[99Greenmachine]

Background...this noise has been around a while. I know for at least a year or so. Here lately the cracked exhaust manifold was so loud it covered it up.

I just replaced that with an APN and it is SO MUCH QUIETER than it was. However, that old noise is back and annoying again.

It sounds like it is around cylinder #3 which is where I tried to keep my iPhone hovered over for most of the video. I don't think it is leaky exhaust seeing as how I just replaced the exhaust manifold haha.

Any ideas?

YouTube - Jeep 4.0L Noise

[99Greenmachine]

bump for the night crowd

[jeepkid03]

Its hard to tell how loud it is. Does it change when you rev it a bit? My best guess would be something valvetrain related, like a lifter or rocker tapping. Might be worth it to pop the valve cover off and see if any of the rockers seem loose.

Some things to think about...

-Do different engine RPMs change it?
-Does it change based on engine temp?
-What oil are you running, and does it change with a different weight oil?
-Has it gotten worse?
-Whats your oil pressure?

[99Greenmachine]

Originally Posted by jeepkid03

Its hard to tell how loud it is. Does it change when you rev it a bit? My best guess would be something valvetrain related, like a lifter or rocker tapping. Might be worth it to pop the valve cover off and see if any of the rockers seem loose.

Some things to think about...

-Do different engine RPMs change it?
-Does it change based on engine temp?
-What oil are you running, and does it change with a different weight oil?
-Has it gotten worse?
-Whats your oil pressure?

I will tell you this:

The video was on a cold start up. The warmer it gets, the less the noise is. It sounds like a rythmic clicking. I will check RPMs next time i drive it.

It really hasn't gotten worse, it's just there. I run 10W-30 Valvoline MaxLife. Have for about 20k miles. In the winter I switch to 5W-30. Oil Pressure is normal...nothing shocking about it.

[sargergp]

Originally Posted by 99Greenmachine

I will tell you this:

The video was on a cold start up. The warmer it gets, the less the noise is. It sounds like a rythmic clicking. I will check RPMs next time i drive it.

It really hasn't gotten worse, it's just there. I run 10W-30 Valvoline MaxLife. Have for about 20k miles. In the winter I switch to 5W-30. Oil Pressure is normal...nothing shocking about it.

Doesn't sound like oil or pressure issue. Since it lessens with warm up I would guess probably a weak lifter. they will loose oil prime while setting and then pump back up when started but not be able to hold well enough to smooth out. I would recommend the same as a previous quote. Pull the valve cover and check for a loose rocker, the lifters are fairly easy to change on these engines and if it gets bad enough it will effect power and efficiency.

[jeepkid03]

Sounds like a lifter. What oil filter are you using? Does it have a good anti-drainback valve? Purolator Pure One filters are a good one off the top of my head. My friend's '89 XJ had a lifter issue for a few months and heres what we did...

We drained the oil and replaced it with 1 quart Marvel Mystery Oil, 5 quarts Shell Rotella 5w40. This gets the pressure up a bit while the engine is hot, and the Marvel Mystery Oil helps clean out the gunk in the lifters. Check your oil frequently to see how black it gets. We ran it for 3,000 miles then changed it back to 5w30 Valvoline Syntec and the noise is gone. If your oil gets really black within 1000 miles, I would change it and do the same thing over again. This method might take up to 3 changes to work, but it did its job and his noise hasn't returned. If you go through this process and it doesn't help, then the noise is probably a collapsed lifter, and not one that just has crud stuck in it.