ok here we go... I have a 97 S10 Blazer with a 4.3, 3 months ago I got home from being gone for 3 months (Blazer was sitting). The truck started to chug about 20 mins after I was driving so I revved it up to which i use to have to do before I left. At that point it started ticking/knocking, I drove it home (50 kms) and check the oil for metal, and there was none so I continued to drive the truck, I figured it was just a collapsed valve. Last week I done an oil change on it and still no metal, so last night I decided to take the intake off and check the valves and they seem ok, I still have to check the valves on the right side but it sounded like the noise was coming from the left. I will give a brief description on when the noise comes and goes.

1. at idle i can hear a slight ticking
2. at easy acceleration I hear ticking
3. at hard acceleration I hear ticking - almost knocking
4. at easy deceleration (foot still on the gas pedal) I hear more of a knocking then a ticking
5. at full deceleration (foot completely off the pedal) i hear... well I'm not sure if it's a tick or a knock

I really hope its not a spun bearing. I do have another motor but its from a 95 and the intakes are difference and not sure what else would be difference.

 

We need more info...miles on motor etc-Was the unit properly serviced for storage? Fuel stabilizer,Marvel in the cylinders,oil changed before the down time etc? Seems like it wasn't to me and now you may have a valve train issue that may be rectified by an oil change with an additive. But I'm worried that if it IS more like a knock-there may be main bearing issue.I have heard this story more than once in my life:good motor parked-then bad motor started,usually due to internal corrosion that isn't baked away by daily use!
Good luck!

 

As for miles, I have no idea as it came from a wreckers, but when I bought it I was told something like 120000kms. I done nothing to it before I left cause my friend was going to drive it for me, but I dont think he did as much as I wanted him too.

Well I pulled the intake off today to look at the lifter and push rods. I couldn't find anything wrong with the lifter, push rod and valve springs. I have no idea where the problem is. Years ago i had a collapsed lifter in my Cutlass and the sound is similar but maybe closer to a knock, but if it was a main I figured i would have had metal in the oil and i didn't I just changed the oil last week.

I have another 4.3 sitting in a 95 Jimmy and I think this would be a good time to pull it and have it ready if the one in my Blazer goes.

If it wasn't for the fact that I live in Newfoundland I would have got rid of this lemon years ago but it's 4X4 and it's cheaper to repair this one then buy someone else's problem and run it to the same thing.

 

Well the car may not totally be a lemon-but it could be finished-much past 300k (US)
They are done!Especialy if rust if evident. Rebuildable completly and may go a million miles or more! Is it worth it? HMMMM!