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Post by busaddict on Apr 18, 2015 15:53:58 GMT -8
I just replaced an old and crumbling EMPI muffler on my '74 bus with a better quality Bugpack version. With some fiddling around it wasn't too difficult to get a snug fit...but my exhaust is still a bit loud when I give it gas and there are a few pops in there on deceleration. So I put a hand over the exhaust pipe and nothing really happened, I think the exhaust is leaking from the head area. Can't quite pin it down, but I need to get this fixed soon. Have the header bolts come loose with the years? I guess further inspection will be necessary, stay tuned. Suggestions and moral support welcome.
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Post by Brenticon on Apr 18, 2015 16:28:49 GMT -8
Have fun! Careful with header bolts, don't wanna break them off. After multiply attempts at a quiet bus, doesn't hurt to drop the whole exhaust, check flanges, check gaskets, clean them, make sure everything's flat. Nothing like tearing it down and puttin it back together, to have a better understanding Good luck Tom
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Post by busaddict on Apr 18, 2015 16:37:49 GMT -8
Have fun! Careful with header bolts, don't wanna break them off. After multiply attempts at a quiet bus, doesn't hurt to drop the whole exhaust, check flanges, check gaskets, clean them, make sure everything's flat. Nothing like tearing it down and puttin it back together, to have a better understanding Good luck Tom Thanks Brent. A few questions if I may. Can this be done with the engine in? How long does it take? And can I carefully tighten the head bolts and try to make it better?
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Post by Brenticon on Apr 18, 2015 16:55:42 GMT -8
Yes, while the engine in. Do yourself s favour and jack the back end way up, and give yourself some room. Working on your back sucks, so get comfy. There's copper rings, cheap, between the head and header. Maybe think of removing and replacing. Make sure you spray exhaust bolts. I swear by "Moovit" now. Is yours just header pipes that go straight into heater boxes? If so, should be a couple hours of fun. Did you get new gaskets got your bug pack exhaust? Remember to clean up flange areas, a light grinding does wonders I also use muffler cement to keep my gaskets in place, nice thin layer.
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Post by busaddict on Apr 18, 2015 17:07:41 GMT -8
I need to get the books out, good tips, thanks. The engine is in tune, starts and idles quietly (for a bus.) When I accelerate especially in something like 3rd, there is some noise or chatter, and the engine feels like it's not giving its best. I had one gasket with the new muffler, I roughed up the old surface with a little emery paper and wiped it off with a towel. That part seems to have sealed nicely. I really need to get up on ramps or stands to see what's happening exactly. I did a lot of driving in this bus last summer but only noticed the noise etc. on my last trip over the Malahat in the fall.
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Post by Brenticon on Apr 18, 2015 17:28:20 GMT -8
Ramps work great!
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Post by Volktales on Apr 18, 2015 18:07:48 GMT -8
Those pops on deceleration usually indicate there is an exhaust leak somewhere. Brent is the expert on bus exhausts...
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Post by busaddict on Apr 18, 2015 18:10:25 GMT -8
I don't think this is a completely new problem. My old EMPI exhaust always popped. I was told by mechanics that aftermarket mufflers do that. If I have an exhaust leak is it OK to drive the bus?
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Post by Brenticon on Apr 18, 2015 18:48:31 GMT -8
Just wear ear plugs if it gets any bigger
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Post by busaddict on Apr 18, 2015 19:20:29 GMT -8
lol, is it possible that only the heater boxes are leaking, and if so would that be such a big deal?
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Post by busaddict on Apr 19, 2015 15:43:07 GMT -8
I adjusted the valves today and the van does drive well enough, it's just that something clatters like a box of hammers when I accelerate. The engine is in tune, starts right away, and idles as good as it ever has. (SVDA 7.5 idle/30 full rev hos off/40 all in, Dwell 52) I need a better diagnostic, although I think the exhaust is escaping from the passenger side heater-box. I want to get this baby purring again.
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Post by busaddict on Apr 22, 2015 20:21:32 GMT -8
Hey Brent, so I can do this in a day if it's a simple exhaust leak? Seems to be coming from the right side. Although the bus was running quite well, and idling fine, I re-tuned it and managed to get it a bit better, so that power loss in 3rd was a separate issue. Good power now.
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Post by Brenticon on Apr 22, 2015 21:32:10 GMT -8
Good luck with nothing breaking, but if you have spare nuts, bolts and gaskets. , it shouldn't be more than a couple hours
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Post by PICTUP on Apr 23, 2015 6:38:54 GMT -8
The nuts securing the manifolds to my heads on the Riviera seem to keep coming loose. I'd tighten those up on yours first before taking everything apart. They are just a sled plate removal away and it might be a good way to see if that is indeed your problem. Unless your gaskets are blown out, but I don't know enough about that to know if it actually occurs
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Post by 1hotvw on Apr 23, 2015 6:39:45 GMT -8
well if you had the same issue with the last exhaust and all your flanges are flat maybe one heater box has a hole inside?
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