I just redid my rear main seal about a month ago, since it was leaking like a screen door. That is the third time in 18 months. This time I checked the main bearings and they are about shot. A friend of mine who knows much more about the insides of an engine than I ever did, told me they were shot and could go tomorrow or 6 months from now depending on luck and how I drive. My luck has been pretty good but long story short, when I jumped in to drive it this evening and started it up it felt like someone was beating on the floorboard of the driverside of the truck (from underneath) with a hammer! iI took it around the block to see what it would do, and everytime I accelerate the knocking got worse, when I sat at a stop sign the engine dropped down to nearly a stop (but didn't die). I know my C6 housing is cracked at the top on the drivers side, thanks to a trailer truck on I-64 and a piece of metal, but I have a T-18 4spd with all the bells and whistles ready to go in in a few days. Is this the bearings geting ready to go out, or is the tranny possibly to blame? When I run the tranny through the gears revving the engine, the shudder doesn't seem to be affected. The last week it has been there, though much less noticeable, but would smooth out as I started driving. This evening was cool and raining could this have an effect on the bearings as well? I just want to get a couple more days out of her before I take her int o the shop and replace bearings, timing kit and tranny. Anyone have any advice??

 

how is your oil pressure? does the knocking get worse at higher rpm? i assume you left the old bearings, did you tighten the rear bearing cap correctly after replacing the rear main? try putting the truck in nuetral and see if it still knocks. it could be somthing in the trans but if you have low oil pressure its problably in the engine. take a long steel rod (rachet extension, pry bar) and listen in the end of it while pressing it to the block ( with it running) see if you can pin point where its coming from. if its in the block i wouldnt run it, you can quickly damage the crank. when did this noise start? after you took the rear main cap off? check these things and maybe you can find want your noise is... let us know

 

It has had a shudder when I start it up for a while. The piece of metal I alluded to that hit the tranny on the highway broke my slip yoke, and when I put the new one on I had to use a hammer to get it on. After it went past about 1 1/2 inches onto the tranny output shaft it slid on the rest of the way fine so I think it may have been the output shaft was bent as well. I plan to drive it like this for only a few more days, (as little as possible) but just want to be sure what the possibilities are before going any further. Also, though it didn't seem to increase with RPMs at first I definately heard more clunking/knocking in reverse, and when I start out (as I said it seems to smooth out) I can actually here the kocking subsiding after the intial shift from 1st, then 2nd and finally in 3rd it is almost inaudible. I will check again this morning to see what it sounds/acts like. Thanks for the info.