Brief engine rattle at start-up
 

My wife is primary driver of our 2010 unlimited Rubicon. In Colorado last week and noticed a brief rattle/tapping noise from engine at start-up. Basically sound like valve chatter. Thought it was the cold weather, but wife mentioned it is a normal occurrence. Is it normal for the 2010 JK to make this noise?

Sounds like dry start to me. Certain oil and filter combinations make this worse or better.

Personally I have had really good success with conventional oil and WIX filters.

Changed oil just before trip. I am using and always have used Mobil 1 synthetic and Wix filter.

Hmmm....and this noise only happens at start up?

Only at start up, and for maybe 2 seconds. Using 5/20 oil as recommended by manufacturer.

Definitely sounds like dry start to me as well. This happens to my '11 JK as well and happened to my '09 ford fusion. I believe there is a thread on this topic on this forum but forget what it's called. I think there were people on that thread that found oil/ filter combos that stopped this from happening.

I recently call our local dealership, they said its normal and they cant do anything about it, It's just the design. I have a 2011 jku just over 11k and it only does it when it is really cold outside

There are more threads than you probably will care to read concerning which oil filter is best for your JK 3.8 engine. There are hundreds of claims, but in reality every filter suffers from some degree of oil drain back in the horizontal position. This results in the "dry start" sounds you report.
Another angle is discussed in this thread and others like it:
https://www.jk-forum.com/forums/show...e-start-Lubers

I do not endorse my pre-oiler approach other than to say it is the way I played with the problem. (Your needs may differ!)

I have a 2010 sahara with 30k on it, I occasionally have the same problem

My wife has this problem with her 08 JKUR. I talked to the service tech. and he said it was nothing to worry about.