I am posting this thread due to a total lack of information out there right now on these newer 2016-up Pentastar 3.6 liter V6 engines that have the VVT and new VVL (variable valve lift) on the intake camshaft.
Starting from my first encounter with this newer engine I had a customer come in with a P0303 misfire code... the complaint was that the engine was making noise upon start-up after sitting all night, run rough for about 10-20 seconds and then subside as the engine warmed up... given the Pentastar reputation for collapsing and noisy lifters, and also with their roller rocker arms coming apart and grinding camshaft lobes off I figured the fix was going to be pretty straight forward... either it was going to be lifters or a combination of lifters and rocker arms (also called roller followers in some circles). If the customer was lucky it was just going to be leaking lifters, as he caught it right away. I figured the camshaft would be okay because it was only making noise for a breif time after cooling off and sitting for awhile -- after less than 10-20 seconds the tick would go away, along with the rough idle. Once the engine warmed up it would seem to start fine without any noise, but if it sat long enough to cool -- the engine would make the ticking sound and run rough.
My first thought was to remove the valve cover and inspect the lifters, followers and camshaft lobes on cylinder #3 (P0303 misfire in cylinder #3). Since the design has changed a bit from the earlier years the intake manifold sat over the passengers side head and had to be removed to get access to the valve cover...
what is even worse on these later 2016 and up Pentastar engines is the fact that they have added a water cooled EGR system which makes removal of the valve cover a real PITA! There is a plastic wire loom mounting pedistal that needs to be trimmed, and also a wire loom bracket at the back outboard corner of the valve cover that also needs to be removed if you're going to pull off the valve cover without having to remove the EGR cooler assembly. There is a tab that has to be pressed in to remove the wire loom bracket from the valve cover. This kind of rediculousness is classic Chrysler, and they have been doing silly things like this since the dawn of time... so it was not shocking. I should also mention that the PCV valve at the back of the head must also be removed.
Once you get the valve cover off, if you have not worked on these newer engines you might be shocked to find that the intake camshaft has THREE lobes! This is the VVL part of the newer system that has what is your typical roller follower, but also has two wheels -- one on each side. These two wheels opperate your low lift... the center lobe is controled VIA solenoid and oil pressure. Inside the intake rocker arm (which list for over $120 EACH) is a intricate valve that is by default locked to the high lift center lobe. When pressure moves said valve the center of the follower will lower and it will run in the low lift mode to improve economy. It's a pretty odd way of doing it, but it's more or less Chryslers versions of Honda's V-Tec. It can go from .200 lift, to a little over .400 lift with the command of the solenoid and oil pressure.
All that said, all of the lobes on #3 cylinder were ok! Also, none of the lifters seemed to be collapsed or weak! Every single cam lobe had your typical wear marks for a 100,000 mile engine and looked very good! So I was stumped at what was going on in the #3 cylinder to cause a momentary misfire with what sounded like lifter chatter from a bleed down lifter that went away very shortly after starting.
This would also be a good time to let people know that there have been MAJOR changes for the 2016-up timing chain, camshaft and phaser design! The old tools that used to work in compressing the tensioners and aligning the phaser sprokets no longer work... the chains from the idler gear to the camshaft phasers has also been changed and is much smaller than previous Pentastar designs... in other words, if you go into the new 2016-up Pentistars thinking you can fix them or use parts like you have in the earlier designs you would be WRONG! Just giving this fair warning for professionals as this can cause you to mis-quote the job since the newer stuff is much more expensive and is also hard to find! At this time most of the aftermarket is clueless about the change and seem to imply that pre-2016 parts will work in the post 2016 models -- THEY WILL NOT! Not only are these parts for this newer revision harder to find, they are much more expensive. Many of the kits you see will not actually fit the 2016-up VVL style engines. You have to be very careful when buying parts unless you are buying from a dealership and using the VIN number for parts lookup.
All that aside, we still had to find out what was causing this issue. I scoured the internet looking, and there are many others having the same issues but none ever posted back what the problem was with their car... Well, I'm going to tell you and show you!
If you have a 2016 and up Chrysler, Jeep, or Dodge with the 3.6 liter DOHC V6 Pentastar and the newer VVL style heads and you're getting a code P0303 that runs rough momentarly with what sounds like a lifter tick (due to bleed down lifters) and then smooths out shortly after -- then it's a good chance that you have a blown head gasket, cracked block and or head. I used a Snap-On borescope and a coolant pressure tester to take actual video of the leaking while under 21lbs of pressure when cold. I'd suggest using a bore scope and a coolant system pressure tool to perform this test first so you can save the time. If you have a constant ticking that does not go away, I'd still peform this test first because if the head gasket is leaking everything else is secondary and can be easily replaced while the head is off.
I am unsure what the customer wants to do at this point, but I wanted to get the information out there for others who might save some time inspecting and or replacing the lifters and or followers/camshaft because that takes up a lot of time! It takes up even MORE time trying to research the issue with what little is out there on the internet right now on this newer design. Keep in mind, independant garages are just now seeing these vehicles as they come off warranty -- however I have had another 2017 Chrysler Pacifica that came in with the same issue, but that vehicle only had 40,000 miles and still had an extended warranty, so I advised the customer to take it to the dealership to avoid having to pay out of pocket.
When a Ford has a cold start rattle for a few seconds, it's almost always cam phasers (the variable cam timing sprockets). I do a ton of them on the 3.5 ecoboost for cold start rattle after sitting over 6 hours. The noise goes away after a couple seconds and usually won't happen again until the vehicle sits for several hours. Ford even has a tsb about it. Usually if they are bad enough to set misfire codes you'll also get some cam timing codes... Usually for cmp circuit fault, but it's actually due to the phaser being so worn that the PCM can't believe the timing is off that much and falsely thinks it must be a circuit issue.
I'm kind of surprised Chrysler doesn't have its own section on your site and has to be found under Fiat. Chrysler deserves their own section Rex, even if they do have a foreign parent company now.
Yes, very familar with the classic F150 cam phaser rattles due to broken/worn tension springs... but this is a different rattle, and it's actually due to the piston rocking as it's trying to push the antifreeze out of the cylinder for a few brief seconds. You can watch the misfire counter rack up 200-300 misfires on cylinder #3 with the scanner for that brief period of time the coolant is being expelled (usually 5-10 seconds). Once the coolant is gone the noise is gone and the misfire stops. Again it's ONLY on cylinder #3.
If you watch the video post above on a computer monitor you can see the marks in the cylinder walls where the piston has been rocking. Also, this is the last photo I took after the engine sat for about 6 hours under pressure... look at the amount of coolant that has pooled in that short of time!
Look to the right, you can see the small pool of coolant after sitting just six hours! Remember, coolant does not compress -- so when the spark plug is in there and the engine is sealed, depending on how long it sits and how much coolant pools -- something has to give and it's the piston rocking back and fourth on that compression stroke. Bad cam phasers do not allow coolant to get into the cylinders, leaking head gaskets -- cracked heads or cylinder walls do.
-- Edited by SELLC on Thursday 10th of October 2024 11:08:23 PM
Also, Chrysler is a foreign owned company now... thus it must remain under it's parent, Fiat.
It's very sad, I know... originally this forum was called "The Big Three" when we first opened. It's crazy how so much has changed in such a short time. Take a look around the main page of the forum -- Lamborghini, Bugatti are now listed under their parent - VW... and Jaguar under it's parent, TaTa... A lot of people don't even realize these facts -- but that is exactly what they are... facts.
Sad as it may be.
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What is to give light must endure burning -- Viktor Frankl
And I don't mean to correct you, but pistons don't rock in the cylinder bores, it's impossible...And yes, water doesn't compress, so "something" has to give...The question remains what is that something ?...
You may find that you have broken piston-rings, or a cracked piston in the ring-land, & should that be the case, perhaps you'll find water in the sump, or, alternatively, once the engine is really warm, water vapour may be expelling through the crankcase ventilation system & into the air-cleaner housing. Maybe look for water deposits there, or steam / vapour venting through the breather pipe...
Bummer...Big job to repair, & likely a replacement motor is the cheapest sure-fix ???...
Good luck, nice tools too btw.
-- Edited by Rastus on Thursday 10th of October 2024 07:08:27 PM
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"Only an alert & knowledgeable citizenry can compel the proper meshing of the huge industrial & military machinery of defense with our peaceful methods & goals, so that security & liberty may prosper together". Dwight D.Eisenhower.
And I don't mean to correct you, but pistons don't rock in the cylinder bores, it's impossible...And yes, water doesn't compress, so "something" has to give...The question remains what is that something ?...
Thank you Rastus, it was a pretty tricky diagnosis. The sounds it was making, the code it was setting and the things it was doing really threw me for a loop until I got the intake off and was able to inspect everything. Even the spark plugs were covered by the manifold on that side! In the end it was the tools that allowed me to pin-point the issue without having to tear the entire engine down.
That's not true about the piston rocking in the bore being "impossible", Rastus! Are you familar with the term "piston slap"? Piston slap is when the piston skirt "rocks" in the bore, usually when it's all the way at the top of the stroke on it's way down. Pistons are actually tapered believe it or not! So it's not impossible -- and actually it's quite common on worn engines. Wear can be on the piston itself, the cylinder wall and even with the wrist-pin... or in this case, trying to compress a liquid (aka the start of hydro-lock)
In this case the customer has decided to get rid of the vehicle because there are just too many unknowns until such time the head is removed... what is known are the costs involved and even in the best case scenario this repair is going to run anywhere from $8,000 - $12,000 depending on how it gets handled... of course the reman engine would be the most expensive path, but it's the only option that removes any surprises that may crop up once the head is pulled. I made an offer to waive the inspection cost if he brought me the title -- but the owner wishes to try his luck on the open market. Since my inspection cost are a little over a grand, and the fact that repair cost could near $12k -- the margins are just too close based on the current value of the car on the market. It also has 100k miles, and it's a Chrysler with a known problem child engine... so I'll just put it back together and release it since a deposit was made that covers the inspection cost. It's a shame too because it's only a matter of time before that leak gets worse -- and each time he starts it after sitting over-night is a chance that it fills up with enough coolant to actually cause a serious hydro-lock that will destroy the engine to where the only option would be to install a used or reman engine -- which is a pretty big job on these 4X4 Jeeps.
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What is to give light must endure burning -- Viktor Frankl
Oh for-sure Stellar pistons are tapered, where they're smaller in diameter at the crown, & taper to full size at the lower-end of the skirt, as that's why there's 3 x measurements with a micrometer to investigate for wear during a tear-down. And the reason for this taper, is because of heat, where in operation, the crown expands due to being exposed to the peak 1200-degree / average 5-600-degree + or - Celsius temperatures...But they won't rock-in-the-bore unless they're broken, or done a million-miles...100,000-miles "should" be where an engine is well into its long operating cycle, & not worn out.
That said, the engine is in your hands, not mine. I don't even think we get them over here in Oz...But to have 1 x cylinder only doing this is unusual, & all cylinders should have the same amount of wear, & so have the same noises...I would still suspect a broken / cracked piston...
And don't forget, cracks can be invisible to the eye, it's only when exposed to the high operating pressures in operation that they'll open-up.
It seems we're not necessarily going to get to the bottom of this, which is a bummer...But a bigger bummer is if you're the unfortunate owner...
Throw-away society hey !
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"Only an alert & knowledgeable citizenry can compel the proper meshing of the huge industrial & military machinery of defense with our peaceful methods & goals, so that security & liberty may prosper together". Dwight D.Eisenhower.
I never said piston rock (slap) was "normal" -- just that it happens a lot and isn't at all impossible. Something is giving, from the marks on the cylinder wall it's not good! It very well may have a ringland or chunk missing on the oil control ring... but odds are the leak is small enough right now to where it just rocks the piston enough to get a slap sound until such time as all the coolant is expelled from the combustion chamber.
It's a real shame too! This Jeep Grand Cherokee is immaculate! It's an older gentleman's wife's car and you can tell by the photos above that he was religious about oil changes because inside the engine it's more or less spotless! The outside and the inside are much the same! For sure worth putting some money into!
I agree engines should generally last well over 200,000 miles -- at least the engine and it's internals... but them days are over! Now days you have DOHC, VVT, VVL, phasers, solinoids, mangnetic pickups and much more tech that is now considered low tech, but it's new tech on top of old tech! This particular engine has a SUPER EXPENSIVE timing chain componet kit alone! Think there is something on the order of four chains, three tensioners, many guides and gears -- along with the phasers, solenoids and pickups! That doesn't factor in the machine work, gaskets, plugs, fluids and such -- nor does it factor in the most expensive part, the labor! I can only assume this issue is the result of a poor design -- at least for 2017 because you can clearly see that this guy took good care of his vehicle and maintined it religiously! Perhpas Chrysler has updated the design? Who knows! Back in 2017 money this paticular Jeep sold for almost $40,000 (not including taxes and registration fees). That is a whole lot of money! So YES! It damn well SHOULD have lasted 200,000+ miles! The old Jeeps with their inline 4's and 6's with cast iron blocks and heads were tanks known to easily make 250,000 miles with just regular repairs. But not now, these newer high tech aluminum block/head V6 engines have a lot of moving parts and sensors watching all over them. I'm sure someone is going to get stuck with this thing and have to fix it... how they fix it, well -- that will just depend on who gets it.
I got a feeling we are going to see a lot of this in the near future as cars have been selling for a premium, and a lot of people are upside down on their vehicles... I am seeing major failures across the board with all manufactures of these newer high-tech engines, and you'd be shocked that a lot of them have under 100,000 miles! But to be fair it was happening back in the 1980's and 1990's too -- only the cars were only $12,000 or less and people would just throw-away once they were looking at a repair bill of a few thousand dollars. They would just use said few thousand dollars to put down on a new $12,000 car -- but now, that $12,000 car is $60,000 new! That's inflation -- and I'm not talking about the hyper-inflation that has occurred over the past few years -- although that isn't helping any.
As time goes by the parts for this Jeep will become available for cheap in the aftermarket... this Jeep is only seven years old so it's right on the edge...
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What is to give light must endure burning -- Viktor Frankl
