My wife told me the other day that the blazer was making a knocking noise. I checked the oil level and it was down almost 2 qts. Anyway I put oil in and cranked it up. It continues to make a knocking noise. After letting it sit the noise went away but now is back. I'm just wondering if its probably a lifter or valve. Any ideas. And can I still drive it a couple of miles a day until I get it fixed?

 

It's hard to say what it is from that description. Some knocks are hard to diagnose even when we can hear them.
Is it a light tapping from the top of the engine or a loud solid knock from the bottom?
You can use a long screwdriver as a stethescope. Put the screwdriver on the engine or oiplan and the handle to your ear.
If you can write a very descriptive explanation of the sound and location, loud, hard, solid, tinny etc... then perhaps we can help.

 

The noise seems to come from the top of the engine. It changes as the rpms change. When the engine gets warm the noise goes away, although my wife says she still heard it faintly. The knock it a solid sound, almost like a valve rattle when using low octane gas, but louder.

 

I have a customer whose lifters rattle like h***. Every other shop wanted to sell him a motor. So when he came to me, I gave him his options. Motor, lifters, or try an additive. They chose the additive, it is a CRC brand lifter cleaner from NAPA. I changed the oil and put in the additive, the noise almost instantly went away. Although whenever they are overdue for an oil change the lifters start to tick (usually start to go nuts after 3500miles on the oil). Then they come back for another LOF. He has been doing this for 10k miles already with no problems, he just now has a 'reminder' to change his oil!! The truck runs like a top, and has no noticable problems, fuel milage is the same and drivability is not effected.

 

Sounds like a dirty lifter, because it sounds like when the oil is cold it does not flow that well which is normal there might be a piece of sludge etc. stuck inside the lifter, the additive could clean it out and solve your problem...

 

I have a 96 S-10 Blazer 4.3L engine. When its cold say around 45 or colder the engine will not start with pedding the gas and holding it around 2000 rpms when it findly starts. I have to hold it at these high rpm to keep it running, which isn't good for a cold engine. If its above 45 it starts fine and will start fine the rest of the day once the engine is warned up in the morining. I have taken it to a shop for repaires and they replaced the throttle position sensor. NO HELP. Took it back and they replace the coolant temp sensor. No Help. I cleaned the throttle body and that helped a little.What gives with this????

 

Might be best to start your own thread. It will draw more attention.
Idle air control, IAC is a possbiliity.