Noise in 4 wheel Drive
 

Hi again everyone -

I am a novice on this.

We may purchase a 2004 GMC 2500 4x4 diesel. It has electronic 4 wheel drive. My question is - when you are driving along and decide to put it in 4wheel drive (high) and press the button - should I expect to hear ANY (or what kind should I hear) noise? I want to make sure that I understand this before we take it on a test drive.

I have a 1500 Dodge with a manual lever to put it into 4 wheel drive so yes I hear a noise when it goes into gear

Thanks for all the information -- I truly appreciate your time


3pointstar

I have a 2003, same running gear. I do hear a solid "clunk" as the front differential engages. I can't remember the speed, but you are only supposed to do it at 35mph or less. IIRC, there is a solenoid that is engaging the front differential. As such, it's either open or closed (on or off), kind of like your magnetic actuators for Silent Choice exhaust on a boat. Further, it doesn't ease into place like you would do with a manual floor shifter.

Depends on how cold it is out.. Steels the colder it is the thicker oil or gear lube makes them slow engaging and they will make some noise..slower speeds seem to clunk less..

Sydwayz - thank you so much - I feel like an idiot to some of these questions - an old fart is supposed to know this but I just don't have the experience. I hope this deal really goes thru - the truck looks like it came out of the box - it has 170k -- We have a couple of diesels - and to be honest they really don't get "really" going until after 100K. Our Benz E320 CDI 2006 has 135K and to be very honest at 125K it was like the car got hit with the fountain of youth -- fuel economy went up- which was great before, the get up and go is the best ever. down side it seems that I can't blow any smoke out the exhaust-- URGH

is there anything else that I should be looking at the trucks within a year or two

again thanks so much for your help

3pointstar

LLY or LB7? They had both in '04. My '04 was an LLY so they referred to it as a '04.5.

My 08' you don't hear a thing. Turn hard left or right on pavement, it'll tell you if it's engaged!

I was hoping to learn that from the VIN number but so far I haven't been able to get the information-- I'm stopping by a GMC dealer tonight. It's a GMC 2004 Durmax 2500 club cab short bed- white with gray leather. Lord willing I'll test drive it Saturday and maybe drive it home Saturday afternoon. Do the designations that you reference LLY or LBZ have anything to do with the Transmission?

thanks

3pointstar

The WORST issue on those trucks is the brake and fuel lines. They ALL rust out. Plan on replacing them, unless they have been done already. There are kits out there in coated and stainless steel.

My two 2500HDs have been 8.1L Gasser with the Alison Automatic transmission, so I can't comment on anything from the Duramax side. I've replaced brakes on mine, and pitman/idler arm. Also, they do have some main ground issues, especially with trucks that have been exposed to salt. I just had to replace my front bumper due to rusting from the inside out. The back one is probably next.

You'll be able to tell when the 4x4 actuates. I have a 2007 2500HD and can just barely feel it in the floorboard when it engages. I throw mine in and out of 2H/4H at any speed, as long as your front and rear axles/tires are moving at the same speed and you aren't making a bunch of tight turns. When using 4L max speed is 45 per the manual.

Sometimes when going from 4H to 2H, I have to get out of the accelerator a little to get the actuator to release, but I've always shifted all of my GM's at speed, at least the ones with matching gear ratios.

www.dieselplace.com is a good place for some research.

In 2006 they changed to the LBZ engine and 6 speed Allison trans. The 6 speed makes it sooo much better on the highway. The 5 speed will be at 2000 RPM's at about 65 mph which sucks for MPG's.

Seems that many LLY's were bad about running hot, some worse than others. Dad had an 05 LLY and I remember it would start climbing to 210 or a little higher towing a heavy loaded enclosed trailer if I was behind a semi on the highway. Pull out and pass or just get airflow through the radiator and it would cool back down. I was watching the temp on a Edge Juice with Attitude box in the dash.

Try to look at the service records/history if you can and see whats been done.