have a 2004 LLY with 1,000 miles. I followed all the break-in rules. I pulled my 5th wheel today for about 30 miles. When the truck got good and warm (keep in mind I am still pulling at 50 mph or less), the truck started making weird noises when comming to a stop. At first, I thought it was the transmission. However, the truck would make the same noise when I pressed on the brake and reved the motor at the same time with the truck in neutral. It seemed to subside after I quit pulling the trailer. The noise put me in mind of a power steering pump going out (being strained and complaining about it). All fluids appear up to reccomended levels. I need to pull my 5'er next week to go camping. Anyone out there have any ideas on this one??


Thanks in advance.

the break in says nothing over 50? oh well. i just pulled a reg trailor that weighs about 8000# with only 2100 miles. i did not beat the truck doing it but it pulled fine. and i dont have a clue of what might be the problem.


have you tried reving the engine in park? because in nutral the tranny still spinns. try doing that and see if it still makes noises.

My truck makes this noise. It sounds like its coming from the brake booster.

Mine does to i think it is the power steering pump but it wont do it when i go to the dealer so they wont fix it. http://www.dieselplace.com/forum/smileys/Angry.gif

I get a similar noise as well. It is some times there when I am not pulling (it is very faint), but ALWAYS there when I am pulling. It does seem to resonate from the brake pedal/Power steering pump (remember these trucks have hydro-boost and the brake "booster" assist comes from the power steering pump, not the engine vacuum (diesel: NO VACUUM). I get it when I am hill climbing too, and once on vacation in CA. it got pretty loud then went away.


This is a new noise, that I didn't have with my LB7. I don't believe that there were any changes with any of these parts for the LB7/LLY change, so it is hard to say what might be causing the noise. I have a guess that it might be Turbo related, but I am not sure just how.


Chris R.

I get the groaning too. Only when the truck is good and hot, and/or when loaded. Definitely power steering related, as it really gets louder when I turn the wheel at low speeds. Since thers's plenty of warranty left, gonna wait and see how it performs over time.

Thanks for the response. It seems that I am not alone. I trust it has not caused any of you roadside grief.

I haven't experienced this problem yet.... But believe me, with my towing woes... I am sure I will... Anyway, take your trailer to the dealership and have the SM go for a ride with you. I had a tranny issue on my Dodge that I went in for 7 or 8 trips only to be sent away without a resolution (cannot duplicate).. I decided that the next time it did it, I would drive there (trailer attached) and take the SM for a ride.... Went there the next time it did it and yep... took a SM For a drive - had a new tranny and TC within 3 days... 8 wasted trips only to find that they wouldnt' do anything until they heard the tranny slip... Fixed that...


Just a suggestion..


~J

I too have the noise.It's loud.I 've been thinking it was the Allison.My 02 D/A did not make it. It is a moan or low pitch whine and its only present when towing.

Mine makes the noise too.I have a manual transmission. The noise gets louder when i press the brake pedal,but i can press the clutch pedal in and it stops.I wish it would do it all the time.

I have this noise also, when braking and while towing. Engine has to be hot. 7k miles Edited by: BMCD

The noise you are talking about is the clutch fan. It kicks in at low rpm's when the engine is warm.

I was going to say Fan Clutch as well.

This noise is not the fan clutch. I live in the mountains and know very well what it sounds like when the fan kicks in. Have you ever heard what it sounds like when someone is driving a car that is low on power steering fluid, how it makes that whine? That sound though not as loud, is what I hear coming up through my brake pedal from the hydroboost. I also can hear mine when I am out driving around town and working my steering more, I hear it when I steer.


I wish this was as simple as the fan blowing, but it's not. And my 2002 did not have this noise at any time.


There is a second noise that I hear when pulling hard, usually up hills that seems to resonate from the turbo and it seems to come in through the brake pedal too. It has the sound of "water running through a high preassure line" type of whine. I had decided that this might just be normal for the type of turbo that we now have. Time will tell.


Chris R.

When I hit the brakes my truck makes like a cracking noise, or the noise you hear on old big wooden boats when the wood is under a load. I just had the brake booster changed because it was leaking power steering fluid, it was fine before this.

Just bought my LLY in April, it has a build tag of March... if that makes any difference. I sold my '02 2500HD Crew Long bed for this one and absolutely love it. It's a 3500 SRW Crew Long bed and I can't wait to get my trailer on the road.


I just passed the 1800 mile mark and I'm currently hearing a noise that is similar to what is described. To me it sounds like a tranny whine... happens more when cold then hot. Back in 86 I had a chevy camaro that whined to no end when really getting on her.


If you all hear of a resolution please let me know. Awesome forums guys... Thanks Webmeister http://www.dieselplace.com/forum/smileys/Big Smile.gif

I've got the same noise in my LB7. I just pulled my 5th wheel through some big hills over in Ark. The noise didn't start until the engine got real hot, EGT was up around 1200, both engine and tranny was working hard. It sounds like an additional fan cutting on to cool the engine.


Doug

I was at the dealer yesterday and He told me that it is a hydraulic boost to the brake system that activates when there is low pressure in the brake system, like after you have been running for 100 miles without using the brakes. It sure is loud!

I have been noticing a similar situation when I brake suddenly. It is intermittent and unpredictable. Skeetdiesel's response seems to make the most sense, based on what I have been hearing. Execpt for the sound, everything seems to work normally and I was going to just drive it till something more concrete shows up. It doesn't seem like the kind of thing that is ever going to happen when the service tech is listening.