Manifold broke in half on 300hp Cummins

[Bobmn]

Hello to all; Well, it happened to us! 29000m. 2001 Discovery. I know Cummins has had this problem for a while. I am working on the engine now and I have the rear half off. Not fun..but I have done worse! What manifold do people use? Aftermarket? Oem? But, has Cummins made the new ones any better? 3p. is better? I have read about the aftermarket...sounds good, but have heard about the turbo mounts are not the same. Has anybody went this way? And, if so, any tips on changing it out, and what manifold is best? Thanks Bobmn

[slickest1]

I replaced mine on my 8.3 350hp Cummins. Well actually I had it done while my coach was in for a couple other things. My mechanic recommended going with stock Cummins. The new Manifold is much heavier than the old one was. I could have done it myself but didn't have a place to do it at the time.

[Bobmn]

Hello Slickest 1; Thank you for the come back. I know what you mean about having a place to work! We have a large heated shop, here on our farm. At 71,I REALLY like it!! It was worth taking a couple of hrs to make a spot to get the Bus in. I used two 2x4's, cut to fit, to get the the bed up and out of the way. Today, I got half of the manifold off,and no broken bolts!! It was cracked in half, so the rear wasn't to bad. Leaning down to work, isn't fun, but I go slow, and take breaks......a lot! I am leaning towards the stock manifold. There is a two piece there on now. Well, 3 with the break!! The yr is 2001 and I don't know it came from the factory. I think so , as I got it from a friend that got it new. I see there is another manifold story right next to mine.......I'll ck that out also. Thank you BobMN

[slickest1]

Hi Bob, sounds like a great place to get the coach in. The new manifold was quite a bit beefier than the old one. The casting looks like it has thicker walls. I had read somewhere where cummins had some trouble with them. It makes me wonder if they upgraded them. Good luck with your project. Don't break any studs off, they can be a real pain.

[JBDISCOVERY]

BOBMM,
replaced the exhaust manifold two years ago on a 1999 Discovery with a 275 ISB. Pretty straight forward. Got the bed up, worked on the bolts, used a Cummins replacement manifold. Went back in without alot of trouble. No problems for the past two years.
JB

[NBM]

I just replace my manifold a couple days ago. I searched for aftermarket but could not find one that mounted the turbo in the same position so I went to Cummins and got an OEM manifold for about $300. I went ahead and replaced the bolts also. One thing I would suggest is to never seize the bolts and turbo studs. The first manifold held up for 11 years and 55000 miles if this one lasts as long I will be happy.

[mahon1993]

I didn't have a cracked manifold, I had broken bolts. Manifold warped and snapped off the bolts. It was a real job removing the broken bolts. Bobmm be sure to use all new bolts when installing the new manifold and use a torque wrench.
Greg

[GreaTOne65]

OK, guys, same song, second verse! LOL!! Like you all, I have been there two. My '99 Cummins, 5.9 lost the manifold, 2 years ago, it cracked between the 4-5th cylinders. I inlisted the help of my SIL, I propped up the bed, and he did the work in there,(I don't think I could have done much with my head down like he did), I took out the air cleaner, and unhooked the exhaust system. I then worked on the outside. We used an air impact wrench on the bolts, and were rewarded with no broken bolts. I had ordered one of the 3 piece types but found out it was going to take quite extensive rework on the exhaust and intake systems, that I didn't have time for, so sent the 3 piece one back,(drat), and went in and got a OEM, both were 2 piece, by the way. I figured, the original lasted for 90,000 mi. if this one goes that far, chances are it'll out live me!! LOL!! So far so good, it runs just as it did..

[Perry White]

Cummins service bulletins recommends at least a 2 piece exhaust manifold on anything over 250HP.

[Bobmn]

Hello to all; WOW!! Thanks for all the grt ideas! I ck'd with Cummins in Duluth Mn (50 miles). $290.00 plus gaskets and new bolts, and shipping. I also tried to find a aftermarket 3p. with the stock turbo location, but no luck! Also, about never seize, I have used this for yrs! We have a lot of old tractors, and you WILL be fixing things again sooner or later! Did anyone make the bolt holes a little longer, on the new manifold? I did this on our 94 460 ford engine. Lots of Ford (and Chevy) manifolds had problems. I used my die grinder to make the holes longer, so it could "move" a little. Thanks again! BobMn. PS..Does pic this bring back any............backaches?!!!!!!!!

[GreaTOne65]

Thanks, for the picture! Yes, it did bring back some memories, my knees hurt for over a month afterwords!! LOL!! Just glad it's done.