"Shhhh" sound from engine; turbo?

[boheir]

I have an 05 ISL, THOUGHT IT MIGHT BE A BELT TENSION PULLEY, BUT WAS AN EXHAUST LEAK, ONLY NOTICEABLE UNDER POWER, DROVE FROM PALM SPRINGS TO TORONTO...NO PROBLEM

[Dtwallace]

Originally Posted by vmallet

Thank you for the various inputs. I did a visual inspection today with the engine at rest to try to find something obvious (loose clamp or crack somewhere) but nothing jumped at my untrained eye. I tried to wiggle the hoses/clamps that go from the turbo to the cooler and from the cooler to the intake and things looked sturdy enough (again, to my untrained eye...)

I am hoping to try the running test DTW suggested tomorrow when it is time for us to break camp again, I imagine putting the coach in gear (even with the breaks fully applied) is probably not the best idea with the jacks down and the slides out...

And just to make sure I am looking at the right things, could you confirm my understanding of what's what? Below are two pictures taken from underneath the coach looking up, front of the coach is left, rear is right:
1- exhaust coming out of turbo and into exhaust system
2- charge air coming out of turbo
3- fresh air coming into turbo from air filter

Vince.

Picture number (2)

In this picture, I can clearly see your leak, it’s that outlet side of the cold side of your turbo.

You see the black deposits on the top of the turbo? That’s the track it creates when air is escaping.

The hose that is coming from the turbo to the change air cooler is clearly damaged and ready to completely fail.

I would not travel too far in this condition, as when the hose completely fails, you will loose 80 percent of your engine power when the (ECM) derates your engine to keep it from smoking.

Also, if you did make it home in that condition, with the engine not getting full boost when it needs it, you will be putting excellerated soot into your DPF exhaust system.

You should be able to have that hose replaced at a truck stop repair shop.

Good luck

DTW

[Dtwallace]

Originally Posted by vmallet

...and another question: we are on our way back to California from TX and have another 1,800mi ahead of us with a few stops here and there. Is it reasonable to wait until we are home to have it worked on while it's easy and the cats are out of the rig and drive with the leak or should I change all our plans and do what I can to find help ASAP? (nearest Freightliner center on our route is in ~500mi in El Paso).

I know the description of the problem is not a lot of information to work with though..

Vince.

To me, your discription was spot on. I’ve experienced this issue a few times as an (OTR) trucker.

That sound is the same as a split charge air cooler, and you won’t notice a loss in power until you need 100 percent.

Take a good look at that hose, maybe it’s lose and can be saved.

DTW

[guardrail53]

Originally Posted by TripleEEE

Bottom pic. #2

Hose looks like it should be pushed further on to the turbo. Up to the "nub"

Loosen clamp and try to push further on.

Good eye, TripleEEE,
Hose is supposed to be past the nub sticking up by 2" or better! The nub is to hold the clamp and the hose from blowing off! Saw it right away! Loosen the clamp up, and push the hose on 2" past the nub, and then slide the clamp up past the nub and tighten to secure! Those clamp have a spring, that will keep tension on the hose and let it contract and expand with the heat the turbo makes! Snug the clamp so the spring is in the half way position!

Originally Posted by Dtwallace

Picture number (2)

In this picture, I can clearly see your leak, it’s that outlet side of the cold side of your turbo.

You see the black deposits on the top of the turbo? That’s the track it creates when air is escaping.

The hose that is coming from the turbo to the change air cooler is clearly damaged and ready to completely fail.

I would not travel too far in this condition, as when the hose completely fails, you will loose 80 percent of your engine power when the (ECM) derates your engine to keep it from smoking.

Also, if you did make it home in that condition, with the engine not getting full boost when it needs it, you will be putting excellerated soot into your DPF exhaust system.

You should be able to have that hose replaced at a truck stop repair shop.

Good luck

DTW

DTW saw it too!

Rail!

[vmallet]

What an adventure! Thanks again to taking looks at this situation.

Re: the hose needing to be past the nub: I am not really sure I fully understand how it really should be, thanks for your patience I'm attaching a picture of the hose in question taken from the other side (from the access bay in the bathroom). I felt around and it looks like the hose is clearly past a nub by a couple of inches with the clamp also past the nub. In the picture I have my finger pointing to the nub I can feel under the hose. This is true on both sides of that short hose. There is another nub on the gray metal elbow that looks to be a "don't push the hose in too far" nub.

Can you make sense of this picture and does this correlate the previous findings?

(turbo outlet side is on the right, cooler side on the left)

[vmallet]

More findings: we did the suggested test with my DW revving the engine and me looking down the bay. Turns out revving to 1500RPMS without engaging the transmission was enough to produce about 6PSI of boost and for me to hear/see some drama.

I saw a break in a small hose but I don't know what it is so bear with me while I try to describe what I saw... Attaching four pictures.

First picture (IMG_0060): taken from the access bay on top of the engine; bottom of picture towards front of the coach; looking at intake side of the engine, there's a sort of box (1) that has a couple of pipes coming into it. One of the pipe is (2) in the picture, coming from the rear of the coach (from the charge air cooler?) and routing under the box and finally into a rubber elbow that connects it to the box.

It looks like there were 'support clamps' to keep the metal pipe (2) from moving around; these clamps seem to have broken, the pipe is wiggling around when revving, and it looks like it tore a hole in the rubber elbow.

Picture 2 (IMG_0059): a close-up of box (1) with the metal pipe (2) routing under it and coming into the rubber elbow (3); here the crack is very visible at the top of the elbow.

Picture 3 (IMG_0062): close-up of the rubber elbow (3)

Picture 4 (IMG_0063): a close-up of the two broken support clamps (4) on the metal pipe (2). It's unclear to me where those metal clamps were attached to before breaking.

It seemed the Shhh sound was coming from the left / intake side of the engine (where the piping is) but it was loud in there and it could have been the sound bouncing around.

Vince.

[twinboat]

That hose is the air compressor intake hose. The air compressor is supplied with filtered air from the boosted side of the intake manifold. That's why it gets loud under load.

In picture 4, I can see the head of a bolt with the remains of the clamp under it. New hose, new clamps and it should be good to go.

You probably want to get that hose replaced, only because at idle and low RPMs, unfiltered air can be drawn into the intake and compressor.

It is said that 1 hand full of dust will ruin an engine.

[guardrail53]

Originally Posted by vmallet

What an adventure! Thanks again to taking looks at this situation.

Re: the hose needing to be past the nub: I am not really sure I fully understand how it really should be, thanks for your patience I'm attaching a picture of the hose in question taken from the other side (from the access bay in the bathroom). I felt around and it looks like the hose is clearly past a nub by a couple of inches with the clamp also past the nub. In the picture I have my finger pointing to the nub I can feel under the hose. This is true on both sides of that short hose. There is another nub on the gray metal elbow that looks to be a "don't push the hose in too far" nub.

Can you make sense of this picture and does this correlate the previous findings?

(turbo outlet side is on the right, cooler side on the left)

Yes, that hose is good to go! As long as it has no holes, it is in the right position!
On looking at the first picture again, and blowing it up, I see the connection under the #2, that I thought was not right, it is clearly ok! That is a metal on metal connection from the turbo to the 90* elbow, and it looks good too!
Sorry, I did not see it clearly at first!

Glad you found the bad hose under the air compressor, and the broken clamp! Good Job! Fix those, and you should be good to go! Rail!

[Dtwallace]

Glad to see you found the leaking hose. I would be sure to recheck the rest of the systems hoses as I’m sure you have other pending issues that would effect its reliability on the road.

Happy trails to you and yours
DTW

[Mark D]

Do you hear it at the rear inside? We had an issue with the seal for the access hatch. When under load some air would whistle through a small gap and make a hiss.

We found where it was by looking at the back of the bath mat. You could see the area. We built it up and it fixed the noise.

[vmallet]

Well well well... We were starting to reroute our trip to go to the nearest Freightliner Oasis service center to have them look at the problem but when I called to confirm it was cool they said "oh no, not before a month from now!". I called Freightliner's help line and they listened to my description, had me send the pictures over, and like twinboat said they said it was the line to the air compressor intake. They gave me part numbers so I could have them ordered and suggested that with a bit of duck tape, I could easily wait until I crossed paths with a Freightliner dealer...

I duck taped the rubber elbow, called the Freightliner dealer next on our path to order the parts (El Paso in ~500mi) and off I went to our intended destination. When we reach El Paso in about a week I will get the parts and if they can't work on it I will do it myself (it looks like replacing the rubber elbow and the support clamps shouldn't be too hard; hopefully).

Once I get back in California I am planning on having a full-on service review of the chassis and I will make sure to point out the black areas around the turbo to make sure they inspect the whole system. Like DTW says there might be some other issue that has been lurking around for some time.

Vince.

[vmallet]

Two weeks later and the saga continues!

The pressurized air blew right through the duct tape I put in there. 2nd iteration I put more duct tape with a couple of hose clamps to hold it in place, air blew right through that one too.

By that time we were in El Paso, and I was told the rubber elbow I had ordered had been on back-order for a while apparently and no sign of it arriving any time soon. I had scheduled an appointment with Freightliner but with the hassle of having to leave the coach there for some undetermined amount of time while having to take the cats out, and the part not being anywhere, I decided to abort and do a better temp fix until we reach California.

At least El Paso Freightliner had the two support clamps I had ordered. For the third iteration I used some self-fusing silicon tape for the rubber elbow, and spent a few hours replacing the broken clamps. A short trip told me that air pressure wins against just a few layers of the silicone tape, so I redid the taping with a bunch of layers of silicone tape with a few high-temp zip-ties to keep everything tight and for the past few hundred miles things have held up and no more "shhhh" sound! With the whole piping properly clamped down after replacing the broken clamps the crazy pipe vibrations/shaking are gone too which should make this whole setup last for a bit longer.

I did call a Freightliner service center in California to order that rubber elbow again and it is still on back-order with no known ETA. I wonder how people with real trucks do when they need to be on the road?

[Mark D]

You may want to try a speed shop, maybe one that deals with diesel pickup trucks. If it's the tube I am thinking of they may sell one of the diameter that is either universal or possibly piece two together or cut one down that will fit. Sounds like it may be worth a try.

[guardrail53]

Funny you shoukd ask, about what us O/O's did!
I had one of the long springs that hold up the air lines on the adjustable rear tandems break, the air lines dragged on the road, wore thru, and applied the trailer brakes and brought me to a stop on the side of the road! I fixed it with black electrical tape, wire ties, more tape, more wire ties, more tape, and hose clamps! Worked till i could get to a hardware store, buy the proper fittings, splice the air lines, and got to my destination, and delivered my load! Then i replaced the springs and the air lines! What ever works to get you to the safe place so you can fix it right! Rail!