I have a 1994 s10 blazer 4x4 4 door that I recently got from my inlaws. Had been sitting in their barn for 8 years with a bad cpi unit. Long story short, I have got it running and operable, and noticed that it would thump and knock loudly (sounds like its coming from the front, or right under the front floorboards) when I hit a bump. The shocks were terrible, so I replaced the fronts and rears thinking that it would solve the problem. It didn't. Sure rides nicer, but the noise is still there. It seems fine when hitting the bumps with both front tires at the same time, but hitting one tire at a time, especially when turning is where I notice it the most. Any ideas? This vehicle has 146,000 miles on it.

 

Ball joints, sway bar ends, could be idler &/or pitman arms. Have you given it a full chasis lube yet?

 

I have only greased what I could reach as I changed the brake pads and calipers. I will crawl under there today and hit everything that hasn't been lubed up and see if that helps. I have driven it about 250 miles since I got it up and running. Once I lube it up, how can I go about pinpointing the problem? Excess play?

 

if its under your feet, its I would guess either cab mounts or torsion bar mounts.

 

Yup I agree. Sitting so long maybe body mounts rusted etc.
I suggest searching in here for how to check the front end "shake it down". There are lots of posts that may give you other ideas as well.

 

I greased everything else, and drove it about 5 miles. Lower ball joints were pretty dry, but everything else was ok. Seemed better, but I didn't go over any really rough ground. I will try to "shake it down" and see what happens. As far as rust goes, this thing is really in good shape for an ohio car. It was stored in a barn with a concrete floor so I'm thankful for that. Body rust is limited to driver door at the bottom, and tailgate at the bottom. Underneath looks like a dream. Body mounts will be replaced with the 2" body lift this week, so we will see if that was a factor. I will look at the torsion bar mounts and see what they look like. Any advice on how to check torsion bar mount wear? (I have been rehabbing this vehicle off of blazer forum posts and a haynes manual). Maybe i just need to go over the front end and use that as an excuse to do a 1.5" suspension lift?

 

You could just jack up the torsion bar mount at the ends and see if it moves. When they are broken, it usually comes apart into 2 pieces. It's pretty obvious when they are are shot.

 

I previous owned a 92 the thumping you are talking about is the rubber mounts for torsion bar if you put the truck in a twist it breaks then the the thumping sound starts. The old come out easy but the new ones have a long stud that is a pain.

 

I replaced the torsion bar crossmember mounts on my 95 4wd. Once I remove the mounting links I found out that the bolts they that went through the frame and through the mounting links were 1mm too narrow so the links were slapping the bolt and sending vibration through the frame.