Engine Noise

[Wahugg]

Hey all!

Sorry for waiting this long to start a thread separately from the chat thread, but here we are.

So my situation is pretty simply;
-Upon a cold start, a good heavy knock is present and will not go away until the motor is warm
-Knock gets worse when under load, but again goes away once warm
-When the ambient temperature is 50F<, the knock is only ~20% as loud as it was during 30F weather.

Some suggestions as to what might be wrong;
-The Valve Terrain
-Exhaust Manifold
-Torque converter
-Carbon build up

First off after doing research, I think the Torque converter is not my issue. I have no pulsating, shuddering, or acceleration slop that seems to accompany a bad torque converter.

Secondly, I am putting my original idea of it being a bad bearing on hold. Despite the knock sounding deep and from the bottom end, you guys are correct on the fact that a bearing would be a constant knock.

This leaves us with the possibility of carbon build up, valve terrain issues, or a cracked exhaust manifold.

To test/solve carbon build up, I plan or running two cans of seafoam through the motor. Even if this is not my issue, this is probably a good idea anyway.

To test for a cracked exhaust manifold; I am going to stop the fan and drop climbing chalk around the exhaust manifold and see if there are any obvious air currents originating from the manifold area disturbing the chalk dust.

Finally I am not sure how to test or diagnose valve terrain issues, so hopefully by this point the issue will be identified and solved.

I will get a video up when the weather is cooler and the knock is more audible.

Thanks All!
-Wahugg

[Norcrosski]

My 02 is doing the same knock but has gotten worse in the last few months any help on this issue would be great full

[Aries]

I also have an 02 that has/had the same knock. It became less noticeable when I switched to Mobil 1 100% synthetic. "I don't believe it ether" but it happen" some mornings it's less noticeable others I don't hear it at all.

There's a post here on ORTB that we discussed the knocking sound. Here's what I found on TV where some 4.2 Atlas motors had a bad cylinder sleeve <Link

Here's the topic [url]http://forums.trailvoy.com/showthread.php?t=427&page=2[/url]

[Wahugg]

The bad cylinder sleeve pertains to the 02's, all other years seem to be fine. Want to post up your symptoms in detail to help see if our issues are similar.

-Wahugg

[Norcrosski]

my symptoms on my 02 started out right after I bought it. it was running 5w30 oil and needed a change so I changed it to pen 10w30 and knock went away for about 300 miles and came back (176000). when it is 60 plus outside once to operating temp it goes away but below 60 it is getting to be a really hard knock but changed the oil at 179000 and added lucus oil stabilizer to it and went away till 2 oil changes later at 185000 know it wont go away it idles all the time rough new plugs and all have good pwr I just figured it would either become a major issue or not but any input is helpful

[Wahugg]

Update!

I know with out a doubt that it is valave terrain noise. For the past week, I've driven the piss out of it on top of the testing methods I listed above. I go back to school in two weeks so I wanted the problem to agrovate till it bacame obviously aparent.

The sea foam made quite the show, but did nothing. Same goes with the chalk dust around the exhaust manifold. The compression test had no major deviation the 7% difference from the lowest and highest values.

After driving the crap out of it the past week, it has begun to made a very obvious clack spound on top of the knock which helped to localize it towards the rear/ top end, rather than the bottom end.

As nothing abnormal is hapenning such as misfires or oil consumption, I am going to inquire no further until something else arises.

Thanks to everyone, especially Regulator and EricSS.

-Wahugg

[Trail X]

Valve train... not terrain.

Video that includes the noise would still help us help you, unless you are 100% certain its coming from within the valve cover.

[dvanbramer88]

One downside to the design of the I6 in the TB's. On my truck or our Jeep, you could take the valve cover off and run it. And watch the valve train work. Real easy to spot a problem. Whether it be a bad lifter or rocker arm or whatever.