Ticking noise in gear at idle

[lydo6fp]

Hi everyone. Wondering if anyone has experience that could help me figure something out that's bugging me. I have a 97 Sierra 1500 with the 4.3 / Automatic transmission. When the engine is hot and I am in drive, foot on the brake and idling, I hear a ticking noise as shown in this video:

Video

I am wondering if it might be a rod knock, lifter tick, exhaust leak, or flexplate/torque converter issue. The only time this is noticeable is when it is in gear and idling. It is quiet and smooth sounding when the engine is not hot. Does anyone have any advice? I also do notice a loud rattling noise at times when rolling coming under the truck that I initially thought was the catalytic converter. I have no drive ability issues otherwise, just afraid I'm going to blow my engine if I keep driving it. Thank you.

 

[Schurkey]

What is the TRUE oil pressure, tested with a known-good gauge?

 

[Teddygraham]

That’s a tough one, I was going to say, hey my 4.3 with 325k does the same thing and it’s just a bad lifter.

Until I herd your video, sounds very sad. Honestly can’t tell with the audio quality but certainly need to get a mechanical gauge on that.

If you blip the throttle does it knock as rpm’s come down? I do believe that’s on me trait of a rod knock.

You could also pull one plug wire off at a time and sometimes the drop in pressure will greatly reduce the rod knock noise… helping you possible confirm it’s a knock and locating which cylinder

 

[Teddygraham]

Also was thinking the noise sounds slow, like 1/4 speed slow which would be valve train. Pull rocker covers off and see if everything is moving like it should while it’s running

 

[lydo6fp]

That’s a tough one, I was going to say, hey my 4.3 with 325k does the same thing and it’s just a bad lifter.

Until I herd your video, sounds very sad. Honestly can’t tell with the audio quality but certainly need to get a mechanical gauge on that.

If you blip the throttle does it knock as rpm’s come down? I do believe that’s on me trait of a rod knock.

You could also pull one plug wire off at a time and sometimes the drop in pressure will greatly reduce the rod knock noise… helping you possible confirm it’s a knock and locating which cylinder

Thanks. The noise goes away completely when any throttle is applied. Don't hear anything until idle.

 

[lydo6fp]

What is the TRUE oil pressure, tested with a known-good gauge?

I will have to do a true oil pressure test. The most annoying this it looks like a former owner managed to break the oil pressure sensor off its stud and plugged the hole somehow. I have no accurate reading on the pressure from the dash gauge.

 

[Schurkey]

Thanks. The noise goes away completely when any throttle is applied. Don't hear anything until idle.

Verify that the flexplate is not cracked. The one-piece rear main seal flexplates are known for cracking around the crankshaft bolt circle.

 

[Teddygraham]

You could also try putting in really thick oil or a Lucas oil additive just as a temporary measure for testing. If it’s a lifter collapsing, it would probably quiet down