, cam, headers, etc. 1989 Corvette...RIP |
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| Durango_Boy | Re: Pesky Header Leak...Seeking Creative Alternatives !!! | ||
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Elite Guru
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Quote:
I had more leaks before I cut the flange and some manufacturers don't even use the full length flange to begin with. Really it's a quick way to get the tubes all welded to the same plain. The flange thickness is what's important so you get compression before the flange starts bending. The fact that they are all now separate makes installation and removal easier, as well as the fact that now I can change a single primary's gasket without changing any of the others. I'm so much more happy with them cut apart than I was with them as a single one piece. Matt, I am using ARP 3/8" hex head header bolts. They allow the use of a 3/8" wrench or socket which gives more room that the traditional 7/16" wrench bolts. On top of that these have double sets of a unique lock washer. They don't back out and I mean that seriously. The problem is that the bolts are typically tucked into a dimple and there isn't room to get anything all the way around the head of the bolt. That's why I dimpled them for a deep wall socket so I could get a ratchet on them. I tried Allen fasteners first and broke two Allen wrenches trying to tighten them. The extensions just had to be too long and they weren't strong enough for that kind of torque before they would twist and snap. |
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Posted on: 2012/4/26 11:44
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| BillH | Re: Pesky Header Leak...Seeking Creative Alternatives !!! | ||
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The Stig Moderator
 
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That works for small gaps. I do it on the racecar. But it's messy, wouldn't look good on a street car. And my heads come back off every 3 hours of run time. |
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Posted on: 2012/4/26 13:28
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| Matatk | Re: Pesky Header Leak...Seeking Creative Alternatives !!! | ||
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I never broke an allen wrench tightening my headers and I have no leaks.
Perhaps it's something with the heads themselves. |
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Posted on: 2012/4/26 13:33
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2002 EBM convertible, Magnusson supercharger, cam, headers, etc. 1989 Corvette...RIP |
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| Durango_Boy | Re: Pesky Header Leak...Seeking Creative Alternatives !!! | ||
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Elite Guru
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Bill, what're your thoughts on using a couple layers of the dead soft aluminum gasket, sandwiched with the standard gasket? Face the aluminum to the header primary tip, layer of copper RTV, then the gasket, clean to the face of the cylinder head? |
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Posted on: 2012/4/26 13:53
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| BillH | Re: Pesky Header Leak...Seeking Creative Alternatives !!! | ||
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The Stig Moderator
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Might work, might not. I'd be really supprised if the cyl head is the problem. Flat filing the primaries was a start, sometimes not that easy to do. It isn't easy to hold the file flat while you're using it, have to maintain the pressure on top of the file with your left hand. You have an extra set of heads laying around? I think if you do, you could clamp one to the bench and work on getting the headers flat much easier that way. What I would do is work with them off the car, bolt them up lightly to a head to start, check the mating surfaces with a .0015 feeler gauge and maybe Prussion Blue. IMO, having to overtighten the bolts means something's not flat. And you can't be sure you have the surface flat by just filing (though that's a good start). You could also use a standard gasket (on the bench), lightly tighten up the header, pull it off and look at the pattern on the gasket. I always tighten the center tubes firet then the outer ones. Headers are always a pain. |
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Posted on: 2012/4/26 14:14
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Every man dies but not every man lives. |
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| Durango_Boy | Re: Pesky Header Leak...Seeking Creative Alternatives !!! | ||
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Elite Guru
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I don't feel I have even come close to over tightening and even now with the socket access I am being very careful with how much torque I'm giving them. Last thing I want to do is strip out the threads in the aluminum.
I spent about 3 hours per set of headers when I filed them. I was super careful to change directions and maintain an extremely flat pattern with a lot of pressure. It was hell. Arms and hands burned from the workout. After I was sure they were all flat I squared them again, and checked them on two different squares. Then re-Sharpied and re-checked by lightly running the file across again and all the Sharpie filed right off. I have no doubts I got the primary tube tips flat. The leak is always at the top of the primary and not bad enough to burn / blow out the gasket. More like light puffs. I think it's a header design flaw and the top of the primary is not mating perfectly with the cylinder head when the bottom of the primary is flush. The leaks were always worse on the tops and all have been sealed except for the centers...which is a pair of tubes instead of a single so it's not as capable of flexing when torqued down to the head. My thinking is that I need more gasket thickness so the bottom can squish a bit more to allow the top to make more solid contact with the gasket hard against the cylinder head. |
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Posted on: 2012/4/26 14:39
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| BillH | Re: Pesky Header Leak...Seeking Creative Alternatives !!! | ||
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The Stig Moderator
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That may do it. It would still make me wonder why though. Can you check the thickness oF the header flange around the bolt holes? If the bottom of the flange is thicker than the top (at the bolt hole)where bolt head/washer contacts it, it may be pulling the bottom tighter than the top of the flange. Just throwing out ideas. |
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Posted on: 2012/4/26 14:59
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Every man dies but not every man lives. |
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| Durango_Boy | Re: Pesky Header Leak...Seeking Creative Alternatives !!! | ||
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Elite Guru
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When I had the headers out I checked that and I made sure to clearance under the holes to clear out some of the weld slag in case it was interfering. Kind of sloppy but not in the way and I just cleaned it all up. I would try two sets of standard gaskets but I fear that may be a tad too thick. My exhaust temps are a tad on the high side and I'd be worried about burning through two sets compressed together. My thinking is that the thin layers of the dead soft aluminum would give me the extra thickness I think I need and at the same time would not burn through or burn out. |
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Posted on: 2012/4/26 15:16
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| BillH | Re: Pesky Header Leak...Seeking Creative Alternatives !!! | ||
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The Stig Moderator
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Might work, I can't think of much else.
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Posted on: 2012/4/26 17:21
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Every man dies but not every man lives. |
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| rklessdriver | Re: Pesky Header Leak...Seeking Creative Alternatives !!! | ||
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Senior Guru
 
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That's all I have EVER done... IF the header flange mating surface is flat, this will never leak. If you know how to apply silicone it won't look like crap either... It only takes about a pencil sized bead and just a little squeezes out evenly around the flange. DB- Putting more gasket material in there is only going to make it worse. Here's why: You headers leak after a few drive cycles because of all the leverage applied at the header flange. It tweaks around and crushes the gasket causing it to leak. Those side mount exhaust are hard to seal up because of all the leverage directly applied to those super long header primary tube's. If you flanges are flat, then just run a bead of high temp silicone around the exhaust ports and bolt the header up with no gasket.... let dry over night. Will |
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Posted on: 2012/4/26 23:05
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1984 Corvette. 434 SBC with a Powerglide. Best pass - 8.48@160MPH 1.23 60ft on MT 275/60R15 Radials. 1972 Corvette. LS5 454 BBC with M20 4 speed. Best Pass - Doing good to just pass a gas station. |
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| Durango_Boy | Re: Pesky Header Leak...Seeking Creative Alternatives !!! | ||
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Elite Guru
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Quote:
I'd consider that but there's a problem of accessibility. There are only two ways to put side mount headers in the car. They can go in before the engine, and then drop the engine in between the,, or you can put the engine in and bring the headers up from underneath. Applying to both methods in a C3, the headers will literally scrape and drag across the mating surface of the cylinder heads. There is also not enough room to pull the header primary out to lay the silicon down if both are in the car. One has to be done before the other and I think the installation itself would smear the silicon all over the place before I was ever able to bolt the two together. I'm only saying this because I have put 5 sets of side pipes into C3s and not once did I ever feel like I would have been able to put silicon in as a gasket without it smearing everywhere before the 1st bolt is put in. Working with small tolerances. Sliding gaskets in is easy. I'll try my sandwich idea. If it fails I'll have to pull the headers out again and 'maybe' replace them with another set because I think these have a flaw and the upper edge of the flange sits out farther than the bottom edge when mated to the head. |
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Posted on: 2012/4/27 1:58
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