Been seeing alot of spun bearing and engine failure worries..Fact is, there are sooo many sounds in an engine that can tick...etc. A lifter? Had one in my 4.0 that went for 180,000 miles without rearing its ugly head as anymore than just annoying. Share if you have had noises, what they came from and the condition..such as I have a slight tick at idle only hear it when I am inside the Jeep in park. No noise when I accelerate. A mechanic told me to use 5w-30 oil and forget about the 5w-20 BS from Chrysler as they just wanted to get me through warranty and post better gas milage. At 45k I am going to try the heavier oil hopefully not too late...anyone else have any stories etc? Please share. I know I have read a few about the worst case scenario of a spun bearing etc but every little noise doesn't mean devestation..esp on a Jeep.

 

I do know that many people confuse the sound of the injectors ticking at ldle with ticking valve tappets; all multi-point EFI motors have injector tick to a degree, though I have noticed that the JKs V6 sound is on the more noticable side compared to other EFI vehicles I've previously owned. Ticking injectors sound more like the whirring sound of a sewing machine though, instead of the metallic tap of valves.

Also, the symptom of a ticking sound at idle that disappears at revs sounds like a cracked or leaking exhaust manifold; the sound of a ticking tappet (or injector) will increase in rate with increased revs. Cracked exhaust manifolds are a known issue with the JK.

As for oil yeah, many of us run the 5W30 (or even 10w40 in hot climates) instead of the thin 5w20 Chrysler specified simply in order to (coupled with it's high stock axel and transmission gearing) squeeze out a few more MPGs from the motor and meet it's CAFE targets for the fleet, to offset the guzzling Hemis they shove in some of their other vehicles.

 

Good info...Exactly what I had in mind when I started this thread. So isa craked exhaust manifold bad to drive with..? Will it cause any damage?

 

Apart from the risk of getting exhaust fumes into the cabin via the ventilation system (if you're at standstill and idling for a long time with the blower fan on then this is a possibility) it's not particularly dangerous as such; there's a heat shield fitted over the manifold anyway, thus reducing the chance that escaping hot exhaust gasses could melt a spark plug lead or start a fire or something.

The manifolds are cast iron and not particularly well made it seems. The good news is that even if you're out of warranty, it's fairly easy to replace the manifolds and they are fairly cheap so it won't cost you a fortune anyway. The cracks are usually quite visible and an inch or so long, so it's just a matter of removing the heat shields (undoing a few bolts) and having a look at the manifold underneath.

Have a look at this thread:

https://www.jk-forum.com/forums/show...acked+manifold

Here's a pic of one; you can see the crack on the 1st pipe near the join:

 

Great stuff...Thanks so much. I actually added the 30weight oil today and the noises are all to a min so may have just been a lifter etc. I may need to check the manifold out though just to ease the mind. I was under the rig today and saw everything you are mentioning. Including the heat shields. Much obliged.

 

I bought a used 2007 rubi with ~20k miles on it. It had a faint tick/knock when I bought it but nothing too bad, I thought it might even be my imagination. It would happen around 2k rpm when I was accelerating. Sounded like it was coming from the firewall side of the engine when I'd stick my head under the hood while it was running.

Well after I put 2k miles on it, the sound got louder and I took it into the dealership. They tried coolant dye and that didn't reveal anything and they said they'd have to tear the engine apart a little bit for a diagnosis. Problem is the 3.8's are more difficult to work on than the 4.0's, so they couldnt schedule the 16 hours labor it needed for another 2 weeks.

2 weeks is today, which is when my appointment for dropping it off was. It died yesterday while driving on 95. CEL came on, then I lost power steering, and the TCS light came on.

I'll let you guys know when I learn more from the service guys.

 

Oh geez..I am sorry to hear that. Yes keep us posted.

 

Mine gave no previous warning but I can only hope you dont have a similar problem to what just happened to me. See my post. I'm told by the dealer that I need a whole new engine at about 6 grand

 

well the two things I have are when I accelerate or try and hold 70-75mph I get a whistle like sound (turboish) and it can be heard from the outside. Replaced a broken/cracked throttle body and still have issue, gave up...for now. Other sound is when its cold out it'll make what sounds like metal to metal slapping but then goes away once the idle levels out/warms up.

 

same here on the whistle....LOUD...