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Cummins 8.3 Exhaust Manifold Cracked

March 25, 2015, 06:50:16 pm

I had my 2001 U270 in for it annual service and the mechanic found two gaskets not sealing and a crack on the rear exhaust manifold, this is a two piece manifold with four ports on the rear section and two on the front section.  Bolts were OK, The new manifold is cast of a different Iron, much heavier in weight.  $870.00.  Miles on the engine. 80K.

Al

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Re: Cummins 8.3 Exhaust Manifold Cracked

Reply #1 – March 25, 2015, 07:08:57 pm

Be sure the new one is also 2 piece.  Is it a Cummins part?

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Re: Cummins 8.3 Exhaust Manifold Cracked

Reply #2 – March 25, 2015, 07:09:59 pm

I had my 99 270 crack its exhaust manifold too. It seems that that year it happens about 70K miles.  They replaced it with the two piece version and it ran fine till I sold it.

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Re: Cummins 8.3 Exhaust Manifold Cracked

Reply #3 – March 25, 2015, 07:31:22 pm

They only replaced the rear section of the two piece manifold.  It is a Cummings supplied replacement.  New gaskets for the old front two port section and new gaskets for the new rear section.  This engine had a two piece manifold from the factory when built in 2001.  There are many posts about cracking on the older one piece manifolds, not so much on the two piece.  Mechanic said he would see this on over the road trucks with the two piece manifolds at 100K miles.  Cummin's must have been aware of this as they changed the casting material. 

Al 

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Re: Cummins 8.3 Exhaust Manifold Cracked

Reply #4 – March 25, 2015, 11:00:31 pm

I was not aware they will replace just one-half.  My understanding is that mechanical C8.3 engines only had one-piece exhaust manifolds.  And that ISC8.3 came with two-piece exhaust manifolds.  When my original one-piece exhaust manifold shrunk from both ends and was being replaced at Cummins, the tech thought he could use a two-piece manifold, but in the end he had to replace with a new one-piece manifold.

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Re: Cummins 8.3 Exhaust Manifold Cracked

Reply #5 – March 26, 2015, 09:43:20 am

My 2001 U270 was built with the 8.3 ISC engine and I did not expect to have a exhaust manifold failure like the early one piece castings.  A good experienced mechanic is the best insurance for safe travels.
Al   

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Re: Cummins 8.3 Exhaust Manifold Cracked

Reply #6 – March 26, 2015, 12:15:05 pm

Our 2000 8.3 manifold was one piece but due to shrinkage and a leak I changed it out 4 yrs ago to the 2 pce. Cannot remember exactly but I think I only paid around $400 for it from Cummins parts.
JohnH

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