95 K3500 Vibration

[faughtj]

I have a 95 Chevy K-3500 4wd with the 6.5L TD, auto transmission. It is a chassis cab with an 8' dump bed. A few days ago, I was driving home, and it was noticeably low on power. The other significant change was that it sort of bucks or has a heavy vibration on acceleration. Seems to be from around 15-20 mph up until about 60 mph and then smooths out some. Then, on Monday, I had about 7000 lbs of topsoil in the bed. I use OD when the bed is empty, and 3rd gear when loaded with significant weight. The vibration was worse with the extra weight. I changed the air filter, as it needed it anyways, and this did not help. I've searched here, and it almost sounds like an EGR problem? Or, something in the transmission or driveshaft? Just wondering if anyone has any direction to point me. The truck has about 105K on it and had been running pretty good until this. Thanks in advance for any help!

[tom.mcinerney]

Check codes.
Since low pwr--refresh fuel filter, check lift pump output. Then 'crack' injector unions to see if an injector/cylinder dropped out?
Check boost, too, for low power. Mileage? Have maintained cooling sys?
Try see if vibration in engine or drive train. Is smooth at stop/neutral? If estab vibe rolling; shift neutral vary engine rpm, does vibe follow?
Have maintained harmonic balancer?

[JohnC]

Or check the drive line. The extra weight changes the angle and length of the shaft.

[CareyWeber]

Originally posted by faughtj:
I've searched here, and it almost sounds like an EGR problem? Or, something in the transmission or driveshaft? Just wondering if anyone has any direction to point me. The truck has about 105K on it and had been running pretty good until this. Thanks in advance for any help! faughtj,

All GM 2500 / 3500 trucks with >8600lb GVW do not have EGR valves. EGR's were used on 1500 / Lite duty 2500's.

I'd look at the drive shaft carrier bearing / support if your truck has one.

Carey

[faughtj]

Thanks for all the information.. I am definitely a novice, so could you point me to where I can find the carrier bearing? Is this something that can be seen or does a u-joint or other part need to be disassembled? Thanks again and hopefully I can dig into it this weekend and solve the problem.

Jason

[JohnC]

Some trucks have a multi-segment drive shaft. They use a big carrier bearing mounted in rubber to support the shaft about midway from the trans to the axle. Also, take a close look at the u-joints. if they are rusty where they should be greasy, or if thy have play or are binding up you'll get a vibration. Also, all drive shafts have some sort of a slip joint to allow for variation in length. If it's at the trans end it's lubed by the trans oil. If it's in the center there will be a grease fitting. The front drive shaft definitely has a grease fitting. If they bind up, more vibration.