3.8L ticking when cold/startup plus low idle and shake. Common issues?
Thread Starter
JK Enthusiast
Joined: Aug 2013
Posts: 188
Likes: 2
From: Ocala, FL
3.8L ticking when cold/startup plus low idle and shake. Common issues?
My 07jk has 133k miles on it currently and I've had a fairly loud ticking upon startup that seems to go away once everything gets warmed up. It sounds like its possibly an exhaust leak but I havent had a chance to really look it over. I also have noticed the rpm dropping a bit when stopped at a light and a bit of shaking.
Do either of these symptoms sound like any common issues with the 3.8s? I'm hoping the ticking is just an exhaust gasket or something but I dont know what would be causing the shaking and low idle.
Do either of these symptoms sound like any common issues with the 3.8s? I'm hoping the ticking is just an exhaust gasket or something but I dont know what would be causing the shaking and low idle.
JK Jedi
Joined: Apr 2010
Posts: 4,468
Likes: 211
From: SE Michigan
Not a common issue on our JK, Ticking on cold start that goes away after warming up typically points to valves. You may need valve adjustment or replacement.
If valves that typically comes from not changing oil regularly or letting the oil level run low.
If valves that typically comes from not changing oil regularly or letting the oil level run low.
JK Freak
Joined: Mar 2011
Posts: 791
Likes: 0
From: Vancouver, BC
Yeah, sounds like some valve problem, and from what I've heard these are not adjustable.
The shaking and dropping RPM is a misfire at idle. Could be a vacuum leak, could be a bad spark. Could be many things, really. No way to tell from just symptom description, you gotta diagnose it. If you never changed your plugs or wires yet, then you can start there if you don't know what to do. I had a bad spark plug just after 35K miles.
The shaking and dropping RPM is a misfire at idle. Could be a vacuum leak, could be a bad spark. Could be many things, really. No way to tell from just symptom description, you gotta diagnose it. If you never changed your plugs or wires yet, then you can start there if you don't know what to do. I had a bad spark plug just after 35K miles.
Thread Starter
JK Enthusiast
Joined: Aug 2013
Posts: 188
Likes: 2
From: Ocala, FL
Any good links on valve replacement? Google it just finding all sorts of videos regarding EGR valves...
Id like to determine if its something I can do with my Dad one weekend or if I need to start looking for a shop.
Yeah, sounds like some valve problem, and from what I've heard these are not adjustable.
The shaking and dropping RPM is a misfire at idle. Could be a vacuum leak, could be a bad spark. Could be many things, really. No way to tell from just symptom description, you gotta diagnose it. If you never changed your plugs or wires yet, then you can start there if you don't know what to do. I had a bad spark plug just after 35K miles.
The shaking and dropping RPM is a misfire at idle. Could be a vacuum leak, could be a bad spark. Could be many things, really. No way to tell from just symptom description, you gotta diagnose it. If you never changed your plugs or wires yet, then you can start there if you don't know what to do. I had a bad spark plug just after 35K miles.
JK Newbie
Joined: Jan 2014
Posts: 50
Likes: 0
From: Greenville, SC
Depending on how bad the tick is; I would think a lot of people would just drive it, and keep oil topped off. Be sure you're using proper weight oil. If tick is really bad, take it to a mechanic you trust for their opinion. Changing valves is not a weekend job in my opinion. For most DIY'r's; It typically requires pulling heads and taking them to a shop. If it needs valves, it may need some other engine freshening up as well. Take it and get a mechanic's opinion. I think they'll tell you to drive it.
Last edited by BRinSCupstate; Dec 3, 2017 at 04:49 AM.
