Noisy Engine... Thoughts?
My 3.7 has been noisy since the day I got it, when it had 23K on the clock. I just passed 83K yesterday, and nothing much has changed. I thought I'd see how many other 3.7 owners have this noise, and whether it ever caused a problem.
The noise can be heard at idle, sort of a clicking. But no biggie.
There is no significant engine noise in the cabin during normal driving or acceleration when the engine is under load, like when getting up to highway speeds or maintaining speed on the flat or climbing hills.
Here is where I notice it: There is a clattering or tapping sound from the engine when it is at high RPM's and coasting, when not under heavy load. This happens at the top of gears just before upshift, like when you are cresting a hill in 3rd, just before it shifts into 4th. It happens when coasting down long hills on the interstate in 4th, or when descending steep hills in a low gear (at high RPM's). It happens when in tow/haul mode on the highway when there isn't a heavy load in tow. (I use tow/haul on 45-50 mph roads with undulating hills to keep the transmission from shifting between 2-3-4 all the time. Tow/haul keeps it in 3rd.)
What I've found is that RPM's usually have to be over 2500 for this to happen, when there isn't a heavy load on the engine. The tapping or clattering or hammering sound corresponds to the turning of the engine/cylinders. It sounds like metal banging on metal. I have had my oil tested by Blackstone Labs and there aren't any extra metal deposits in it, and I haven't noticed any change in performance or an increase in noise over the last 60K miles. 1 qt of Lucas Oil plus 4 quarts of regular oil makes it a little quieter. I was on a long trip through the PA mountains yesterday and noticed it a lot.
Thoughts? Thanks in advance!
2008 Liberty Sport 4x4 Automatic