94 Caprice wagon woes

chevrolet
capriceclassic

#1

So have a 94 caprice wagon with the lt1 - had been making some noise on first cold start of the day, going away after a min or 2, for a few months, and then last week the optispark went bad on it. Should I worry about the noise? And how much of a pain is replacing the distributor?


#2

Can you describe the noise?


#3

To me sounds like halfway between a rod knock and a valve tap - basically the car sound like a diesel for the first few min after startup when the temp is below like 40 - but like I said it goes away within a min or 2.


#4

If the noise is duller than a valve tap and clears up after a minute or two you might have some piston slap. Probably not serious since it fades away as the aluminum pistons expand as they heat up.

Regarding the possibility of valve tap, is the oil fresh and of the proper viscosity? How many miles on the engine?


#5

That year of Chevy?

Timing chain!

Drain the oil and look in the drained oil for plastic pieces.

If any are found, the plastic teeth on the cam gear are coming apart and falling into the oil pan.

Tester


#6

When you replace the Optispark be sure to use a genuine AC Delco part. I’ve had nothing but trouble with the aftermarket brands.

Replacing the distributor involves removing some of the accessories and the water pump from the front of the engine, and if I recall the harmonic balancer as well. The distributor mounts between the engine block and water pump. Since a leaky water pump can damage the distributor you might as well replace it as well.


#7

I’ll go with piston slap, too. What you described is piston slap from loose fitting pistons. Nothing to worry about, its just annoying. The timing gear on an LT-1 is metal, not plastic so no worries there.

Sorry about your Optispark… NOT the best idea…


#8

Yeah no kidding about not the best idea - “oh, lets put a precision optical device on the bottom front of a motor, which is exactly where all our engines are known to leak from, both oil and antifreeze. Oh, and let’s put a vacuum on this precision device also, so if the seals go bad on it, it’ll suck EVERYTHING into the optical sensor and foul the sensor disk.”

Good job, Chevy