2003 Chevy Blazer Engine Failure After Radiator Repair

Hello,

I had a mechanic replace the radiator and intakes in my sons 03 Blazer. They also converted it to the green antifreeze since the red turned into brown sludge which ruined everything. 1 year warranty on radiator. I planned on changing the fluid every year to prevent corrosion.

45 days later the oil line connection to the radiator failed and came apart while my son was driving. He made it to his destination about 3 blocks after he said it was making noises and running funny. I checked it out before being towed and there was at least a quart on the ground where he parked it. We had it towed back to the repair shop. They said the plastic clip that held the oil line in place came apart. They reconnected (or replaced?) It, filled it with oil, and it was good to go.

The next day my son drove it to school and it was knocking very badly. I drove it and confirmed the knock, I also noticed that the oil pressure would drop really low at idle and come up to around 20 when gassed.

The mechanic said that he would stand behind it. He wanted to put a crank kit in it and that he would cover the labor only. I have to buy the parts (or pay for whatever I thought was fair).

Is it likely that the plastic clip failed in a month? The one before this one lasted over 7 years.

Is the entire engine security of the Blazer riding on a 25 cent part?

Is it more likely that the clip / lines were installed wrong?

Would you warranty this and cover parts also, or not at all?

Thanks for your help. I'm trying to decide what is fair. I don't want to rip the guy off, but I also don't want to get ripped.