Hey guys, I've had my blazer for about two months now. It's the 4.3 w/ 5Speed. It has about 108,000 KMs on it. Now this here has always happened but I figured its worth asking about anyways - when I upshift, every now and then something in the trans/tcase or driveline somewhere will clunk a bit, sometimes it happens more than others, but i've never had an issue with driveability. clutch doesn't seem to slip or have any issues other than the clunking sound when up shifting, or even just engaging into first or reverse can be a bit pingy/clunky at times. The new problem I am noticing, which still has not actually affected my driving, but it is a new sound, is when downshifting from any gear to any gear sometimes there is a slight rattling sound, or kind of a scratchy sound. it is not a grind. I am curious what other information you guys might need to help me start diagnosing this **** before it gets out of hand! lol
Thanks for your time - PS I have read about the upshift clunk a bit and mostly from what i've seen it is considered to be "normal" - but I am always open to second opinions if it helps me solve my issue. Any more info needed from me? Just ask and I will try to provide it asap. Also, do I have a transmission dipstick under my hood? looking around today I could not find it, but I swear I was checking it when I bought the vehicle. Thanks again!

 

Any ideas from anyone?

FYI the upshift clunk seems to occur when I shift at lower RPMs. shifting at higher RPMs seems to be quite smooth

 

My 91 T-15 5 speed had a fill and drain plugs on the side of the transmission. I drove that truck 20 years and it was the only component I never had to service or replace.

That's pretty low kilometers to have a problem with it. Unless it's been abused by a previous owner. You mentioned that it can make noise by just engaging 1st or reverse. I would chock all 4 wheels, lay under it and have someone shift from 1st to reverse until the noise occurs so I can determine exactly where the noise is coming from. Rule out U-joints, exhaust and exhaust shields. If it is the transmission it will have to be removed for repair. I'm more inclined to think the problem is with your clutch.

Sorry this isn't much of an answer.

 

Just an FYI after replacing both U Joints on my driveshaft, this issue appears to be resolved

 

Thanks for the update. Glad to hear it wasn't anything too complicated or expensive.