Duke
Duke MegaDork
9/6/18 10:14 a.m.

Boss has a 2015 Wrangler Unlimited with the 3.6 Pentastar in it.  About 70k on it.

It started idling rough.  It was missing by the time he got home.  Took it to his 'trusted mechanic', who said it showed a misfire code and started making a lot of scary talk about this engine being notorius for a lot of major trouble with cracked heads, etc.

So what's the actual deal?  I thought the cracked heads thing was typical internet (5% is ALL OF THEM) conventional wisdom, and I thought it had been solved by 2015 anyway.

I bet it's just a coil pack.  Supposedly 'trusted mechanic' said they check out, and reset the ECU, and it's running OK now.

I'm also asking because I have the same engine in the Concert Coach.

Donebrokeit
Donebrokeit SuperDork
9/6/18 11:13 a.m.

My guess is coil pack and plug, together. 

 

Some 3.6 have issues with the cams and lifters (tap noise), some have burnt valves (no noise)  sometimes. Have only seen a few (less that three) blow the bottom end, all had no oil and no records of oil changes.

 

Paul B

TGMF
TGMF Reader
9/6/18 11:41 a.m.

Cracked heads are a thing with early engines. I know a guy with a wrangler...not sure what year, probably early production, thats had several engine failures. He won't take his jeep off road anywhere because he doesn't trust it will get him back home. 

Misfire is a symptom, once detected by the ecm it shuts off that cylinder's fuel to save the catalyst.  Once code is cleared, it will run well, till the crack causes enough of a misfire to set the code again.  

*edit, looks like that was for 11-13MY vehicles equipped with the 3.6.  Extended warranty program for those 10yrs 150k. 

 

Professor_Brap
Professor_Brap HalfDork
9/6/18 11:45 a.m.

I have seen a half dozen or so wipe cams around the 90-100k mark a 2 this year have had ring failure. 

Knurled.
Knurled. MegaDork
9/6/18 12:04 p.m.

I regularly swap the oil filter housing assembly. Kind of a dumb design, and the engine valley will hold 2 quarts of oil before it starts leaking over the trans.

RossD
RossD MegaDork
9/6/18 12:08 p.m.

My '14 Grand Cherokee's 3.6 has 102,000 miles on it. No engine troubles. Knock on wood.

Cotton
Cotton PowerDork
9/6/18 12:11 p.m.

Take it to the dealer.  If it's the head issue it is under a factory extended warranty for 10 years/150k miles.  Our 2012 threw a misfire code and had 110-120k on it.  Took it to the dealer and they replaced the problem head under the additional warranty.  Just FYI ours did have a misfire code,  but did not run any different.

 

Edit - oops just saw TGMFs edit,  so maybe 2015 is out of scope for the extended warranty.

stanger_missle
stanger_missle SuperDork
9/6/18 1:04 p.m.

Yep, what Cotton said. The affected engines were from 2012-2013. I have an early build 2012 Wrangler that had the cylinder head defect. It threw a DTC but driveability was not affected. I only have 41k miles as of today.

I would take it to the dealer and see what they find. Might be as simple as a plug or coil.

The TSB number is 09-002-14 Rev. B

Pentastar repair info

 

Duke
Duke MegaDork
9/6/18 1:06 p.m.

Thanks, all!

Duke
Duke MegaDork
9/12/18 1:17 p.m.

Sooooo...

What do we know about camsahft issues with these engines?

Boss took the Jeep to the dealer because it began running rough again.

Dealer is replacing all 4 camshafts and about 12 "rockers" - luckily under warranty. 

Clearly if it has 4 camshafts, it has zero rockers, but I won't really argue semantics about calling them "cam followers".

 

So what's the deal?  The engine has about 70,000 miles on it and is a 2015.

Duke
Duke MegaDork
9/12/18 1:18 p.m.
Professor_Brap said:

I have seen a half dozen or so wipe cams around the 90-100k mark a 2 this year have had ring failure. 

Looks like this is what got him...

Anybody know the underlying issue?  Top end oiling problems?

Ian F
Ian F MegaDork
9/12/18 1:24 p.m.

As I now own a 2017 3.6, this subject is of interest to me.

2002maniac
2002maniac Dork
9/12/18 3:23 p.m.

Related concern:

I have a 2012 T&C van purchased 2.5 years ago with 70k miles on it.

It is now at 115k and I began to notice last summer that it would begin to overheat on a warm day going up a steep grade. The first summer I owned the car it wouldn't overheat in the slightest even in 100 degree weather.  The highest I have seen it get is 230 degrees which doesn't seem dangerous, but with the mention of cracked cylinder heads it does make me nervous.  Is this an indication that I may have a cracked head?

I've never had any misfire codes (or any codes at all).

I'm worried if I take it to the dealer, I'll end up with a very expensive labor bill if they tear it down and find nothing wrong with it.

Knurled.
Knurled. MegaDork
9/12/18 6:30 p.m.
Duke said:
Professor_Brap said:

I have seen a half dozen or so wipe cams around the 90-100k mark a 2 this year have had ring failure. 

Looks like this is what got him...

Anybody know the underlying issue?  Top end oiling problems?

Overlong OCIs, and the multistage oil pump is also known to be problematic.

TGMF
TGMF Reader
9/12/18 7:20 p.m.

In reply to 2002maniac :

You've got till 2022 and 150k miles for it get bad enough where you're certain it's broken. 

Ian F
Ian F MegaDork
9/12/18 8:07 p.m.

In reply to 2002maniac :

Has anyone added coolant? I recently downloaded an owner's manual for my 2017 (it didn't come with one) and I noticed when reading through it that the coolant system uses "don't mix it with anything!" coolant with the warning that if mixed with the wrong stuff, the cooling system will be compromised.

2002maniac
2002maniac Dork
9/13/18 7:46 a.m.

I've kept it topped off with the compatible Zerex coolant (HOAT pink/orange).  It's used about a gallon total in 45,000 miles at a fairly consistent rate.

rslifkin
rslifkin UltraDork
9/13/18 9:49 a.m.

In reply to Ian F :

Mixing is an issue with any modern coolant.  Basically, if you need to add, make sure you know what's in there so you can add something compatible.  When buying a used car, if you have any doubts about what's in the system, flush it and refill with something compatible.  

Ian F
Ian F MegaDork
9/13/18 12:00 p.m.
rslifkin said:

In reply to Ian F :

Mixing is an issue with any modern coolant.  Basically, if you need to add, make sure you know what's in there so you can add something compatible.  When buying a used car, if you have any doubts about what's in the system, flush it and refill with something compatible.  

Oh I know... it's why I buy coolant for my TDI at a VAG dealer and only at a VAG dealer.  Same with coolant for my MINI.  The only cars that get "green stuff" are the Triumphs. It does mean I have a lot of coolant around... 

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