Exhaust Manifold Options

[Kevin Schitoskey]

Facing the dreaded Exh manifold replacement for my 99 ISC 8.3.  I had some sticker shock when contacting Cummins - $ 1,074 for the 2 piece manifold.  Couple of questions for the group:

1. Does anyone have any experience with aftermarket (read: non-Cummins) manifolds like below?  

https://www.fridayparts.com/exhaust-manifold-long-3964070-short-3937477-for-cummins-engine-8-3-8-9-8-3c-qsc-isc-isl-qsl-l8-9?msclkid=d9f3fd81b0fd15595c259e59f6d0a446&utm_source=bing&utm_medium=cpc&utm_campaign=PLA-usafreeshipping-US-9.23&utm_term=4586750202629092&utm_content=pla-usafreeshipping-us-9.23

2.  The crack is in the smaller of the 2 piece manifold.  Am I correct in assuming that these must be replaced as a matched pair?  Replacing only the small portion would save a turbo removal, fewer bolts to break off, etc. 

Thank you all in advance for your input.

[Chuck B 2004 Windsor]

The bitterness of poor quality remains long after the sweetness of low price is forgotten.  Chuck B 2004 Windsor

[cbr046]

Some have had success w aftermarket, some not.  I think @jacwjames had poor quality with a Ford gasser manifold (aftermarket).  Not sure about the Cummins aftermarket.

I'm in the same boat and honestly I only want to attempt this job once.  Biggest issue is not going more than 2 weeks without a trip, so downtime due to my inabilities (broken bolt extraction mostly) isn't allowed.  Well that and spending $1k . . . .

From the $320 Fridayparts website - "aftermarket parts For HYUNDAI excavators, wheel loaders, bulldozer, backhoe, skid steer loader and so on".  We probably generate a LOT more heat from those long climbs than a bulldozer or backhoe.  Something to consider.

Make sure the turbo flange is the correct position / orientation.  That's the biggest difference I've seen with different ISC manifolds. 

- bob

Edited January 31, 2023 by cbr046

[BradHend]

Aftermarket wasn’t an option for my manifold, part#s 3955199, 3955197.  Not sure if you followed along my post about my manifold issues, but long story short - I had to have Cummins specifically make the larger 3955199 section with the EGR and turbo flanges on it.  Cost me 1200 just for that, then another 450 for the smaller section.  Literally scoured the globe trying to find it, be it new, used, salvage - notta. 
 

Your comment about the 2 pieces being a matched pair I hope doesn’t bite me in the butt. My two sections most definitely are not a matching pair, however the taper fit is beautiful and the ports are all perfectly in line with each other. 

Crazy times. 

[Jdw12345]

If your manifolds are 24 years old, I would say that’s acceptable service, I would be purchasing new Cummins manifolds. I would think that change’s would have been incorporated into the new manifolds, for the better, we hope!

[jacwjames]

2 hours ago, cbr046 said:

Some have had success w aftermarket, some not.  I think @jacwjames had poor quality with a Ford gasser manifold (aftermarket).  Not sure about the Cummins aftermarket.

I'm in the same boat and honestly I only want to attempt this job once.  Biggest issue is not going more than 2 weeks without a trip, so downtime due to my inabilities (broken bolt extraction mostly) isn't allowed.  Well that and spending $1k . . . .

From the $320 Fridayparts website - "aftermarket parts For HYUNDAI excavators, wheel loaders, bulldozer, backhoe, skid steer loader and so on".  We probably generate a LOT more heat from those long climbs than a bulldozer or backhoe.  Something to consider.

Make sure the turbo flange is the correct position / orientation.  That's the biggest difference I've seen with different ISC manifolds. 

- bob

At the time Ford was having trouble with the manifolds, passenger side failed under warranty and was replaced with a Ford manifold. 

Then my drivers side failed and I replaced with an aftermarket which is still on the engine now.  As far as I know the current owner has not had a problem with the aftermarket. 

The passenger side replaced under warranty with an OEM Ford warped after a couple years (or less), but instead of replacing I just had machined flat and as far as I know it is still  in place. 

3 hours ago, Kevin Schitoskey said:

Facing the dreaded Exh manifold replacement for my 99 ISC 8.3.  I had some sticker shock when contacting Cummins - $ 1,074 for the 2 piece manifold.  Couple of questions for the group:

1. Does anyone have any experience with aftermarket (read: non-Cummins) manifolds like below?  

https://www.fridayparts.com/exhaust-manifold-long-3964070-short-3937477-for-cummins-engine-8-3-8-9-8-3c-qsc-isc-isl-qsl-l8-9?msclkid=d9f3fd81b0fd15595c259e59f6d0a446&utm_source=bing&utm_medium=cpc&utm_campaign=PLA-usafreeshipping-US-9.23&utm_term=4586750202629092&utm_content=pla-usafreeshipping-us-9.23

2.  The crack is in the smaller of the 2 piece manifold.  Am I correct in assuming that these must be replaced as a matched pair?  Replacing only the small portion would save a turbo removal, fewer bolts to break off, etc. 

Thank you all in advance for your input.

When I replaced mine in ~2015 the cost for the manifold, bolts, and gaskets was $600. 

I would be concerned with fit if you tried to replace only one section, it could work and if the fit was good I wouldn't worry about it.  Big if though!!

On my Class C Ford 460 I did use an aftermarket on the drivers side and it worked good, it was beefier and had additional ribs cast into the manifold.  Much cheaper and readily available. 

The passenger side failed under warranty and was replaced with OEM, took them +4 months because no manifold in the USA anywhere.   Guess what, it warped within ~2 years, but I didn't replace, just had it machined flat. 

I guess if I had a problem I wouldn't be concerned about using an aftermarket since I'd do it myself but if you are paying labor I spend the extra on OEM.  Recent posts say that some Cummins shop just charge a flat rate of $2500 to replace a manifold, probably more now due to the increase in the part. 

[Ted Carbonaro]

I just replaced my ISL400, 2pc cracked manifold at Cummins Salt Lake City, October 2022. Bare manifold $780. all necessary parts $1100. Labor $2020. Yes, quite expensive and as full timers I felt that I wanted it done once and done right. Lucky for me, about 650 miles later, by chance I discovered that the two lower turbo to manifold nuts and studs either fell out or were never installed! Yikes!! I called Salt Lake service and they quickly authorized Cummins in Mesa AZ to rectify the situation. Cummins Mesa was fantastic about it and installed a new turbo gasket as well. I now have a quiet engine that gets a full 32psi boost. 

 

[Simplysmn]

I bought a  2 piece from Ebay that seems to be holding up pretty good we have had it on there since 2020 n no issues. 

 

[TomV48]

4 hours ago, Ted Carbonaro said:

I just replaced my ISL400, 2pc cracked manifold at Cummins Salt Lake City, October 2022. Bare manifold $780. all necessary parts $1100. Labor $2020. Yes, quite expensive and as full timers I felt that I wanted it done once and done right. Lucky for me, about 650 miles later, by chance I discovered that the two lower turbo to manifold nuts and studs either fell out or were never installed! Yikes!! I called Salt Lake service and they quickly authorized Cummins in Mesa AZ to rectify the situation. Cummins Mesa was fantastic about it and installed a new turbo gasket as well. I now have a quiet engine that gets a full 32psi boost. 

 

My ear is not so good.  What should I be hearing with a bad manifold? On oil change the tech recently said that he heard a small manifold leak.  I hear nothing new.  I stand by the engine as ground guide when DW moves us on and off a site but of course do not hear much from up front driving. I try to stay out of my foot in the CARB, so to speak, and seldom hit max boost but noticed that I did hit 32 on the boost momentary one time last week, when I called for it.  (is it psi?  I thought it was column inches of manifold pressure? What do I know)

[Ted Carbonaro]

I suspect that my manifold had been developing a small leak long before I heard it. I was losing boost on hills before I noticed the progressively louder squeal that almost sounded like a loose, squealing fan belt. I learned from another Monacoer that it was the leaking manifold. 
Along the way I also learned not to be afraid of using the accelerator peddle. You need rpm’s and boost to tow up hills. 

[TomV48]

1 hour ago, Ted Carbonaro said:

I suspect that my manifold had been developing a small leak long before I heard it. I was losing boost on hills before I noticed the progressively louder squeal that almost sounded like a loose, squealing fan belt. I learned from another Monacoer that it was the leaking manifold. 
Along the way I also learned not to be afraid of using the accelerator peddle. You need rpm’s and boost to tow up hills. 

Thank you for the points on what sounds to listen for.  And oh, I'm not afraid of using the accelerator,  I just baby all of my mechanical toys. Nearly 285000 miles on a 2004 Ford explorer chassis by not pushing it too hard.

[Dr4Film]

I had mine replaced on my previous Windsor by Action Mobile Truck Service in Orlando FL for about $1500 back in March of 2020.

Frankly, if you or someone you are having do the job, replace both at the same time. Why go in there again later and do it all over again.

[Kevin Schitoskey]

Thanks to everyone for your responses - this is an amazing group.  I have followed the threads mentioned above, as well as the huge number of conversations on this subject.  This coach is new to me so I can't comment on the noise - the crack is obvious and I can literally feel the escaping gases.  

Sounds like best path forward is to bite the bullet and get the new manifold set.  This will give me a chance to get acquainted with the turbo, replace its oil lines etc. etc.  Like I keep telling my wife - this coach is not just an investment, it's a hobby.  And it's cheaper than golf.

Safe travels and thanks again.

[jacwjames]

11 hours ago, TomV48 said:

My ear is not so good.  What should I be hearing with a bad manifold? On oil change the tech recently said that he heard a small manifold leak.  I hear nothing new.  I stand by the engine as ground guide when DW moves us on and off a site but of course do not hear much from up front driving. I try to stay out of my foot in the CARB, so to speak, and seldom hit max boost but noticed that I did hit 32 on the boost momentary one time last week, when I called for it.  (is it psi?  I thought it was column inches of manifold pressure? What do I know)

On mine the manifold developed a crack.  It had a high pitch hissing noise, one day it was fine, next day I heard the sound.  Went back and popped the engine hatch cover and it was easily visible.

A gasket leak won't be as loud and may develop slowly over time.  But it you go back and so a visual inspection there will signs of black soot buildup next to the exhaust manifold where it mates to the head.   If a manifold warps it will cause a leak at the mating surface.  If there is a gasket leak it will take about as much labor to fix as replacing the manifold so while you have the manifold off it needs to be checked for trueness.  Put it on a flat surface and look to make sure each port is making good contact, if you have a thin feeler gauge you can see if there are any wide gaps and/or use a flashlight and look for light.  A new gasket set will seal small gaps but if there is a large one the manifold is probably warped. 

[dl_racing427]

On 2/1/2023 at 12:43 AM, TomV48 said:

Thank you for the points on what sounds to listen for.  And oh, I'm not afraid of using the accelerator,  I just baby all of my mechanical toys. Nearly 285000 miles on a 2004 Ford explorer chassis by not pushing it too hard.

I've found that the WORST thing you can do for an engine is to baby it.
Running an engine hard gets enough airflow and heat going to keep things clean and running well.
I daily drive a 2004 Focus, that currently has over 330,000 miles on it, with little more than routine maintenance.
I run it as hard as you reasonably can on public roads.  It sees full throttle several times a week, and regularly gets revved to 5-7k rpm.
The oil level still drops less than 1/8" in a 10,000 mile change cycle.
I'm just curious how long it will last. LOL

[dennis.mcdonaugh]

I didn't hear anything when I found my manifold cracked.  I was lubing the PAC brake and saw the black soot on the crack in the smaller of the two manifold pieces.