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09-15-2018, 11:16 AM
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#1
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Bus Nut
Join Date: Oct 2016
Location: Iowa
Posts: 447
Year: 1989
Chassis: International
Engine: 9.L
Rated Cap: 64
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Metal on metal rust
I know a little about galvanic something(not enough to know the name). Where the exhaust hangers are strapped around exhaust is where my exhaust is rusting/rusted through. Is the purpose to keep you paying $200+ to fix it every 5 yrs or so?
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09-15-2018, 04:25 PM
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#2
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Bus Geek
Join Date: Dec 2017
Location: Dawsonville, Ga.
Posts: 10,482
Year: 1999
Coachwork: Genesis
Chassis: International
Engine: DT466/3060
Rated Cap: 77
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Galvanic corrosion happens with dissimilar metals, not steel on steel. Heat and vibration is probably what got that connection.
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09-15-2018, 05:30 PM
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#3
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Bus Nut
Join Date: Oct 2016
Location: Iowa
Posts: 447
Year: 1989
Chassis: International
Engine: 9.L
Rated Cap: 64
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So, how can it be stopped? Im considering wrapping the pipe in that fiberglass cloth and then putting the hanger over it..im guessing its going to be a $400 fix to replace the pipe from the first hanger back.
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09-15-2018, 08:45 PM
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#4
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Bus Crazy
Join Date: Feb 2012
Location: Salt Lake City Utah
Posts: 1,635
Year: 2000
Chassis: Blue Bird
Engine: ISC 8.3
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In addition to heat and vibration there's always a little gap between the pipe and a strap-style hanger. Dust, water, and road salt get in there and accelerate the corrosion. It's hard to guess whether fiberglass wrap or other spacer between the pipe and the strap would help.
Weld-on hangers eliminate those problems above, but the welding burns off the coating (whether aluminized or galvanized) and then it's at risk of rusting again. Is that a net win over a strap-style connection? Maybe.. at least it lacks the gap that holds debris and lacks the vibration which turns a little dirt into a grinder.
I put an exhaust system on my pickup truck a few years ago which had an interesting solution: hanger hooks welded to u-bolt style clamps. The u-bolt style clamp won't vibrate the way a strap-style hanger can and welding the hanger there also avoids burning the coating off the exhaust tube.
Depending on how advanced the corrosion is on your exhaust, u-bolt clamps might not be an option. If the tube is weakened too much these would be liable to crush or even tear through your tubing.
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09-16-2018, 04:54 AM
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#5
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Bus Nut
Join Date: Oct 2016
Location: Iowa
Posts: 447
Year: 1989
Chassis: International
Engine: 9.L
Rated Cap: 64
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Quote:
Originally Posted by family wagon
In addition to heat and vibration there's always a little gap between the pipe and a strap-style hanger. Dust, water, and road salt get in there and accelerate the corrosion. It's hard to guess whether fiberglass wrap or other spacer between the pipe and the strap would help.
Weld-on hangers eliminate those problems above, but the welding burns off the coating (whether aluminized or galvanized) and then it's at risk of rusting again. Is that a net win over a strap-style connection? Maybe.. at least it lacks the gap that holds debris and lacks the vibration which turns a little dirt into a grinder.
I put an exhaust system on my pickup truck a few years ago which had an interesting solution: hanger hooks welded to u-bolt style clamps. The u-bolt style clamp won't vibrate the way a strap-style hanger can and welding the hanger there also avoids burning the coating off the exhaust tube.
Depending on how advanced the corrosion is on your exhaust, u-bolt clamps might not be an option. If the tube is weakened too much these would be liable to crush or even tear through your tubing.
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I'll get some pics of it..its weird that the only rust on the pipe is where the hangers are, maybe an inch on both sides. Everywhere else looks almost new..when i replace the pipe the hangers need replaced too.
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09-16-2018, 09:38 AM
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#6
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Bus Geek
Join Date: Mar 2011
Location: Houston, Texas
Posts: 8,462
Year: 1946
Coachwork: Chevrolet/Wayne
Chassis: 1- 1/2 ton
Engine: Cummins 4BT
Rated Cap: 15
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One word...stainless.
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09-16-2018, 02:11 PM
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#7
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Bus Nut
Join Date: Oct 2016
Location: Iowa
Posts: 447
Year: 1989
Chassis: International
Engine: 9.L
Rated Cap: 64
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Quote:
Originally Posted by Tango
One word...stainless.
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Assuming i can get stainless hangers. Isnt the pipe already stainless?
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09-16-2018, 07:20 PM
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#8
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Bus Geek
Join Date: Sep 2014
Location: Eustis FLORIDA
Posts: 23,764
Year: 1999
Coachwork: Thomas
Chassis: Freighliner FS65
Engine: Cat 3126
Rated Cap: 15
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Quote:
Originally Posted by mikeypj
Assuming i can get stainless hangers. Isnt the pipe already stainless?
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Its usually aluminized steel.
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09-16-2018, 10:28 PM
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#9
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Bus Geek
Join Date: Mar 2011
Location: Houston, Texas
Posts: 8,462
Year: 1946
Coachwork: Chevrolet/Wayne
Chassis: 1- 1/2 ton
Engine: Cummins 4BT
Rated Cap: 15
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Don't know of ant buses that come from the factory with stainless exhaust systems.
Gotta DIY it.
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09-17-2018, 05:03 PM
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#10
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Bus Nut
Join Date: Oct 2016
Location: Iowa
Posts: 447
Year: 1989
Chassis: International
Engine: 9.L
Rated Cap: 64
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Quote:
Originally Posted by Tango
Don't know of ant buses that come from the factory with stainless exhaust systems.
Gotta DIY it.
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This exhaust is not the original..my bus is an 87.
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09-17-2018, 05:07 PM
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#11
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Bus Geek
Join Date: Sep 2014
Location: Eustis FLORIDA
Posts: 23,764
Year: 1999
Coachwork: Thomas
Chassis: Freighliner FS65
Engine: Cat 3126
Rated Cap: 15
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Will a magnet stick to it? If not its likely stainless. If so its aluminized steel like 99% of the other school buses out there.
My 85, 92, 98, 99, and 2004 all appear(ed) to have the original exhausts.
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09-18-2018, 05:01 PM
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#12
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Bus Nut
Join Date: Oct 2016
Location: Iowa
Posts: 447
Year: 1989
Chassis: International
Engine: 9.L
Rated Cap: 64
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Quote:
Originally Posted by EastCoastCB
Will a magnet stick to it? If not its likely stainless. If so its aluminized steel like 99% of the other school buses out there.
My 85, 92, 98, 99, and 2004 all appear(ed) to have the original exhausts.
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If this exhaust is original its really clean, minus the rust spots..lol..either way its gotta go before we hit the road. Maybe put a cherry bomb muffler on it! Bwahahaha
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09-22-2018, 05:57 PM
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#13
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Mini-Skoolie
Join Date: Jan 2018
Location: Murrells Inlet South Carolina
Posts: 12
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Stainless steel doesn't really rust and if it does its usually surface rust. Pimp that bus go titanium with a borla exhaust. HAHA but seriously if you plan on keeping the bus around for a long time think about replacing it with stainless its a bit more expensive but should be around for the life of the bus well worth the investment.
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09-22-2018, 06:46 PM
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#14
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Bus Geek
Join Date: Dec 2017
Location: Dawsonville, Ga.
Posts: 10,482
Year: 1999
Coachwork: Genesis
Chassis: International
Engine: DT466/3060
Rated Cap: 77
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Quote:
Originally Posted by mikeypj
So, how can it be stopped?
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Don't put bare steel and aluminum together. Insulate somehow. I imagine your issue is not galvanic corrosion, but failure of the pipe. That hanger may hold heat at that point and with water and vibration just wore it out. Once the aluminized wore off the rust started.
4" stainless pipe runs about $12/ft. I doubt any bus company is building that into the budget. No ROI.
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