Exhaust Manifold Failures and Consequences

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Exhaust Manifold Failures and Consequences

April 02, 2013, 12:08:26 pm

A salesman noted a bit of a noise from my engine that I had not detected before or after he told me nor had service technicians when doing the annual maintenance. The service people did then investigate and conclude the slight noise was probably an exhaust manifold leak. For those not familiar with this topic, I will review what I have found and learned and hope that others with more expertise add to this topic. You do need to know about this threat to your engine.

The exhaust manifold obviously carries exhaust away from the engine compartment. When the manifold fails to completely perform that function, fumes can enter the coach. This was not detected however in my coach so that telltale signal was missing.

The manifold if leaking can reportedly injure the engine. And exhaust gases are used by the turbo system. If that is not performed well, you will notice a loss of boost (power) and mpg.

If left unattended (repaired) the leak can also leak hot gasses into equipment and areas where it does not belong. several sources said one should not drive if the loss is very significant though there were reports of fairly major exhaust leaks that did not cause damage.

Why does the manifold system fail? The gasket can develop a leak and, or the manifold itself can develop a crack. The heating and cooling of the manifold, over time, stresses the system and can in time cause the failure. One technician observed that they are seeing an increase in these failures and it seems primarily related to the age of the coach (he did not say miles but that may be more important?).

How to repair? You might undertake this but you may take the coach to a professional. It is not unusual for one or more bolts to break off and pose a particularly difficult removal. Also if the manifold can be reused, it may or probably needs resurfacing. Replacing the gasket requires dismantling the turbo system. A Cummins repair shop estimated 11 hours for this work.

So, what was wrong with ours? No gasket! No explanation, Tyler Truck only speculates that someone left it out on prior work. Cummins told me that they never built this engine without the gasket.

How to check for a leak? I will try to listen better to the engine. Look for signs of a leak with the engine running using a flashlight? Note any loss in boost could be a reason to check for this. Look for bent manifold bolts.

Re: Exhaust Manifold Failures and Consequences

Reply #1 – April 02, 2013, 12:50:20 pm

I had a cracked manifold when I bought the coach (did not know) but noticed black exhaust type marks on it then checked the gaskt joint. It was also leaking a bit. Took it all apart (first time ever) and broke 1 bolt in the hardest place to do it, and that was because I feel that even though I heated the block up around the bolts with a oxy/acet torch I could not get this one as hot and all except this one came out fine. I drilled the bolt and used a stud remover after giving the head a good heat up (easier now as manifold was off) and out it came. Luckily the seat area was good and I put on the newer 2 part manifold which Cummins said was part of the reason the first one cracked (stress??) Anyway all worked out fine. Friends a few weeks later arrived in their Monaco and guess what-He had been carrying a spare manifold he got in Costa Rica as his too was leaking. We set about doing that one with some confidence now. We also broke a bolt on his but not to worry it came out after drilling too.
I had a tough time in some awkward positions but we managed it. Not a hard fix as long as you have a few tools.
John H

Re: Exhaust Manifold Failures and Consequences

Reply #2 – April 02, 2013, 01:49:45 pm

Aside from all the items listed above, extended operation with a missing gasket or crack in the manifold adjacent to the cylinder head may, if not repaired, cause erosion in the exhaust port mating surface as the hot gases travel from the port to the outside . In extreme cases, this could require removal of the cylinder head to surface the entire exhaust port area on the side of the cylinder head so the exhaust manifold gaskets will seal completely.

Pierce

Re: Exhaust Manifold Failures and Consequences

Reply #3 – April 02, 2013, 01:54:54 pm

I had that happen on my ISC. It was not a huge deal and we did not break off any bolts so it was a simple fix.

Re: Exhaust Manifold Failures and Consequences

Reply #4 – April 02, 2013, 02:18:01 pm

Any exhaust leak on a diesel will leave a black "soot trail". When inspecting motorhomes, I go over them with a good flashlight: head to exhaust manifold, joints in exhaust manifold (most are 3 piece), manifold to turbo, turbo to exhaust brake (if present) and exhaust brake or turbo to exhaust.

It would have to be pretty bad to be able to hear a leak at idle on a large diesel.

Brett

Re: Exhaust Manifold Failures and Consequences

Reply #5 – April 02, 2013, 02:33:41 pm

Thanks Pierce, I had heard that possible problem, indeed Tyler wanted me Timothy drive there without more local inspection. I was hesitant to post some worse case options on this issue being a bit of a novice

But I did want to elevate the issue for other newbies to pay attention to it. I did not consider it until this!

Bret, I used a flashlight and saw no soot. I am not sure how Stewart heard anything for even after I was told he heard something I could not.

Tyler on phone said sometimes you could get fumes in the coach with such leaks.

Thanks all, mike

Re: Exhaust Manifold Failures and Consequences

Reply #6 – April 02, 2013, 02:46:48 pm

I had a horrible exhaust leak that was caused by some backyard mechanic, no not mechanic, only an idiot would replace abroken head bolt with a drilled through hole an use a common bolt, nut and washer, in addition to using common SAE bolts to " secure" the manifold. In any case the Cummins mechanic told me that exhaust manifold leaks are not uncommon on diesel pushers and easily fixed if addressed early on. Such was not the case with my exhaust leak. Cummins took care of it and everything is good.....for now.

Roland

Re: Exhaust Manifold Failures and Consequences

Reply #7 – April 03, 2013, 01:34:39 pm

Mike, good topic. I don't remember seeing a discussion on this, but then I haven't been on here all that long. Good to be aware of and as Brett does, inspect it occasionally with a flashlight. It seems odd you didn't see some soot on your inspection.

Re: Exhaust Manifold Failures and Consequences

Reply #8 – April 03, 2013, 01:46:10 pm

Hi dick, hope yous guys well out west. Cummins told me that some engines just burn cleaner than others, did I know what engine was in the coach where I saw all the soot? No.

Bret is always on target that I wonder why even with my limited experience I did not hear the leak. In my defense though neither did the technicians that serviced the engine until the salesman had me take it back to ask their opinion. I guess it just a very small leak at that point. Tyler Truck was reluctant for me to drive it to them so I think they are used to seeing much worse.

Our friend don hay said one time he found a black spot on the rear engine compartment vent, came to find it from the exhaust leak.

Cheers to you two, mike

Re: Exhaust Manifold Failures and Consequences

Reply #9 – April 03, 2013, 01:56:42 pm

Had similar in our SOB 8.3L Cummins.
Important topic; gave you a slap, oops, pat on the back for making all aware! :-)

Re: Exhaust Manifold Failures and Consequences

Reply #10 – April 03, 2013, 07:53:14 pm

Great info Mike, and I did call MOT about the generator problem. To wet here to check out what they told me to look at-- more to follow

Re: Exhaust Manifold Failures and Consequences

Reply #11 – April 04, 2013, 01:16:24 am

Yep, thanks for the tip. I decided that, having to drive 30 miles to the smog test station, that I might as well drive another 70 to go to my pal's shop, so I could show off our new to us rig and have him go over it and look for anything I might have missed, and to look at where I could see evidence of an exhaust least. He decided we best get after it. But I found yet another good reason to do an over and under crawl... one of the fanbelt idler pulleys was wobbling like crazy and was ready to let go. it was making a noise I though might have been just loose sheet metal around the muffler or maybe the radiator cover rattling. Gollygee, that wasnt' it! The bearings had siezed who knows how long ago, turning the bearing shaft into dust along the way. I'm really glad it held together ong enough to get me there. 2 bearings and a cap and a shaft from the nearest Cat dealer turned out to me not that spendy so we're doing both idler pulleys and the fan bearing. And the driverside exhaust manifold gasket. That should be the end of it for quite some time but I think I'll do a top and bottom engine check whilst running, before each trip, just add it to the checklist.

Re: Exhaust Manifold Failures and Consequences

Reply #12 – April 25, 2013, 11:20:53 am

Update: the cost of repairs can be over-estimated or charged

First, there was quite a bit posted over the past couple of years so I was not the first to experience this problem, I just raised recent awareness. So thanks to all that came before.

Now the latest, that should offer another awareness idea. I was parked at an RV park this month and met a great couple with a FT who happened to be on the Forum and knew my name and experience, wanted to know what I thought. A repair shop had told him that it would be $8,500 to repair the exhaust manifold due to some supposed problems with the head, bent bolts and so on, what did I think?

In the end an air line over the exhaust manifold to the turbo was protected from heat so he could get to a shop I had used. We called that shop, seemed on the right track with the fix. The story goes longer to a happy ending but this is the essence, and thanks to Dave Cobb and Don Cox for getting involved with me and the owner to have an ending much better than $8,500.

The message.....maybe it is not as expensive a repair as some shop might tell you. Check before spending that kind of coach bucks.

Mike

Re: Exhaust Manifold Failures and Consequences

Reply #13 – April 25, 2013, 06:34:39 pm

That was us. We were at extreme and Jenifer suggested a shop in Lufkin with a very nice mechanic who she has refered work before. This guy worked 3 days and FIXED things rather than just hanging on NEW parts. Total cost was 1/7th the estimat I was given. I will definatly return to Him for any aditional engine work I may need in the future Norm H

Re: Exhaust Manifold Failures and Consequences

Reply #14 – April 25, 2013, 09:43:59 pm

Quote from: nlh1250 – April 25, 2013, 06:34:39 pm

That was us. We were at extreme and Jenifer suggested a shop in Lufkin with a very nice mechanic who she has refered work before. This guy worked 3 days and FIXED things rather than just hanging on NEW parts. Total cost was 1/7th the estimat I was given. I will definatly return to Him for any aditional engine work I may need in the future Norm H

I too have used Bernd in Lufkin. Very satisfied with his work. He actually repaired an exhaust manifold saving $800.

Re: Exhaust Manifold Failures and Consequences

Reply #15 – April 25, 2013, 10:03:22 pm

I think the max I have seen on my M-11 is 27psi.

Re: Exhaust Manifold Failures and Consequences

Reply #16 – April 26, 2013, 12:42:14 am

on mine I have seen 32lbs and can get that any time I want on a good hill. The Banks and Resonator make a difference allright.
John H

Re: Exhaust Manifold Failures and Consequences

Reply #17 – April 26, 2013, 01:49:55 am

We also had a crack in the exhaust manifold, right next to the turbo. The crack was almost 1/16" wide, and we lost major boost (lots of black exhaust smoke, black soot around the rear grill...) Cummins in Gillette WY replaced both sections of the manifold, and said there was an inproved manifold design.

We've also used Bernd (Lufkin) and have been quite satisfied with his work. He replaced all the air bags, and fixed a leaking oil pan gasket.

Re: Exhaust Manifold Failures and Consequences

Reply #18 – April 26, 2013, 10:40:59 am

For turbo PSI readings, before the Resonator, it would run about 26-27 psi, with resonator 28-29 psi, then with the ISM500 turbo & calibration of the ECM, now 32-33 psi, SO I am assuming my manifold is not cracked & leaking too much.
Just another indication the resonator freed up the turbo, maybe 25 hp worth ?
I go with facts and experience, not opinions, I must be from Missouri, show me, dont beat my ears bloody.

Dave M

Re: Exhaust Manifold Failures and Consequences

Reply #19 – April 26, 2013, 12:02:02 pm

I had to replace the head last year. Luckily the old manifold was okay! The labor was worse that the parts.

Re: Exhaust Manifold Failures and Consequences

Reply #20 – April 26, 2013, 01:45:15 pm

I watch my turbo pressure too. I also saw the same initial gains as Dave M saw. I had the Exhaust Manifold crack on my ISC but the ISM has been rock solid. I wonder if that is the difference between Heavy duty engine rating and medium duty.

Re: Exhaust Manifold Failures and Consequences

Reply #21 – January 13, 2014, 06:28:30 pm

I just finished doing the job myself on my C8.3 and figured I would list the cost of parts since there had been some complaints on the web about the charges. Everything bought from Cummins Mid-South.

$368.16 - (1) exhaust manifold
$124.44- (6) gasket, exhaust manifold
$120.72- (12) screw, hexagon head cap
$44.76 - (12) lockplate
$6.30 - (1) gasket, turbocharger
$3.34 - (1) gasket, turbocharger
$23.28 - (4) stud
$9.96 - (4) nut, regular hexagon

Everything included, about $760 in parts though I didn't end up using the turbocharger oil return gasket. The job isn't terribly difficult but is labor intensive (thankfully, I didn't break any bolts) and I would consider it a very good deal if you could get a shop to do it for less than $1600.00, considering the cost of parts.

I was very much hoping that there would be some new and improved parts since 1998 but the exhaust manifold seems to be the same design from 15 years ago though the new one is clearly longer due to how much the older piece had shrunk and bowed the bolts.

I was getting a leak at 3-4 of the gaskets as it gets ready to turn 100,000 miles. The shrinking of the manifold was allowing exhaust gasses to escape since the manifold and head didn't overlap correctly anymore. Since it looks and weighs in as virtually the same part, the exhaust manifold could probably be added to your preventive maintenance checklist as needing to be replaced every 100,000 miles or sooner.

Re: Exhaust Manifold Failures and Consequences

Reply #22 – January 13, 2014, 10:51:33 pm

Robert, What was your technique to not break any exhaust manifold bolts.

We heard that the ISC has a two piece exhaust manifold, but it is not specified for the C8.3. We had ours changed because of shrinkage and several bolts were broken.

Re: Exhaust Manifold Failures and Consequences

Reply #23 – January 13, 2014, 11:19:49 pm

Regarding costs for an ISM, we paid Tyler Truck Center, ism certified, $1249 for the job.

I did hear that one of the repairs local was incomplete, the manifold was not realized to be the wrong size and the job had to later be redone.

Bent bolts can happen from heating/cooling of the manifold, some can just become frozen in and if broken trying to remove will be more serious repair...that explains the price a friend was quoted as I recall, the repair proposal seemed to expect damaging a head in working with the bolts. Anyway, that why I wanted pro to do this. That was what we paid.

Re: Exhaust Manifold Failures and Consequences

Reply #24 – January 14, 2014, 12:24:17 am

Mine was a 2 pce on the ISC C8.3.
John H

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