Well it wasn’t the fuel filters….(to make a short story long)

[Sand-dog]

OMG WWJD, five dollar mistake. because of you I’m now double checking my ISL 9 to make sure everything is tight and secure. I am so sorry you had to revisit this whole situation. Absolutely terrible what you went through. Thank you for all that you did and shared.

 

[Rich W.]

OMG WWJD, five dollar mistake. because of you I’m now double checking my ISL 9 to make sure everything is tight and secure. I am so sorry you had to revisit this whole situation. Absolutely terrible what you went through. Thank you for all that you did and shared.

Well fortunately you can easily access your motor to check such things.

 

[Neal]

@Rich W. are you the original owner?

 

[Rich W.]

@Rich W. are you the original owner?

No I bought it in 2020 with 16k on it. It was pristine then - not so much now (65k and counting). But…WOW, what a difference 8lbs of boost makes. I had the most wonderful day crossing Nebraska and Iowa ever (with boost as high as 32psi). All because this thing now runs as it should. Good enough for me. I’m simply elated that Truck Center Companies was able to finish the job that Floyds started and correct Floyds’ errors.

More on all that later - for now I’m just enjoying a beverage (or three) in a very nice, simple CG on the Cedar River in Iowa awaiting my appointment with HWH on Monday morning which will put me back on schedule, albeit with some unfinished business on the coach. But I don’t care - it ran so well today it was a joy and a pleasure driving and for now I’m just going to celebrate that.

Yes, these folks have my full confidence and endorsement. More on that later too.

 

[Rich W.]

I was just asked about the specific cause of the low boost/power condition that led to this whole conundrum and below is my response to that question:

The cause ended up being a damaged and disconnected air intake hose for the compressor which takes air from the CAC. Compressors used to take air from the air fiter assembly but somewhere along the line they changed over to supplying it from the CAC - maybe more pressure or volume? I don’t recall the reason. But the compressor supply hose is only 1” in diameter so it wasn’t a huge leak. Didn’t shut me down but did rob enough power to make the problem obvious.

Anyway that hose was damaged at some point (I don’t know when or how and unfortunately I neglected to ask for the old hose to examine it) and it was not even connected when it left the shop in Sidney. So Truck Centers in Lincoln replaced that along with correcting a half dozen other mistakes and omissions and now its running better than it has for a quite a while.

I don’t recall it having as much power as it does now, so the degradation of the hose was probably gradual because I didn’t notice it until I set out on this trip. But the difference was remarkable - from a max of 22 psi boost to 32psi. I could tell the difference before I was half a block away from the shop in Lincoln - it was like driving a different machine. Now I just have to get all the other stuff done that I was going to have handled in Nappanee.

Another clue beside low power was increased frequency of regens. This seemed odd but I failed to make the connection. It was due to the increased soot developed by insufficient air supplied during full throttle (max fuel) operation, which was more often due to decreased power.

So the moral of the story is that low boost is more than an annoyance and addressing it is something that should not be put off just because you're on a schedule. After changing fuel filters on the road (in hopes that was causing my low power condition) did nothing to improve things, my plan was to address it at or after Nappanee because I had a week scheduled there and I didn’t want to be late. Live and learn. I missed the whole week there and spent a lot of my coach improvement fund on an exhaust manifold, related parts, and lodging. Oh well - another costly lesson learned in the ownership of a DP.

 

[Bigblockyeti]

I'm also curious as to why the move from drawing compressor air from the air filter to downstream of the turbo? I have my guesses but it seems to me (and has been confirmed by this whole debacle) you end up making a less reliable power plant by doing so.

 

[Rich W.]

I'm also curious as to why the move from drawing compressor air from the air filter to downstream of the turbo? I have my guesses but it seems to me (and has been confirmed by this whole debacle) you end up making a less reliable power plant by doing so.

My guess is that the extra inlet pressure may benefit the compressor system, maybe allows for a smaller compressor or less run time, but it would have no benefit at idle, low throttle conditions, or deceleration, so……? Whatever but I agree, the fewer complications to the intake system, the entire system actually, the better.

 

[Rich W.]

I'm also curious as to why the move from drawing compressor air from the air filter to downstream of the turbo? I have my guesses but it seems to me (and has been confirmed by this whole debacle) you end up making a less reliable power plant by doing so.

I did a little more research after reading your post earlier this morning and this is not an uncommon problem - apparently chafing from clamps or zip ties, and rubbing on supports, as well as weakness in a 90° turn on the hose, can all cause this. And because it causes a relatively small leak (1” hose vs 4” inlet and outlet pipes) it just reduces boost enough to rob power, unlike a turbo boot that will about shut you down. There’s even a TSB on it for Navistar. Just another over-engineered complication we didn’t need.

Navistar version, same idea:

https://static.nhtsa.gov/odi/tsbs/2021/MC-10201757-0001.pdf

 

[Rich W.]

I'm also curious as to why the move from drawing compressor air from the air filter to downstream of the turbo? I have my guesses but it seems to me (and has been confirmed by this whole debacle) you end up making a less reliable power plant by doing so.

I guess it could be as simple as less and smaller diameter hose because the source is both under positive pressure, and closer to the compressor so cheaper. Personally I think its kind of dumb to have any more possible intake leak sources than absolutely necessary. I guess they don’t have high school auto shop anymore.

 

[Rich W.]

Well the issue with Floyds was finally resolved, although not during round one, and not exactly in a timely manner. Part of that is on me for giving them a chance to solve this at the lowest level and waiting for responses. But yesterday I finally talked to the right person and today it’s resolved.

From Floyds this morning:

Rich I went ahead and credited back all the labor you had spent with us here at our location which ended up being a little bit more than what you had spent at the following dealer. I thought it was only fair especially with how much you where inconvenienced with this whole situation, apologies that this didn’t go the way we would have hoped but I do hope you consider us in the future for your next repairs and we will do our best to make it right,

So I’m satisfied and while I hope this didn’t impact the mechanics that worked on it too much, I also hope everyone learned a little something. I sure did!