Cummins Exhaust Manifold

[Andy Clark]

A little while ago, there was a thread about cracked 8.3 Cummins exhaust manifolds. At that time I had an exchange with Bill Sprague about an apparent exhaust gasket leak that I had. He shared his experience with a similar problem.
Well this past week I took the coach in to Freightliner for replacement of said gasket. It definitely was leaking around the #6 leg, as evidenced by sooty deposits on the head below that port.
They finally got the manifold off and found it slightly warped, but not cracked. They were able to get it machined to return the mating surface to a flat condition, so I did not need a new $400 mainfold.
Unfortunately that's the best part of the story. It gets worse from there- 6 of the 12 manifold bolts broke off during removal, resulting in major expenditures of shop time (at $125 per hour) to get them out and install helicoils. A thermostat housing bolt also broke. This is a special order item and took several days to get. In addition, one of the turbo constant-torque clamps broke upon reassembly, requiring another delay because of having to special-order this part.
To make a long story short, it ended up costing me $3100 for this job, even though Freightliner kindly discounted the actual cost significantly, for which I was (and am) extremely grateful.
Now I don't get a "shrieking" when the PacBrake is engaged, caused by exhaust gas leaking out, and I notice a definite increase in power since the turbo is now getting all the exhaust.
So, I thought that I'd share my story and pass along that Freightliner in Mt Vernon Washington is a customer-oriented outfit that does everything they can to ensure customer satisfaction. Even though I'm much (!) poorer now, I appreciate the quality of work that they did and the way they treated me.
Just thought you'd like to know.
See some of you at 7 Feathers.

Andy

[Joel Ashley]

Any idea why the manifold got so hot as to warp in the first place, and seize bolts?  

[Andy Clark]

Any idea why the manifold got so hot as to warp in the first place, and seize bolts?  

 No idea, Joel. Who knows what the PO did or how he drove the unit. The bolts were siezed due to severe corrosion. No obvious evidence of an overheat condition.

Andy

[Tom and Pam Brown]

May not have been heat, could have been a result of water hitting it when at normal temp.  
Or because stuff just happens.

[Joel Ashley]

When we had the old Pace Arrow on the farm, I spent many days in a row - if not weeks - going to the barn, squirting fresh penetrant on bolts, and lightly hammering stacatto on them and surrounding block and manifold, several times a day for 10 minutes or so.  Eventually all the bolts broke loose but the one that had snapped off on its own.  It cost me only the price of grinding the manifold, some new bolts, and a heck of a lot of my time, mostly carefully drilling, penetrating, and slowly extracting the broken stub with the stacatto/harmonics technique to crack the corrosion and heat adhesion.

The Chev 454 in that application had a reputation for warped exhaust manifolds and broken mounting bolts as a result.  My ultimate solution was headers and improved air intake that helped dissipate heat and added to engine overall efficiency.  It also helped the issue those era coaches had with vapor lock of the fuel line that ran nearby around the exhaust.

I keep reading about Cummins exhaust manifolds failing, either warping or cracking, or both.  Just yesterday I was sent an update link to a photo in a Newmar forum I used to frequent, and the manifold had literally split in half along the main tube between ports 3 and 4.  It was a 2003 ISC 350 engine.  Another member had added a comment that his was leaking as well.  Is this known to be a common issue with Cummins?  Were they just not engineering manifold metal composite or heat dissipation correctly?


Joel

[Gerald Farris]

Exhaust manifold and manifold stud failures are a common problem on the early to mid 2000s Cummins engines especially on the ISM series. From what I understand, the main problem is from inadequate mounting stud strength between the exhaust manifold and cylinder head.

Gerald