lunking sound from driveline

[robbig]

Hi everybody, I have a brand new GMC 2500 HD Diesel two wheel drive with crew cab. With about 800 miles on it I'm getting a lunking sound when I just get going from a stop, and when I come to a stop. It seems to be worse after the truck has been driven a while, say 5 miles and up. I've taken it in to the dealer, and they say its normal... according to General Motors.

I'd appreciate any information on this subject beings I'm taking it in again tomorrow.
Thanks Robert B.

[MikeT]

If you have the 2 piece driveshaft, the center yoke may need some grease. This is a known problem with the 2 piece shafts. Tell the dealer that it is NOT normal. It's not hard to do the grease job yourself. It only takes me about 15 minutes and I have to do it about every 10K - 15K miles. GM says that this is a routine maintenance item, but it is not covered in the manual under routine maintenance or anywhere else in the maintenance schedule. The fact that they don't have a grease zerk leads me to believe that it wasn't designed to be a routine maintenance item.

If you want to try it yourself, remove the u-joint bolts at the rear end. Drop the shaft down slightly and pull the yoke off the front shaft. Pump some good grease into the yoke until it is about a quarter of the way full. Replace the shaft and bolt it back to the rear end.

Now take it for a test drive. If it isn't clunking anymore, you know that the dealer was feeding you a line.

Mike .T.

[robbig]

Thanx Mike got the yoke greased yesterday, sounds and feels much smoother. I'll probably have to do this from time to time I guess

Robert

[JohnnyR]

Mike T
Thought I've read in this forum that there is a "special" grease that's supposed to be used for this purpose that is relatively expensive.
Does it make any difference?

[DmaxMad]

I was looking at greasing mine today. How do you get grease in the yoke.? It appears that it is in a sealed boot with crimp style boots. Am I missing something here?