Exhaust Manifold Crack

[Eric Koger]

Today I was performing a preseason systems inspection when I noticed this crack in the exhaust manifold of my 2003 Monaco Dynasty Cummings 400 ISL with about 50,000 miles. I have no idea how long this has been there but I suspect for a while. The engine seems to run just fine. Has anyone had similar issues or experience that might help with next steps. We were planning an out west trip in 3 or 4 weeks but I’m not sure now. Any insight would be most appreciated!!

[RS505]

I did mine about three years ago. It wasn’t too bad.

I’m very mechanically inclined. Used to work in a rental yard. I have good tools and a lot of patience.

There are bolts and sleeves that attach the manifold to the engine. These were not difficult to get out.

There are nuts that attach the turbo to the manifold. These weren’t bad either. There’s an oil supply and drain line for the turbo. Also easy. Clamp ring to the exhaust easy.

Before I started, I went to the local Cummins dealer and bought the two exhaust manifold sections, gaskets, bolts and studs for the entire project. Some stuff was in stock, some of it had to be ordered

The removal process was roughly:

Take off air cleaner and ductwork, look for damage. Good time to replace the air filter. Look for dust inside the hose between the filter and turbo inlet

Use penetrating oil if you want to, and break loose every bolt and nut without removing any of them until all of them are loose (if you have problems, this allows you to retighten everything and take it to a pro)

Take the turbo off by removing the clamp ring, oil lines and the four nuts. You might need help from the bedroom with a rope.

Then remove the manifold bolts. There’s one going to a support bracket too.

While the turbo is off, I recommend inspecting the turbo bearings and replacing the turbo cartridge if needed. These CAPS ISL engines have the cheap simple turbo that only costs about $500

Assembly is the reverse of assembly. I like to dab anti sieze on the bolts

I hope this helps

[jacwjames]

X2 on above


I had to do mine on my ISC, not bad. I started soaking my bolts when I found the crack. In 2015 the manifold, bolts, and gaskets cost $600


If you have a shop do it figure +$2K, a couple years ago some shops charged a flat rate of $2500, probably more now.

[Eric Koger]

Thank you RS and jac both for your replies! I have a new manifold and gaskets on order. Today pulled the air inlet duct from the filter/turbo and started soaking the manifold bolts with penetrate. I will continue that several times while waiting on the parts to arrive. I inspected the turbo and do not see anything concerning. No oil in the inlet area and maybe 0.01" radial impeller motion and no discernable axial movement. So I think I'll let the turbo ride for now. Hopefully I can get all the bolts out without breaking any!! Thanks again for your help!

[shootist]

Originally Posted by Eric Koger

Thank you RS and jac both for your replies! I have a new manifold and gaskets on order. Today pulled the air inlet duct from the filter/turbo and started soaking the manifold bolts with penetrate. I will continue that several times while waiting on the parts to arrive. I inspected the turbo and do not see anything concerning. No oil in the inlet area and maybe 0.01" radial impeller motion and no discernable axial movement. So I think I'll let the turbo ride for now. Hopefully I can get all the bolts out without breaking any!! Thanks again for your help!

Cummins sells a complete kit. About 900$ iirc. Cheaper than item by item by far. The manifolds are used on an excavator ( komatsu i think) and they have some reinforcement in them. I used them last summer, the kits weren't out yet.

[Eric Koger]

I completed the exhaust manifold replacement today! It was a bit of a PIA but not terrible. Luckily the turbo checked out fine so I got by only replacing the manifold, bolts and gaskets. I didn’t have any broken bolts, but there was one spacer completely rust welded to the bolt. Use plenty of blaster days ahead of loosening the bolts. I had to remove the turbo to get the manifold out. The old manifold was completely broken in half and leaking badly. I’m a bit surprised it was running as well as it was. I’m hopeful for a bit more power, and perhaps an uptick in fuel economy now. We’ll find out as we head out later this month traveling from Tennessee out to the Utah/Arizona area.

Thanks for everyone’s input! Safe travels!

[Argosy]

Antiseize on the bolts and studs was a really good suggestion. If you ever have to work on any of it again you'll thank him.