Lifter or injector tick?

[Nick R]

Since changing the oil and valve gasket, and seafoaming, my 97 cavalier has developed a metallic sounding tick at idle. If you listen close to the valve cover, you can hear the rest of the tappets. I honestly cannot tell if the sound is coming from the valve cover or back by the intake manifold. I will try to record it in a few minutes to post it. My grandfather said with 10W-30 it ticked for a while a long time ago, but it hasn't with 10W-40, which is what I put in it. the only difference is that the new oil is Valvoline Maxlife, the old was ACDelco Dino oil. I also seafoamed. So do you guys think it will be an injector or a valve tappet?

EDIT> Uploading to youtube now, about half hour left on the upload =P

 

[Nick R]

Here you go. You can hear it quite well.
http://www.youtube.com/watch?v=ln6N_il3WiY

 

[tomcat27]

pull the wiring connector off the fuel injector and see if the noise stops

 

[bepperb]

Sounds like a tappy valve to me, but the quality of the sound isn't that good.

Does the sound change when the engine is warm vs cold? That should indicate a valve.

Either way, this isn't a very big deal.

I'm sorry I know very little about the GM powerplants. My Honda would be very easy, the Toyota is bucket over so it's a huge pain with days of waiting for parts, and the EX 500 needs it every other year it seems (the other two haven't needed it, but I'm a curious guy).

"A tappy valve is a happy valve" - guy in my EX 500 forum

 

[Nick R]

Well, it doesn't change whether its cold or warm or hot so.... That would indicate an injector right?

 

[mechtech2]

Well, kind of.
An injector will sound louder when the engine is cold because it is dumping more fuel than when at operating temperatures.
Like mentioned, yank the wire to each for a few seconds [while idling] to see if the noise changes.

 

[Nick R]

Well I would but the injectors aren't the easiest to get to, especially when the engine is running and will get hot quickly. I'm not really concerned about it, unless anyone knows of any problems either thing would cause.

 

[severach]

Injectors aren't oil sensitive so changes with the oil suggest the lifter. A screwdriver stethoscope to your head will eliminate the injectors.

My 1996 2.2L Cavalier has a sticky lifter on cylinder 1 intake. The pushrods are easy to pull and inspect. Compared to the others cylinder 1 intake pushrod had a slightly beat down end shape and the polish was gone.

A relative was driving the Cavalier and the engine and exhaust had a loud growl. I occasionally snuck additives in the gas and the growl reduced until the lifter tick could be heard. The lifter tick was so loud that the car was returned to me for fear it might fail soon. That gives you an idea how loud the engine and the exhaust noise had to be to drown out the lifter. With me driving a heavy dose of gas additives went in every tank which rapidly dropped engine and exhaust noise to factory quiet other than the lifter tick. AutoRX got the tick down to where it can only be heard at certain temperature, RPM, and when reflected off nearby objects with the windows open.

The process that leads to this is simple. Intake lifter collapses. The other 3 cylinders dominate the oxygen sensor and can't go any more lean so the cylinder with reduced air goes rich and produces lots of carbon which collects everywhere along the bad cylinder path. Carbon from the bad cylinder slowly pollutes intake and other cylinders through EGR. I've seen 1/8 inch think caked intake carbon. Cylinder carbon increases engine and exhaust noise until the tick that has gotten worse over time can't be heard any more. High mileage Cavaliers are expected to be loud and get bad mpg so nothing is done about it until I come along with a little BITOG know how.

This rapid descent to carbon h3ll can occur because of multi port fuel injection. It wasn't so easy with CFI, TBI, or carburetors where drawing less air automatically draws proportionally less fuel. An engine without an EGR helps to keep the carbon confined.

So far gas additives are holding the problems at bay and the mpg is good so it's hasn't been worth pulling the head to replace the lifter.

 

[mechtech2]

With cars, there can be coincidences - that makes things tough to diagnose.
severach is right - the first thing to check is the valvetrain because of the oil change.