QSM-11 Intake blow-by/bolt missing

[Four Suns]

On my way back from toting my wife and her girlfriends around, I noticed that the port engine was slow to spool up compared to the starboard. The engines ran fine and I got them up to WOT specs after about an hour running them (just for a few minutes though). However, the slower spool up still exists even after restarting the engines. I went down in the engine room today and one of the bolts on the port engine intake, between the after cooler and the head, is missing a bolt. There are now 3 bolts instead of 4 and there is obvious gas blowing by this connection now. What is puzzling is that the blow-by on the head is black. I'm not sure if that is from the intake air or from the gasket/seal (if there is one) blowing apart. I'll post some pictures but I have to go buy a new camera first (don't ask). I'm wondering if I can just put a new bolt in for the rest of the season (2 months) or if I'm hosed and have to pull the after cooler off… again… I have a feeling I'm hosed.

I'm trying to find a way to blame this on someone... suggestions welcome.

 

[Pirate]

Gary- Is your boost pressure diminished? The Q has a common exhaust manifold leak that puts minor soot in that vicinity. That might explain your black residue. I can't post a photo here, but I'll e-mail it to you to see.[/img][/quote]

 

[Four Suns]

This is not on the exhaust manifold but on the top of the intake manifold right by the valve cover on the port engine. I don't have the exhaust problem yet that I know of. This is clearly the intake manifold blowing intake air out right at the joint on the head.

Where do you get the boost pressure reading from? Where is the sensor and does it show on the Cummings display?

 

[fwebster]

May I please guess?.........since I don't have QSM's that's all it would be.

A missing intake bolt will allow a vacuum or pressure leak depending upon how much boost you are developing. If you have a leak, that means you are not getting a complete intake air charge and could explain why you can't spool up the engines normally. The black stuff is likely just a Cummins booger......Gary, I'm sorry; the devil made me do it!

I'd remove a matching intake bolt from another cylinder to measure then go get one at the parts house and put them both back in and re-torque all of them. Betcha you get out of this one for the cost of the bolt.

 

[Four Suns]

Here is a picture of the intake manifold as it is bolted on the head. Notice the bolt missing on the bottom.

I found pieces of the gasket on the guard on the bottom of the manifold so it appears that the corner of the gasket has been blown out. I'm sure this is my wife's fault somehow...

I talked to my mechanic tonight and he is coming out Thursday morning. He didn't think it was a big deal but said it would need new gaskets on both sides of the manifold. He also said that "Those big six cylinder diesels vibrate a lot so you have to keep checking the bolts on them." I swear... If Godzilla's girlfriend needed a vibrator, Cummins would have built it.

 

[Robski97]

Gary,
Im sorry for ur issue... my wife heard my chuckle and wanted to know what could be so funny on a boating website... I told her ur godzilla line... she laughed.... Job well done sir...

As for fault u can blame ur wife ... instead of helping her load and unload the boat u should have been in the Bilge checking on all possible items that could come loose... This isnt related to that other bolt u had rolling around a few months ago ??

Hope it all turns out ok...


Rob

 

[Four Suns]

I'm still wondering why there is so much black there... you would think this is an exhaust manifold. I just had the valve lash adjusted back in June. Does an Airsep suck that much oil into the intake stream?

 

[Dave S]

Gary

From my experiences it is quite "normal" for intake manifolds, throttle bodies, carburetors, etc to carbon up over a period of time. I am not sure what causes this but I have had to clean the intake systems on my cars any number of time over the years because of this. I suspect that black color is just indicitive of the same thing because of the missing gasket. Have you looked at the rest of the intake manifold on this engine as well as your other engine for evidence of carbon build up?

Dave

 

[Asureyez]

Black Dust

Hi Gary

That black soot like material inside the air intake pipes is engine oil vapor and simple dirt that gets past the air cleaners. When particles go through the turbo anything organic gets "cooked" and over time there is a build up on the pipe walls or carbon dust. When you touch it it should not be oily but more like graphite dust.

The loose/missing bolt is a real surprize. Now I have to add re-torqueing engine bolts to my list of to do's (this will wait to cooler weather that's for sure!)

If you remove all the piping you can clean this up with brake cleaner (outside the ER and on the dock please)

 

[Four Suns]

Just as a frame of reference, this is the starboard engine and the same joint:

Very clean... and yes I do vacuum my engine room on occasion.

I did find the bolt and some more gasket material this morning. Here is what I found:

I'll assume it's better news that it vibrated out and did not break off. The history of the port engine is that the bolts on the base of the aftercooler all vibrated lose a year or so ago and I caught them when one fell out into the bilge. The only thing holding the aftercooler in place was the intake manifold, the turbo connection, and the raw water pipes. The starboard engine has never had a bolt come loose but the port engine must have had a different dweeb on the torque wrench.

I also pulled the Airsep off and looked at the turbo:

It spins freely with a little residue on the outer parts of the blades. It comes off very easily. It appears to be the same stuff as that coming out of the joint. The inside of the Airsep and the hose coming from the engine oil side were all clean with no residue or oil in them.

 

[Four Suns]

I took the boat out for spin tonight to measure the boost pressures on the port and starboard engines. At 2000 RPM's, the boost pressure on the port engine is 41-43 in Hg and on the starboard engine it is 48-50 in Hg. At WOT (2330 RPM's) the boost on the port engine is 63 in Hg and 73 in Hg on the starboard. When I throttle up from idle, the boost pressure on the starboard side spikes up to 70 in Hg or so but the port does not... it gets to it's final number gradually.

My wife asked "Why are you making such a big science experiment out of a screw that fell out of an engine. Just screw it back in and forget it." First off.... it's a "bolt" not a "screw"... and you have to make sure these things are right. Women....

The idea I had tonight was to run down river without the bolt in and measure boost pressures then go put the bolt in and tighten it up and measure boost pressures on the way back. I learned you can't put a bolt in between an aftercooler and a head on a hot diesel without burning your arm twice and hitting your head on the ceiling. I did not put the bolt back in.

I did calibrate my crappy fluxgate compass and get a good sunset shot:

Mechanic is coming out tomorrow to fix it.

 

[fwebster]

uhhhh, ..........at the risk of stating the obvious, that black stuff on the manifold/head is oil/carbon residue from a leak created by the missing bolt. What did you expect to find when you ran the boat? SInce the turbocharger creates positive intake pressure and you have a leak, wouldn't you expect the boost pressure to be lower on the side where its leaking?

Maybe you can file that one in your log book under "significantly over analyzed problems", huh? Come to think of it, your wife may be a danged good prospect for diesel mechanic school.

 

[Four Suns]

Ok... so the mechanic goes to pull off this intake manifold and SNAP! The upper left bolt which is about 3 inches long breaks off. The upper bolts on the manifold are about 3 inches long whereas the lower bolts are about an inch long. Here's a shot of the intake manifold removed:

The entire lower portion of the gasket was gone and you can see where the intake gas was hitting the sheet metal guard on the bottom and discolored the paint. Here's another shot showing that the top half of the aftercooler and the heat exchanger had to be removed to use a left handed drill bit and work out the broken bolt.

I call the aftercooler heat exchanger lower housing "the bathtub" (the thing in the lower part of the picture) as that's what it looks like with the top off and the heat exchanger removed. It's a very different design than the B and C series Cummins.

The end of the broken bolt indicated fatigue with the typical linear wave patterns so it appears the vibration killed that bolt as well. It was not a torsion break. We will be replacing every bolt with new ones on this assembly tomorrow. My guess is that when the aftercooler housing lost it's lower bolts last year, it weakened this whole thing and it was just time...

Oh... and yes... I did expect the boost pressure to be lower. Remember I used to work for NASA and we all got paid to drag a simple problem out for months on end with analysis.

 

[Robski97]

So has ur wife said yet " if u only would have just put the bolt back none of this would have happened!!!"

Gary, Gary....

I feel bad for yea... but great comentary.

Rob

 

[Turtlesboat]

I was wondering why the space shuttle keeps having things fall off of it.

 

[Bottom Line]

Remember I used to work for NASA and we all got paid to drag a simple problem out for months on end with analysis.

Ok...we will be expecting a full after action report....

Off thread....what kind of new camera did you buy? Back to our reguarly scheduled programing....

 

[Asureyez]

We are not finished anaylzing this!

Okay so we have a after cooler that danced off the engine ... the after cooler that is attached to the same intake manifold that had its bolts fail, have I got this right?

We need a special commission to think this through! So when we re installed the after cooler which was required because of vibration loosened bolts, we didn't check the adjacent bolts for similar failures ... right?

Gary, did you or anyone of the techs that work on your boat work for Thiokol at the NASA?

Now before we actuaklly fix the problem we have a bigger problem to determine the cause of and that is ... where is all this vibration coming from that is so powerful as to break loose torqued bolts ?????

Suspect ... engine alignment, or cutless bearing vibration, or shaft whip, or ... a flywheel out of balance or a cylinder failing to ignite consistantly.

The vibration will continue to haunt this engine until you root it out and my concern is for those fasterners you can't see.

Please consider requiring the Tech to use thread locker (Permatex BLUE is a GOOD choice, or Loctite Blue (Breaks at 55# torque) on all bolts and don't let him start work unless you see a torque wrench in his tool bag.

While he's there maybe check the head bolts ... retorque as required.

<peanut>

 

[Four Suns]

Re: We are not finished anaylzing this!

Okay so we have a after cooler that danced off the engine ... the after cooler that is attached to the same intake manifold that had its bolts fail, have I got this right?

correct

So when we re installed the after cooler which was required because of vibration loosened bolts, we didn't check the adjacent bolts for similar failures ... right?

correct

Gary, did you or anyone of the techs that work on your boat work for Thiokol at the NASA?

They all got fired went to work for Cummins. :grin: I will say that the "o-rings" on the aftercooler didn't fail...

Now before we actuaklly fix the problem we have a bigger problem to determine the cause of and that is ... where is all this vibration coming from that is so powerful as to break loose torqued bolts ?????

Suspect ... engine alignment, or cutless bearing vibration, or shaft whip, or ... a flywheel out of balance or a cylinder failing to ignite consistantly.

The vibration will continue to haunt this engine until you root it out and my concern is for those fasterners you can't see.

I had the shaft/engine alignment checked last year when I had the props swapped and all was fine. The boat does not vibrate at all so I'm not convinced this isn't a case of improper torque on the aftercooler housing during it's assembly at the plant. All of those bolts essentially "fell out" which just seems like they were not tightened and the result of me not catching it in time is what I am dealing with today

Please consider requiring the Tech to use thread locker (Permatex BLUE is a GOOD choice, or Loctite Blue (Breaks at 55# torque) on all bolts and don't let him start work unless you see a torque wrench in his tool bag.

Done

While he's there maybe check the head bolts ... retorque as required.

hmm... don't really want to fix something that is not broken... yet... if the head bolts fail/come lose, I'll deal with Cummins on that.

 

[Asureyez]

Ooookay ...

You have a 560 HP electric start vibrator! :smt038

 

[Four Suns]

635 HP