SDS Photography

my L89 sounds like it has a knock at startup. but when it warms up it goes away and purrs like it is susposed to. it sounds like it is comming from the drivers side but I cannot say 100%

any ideas?

skeet

What weight and type of oil are you using? I would try 10-30 Mobil 1.

65Z01

And what is oil pressure at start up and at warm idle??

Maybe you can use a section of rubber hose between your ear and parts of the engine to isolate the noise source.

AGENT 86

I'll throw the pre cat into the mix

SDS Photography

I am not sure on the oil as it was changed when my SuperRam was installed

if it was a precat would the noise go away after it warmed up?

cv67

w/65Z01, could be a number of different things. Try the stethescope.

SDS Photography

oil pressure gauge reads 30 at startup

it sounds like a knock now though

Redeasysport

30lbs @ start up is LOW especially with fresh oil.

bogus

WAY low. It should be twice that. You need a real accurate oil pressure gauge to be sure of that reading.

I donno where you should begin... I am worried about the pump, first and foremost.

SDS Photography

i am going to drive it to a friends dads shop, he is a fellow owner and may be able to tell me what is wrong

kopbet89c4

My car sounds not as good on start up. You must be running rich in open loop. Open loop mode also uses a lot of gas. IMO, Once you're in Closed loop, the car will run and sound a lot better.

Atok

That is very low for cold oil, although that is normal for hot oil.

Have you ever overheated the engine? It may be a collapsed piston skirt. Symptoms are a rattle or knock on cold startup. Once it warms for a few minutes it goes away. The first Vortec truck engines had this problem. Not a big deal as long as you don't hammer it when it's cold.

SDS Photography

the engine never has over heated, so are we leaning toward a bad oil pump?

viii

here is my crazy guess and it depends on the year of the l98. my 85 has a knocking sound at start up especially when it is cold. turns out there is a pulsation in the fuel return line (passengers side). the knock goes away at the engine warms up and warms the return fuel. This was addressed in a tsb and recommended a part that I dont think is available.

SDS Photography

it's a 89'