Engine/Transmission (1998.5 - 2002) Engine Rattle with EZ

[DavidHarvey]

Hey folks,



I just added an Edge EZ to my '01 2500 HO and am noticing a very annoying rattle at 1700 rpm. The only think I can think of to compare the rattle to would be likened to a bad catalytic convertor on a gas truck. I can quite figure out where it is coming from, but it sounds like it is coming from the right side of the engine - really hard to tell. It usually hits at around 1700rpm and 15 lbs boost. Any ideas out there?



Thanks - it's driving me nuts!!!

 

[JBlock]

It the timing

MY wife noticed an idle rattle that changed after i installed the EZ.



JB

 

[Sarge]

Rattle........

David, we have about the same set-up. I noticed that after I installed the EZ, that if my foot was in it a little too heavy at a lower speed, I would get a rattle. I opined that it was those extra horses trying to run up faster that the clutch could handle, and it would slip a little. If I backed off of it some, it went away. You didn't indicate if it was in every gear at 1700 RPM, or just sometimes. I noticed it in the lower gears, as the 6er is pretty low in 2nd and 3rd. I really notice it when I tow the 5ver. Sarge

 

[Dkevdog]

This same rattle has been bugging me for some time now, I am going to assume that it came with EZ, but became more noticeable with the addition of the 275's. However, I don't think in my case its the clutch- it happened to me both before and after the installation of a South Bend Clutch.



It is directly related to the go pedal position, and the harder I get on it the worse it is. It is not very apparent unloaded unless I really tromp on it. With the trailer, I have to be careful with it- it will be pretty bad especially in 4,5,6 between 1700 and 1900 rpms.



I theorize it could be a driveline imbalance, but don't know for sure. Ironic that we all seem to see a similar problem though.



Kev

 

[tgbol]

Count me in too. It goes away when I remove the EZ. I think it is torque load on the driveline.

 

[Marco]

Too much timing?

 

[RustyJC]

IMHO, there are 2 "rattles" being discussed here:



1. The 1700 RPM "rattle" under hard acceleration. Having worked for a manufacturer of large industrial engines for 30 years, I recognized this one the first time we hitched our 5th wheel to our stock truck and headed out. You think it's loud unloaded - try it at 21,180 lbs GCW (21,500 GCWR). This is a torsional drivetrain vibration at what is obviously a torsional critical speed. The rule of thumb concerning torsionals in the operating band of an engine - get through 'em as fast as reasonably possible. Don't just sit there and let things "rattle" - you're asking for a torsional fatigue failure. The "rattle" (really more of a "grumble") is probably gear rattle in the transmission as the gears go back and forth through their clearances, although it could come from the clutch disc as the springs load and unload.



2. The idle "rattle" with the EZ became noticeably louder after going from the stock injectors to the DD2's. In fact, with the DD2's, in addition to the deep, heavy diesel combustion noise that's always been there, there's a lighter, almost "tinny" rattle - I heard it at a stoplight and thought, "Good grief, this sounds like my old 65 Mustang when the rocker arm clearances had backed off to around . 030"! This light, "tinny" rattle has a random pattern to it - sounds like the idle of a gasser with a hot cam (sorta neat in that regard). I think Marco's probably right - it's a combination of the EZ's advanced timing that's aggravated by the more rapid fueling of larger injectors. It's a little ratty and random because the governor function, now with excessive gain with the larger injectors, is "fidgeting" with the fuel commands.



Rusty

 

[DavidHarvey]

Thanks

Thanks for all of the replies! I'm just glad that I'm not the only one with the rattle problem. It happens in 4th and 5th gears for me (especially up hill).



It could very well be coming from underneath the truck in the transmission.



So, is there any amount of money that can be thrown at the problem, or is it something that we just need to get used to?

 

[RustyJC]

Re: Thanks

Originally posted by DavidHarvey

So, is there any amount of money that can be thrown at the problem, or is it something that we just need to get used to?

It's just the nature of the beast. The torsional critical speed is a function of the torsional stiffness of the engine's crankshaft, the flywheel mass, etc. None of that is easy to change, and even changing it won't eliminate it, it will just move the torsional critical speed up (with a lighter flywheel) or down (with a heavier flywheel). Although a heavier flywheel looks like a possible solution, it could result in dropping a higher-order torsional critical down into the engine's operating speed range. It would require a torsional analysis to determine this.



Since 1700 RPM is out of the engine's normal operating range when towing (at least with our 4. 10 rear axle), it's really not a big deal. I only hear it when I've "short shifted" and the RPMs have dropped down in that range in the higher gear. With the EZ and DD2's, though, it doesn't stay in that RPM range for long!



Rusty

 

[Dkevdog]

I spoke to another local TDR member about this same problem last night and he was going to have the driveshaft balance checked. I don't know what good will come from it, but he thinks it's a try.



I've not specifically ever accused the EZ of being, or contributing to the problem. I'm going to tow the trailer home for some work this weekend and will disconnect the EZ and see what the differences are. I know Rusty, that the problem is certainly as much load dependent as it is "throttle" related- and with that freight train you're driving, I guess you know that too

. But David, you're right, its most apparent in 4th and 5th, and if (at least for me) I back off the go pedal it stops.



Kev

 

[RustyJC]

Kev,



If, like my rig, it will do it in 5th or 6th gear at 1700 RPM (or 4th and 5th with a 5-speed), the vibration is engine, not driveshaft speed related. You might be able to save him some money if you get him to check this out before he has the driveshaft balanced. I'm not saying he might not have a 1-off driveshaft balance problem, but I kinda doubt it.



Remember the old joke - "Doc, it hurts when I raise my arm. " The doctor says, "Well, don't raise your arm, then!" The fix for this is the same thing. If it vibrates at 1700 RPM, downshift!



The EZ, injectors, etc. will amplify an existing torsional vibration problem. This is because the combustion forces from each cylinder (which are what excite the torsional system to begin with) are stronger and rise more quickly with the BOMBs. They don't cause the torsional vibration; they just make it stronger and more obvious.



Rusty

 

[Vaughn MacKenzie]

EZ and clatter

I tried an EZ on my DD2 equipped '01 HO and didn't like it. My engine clatter and engine vibration increased a lot, sounded like it would on a 20-degree morning. I have seen a lot of posts about this with the EZ box over the years since it came out. IMO it's too agressive on timing when you have injectors; it's a great box for stock injectors. Many with the EZ & injectors haven't complained about it though, probably varying characteristics between trucks and boxes.



I had a Bully Box (van Aaken) on my '01 which worked nicely with my DD2s, so did the Puck and original version van Aaken that I tried (both of which I liked much better than the Bully Box).



Vaughn

 

[Dkevdog]

Thanks Rusty, I'll let him know- mine does exactly as you say, although I notice it in 4,5 and 6th.



Still, for fun I;m gonna disconnect the EZ and see what happens when I pull it home to install Solar panels and an inverter this weekend .



Kev

 

[RustyJC]

Originally posted by Dkevdog

Thanks Rusty, I'll let him know- mine does exactly as you say, although I notice it in 4,5 and 6th.

Kev,



Yeah, being that it's engine-related torsional vibration, it will basically do it at 1700 RPM in any gear, although it's more noticeable in the higher gears. I wasn't implying that my truck only does it in 5th and 6th. Rather, I was just saying that if your friend saw the vibration at 1700 RPM, regardless of which gear the transmission is in, then it's not due to driveshaft imbalance.



Rusty