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09-17-2012, 08:21 PM
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#15
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Senior Member
Join Date: May 2004
Location: Auburn, CA, Havasu, AZ & Mulege, BCS
Posts: 5,385
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I toured the outfit last week that is currently making the improved steel recipe manifolds. Their business is trucks, generally of a higher HP bracket than motorhomes, so they started w/ manifolds in stock for larger blocks. The ISL/C manifold will be coming out soon. Haven't heard pricing yet or firm date, but it is rumored to be competitive. Will likely be a 3 piece design w/better flanges & crack resistant castings. Because of the superior steel (stock manifolds are made of cheap cast iron for cost reasons, and frequently suffer heat erosion inside the tubing & particularly at the turbo flange, which burned metal parts have to transverse the turbo), leave a larger inside bore which drops exhaust temps into turbo by 75-100 degrees. This means less wear on turbo as well as better future reliability of the manifold.
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Baja-tested '08 2-slide 36'
Alpine: The Ultimate DIY'er Project
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09-17-2012, 08:37 PM
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#16
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Senior Member
Country Coach Owners Club Solo Rvers Club iRV2 No Limits Club
Join Date: May 2011
Location: Vancouver, WA
Posts: 37,725
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Hmmm...
Have a 2002 350 ISC with Banks kit that I installed in 2004. Had to drill and tap a hole in the exhaust manifold for the EGT sensor. No cracks or breaks yet.
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2009 45' Magna 630 w/Cummins ISX 650 HP/1950 Lbs Ft, HWH Active Air
Charter Good Sam Lifetime Member, FMCA,
RV'ing since 1957, NRA Benefactor Life, towing '21 Jeep JLU Rubicon Ecodiesel
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09-25-2012, 09:32 PM
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#17
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Senior Member
Join Date: Jan 2008
Posts: 161
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E Mike: Could you rush that shop along? Every time I read about a new issue on the this forum, I go out a check my coach and end up muttering Oh S**t. Sounds like they are building a better manifold. I've only got a few months before I need to crawl under the coach.
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HAX
2003 ALPINE 40FDTS
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09-25-2012, 09:59 PM
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#18
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Senior Member
Join Date: Aug 2012
Posts: 390
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cracked 8.3 exhaust manifold
ha guys haven't had my 1992 8.3 that long. my question to you is those of you that lost your manifold, do you use exhaust brake? wondering if it's just a bad design or if the braking adds to problem. original owner removed exhaust brake when he replaced muffler. had big block cummins with real exhaust brakes. don't like the way they put them on the 5.9s and 8.3s . in the morning going to check mine would never have checked until it was to late. keep the advice coming, again thanks
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09-25-2012, 10:14 PM
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#19
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Senior Member
Join Date: Aug 2011
Posts: 1,126
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they break/crack even on RVs without exhaust brakes...this isn't an uncommon thing on inline 6 cylinders(gas or diesel...road service or industrial/agricultural)....even going back to inline 4 cylinders....ex and int manifolds crack
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96 Dynasty 36' that does NOT wander, thanks to RuppParts.com and their superior "poly" suspension bushings
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09-25-2012, 11:37 PM
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#20
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Senior Member
Join Date: May 2004
Location: Auburn, CA, Havasu, AZ & Mulege, BCS
Posts: 5,385
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They crack & leak on ISC's w/exhaust brakes and on ISL's w/engine brakes. Problem is a combination of weak casting design & cheap metal. The aftermarket manifold has a high chrome content, bigger flanges, and its a 3 piece pressed unit, so each section receives exhaust (& heat) from two cylinders, tho the center section combines exhaust gas from the end 4 cylinders w/the two centers. OEM manifolds have a 4-cyl front (as seen on a diesel pusher) and a 2-cyl rear section. Mine leaks at the fit between the two; have a friend w/an 05 ISL engine w/leak & crack. I've seen leaks at the fit-up and at the head.
Another problem is heat scouring of the "septum" part between front 3 and back 3 cylinders. All the exhaust heat hits & has to turn against this plate, and the plate is the only part in the manifold that is heated from both sides (no place to cool as with the rest of the tube that has an outside surface). The septum erodes at a rate dependent on exhaust gas temp, and sends burning metal particles into the exhaust side turbo vanes, which isn't good for business there, and shortens turbo life.
__________________
Baja-tested '08 2-slide 36'
Alpine: The Ultimate DIY'er Project
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09-26-2012, 09:21 AM
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#21
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Senior Member
Join Date: Nov 2007
Location: Charleston, WV
Posts: 3,469
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Wonderer1,
Like me you have a C8.3 mechanical engine, not an ISC. As far as I can see the exhaust manifold changed when they brought out the ISC and continued this with the ISL. May be its just luck but I have had no problems with my manifold and haven't heard of anyone else with this engine having problems. Just as well as I don't think this new manifold would fit.
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John and Mary Knight
2015 Newmar Ventana 4311 - wheelchair accessible
2015 Cadillac SRX Luxury AWD
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09-26-2012, 11:53 AM
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#22
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Senior Member
Alpine Owners Club
Join Date: Dec 2006
Location: Olympia
Posts: 861
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John,
Now the exception to the rule. I have the C8.3 and have had the cracked exhaust manifold. Have put about 30K miles on the coach since replacement and, so far, all is well.
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Jeff
'99 Alpine Coach
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09-26-2012, 12:20 PM
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#23
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Senior Member
Join Date: Nov 2007
Location: Charleston, WV
Posts: 3,469
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Jeff,
Did you get the Cummins manifold or did you find an alternative?
__________________
John and Mary Knight
2015 Newmar Ventana 4311 - wheelchair accessible
2015 Cadillac SRX Luxury AWD
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09-26-2012, 12:21 PM
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#24
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Senior Member
Join Date: Jun 2012
Location: AB
Posts: 7,587
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Just went through this on my 8.3 a few months ago. Parts, including manifold, gaskets, new Turbo Oil Line, E-Brake Clamps, Engine Oil Filter, Coolant Filter was $960.
However, once I had it apart, figured I might as well put a Banks Power Kit on at the same time. The Banks kit was $2500 but the increase in performance was certainly worthwhile. Saw an increase in fuel mileage from 6.5 to 8.5 MPG.
Also, during assembly, I did some changes to the exhaust system supports. In my opinion, the problem with the manifold is due to improper support of the exhaust system and during heating/cooling it causes stress to the manifold resulting in cracking.
The manifold is made in two pieces to allow for thermal growth of the manifold itself. But, the way my system was supported there was not provision for thermal growth of the exhaust system downstream of the Turbo. I changed a couple of the brackets around to change the direction of support.
Fingers crossed, we don't have to do this again on my watch but I'm sure there will be other things that will get my full and undivided attention.
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2019 Unity LTV CB, pushed by a 2013 Honda CRV, BlueOx Baseplate, Aventa Bar & Patriot Brake
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09-26-2012, 12:34 PM
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#25
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Senior Member
Texas Boomers Club
Join Date: Jul 2000
Location: Cypress, Texas USA
Posts: 8,854
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Quote:
Originally Posted by dennis45
Also, during assembly, I did some changes to the exhaust system supports. In my opinion, the problem with the manifold is due to improper support of the exhaust system and during heating/cooling it causes stress to the manifold resulting in cracking.
The manifold is made in two pieces to allow for thermal growth of the manifold itself. But, the way my system was supported there was not provision for thermal growth of the exhaust system downstream of the Turbo.
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You raise an excellent point. On large industrial engines, there's traditionally a "wrinkle-belly" (a flexible expansion joint) required by the engine manufacturer at the turbocharger exhaust flange to prevent exhaust piping stresses and loads from being transferred to the turbocharger.
Rusty
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09-26-2012, 12:36 PM
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#26
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Senior Member
Join Date: Nov 2007
Location: Charleston, WV
Posts: 3,469
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When I replaced my exhaust I put a length of flexible pipe between the header and the muffler, which allows for expansion and any movement. I thought about a Banks upgrade as I only have 275hp from my engine but when I looked into it I found that the Allison MD3060 has a max. input power of 275hp. So I will stick with what I have and climb hills in the slow lane with the big trucks. There is a lot of that in West Virginia.
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John and Mary Knight
2015 Newmar Ventana 4311 - wheelchair accessible
2015 Cadillac SRX Luxury AWD
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09-26-2012, 12:42 PM
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#27
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Senior Member
Join Date: May 2004
Location: Auburn, CA, Havasu, AZ & Mulege, BCS
Posts: 5,385
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Dennis- @ 6.5mpg I'm betting you also have a substantial leak at the intercooler that, if fixed, would yield additional mileage improvement. 6.5 is pretty low for an ISC.
__________________
Baja-tested '08 2-slide 36'
Alpine: The Ultimate DIY'er Project
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09-26-2012, 01:38 PM
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#28
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Senior Member
Join Date: Jun 2012
Location: AB
Posts: 7,587
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Quote:
Originally Posted by Rich and Cork
Just a heads up for others, I am having to replace my exhaust manifold. It was a full circumferential crack. I noticed this as I was doing my maintenance prior to our Alaska trip. You cannot hear the difference, due to diesel rattle. Take a mirror and a light and stick your head in there and look around. I was concerned that this has probably been broken for a long time and took it to our local Cummins shop to have them determine that nothing else was damaged. They verified turbo, etc were OK. I would guess it was cracked for a long time, based on soot I could see on the engine parts.
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One way to detect this problem is to stand behind the MH when it is under acceleration like moving in the CG. If the manifold is cracked you will hear a "Popping" sound. Especially when it is cold. That's how if found mine. From the drivers seat you may never hear it.
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2019 Unity LTV CB, pushed by a 2013 Honda CRV, BlueOx Baseplate, Aventa Bar & Patriot Brake
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