Exhaust manifold crack on ISC350 and effect on power.

ScottG wrote:

Yea, you loose too much turbo drive pressure and the boost goes down but the engine is still getting the same amount of fuel. So the EGT's go up a lot.

Sorry but even on most 20 year old diesels the amount of fuel put in is dependent on the amount of boost pressure. This is a ISC... electronic controlled and it's smart enough to only put in as much fuel as the engine can burn based on the boost pressure... no increase in EGT.
OP, I had to replace my manifold at 55K miles because of a crack... this is a common problem on the Cummins 8.3, ISC, and ISL.
A can of Kroil or PB Blaster applied over the next week (including the turbo bolts) could save you a lot of money.

I also have an exhaust leak, but it is on an ISL 400 hp. I don't see any cracks in mine unless it is on the underneath side. I do notice that there is some gasket material missing at #4 cylinder and black soot around it. I am having the gasket replaced next week and possibly the manifold if it turns out be cracked underneath. It is a 2 piece manifold and I have been quoted about $550 for it. I hope it needs just a gasket. I have been putting PB Blaster on the bolts to hopefully cut down on labor time.

sprintmod1 wrote:
I have the same engine in my 03 Tradition. Had this exact work done in January before heading to Florida. I was complaining in November to my mechanic about no power climbing hills. We all thought we were having fuel filter/injection/injector pump type issues. With bad weather around, I decided to take it back to him for the pre Florida check up. They found the cracked manifold. Was about $400 for the manifold and about six hours of labor to replace it. Power is back, braking is back and it runs awesome once again!!

Thanks for the response. Curious, was it between 3 and 4 on the manifold?. Would you say it looked similar to this one?

Also, this kinda looks like a two piece because of the seam between 4 and 5. Thoughts????

Thanks in advance.

John.

I have the same engine in my 03 Tradition. Had this exact work done in January before heading to Florida. I was complaining in November to my mechanic about no power climbing hills. We all thought we were having fuel filter/injection/injector pump type issues. With bad weather around, I decided to take it back to him for the pre Florida check up. They found the cracked manifold. Was about $400 for the manifold and about six hours of labor to replace it. Power is back, braking is back and it runs awesome once again!!

John & Angela wrote:

ScottG wrote:
You will also having higher EGT's, especially if it really lets go. If it gets a lot worse, don't drive it at all.

Not driving it at all really. Its about 6 miles to my mechanic so I'm not worried about it. Thought about doing it myself but its a busy time of the year for us. Besides its time for its annual stuff.

I'll post how it goes, and how expensive it was.

Curious though, I understand the rest of the symptoms but don't quite understand exhaust gas temps going up. Is it an unburned fuel thing???. Thanks in advance for the explanation. I like learning this stuff.
John.

Yea, you loose too much turbo drive pressure and the boost goes down but the engine is still getting the same amount of fuel. So the EGT's go up a lot.

Good luck on the repair. It's such a common thing with those engines, I wonder if the replacement part is improved?

John,

Suggest you use some PBlaster or other penetrating oil a couple of days before taking it in for work. Will make removing the manifold go a lot easier. Dry and oil left before starting the engine.

ScottG wrote:
You will also having higher EGT's, especially if it really lets go. If it gets a lot worse, don't drive it at all.

Not driving it at all really. Its about 6 miles to my mechanic so I'm not worried about it. Thought about doing it myself but its a busy time of the year for us. Besides its time for its annual stuff.

I'll post how it goes, and how expensive it was.

Curious though, I understand the rest of the symptoms but don't quite understand exhaust gas temps going up. Is it an unburned fuel thing???. Thanks in advance for the explanation. I like learning this stuff.

John.

You will also having higher EGT's, especially if it really lets go. If it gets a lot worse, don't drive it at all.

Yep based on my experience.

Don't forget to add Fire Hazard to the list of problems a cracked exhaust manifold can cause.