91 blazer

ok a month ago the intake manifold casket went out in my 91 Blazer s10 4.3, I had it repaired at a chevy dealer. I wasnt happy with them. they said they had to rplace the water pump as well. got it back and it started to over heat, took it back they said the water pump wasnt working, so why dint you check it before you had me pick it up, no response. At idle in gear I get this knocking sound that wasnt there before, when you switch to nuetral you dont here it. also starting from a stop it sounds like and exhaust leak until the vehicle picks up speed then it seems normal. Also the oil pressure guage shows below 40 psi, when it used to show 80, but I think maybe thats just the send unit is bad. but all of this happened after the intake manifold repair, My biggest concern is the knocking and the seeming exhaust leak, but I am not happy with the chevy rpair as when I got it back the hoses where loos and coolannt needed to be added and some bolts wherent put back.

why did you take this to the dealer.any mechanic can replace this intake gasket or waterpump. I wonder if they didn’t change the oil after the intake gasket. water could have mixed with the oil and ruined main bearings. Check exhaust pipe for holes or muffler. thy didn’t do anything to break that

Go back and complain, without being apologetic about it.

I am in the procee of a letter to the service manager. this vehicle was in excellent condition up to this point, it doesnt burn any oil to next oil change, If i have bearings replaced will that pit tpoo much pressire on any other part of the engine such as piston rings or valves