"rattle" "flap" --nuts

[merryman]

I don't know if its engine or drive train or not??
But its driving me nuts!!
Its a "FLAP, flap, flap or
its a "RATTLE, rattle, rattle,
noise when;

pulling hard (with a heavy load) in either 4th at around 40 mph or in 5th at around 55 mph and sometimes just as I down shift from 5th to 4th. It only last for about 1-2 seconds and is in decreasing loudness, i. e. , the first "flap" or "rattle" is louder than succeeding two or three. It is gone before you can really listen to it, and it does seem less loud than it did a couple months ago before removing the air box.
It usually only happens once per mountain grade, but occasionlly move than once, and the noise is most often, only for about 3 "flaps" or "rattles"
There were posts about this noise a few months ago, but I could not find them. At that time some suggested it was the boot between the air box and the fender, but I have remove both and have a K&N "cone" type filter, and the noise is still there----but it does seem more "metallic" in sound than it did.
Has anyone another good idea as to the source/cause of this noise???
We just returned from an 1800 mile round trip to Bishop Ca. ,(big Mule show) and this noise occurred on most substantial grades, but seems to have no effect on power etc. , but is allways disturbing.
I would appreciate any tips.

Vaughn

 

[work2muchplay2little]

Do you have an exhaust brake?

 

[ToolManTimTaylor]

Umm Wastegate comes to mind. Pulling heavy loads and during shifts... . perfect recipee for the wastegate to open to bleed off excess boost.
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[B.G. Smith]

Could be the turbo surging when you let up on it with a heavy load. What mods do you have?

------------------
White 99 3500, QC, 3:55, auto. most options except leather, Line-X bed liner, fiberglass running boards Rancho 9000s, bug shield and window vents, black vented 5th wheel tailgate, 110 gal. aux. fuel tank.

 

[merryman]

Thanks guys for the responses.
I do have an exhaust brake, its the jacobs-cummins E-brake. I have gauges-pyro, boost and fuel pressure, but no other engine related mods other than a K&N cone type filter.
Now that someone points the way, the exhaust brake makes sense----but I really do not understand the explaination.
Is this event something that could be damaging?
What would stop it?
My other problem I would like to solve is high EGTs when pulling hard-- I usually have to back off the throttle a little to avoid EGTs going to 1000 degrees post turbo, before running out of power. I gross 19K+.
Considering a 4" exhaust, but reports indicate that will give only small assist.
I have been fighting with my self regarding the Bombing that it is said will solve it; and add some welcome power.

Thanks guys.

Vaughn

 

[work2muchplay2little]

merryman, I guess I'd start by inspecting the linkage and valve of the exhaust brake, have someone operate the unit while you watch it. Might be as simple as adjusting or lubricating it. If no go, might visit your friendly neighborhood Cummins shop.

Regarding the EGT's I saw a decrease of about 250 F with addition of Psychotty air and 4" exhaust. I see you've got the K&N filter; the Psychotty shroud funnels cool air from the front cowling. These won't gain you but 15-20 HP. The Edge EZ will also help with EGT's by advancing the injection pump timing, will add about 60 HP as well. Good luck!

[This message has been edited by work2muchplay2little (edited 05-31-2001). ]

 

[Extreme1]

I'm thinking Tim is right. Next time you down shift when it would likely happen, back out of the throttle a little more slowly. Of course I never played with an e-brake...

------------------
'94 3500 4x4, 212,000 miles, Goerend Brothers Torque Convertor + VB Mods, TST #5 plate, 215's, 235-85-16s, Rancho 9k's w/remote, Isspro Gauges & Amsoil everything.
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[SteveAZ]

Humm flap flap and rattle rattle sounds.

Have you driven over a ford lately?

Sorry for the wise crack, couldn't resist.

 

[ToolManTimTaylor]

Like I said upstairs, but want to elaborate I dump my wastgate constantly (Heavy right foot for some wierd reason after the mods #ad
) anyhow I usually dump right at 37-38 PSI mainly I get up to full spool and some Freak~Species of man/woman usually driving a Slaab , Fhonda, BeeMW, or whatnot decides Now is a good time to pull out in front of me then you get the famed Phwump~wump~wup~woosh <----- technical sound effect of course #ad


L8TR , TMTT1

 

[Bill Stockard]

merryman,



Does it sound like a loose piece of rubber on the tire only under a hard pull at higher RPMs? If you ease up on the throttle, will it go away? My truck did that and it was only right after I shifted down and was in a hard pull at higher RPMs--5th gear at 2500 RPM under heavy throttle. I noticed it the first time going west towing a heavy 5th wheel on I-80 in Wyoming with a 30-40 MPH headwind going to May Madness last year. Right after I shifted down and really got on the throttle the "flapping" sound like a tire was about to throw a tread would start. My natural reaction was to back off the throttle and it would go away.



The Dodge dealer in Rawlins, WY changed out the heater restriction/connector in the head, but the sound was still there. While at MM, Carson Dodge rerouted the heater hose to the front of the head using a formed heater hose from a Jeep Cherokee. So far I have heard the sound once more south of Minden on US 395 on the way home from MM. I haven't heard it again now in over a year.



Here's a photo of the re-routed heater hose.



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By the way, I now longer have the heavy 5th wheel--just a heavy slide-in camper.



Bill