My son bought a blazer with about 134k. V engine and autumatic with 4x4. The truck sounds like a rod knocking. He was going to drive it home anyway because he has another engine. The trasmission wouldn't shift out of first but did go to second once as he drove it around the block. He decided to have me tow him home. When i arrived he was trying to get it to blow up. Revved it like hell and never threw a rod. The guy he bought it from said the engine and trnsmission problems all started at once. Is there some timing ring or something messed up or is it just a coincidence with the engine and tranny problem.?
I don't know if it is a v6 or v8. i think v8. overdrive tranny or not i don't know. thanks in advance

 

full size Blazer or a Small Blazer?

 

Small size and i have found out ir is the 4.3. ot a 350 a 305 type.

 

If it's an s-series blazer, then it's a 4.3L. V8's can be swapped in though.

 

Bumpin for an answer! thanks

 

with eratic shifting that could be anything from an electronic relay in the trany,blockage due to debre, needing a rebuild,to just a bad trany filter. Hard to say without knowing the color of the trany fluid, Miles, engine size, ect...

As for the knock could be anything from a spun bearing (rod or main) to stuck lifter, busted piston, warped crank, busted torque converter..... too many ifs. Does the knock increase or decrease with reving? Louder at idel or at higher RPM's? Sounds like a dull thud or a metal tapping? Or does itsound like a chain slapping around?

 

It is the 4.3 engine. The knocking noise sounds the same revved or not. I have blown up a few Chevies in the past and i heard it and thought it should have been blowing up at the rpm he was at. I don't know the exact rpm. He was just sitting there revving it but not to the max and just holding it there.

Is the electronic unit for the tranny removable from the outside or do we have to remocve the tranny to get to it? How can i further diagnose the tourque convertor? Thanks for the info