Hey Guys,



I've got this issue with my 2008 Jeep Rubicon w/ 190k miles. Its making this ticking noise and I cannot figure out what it is. It originally had cracked exhaust manifolds which I replaced. I then did an engine oil flush with liqui moly and added lifter additive with 5w-20 fully synthetic and a new mopar filter. I just did another oil change 200 miles later with 5w-30 and lucas oil stabilizer and at that time added lucas fuel injector cleaner. I ended up getting a misfire last night and put in new NGK spark plugs which got rid of the misfire. Today, I cleaned out all the fuel injectors using carb cleaners and a battery to cycle it through them. Put the injectors back in along with a new one for cylinder 5 where the misfire was coming from (darn injectors at dodge cost $112 a piece and the only had one). Anyways, there is still this loud ticking/tapping noise coming from the engine. Funny thing is at cold starts, it will not tick until around 30 seconds of idling. It did this after both oil changes and on every cold start that I can remember. Dash is currently clear and there are no codes. I used a stethoscope and could hear ticking that looks like it is coming from under the intake manifold so I suspect that is where it is. I also hear a tiny bit of ticking coming from the valve covers but I assume that is just normal and I would assume it isn't lifters/rockers since on cold starts it does not make the tapping noise. The noise also increases when I step on the gas pedal but the second I release it, it goes away then comes back when it idles. I'm going to post the link to a video of what the noise sounds like. Does anybody have an idea on what it could be? Also if anyone is in the Sacramento CA area, I am willing to take it over to a shop that anyone recommends.

 

https://fourwheeltrends.com/is-your-...%20dying%20out

 

ONE Question.. Does this noise (more than a Tick to my ears) increase with engine speed? Slowly rev up and does it speed up?

 

The video in the link that Oscar posted is great info. It shows you how to spot which one is bad and also explains why it is tapping. Not a very fun task, especially if it's not the rear like that video was.

 

Yea it does. But when I take my foot off the gas it gets quite for a second then comes back at either on its way down to idle rpm or when I put my foot back on the gas.

 

Are there any videos out there like that for the 3.8 engine?

 

Sounds to me like the ticking frequency is half the crankshaft speed. Since the cam shaft turns at half crank speed, I would look into the valve train.

 

IMO I would search Wrist Pin Knock to compare your sound. With the miles on your engine it is a possible.

 

190K miles is pretty good for an engine and one should expect ticks and rattles. I agree with Jay about wrist pin or piston skirt. Remember every time a piston fires it is moving because there was an explosion on top of it. Sounds like crank rotation related sounds. Hard to tell though from a video. They don't last forever but ones that last that long make a good rebuild platform. I have heard many 3.8 Vans making similar noises with similar miles.