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-   -   Pentastar tapping (http://www.jeepgarage.org/f107/pentastar-tapping-46794.html)

jp467 08-29-2012 11:52 PM

Pentastar tapping
 
Well I have about 6400 miles on mine 12 Overland and I do hear a tapping from the left side of the engine. I don't know if mine is normal or not but I hear it when I am driving next to a brick wall or something the noise can bounce off of. Today I had the hood open listening and I hear it from the left head but nothing from the right head. It runs smooth and doesn't seem to have any issues with the way it performs. I think I read somewhere they won't do anything without a cel on is this correct?

JTS97Z28 08-30-2012 10:02 AM

Re: Pentastar tapping
 
Well to be honest the Pentastar is kind of a noisy engine in our Jeeps with the windows down and especially when driving next to a wall. However with windows up its 100% silent. So unless your getting excessive noise even inside the cabin I wouldnt worry about it as we all get some engine noise with the windows down. As far as only hearing it on one side of the engine I personally havent listened closely to my 2012 Pentastar, but I havent noticed anything that I would raise concern over. You have plenty of warranty coverage, your Jeep is running fine, just leave it alone and enjoy it. Remember, anytime you try and get a dealership to work on your Jeep your risking them screwing something else up. Man, I dont even want those guys sitting on my new Leather seats. Unless you absolutely need to get it into the dealership, try to avoid them at all costs.

jp467 08-30-2012 11:42 AM

Re: Pentastar tapping
 
Quote:

Originally Posted by JTS97Z28 (Post 677122)
Well to be honest the Pentastar is kind of a noisy engine in our Jeeps with the windows down and especially when driving next to a wall. However with windows up its 100% silent. So unless your getting excessive noise even inside the cabin I wouldnt worry about it as we all get some engine noise with the windows down. As far as only hearing it on one side of the engine I personally havent listened closely to my 2012 Pentastar, but I havent noticed anything that I would raise concern over. You have plenty of warranty coverage, your Jeep is running fine, just leave it alone and enjoy it. Remember, anytime you try and get a dealership to work on your Jeep your risking them screwing something else up. Man, I dont even want those guys sitting on my new Leather seats. Unless you absolutely need to get it into the dealership, try to avoid them at all costs.


I agree... I won't do anything unless I have a problem.

padgett 08-30-2012 09:04 PM

Re: Pentastar tapping
 
Heard there is about to be a TSB issued on the heads. Anyone see it ?

HoustonRider 08-30-2012 09:08 PM

Re: Pentastar tapping
 
yep. Dealers are replacing heads on the V6. Parts are backed up for 3-6 weeks, Jeep is picking up rentals for Jeeps that have been damaged (holes in pistons, or damaged heads). May wanna visit your dealer if you are hearing it :)

padgett 08-30-2012 09:53 PM

Re: Pentastar tapping
 
Holes in pistons ? Definately leaning out then, wonder if can see in O2 sensor.

Anyone know which is bank 1 and which is bank 2 ? Am showing a slight difference in
long term fuel integrator, -5% in LTFI1 and -6% for LTFI2 with engine stopped.. This is usually a function of load and O2.Will monitor.

MattE 08-31-2012 12:46 AM

Re: Pentastar tapping
 
I purchased a 2012 Laredo to take back to Canada. I asked about the head issue, as I will not have any warranty when I Bring it back. I will have to pay the bill myself if this becomes an issue with mine. I will be taking delivery in two weeks. I was quoted $1,300 labour and $500 for the head. I will save $10,000K by purchasing in the U.S, so even if this head goes down, it's still worth it.

If there is a TSB, does this mean that all Pentastar's will have their head changed? I would like to know more details about the TSB before taking delivery.

Thanks!
Matt

padgett 08-31-2012 07:36 AM

Re: Pentastar tapping
 
TSB (Technical Service Bulletin) just tells dealers how to recognise the problem & how to fix but is official recognition that there is an issue. For all heads to be replaced there would have to be a recall.

What I am looking for is a reflash of the PROM with new maps that will richen the mixture under certain conditions and possibly bring the cooling fan in sooner.

I *suspect* that what is going on is that each cyl is slightly different & in the pursuit of MPG (in general a lean mixture will give more MPG) the engineers got either a bit agressive or missed a corner of the envelope (aircraft terms, I used to design engine and flight controls) that allows #2 to go overlean.

On a normal engine when this happens you usually can see the exhaust pipe glow (can use the temp of each pipe as a measure - why an EGT gauge is essential in a boosted engine - have seen the problem a lot there) but with the manifold in head design this is missing.

So under certain conditions (probably high temp, moderate load (no power enrichment) such as towing or just max load on a hill) #2 is leaning out and going into detonation (could tell a lot just from seeing a bad valve or even the spark plug, anyone have a picture ? Surface may be pebbled/irregular).

At first I thought was mostly off road people (conditions are good for overtemp/overlean) getting gas from low volume stations, who do not use the a/c much (cooling fan comes on with a/c) but 500 failures a month is A Lot. (3-5% failure rate is enough to make a car a lemon).

Would need to see demographics but regional gas mixtures might have an effect. It is interesting that the problem really surfaced when we started getting 100+ temperatures in many places. CJF may be praying for a return to cooler weather. Also a 10:2 c.r. in an oversquare engine on 87 PON is pushing things a bit.

Would also be interesting to see if more prevalent in a Limited 4x4 than a 4x2 Laredo (1,000 lbs heavier, same engine)

So lotsa possibilities and little info but would bet on "something" causing a lean condition in #2 with moderate to high load, high temp.

Sammzway 09-02-2012 11:08 PM

Re: Pentastar tapping
 
Can someone post the TSB here? I'm also interested on staying current with all the TSBs although there is no problem on ours. 32k miles and still running strong.

ColdCase 09-03-2012 08:51 AM

Re: Pentastar tapping
 
TSBs are on WK2jeeps.com

padgett 09-03-2012 09:30 PM

Re: Pentastar tapping
 
No TSB yet, will probably appear here eventually.

Jimbo 09-04-2012 11:03 AM

Re: Pentastar tapping
 
Do you see a sharp drop in mpg at 6400 mi?


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