I just recently bought a 98 blazer. When I got it I received the code that pretty much was the egr code. The light turned off didn't think of anything. Well when the thermastat is just a notch half way there is a knock under the console, where about the radio is. I also lose oil pressure when its heated it goes from 60 to around 20. And it only is knocking when I'm idileing. What's going on? Ay ideas?

 

maybe others with s10's understand what "thermastat is just a notch half way" is but I don't.


Have you changed the oil since you purchased it? How many miles are on the engine?
It is typical for oil pressure to decrease when the engine reaches operating temperatures. 20psi would be nothing I was concerned at at an idle. Good rule of thumb is 10psi for every 1,000 rpm.

Knocking could be lots of things. Loose bracket in the engine compartment, or what you think it is, a rod, valve or piston...

 

My blazer is the suv 4 door. Sorry what I ment was a line just under halfway. And yes I hae changed the oil. 143,000 are on the motor. The best way is the sound kind of sounds like a flat, and goes thud thud thud, then a pause and it will do it again. I cannot hear it on the outside. But its loud on the inside.