ISC Exhaust Manifold Cracks

[TechWriter]

I've been told to prepare for exhaust manifold cracks in my 2001 ISC.

If so, what's the $$$?

[dons2346]

About 1 large from what I have heard. You might be lucky and have a two piece manifold.

[RVhauler]

Why replace manifolds when the cracked can be brazed. used to braze the manifolds on the Ford Gas 460 cube. never had anymore problem after being brazed.

[spike45]

Quote:

Originally Posted by dons2346 About 1 large from what I have heard. You might be lucky and have a two piece manifold.

According to Quick Serve On Line, the two piece manifold was introduced in 2008 for reasons of manifold gasket leaks that could not be fixed by replacing gaskets.

Technical Service Bulletin, TSB 100749 issued 26-Sept-2008

[deandec]

Quote:

Originally Posted by TechWriter I've been told to prepare for exhaust manifold cracks in my 2001 ISC. If so, what's the $$$?

Mine cost $1500 at an Independent repair shop. Three bolts broke during the removal. One required removing the thermostat and hence coolant etc to access for removal.

That was about $300 less than the Cummins West estimate but more than the estimate I was given by the shop.

[GaryKD]

Hi TechWriter,
Do not allow the engine to overheat. That may facilitate manifold cracks. If it starts to overheat, consider pulling off the road.

[Triker56]

Quote:

Originally Posted by GaryKD Hi TechWriter, Do not allow the engine to overheat. That may facilitate manifold cracks. If it starts to overheat, consider pulling off the road.

At what temperature is it overheating?

[TechWriter]

Quote:

Originally Posted by GaryKD Hi TechWriter, Do not allow the engine to overheat. That may facilitate manifold cracks. If it starts to overheat, consider pulling off the road.

Ok, the $50,000 question . . . how do you tell if the manifold is cracked? Obvious? Or . . . ?

[spike45]

Quote:

Originally Posted by Triker56 At what temperature is it overheating?

Turbocharged engines operating at full load as on hill climbing can achieve an exhaust temperature of 1050*F. Cruising should yield exhaust temps of around 850 -900F. I cannot define overheating as an earlier post suggested either. With your automatic transmission you are not going to be able to lug the engine below torque peak RPM before the transmission down shifts.

On the post above about detecting manifold cracks: some small cracks may not be detected until they progress. There are chemical crack detection methods but you probably will need to go to a shop for that. If the crack is bad enough, you may eventually see soot on the engine compartment walls or on surrounding components. Possibly you can hear louder exhaust while the engine compartment is opened and someone is accelerating the engine in Park or Neutral. You may even see a small amount of smoke. Not likely at early cracking phase until it progresses and widens.

[GaryKD]

Hi Triker56,
You have a good question that I can not answer. I have no fancy gages, just what came with the coach. If the engine derates itself one has gone too far. For me, If the temp gage goes about 3/4 the way up, I will stop and let the engine cool. If accurate, 3/4 the way up the gage is about 220 F. That being said my engine rarely gets over 200 F. I have no data to back this up, just experience and gut feel for my engine/coach combination. I six years I have had to stop only once. That was a summer time pull out of Laughlin, NV. Later I learned many coach owners unhook their toads when making the climb.

[J Walker]

The one piece exhaust manifold is on older Cummins engines is something that is likely to fail eventually. More conservative driving and pulling fewer grades can help, but the exhaust temperature is still very high. My 11 year old ISB is still fine as far as I know but an exhaust manifold replacement is probably in my future.

[deandec]

My leaks were caused by the underlying gasket failing at 80,000 miles and 15 years. I drive lots of steep grades here in the West in high summer heat.

The one piece manifold had to be resurfaced, $70, to seal to the new gasket, $350.

A Cummins tech noted the leak by sound while he was repairing a broken fuel line. (Check your fuel line clamps for good bolting!).

He then pointed out the black soot around the mounting points of the manifold. I would not have known the manifold was leaking otherwise.