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Hole in Delta header?  Rating:  Rating
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 Posted: 09-16-2005 12:37 am
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kneff
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When I purchased my J-H, it had a Delta header that seemed to be in OK condition. No visible holes or rust. Aft of the header, the exhaust system was toast, so I replaced it with the Delta system.

I did the installation myself, then took the car to a muffler shop to have everything welded together. When I left the shop, it sounded great. Now, the car sounds like it has a hole in the exhaust.

I know, I probably should have replaced the header but it seemed - in fact seems - fine. I can't see any holes, can't find any trace of leaking exhaust. It certainly sounds loud enough for there to be a hole somewhere, though.

I have run the engine while the car is on jack stands, looking for leaks. The loudest point seems to be the 4 into 1 collector at the end of the header, but again I cannot see any visible holes or leaking exhaust.

I tightened all of the header bolts, thinking that there might be a leak between the head and the manifold, but it made no difference.

I hate the thought of replacing the header, especially the though of cutting my newly-installed, newly-welded pipe to get the old header out and the new one in.

Has anyone else experienced this? Any brilliant ideas?


Thanks,
Ken

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 Posted: 09-16-2005 01:45 am
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Mark Rosenbaum
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Shortly after installation, the Delta exhaust system on my car went through a brief 'burn-in' period and became slightly louder than it had been.  It hasn't changed significantly since then.  And while the exhaust note is fairly loud to the driver when the car is stopped, it seems to get left behind when the car is moving above 30 mph or so. 

You can find many difficult leaks by taking some white flour, mixing it with water, and making a thin dough that is applied over the suspect area.  (Mud also works, after a fashion, but I don't recommend it as it doesn't discolor the way dough does.)

Okay, now that you've stopped laughing, I am serious here.  Leaking exhaust tends to burn through the dough, or discolor it more at the leak than the surrounding area.  IIRC somebody sells a high-tech compound for the purpose, but I'd rather spend 25 cents than 25 bucks to get the same results.  Also, if perchance the dough doesn't wash off with water when you're done, it will certainly biodegrade (AKA 'rot') fairly quickly.

If you don't like the idea of using dough, you can try dishwashing liquid that's been mixed with a small amount of water, and look for bubbles.  There are two problems with this method.  First, the fluid tends to evaporate quickly and if you don't spot a bubble as it's being made, there's a fair to good chance you'll miss it entirely.  Second, if the fluid boils, the resulting bubbles are a false positive.

Headers frequently will leak at the manifold-to-engine joint.  Once an exhaust gasket starts leaking, exhaust gas tends to burn away the gasket material, so tightening the bolts rarely helps.  It's important to ensure that the mating surfaces of all the header flanges lie on the same plane -- I've seen name-brand headers for V8s with more than 1/8" of difference between the front and rear flanges.  (As a rule of thumb, the allowable mis-alignment is no more than half the thickness of the flange gasket.) 

Possibly there's a cracked weld in the header or elsewhere in your system.  Here, the weld may leak all the time, only when things are cold, or only when they are hot.  Bent pipes tend to twist as they heat up, and the resultant stress can pull apart a crack that's almost gas-tight at room temperature, or force a leaking crack to seal.  I've seen both.

Assuming you do have a small leak somewhere, a bit of welding may fix the problem.  If this isn't possible, you might try one of those muffler sealing compounds, backed up by a thin metal sheet and a hose clamp.  (Yes, this is a variant on the old beer can and baling wire fix.  It's inexpensive, and it works.)  With luck, this can buy you months or even years before things get too bad to live with.

And finally, should an obverver ask annoying questions, give them a ridiculous answer, such as "Bread dough? Hardly!  It's British tube plaster.  It was developed during World War II and was a bigger secret back then than radar. According to my research this is the proper seal for the frammis joints."  :^}

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 Posted: 09-16-2005 04:12 am
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kneff
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Mark,

Thanks for the suggestions. Besides providing humor for me and my son, it's something I can try fairly easily.

As for the manifold-to-engine joint, how difficult do you think it would it be to replace the manifold gaskets without completely removing the header? I'm guessing that I could get enough room to slip new gaskets in (the J-H uses a separate gasket for each port if I'm not mistaken), but I doubt that it would be very easy to remove residue from the old gaskets without completely removing the header.


Thanks,
Ken

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 Posted: 09-16-2005 07:49 am
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Mark Rosenbaum
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Ken,
Glad you enjoyed the humor.  I try to use it sparingly, as it sometimes doesn't go over all that well.

The JH exhaust gaskets are individual, one per cylinder.  I've seen composite and solid copper ones.  The composite gaskets probably seal better.  Installing them requires jacking up the engine for clearance, possibly prying it to the right a bit, undoing the header and sliding it off the studs in the head, removing any residue, then slipping the new gaskets in place.  A bit of aerosol exhaust gasket sealer applied to the gaskets may keep them from falling off just before the header is slid into place.

As you note, the tricky part is getting rid of the residue.  If a scraper and wire toothbrush don't work, you can try a small rotary wire brush on the end of a flexible shaft such as the ones used for Dremel tools.

If you have the small pattern nuts that Delta sells to secure the header in place, count your blessings, as they are much easier to remove and replace than the original factory ones.  If not, it is prudent to install a set, as you'll probably save an hour of nasty grunt labor when reinstalling the header.

For reference, here's a photo of composite exhaust gaskets.

 

Attachment: Manifold exh gaskets 2.jpg (Downloaded 27 times)

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 Posted: 09-18-2005 02:32 am
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Panini
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I have to agree with Mark on this one. As you may know, I have owned bakeries for years now. The only thing I would do different would be to spray a little H2O on the outside of the dough to to create a little stream. The result will be that rustic crusty look all of us artisan bakers yearn for.

Last edited on 09-18-2005 03:35 am by Panini

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 Posted: 09-18-2005 07:51 am
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Tony Hollart
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Depending on how clean the exhaust system is you can spray with silver paint, leaks soon show up as sooty marks as the exhaust gas escapes from the gaps or holes. If you have not got any holes you end up with a nicely painted exhaust.

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 Posted: 09-18-2005 03:10 pm
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Jensen Healey
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Replacing the header-to-manifold gaskets is one of the most painful and thankless tasks on the JH. If you don't have popping in deceleration the gaskets are probably good. The larger diameter tubing and free flow mufflers are louder and you may need to add another resonator in the system. The original system had resonators and mufflers from front to back.

 

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