What the heck is 'burst rattle'?


Took my duramax in for knocking that happens around or below 2000rpm when on the freeway under slight load. Let of the gas slightly and it goes away.


The service manage points to a tsb and says its 'burst rattle' which is supposed to happen between 1500-1800 rpm. Asked him to explain what it is and he has no answer, just that the tsb says its 'burst rattle'.


Can anyone explain that this is?

Come on guys! 44 views and no responses? Someone here must know what 'burst rattle' is and be able to explain it. Well, maybe not. No one at the dealer could. Well at least I know someone at the dealer didn't make it up. It was in the TSB from GM.


The printout they gave me had a document ID number on it: 1478961. It also had '#PI01845A' which I think is the TSB number and it ws dated 3/18/2004.

do a search for burst

I don't think that doing a search for burst would get him results.


Do you have a TSB # so that a tech can look it up?

Is that possibly the tech term for the intermittent knock covered by one of the TSBs.


Mine had it and the dealer explained how it was similar to the air hammer effect is in plumbing, only this is in the oil system of a new truck. Mine went away after the first oil change.


Doug

<A href="http://service.gm.com/servlets/BlobShtml?ShtmlFile=1478961&amp;evc=numSrch#ss1-1478961" target="_blank">
<H5>Condition/Concern:</A></H5>


A dealer may encounter a customer complaint of excessive engine noise on the new 6.6L (LLY) Duramax Diesel engine. <A name=ss2-1478961><A href="http://service.gm.com/servlets/BlobShtml?ShtmlFile=1478961&amp;evc=numSrch#ss2-1478961" target="_blank">
<H5>Recommendation/Instructions:</A></H5>


The 6.6L (LLY) Duramax Diesel engine contains changes made for performance and emissions . The NEW 6.6L (LLY) Duramax Diesel engine SHOULD NOT be compared to a 6.6L(LB7) Duramax Diesel engine for a noise concern. The 6.6L (LLY) Duramax Diesel engine noises are most likely to be described as a knock or whine noise during acceleration which are considered normal and do not effect the 6.6L (LLY) Duramax Diesel engine reliability and durability.

<LI =1>The 6.6L (LLY) Duramax Diesel engine noise knock noise on acceleration occurs during the transition from pilot to main injection that typically occurs near 2500 rpm. This engine knock noise has always been an operating characteristic of the Duramax diesel, but may be louder due to the new injector configuration to meet emission requirements.
<LI =1>The 6.6L (LLY) Duramax Diesel engine timing burst rattle at 1500 -1800 RPM (light acceleration, light load fully warm). If determined to be excessive compared to a like 6.6L (LLY) Duramax Diesel engine. For diagnostic purposes advise using 1 - 2 tankfuls of a name brand / different source of diesel fuel to determine if the concern is caused by a fuel quality issue.
<LI =1>The 6.6L (LLY) Duramax Diesel engine whine noise can occur on acceleration or deceleration. The new Variable VaneTurbo is always adjusting its position for engine performance and emissions. This in turn may cause the 6.6L (LLY) Duramax Diesel engine turbo to be louder than the 6.6L (LB7) Duramax Diesel engine turbo. NOTE: IF CONDITIONS OF A 6.6L (LLY) DURAMAX DIESEL ENGINE KNOCK OR WHINE NOISE ARE ENCOUNTERED AND THE NOISE IS NOT EXCESSIVE COMPARED TO A LIKE VEHICLE EQUIPPED WITH A 6.6L (LLY) DURAMAX DIESEL ENGINE, NO REPAIRS ATTEMPTS SHOULD BE MADE. ALSO NOTE: VARIABILITY OF A 6.6L (LLY) DURAMAX DIESEL ENGINE NOISE MAY BE CAUSED BY THE FUEL QUALITY AND/ OR THE VEHICLE OPTION CONTENT. </LI>

mpdlt - I reported tis to the service manager when I took it in for the first oil change and it still does it.


gearhead - I always do searches to try to find out if somehting has already been addressed. only found the text Mic_ posted which is exactly what the dealer gave me. Was not able to find any specific discussion of 'burst rattle'.


Max power - As I posted above, there was a number on the doc the service manager gave me - '#PI01845A' - not sure if this is the TSB number.


So, the TSB says -

<LI ="1">The 6.6L (LLY) Duramax Diesel engine timing burst rattle at 1500 -1800 RPM (light acceleration, light load fully warm). If determined to be excessive compared to a like 6.6L (LLY) Duramax Diesel engine. For diagnostic purposes advise using 1 - 2 tankfuls of a name brand / different source of diesel fuel to determine if the concern is caused by a fuel quality issue.</LI>
Have gone through a few tanks of 'name brand / different source of diesel' and it still does it. No change.
If it is normal, that's o.k., I just want to be able to understand what it is to know if its normal. If you read the complete text of the TSB in Mic_'s post you will see you can't even tell if GM is saying that 'burst rattle' is nothing to worry about or that it is a problem that needs to be fixed. All they basically say is if it seems louder than another truck that has it try changing gas. Its tough for me to compare to another truck but I'm assuming the diesel tech did. That's a pretty lame TSB if you ask me.
I also did a search on knocking and, after getting past the pilot injection discussions, I have seen others on the board describe the same sound in their trucks as I have and they are just as confused.
I'm just getting tired of hearing 'its normal' from the dealer for everything that comes up even if it is normal like the typewriter clack / valve tap at idle, the battery not charging message on the dic at startup, the low oil pressure on the gauge...at least for those there was some info I could find by way of an explanation.

In My Dealings With "warrenty" Its Usually "normal" Or So Your Told Untill The Truck Off Factory "warrenty".....then Oh My God All Of The Sudden Your Drivin A Piece Of ....! I Have'nt Had Any Issues Like This With My Gm, But The Others Seem To Run That "game". Just Thinkin Out Loud.........hope That Dosent Happen To Ya

I'll bet it is the knock that you hear when one injector is going bad. That is the exact condition that I had and a new set of injectors solved the problem. Dealer was no help until I had a long crank/no start condition. Give it time, soon you'll have a more serious injector failure. Sounds just like a little guy inside with a hammer trying to get out!

Dr Crane,

Just curious... Were your balance rates high when you had the fuel knock? If so are they better with the new injectors?

:)

Hey, this was my thread and I forgot about it. I still have the knock. I've put about 6,500 miles on it since this post. I have also been using power service for a while and have not really noticed any change. It doesn't seem to get better or worse. I will be bringing it in to socaldieseltech soon to have it checked out.

I have one question. Will a fuel knock in a diesel from a bad injector harm the engine like it would in a gasser or is it just annoying?

I knoiw exactly what you are talking about, the diesel knock when you get to those RPMS' get five time louder than all other positions on the tach. I never asked the dealer why, just assumed it was due to the CAT and the external injector configuration.:eek:

Dr Crane,

Just curious... Were your balance rates high when you had the fuel knock? If so are they better with the new injectors?

http://www.dieselplace.com/forum/images/smilies/smile.gifCan't remember what exactly they were, I know they were in spec but not ideal. No codes set. Don't know what the rates are now, dealer never said, I never asked.
If the knock is due to an overfuel situation, you could eventually burn a hole in the piston. I believe it to be an underfuel condition which won't do too much.
It took 40,000 miles for the problem to turn into a diagnosable injector problem.

Well, I finally got a chance to take it in to socaldieseltech to take a look. The balance rates in park and drive were well within the normal range. Socaldiesletech had a hard time hearing the knock I was describing and didn't think there was a problem. I get good mileage, have plenty of power and no smoking or rough idle so it probably is not an issue.

This is my first diesel so its hard for me to tell what is normal and what is not when it comes to sounds. I'm satisfied with waiting over time to see if it gets any worse. Just happy to be sure there are no obvious problems.

I had the knock you describe, i even heard it while coasting down freeway offramps. Sounded to me like a valve rattle. Got really loud over a period of 2 months and went away on one trip, never to be heard again. In fact i remember telling my wife on that trip "When we get back i'm gonna put the truck in the shop."

I've had the knock since I drove it off the lot. I thought it was normal untill I found this site. I go out of my way to ask other Dmax owners if their truck has the knock and they ALL saw no. I've got a paper trail started at several dealers so if it turns bad I can say, I told you! The reflash didn't help. If anyone figures out how to make it stop please post it. Turning up the radio isn't an option. Overall I'm very happy with the truck! 04.5 lly DA CC SB STOCK.