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Discussion Starter · #1 ·
Hi All,

First put this on the introduction page, but figured here might be a more appropriate location for asking powertrain q's.

Just picked up a used Duramax. Early 2004 with 73K on it. nice shape, flew to TX to drive it home to WA. Have owned 2 Cummins Dodges, very happy with the engine, T/C and Axles; Trannys never let me down, but heard horror stories.

Went GM for the ride, cab room (crew cab, short bed) and Allison. Heard great things about the Duramax engine, but it's a different animal than that Cummins. Stock, it doesnt have as much snap as that Cummins did off the line.

After that drive home, I have two initial questions maybe some of you can shed some light on....

1) On the drive home from TX, I noticed a ticking under load (up hills, acceleration) that was engine speed dependant, much to me like an exhaust leak would in a gasoline engine.... Figured I'd start looking there..... Didnt sound like a rod or wrist pin, besides, at the pace I drove, the engine would have blown if it was one of those. By chance is it 'normal'? Im used to that loud Cummins design.

2) The oil pressure when warm @ idle is pretty low, but comes up right away when you throttle up (GM Gas engines have been this way forever, but I was wondering if its normal for the diesel since Isuzu actually makes it)

I've heard really good things about the edge with attidute setup for both power and economy gains, anyone got better ideas?

Thanks,
Davy
 

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1:The ticking noise could be any number of things. Best to have it checked out by a competent shop.

2: The oil pressure is low on these motors. Does not seem to effect longevity.

As far as tuners, Edge has been both good and bad. There are others out there that work very well also. EFILive is the best way to go for more power and economy both.
 

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1. the ticking "at the pace you were driving" was probably the pilot injection. Engine got louder right?

2. Low oil pressure....I know mine goes to around 25 psi when hot. I run 5w40 synthetic too. I don't know how low yours is going, but as long as it stays out of the red, you should be ok. Those clusters sometimes aren't all that accurate.

Edge is a pretty good programmer for the LB7. It is pretty user friendly too. If you want to tinker more with the programming, go with EFI live.
 

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Discussion Starter · #4 ·
q's about the Allison

Thanks for the feedback!

Next question is about the Allison: Since this truck is new to me, Im gonna change all the fluids/filters to be able to start keeping my records from a known timetable. Any advice on Tranny fluids for that Allison? I have heard some things about going synthetic, but how do you change 100% of the fluid? Is there a Torque converter drain? Or, with that spin-on, and drain plug, is it better to just stick with conventional Tranny fluid and change it more often? The pan has a couple small dents in it, so I was planning on using that as an excuse to go to a larger pan (the truck's gonna get lifted 6" + 35" tires) and should I consider any valve body mods or ??????


As far as the previous questions, I brought the truck into my local GMC Dealership (Smokey Point), they seem to enjoy a good reputation. They came with me for a drive, and right away told me the noise I was referring to was from injectors, and nothing out of the ordinary. It was recommended to me to do the GM injection system service, (every 60K) so I had them do that. they also said they'd check for any updates to the computer for free.

After more questions, and trying hard to listen, Im pretty sure Im gonna go the Edge/Attitude route, and see.
 

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AS for the fluid i cant answer that, maybe Mike L will step in here. but for the valve body question at the very least i would do a trans go Kit and a converter swap to keep the bigger tires and extra power from smoking the trans!
 
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