2015 3.6L Pentastar Cylinder Borescope Result

The complaint of performance is that it will ping on the manual recommended 87 octane fuel and I have to run 89 or 92 to eliminate it. You don't have any concerns about the pitting looking marks in the valves?
Looks like delaminated carbon build up and not pitting to me. Carbon is self limiting in its build up most time and flakes off looking like what you see.

FWIW, did the plugs on my then 2020 3.6L Gladiator at 60K and bore scoped the plug holes also and had very similar but lighter carbon build up build up. I also run a fuel cleaner about every third tank and do a Seafoam treatment every 30K miles also.

You get random misfire codes? What application your engine in?
 
Looks like delaminated carbon build up and not pitting to me. Carbon is self limiting in its build up most time and flakes off looking like what you see.

FWIW, did the plugs on my then 2020 3.6L Gladiator at 60K and bore scoped the plug holes also and had very similar but lighter carbon build up build up. I also run a fuel cleaner about every third tank and do a Seafoam treatment every 30K miles also.

You get random misfire codes? What application your engine in?

It apparently hasn't reached the threshold to trip a misfire code, but if I monitor realtime misfire data it seems to trigger up to 10-15 misfires on a couple cylinders. Application is 2015 Jeep Wrangler Rubicon. I was running a can of seafoam in the tank every 5000 miles for several years and the switched to techron, which is what I am currently running.
 
The part number of the Mopar Piston/Rod Assy is 5184347AH. I pulled the stock image of the piston off the Mopar.com Estore, and the one of the used piston from Ebay. It looks like there is supposed to be a circular divot in the piston crown based on these images, so do you think thats what we are looking at on mine? Perhaps it looks crescent shaped because the other half of the circle has a chunk of carbon built up?


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Yeah, and if you look at your pictures, the location looks right too.
 
The complaint of performance is that it will ping on the manual recommended 87 octane fuel and I have to run 89 or 92 to eliminate it. You don't have any concerns about the pitting looking marks in the valves?
Wonder if the knock sensor is buggered? It shouldn't be audibly pinging like that on 87 if that's what it calls for. I assume it didn't originally, right?
 
It apparently hasn't reached the threshold to trip a misfire code, but if I monitor realtime misfire data it seems to trigger up to 10-15 misfires on a couple cylinders. Application is 2015 Jeep Wrangler Rubicon. I was running a can of seafoam in the tank every 5000 miles for several years and the switched to techron, which is what I am currently running.

Done any oil analysis? If so, how is the iron wear? Even in 2022, these Pentastars are still having bad cam and lifter or rocker arm issues depending on what generation Pentastar.

Have owned a 2013, 2014 Wrangler JK and am on my third Gladiator with the 3.6L. Just about all of them I have monitored with JSCAN and they all have misfire counts on startup for the first few minutes but never tripping CEL for a misfire with the exception on my 2020 Gladiator, it would post a P0300 and a P0304 once in a blue moon on a cold startup.
 
Wonder if the knock sensor is buggered? It shouldn't be audibly pinging like that on 87 if that's what it calls for. I assume it didn't originally, right?

I don't know if it was pinging originally because I didn't know exactly what pinging sounded like until about a year ago. I will be replacing both knock sensors when I replace the oil cooler, because they sit underneath the cooler and I don't want to redo the job if they fail shortly afterward. I have never had a trouble code tripped for knock sensors though.
 
Done any oil analysis? If so, how is the iron wear? Even in 2022, these Pentastars are still having bad cam and lifter or rocker arm issues depending on what generation Pentastar.

Have owned a 2013, 2014 Wrangler JK and am on my third Gladiator with the 3.6L. Just about all of them I have monitored with JSCAN and they all have misfire counts on startup for the first few minutes but never tripping CEL for a misfire with the exception on my 2020 Gladiator, it would post a P0300 and a P0304 once in a blue moon on a cold startup.

Yes I have done 1 oil analysis just to get a baseline, and the result was good per the Blackstone Labs comments. I did this quite a while back though, but I will go through my files and post the results because I don't recall the details. Sorry to hear they haven't fully corrected the issues with these engines. I could sell it now for a decent price, so I'm trying to determine if it would be prudent to sell it or keep it. I would like to get another 10-12 years and 300,000 miles if I decide to keep it, so just trying to get an overall assessment on its health at this stage. I will not buy another Chrysler product if I sell it, because this is the 2nd JK Wrangler I have had that needed fairly major engine work. I had a 2012 that had the failed valve guide in Cylinder No. 2, and required a head replacement as well.
 
I just got done with the cold compression test using the OTC 5605 test kit. The Chrysler factory service manual tells you to crank the engine 3 times and record the results, while the OTC kit says to crank the engine 5 times or until the needle stops rising. Chrylser spec. per the manual is that pressure cannot be below 100 psi, and not vary more than 25% per cylinder, while the OTC kit gives a maximum variation of 10% per cylinder. I notice that the results are significantly different if cranking 3 or 5 times, however, when testing with the gauge it took about 7 cranks for the needle to stop rising. I decided to do the test with both 5 and 3 cranks so here is the results:

5 cranks (2 tests per cylinder)

Cylinder 1 - 149 psi, 144psi

Cylinder 2 - 145 psi, 145 psi

Cylinder 3 - 150 psi, 150 psi

Cylinder 4 - 150 psi, 147 psi

Cylinder 5 - 154 psi, 154 psi

Cylinder 6 - 149 psi, 149 psi

3 cranks

Cylinder 1 - 121 psi

Cylinder 2 - 121 psi

Cylinder 3 - 125 psi

Cylinder 4 - 125 psi

Cylinder 5 - 125 psi

Cylinder 6 - 121 psi

7 Cranks

Cylinder 2 - 155 psi
 
I just got done with the cold compression test using the OTC 5605 test kit. The Chrysler factory service manual tells you to crank the engine 3 times and record the results, while the OTC kit says to crank the engine 5 times or until the needle stops rising. Chrylser spec. per the manual is that pressure cannot be below 100 psi, and not vary more than 25% per cylinder, while the OTC kit gives a maximum variation of 10% per cylinder. I notice that the results are significantly different if cranking 3 or 5 times, however, when testing with the gauge it took about 7 cranks for the needle to stop rising. I decided to do the test with both 5 and 3 cranks so here is the results:

5 cranks (2 tests per cylinder)

Cylinder 1 - 149 psi, 144psi

Cylinder 2 - 145 psi, 145 psi

Cylinder 3 - 150 psi, 150 psi

Cylinder 4 - 150 psi, 147 psi

Cylinder 5 - 154 psi, 154 psi

Cylinder 6 - 149 psi, 149 psi

3 cranks

Cylinder 1 - 121 psi

Cylinder 2 - 121 psi

Cylinder 3 - 125 psi

Cylinder 4 - 125 psi

Cylinder 5 - 125 psi

Cylinder 6 - 121 psi

7 Cranks

Cylinder 2 - 155 psi
They look pretty good to me for a basic test.

You could do a bleed down test on the two cylinders that your noticing the miss on if you wanted?
 
IMO for the mileage that is what I would expect. If it is running well I would do the repair you set out to do and drive it, and if the bug bites to sell it do so.
 
They look pretty good to me for a basic test.

You could do a bleed down test on the two cylinders that your noticing the miss on if you wanted?

I just finished the cold leakdown test, and the results are amazing but seem a bit suspicious to me. I used the OTC 5609 leakage tester with the first gauge set to 75psi test pressure, and I got almost exactly 75 psi on the second gauge for all 6 cylinders or 0% leakage. No evidence of airflow out of exhaust pipe, intake runner, or radiator, however, I did hear a very slight hiss, and was able to just feel air movement out of the oil filler tube on each cylinder.

I rotated one cylinder to just crack one of the valves in order to verify that the tool was capable of reading a difference between the first and second gauge, and it did. I do notice though that when I rotate the tool upside down, it feels like there is something rattling in the second gauge that I don't hear on the first gauge. Do these results seem trustworthy considering that compression readings were about 5-6% difference, and I did hear a slight bit of airflow out of the oil tube? Could the leakdown tester be suspect?

Leakdown_Tester.jpg
 
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I just finished the cold leakdown test, and the results seem a bit suspicious to me. I used the OTC 5609 leakage tester with the first gauge set to 75psi test pressure, and I got almost exactly 75 psi on the second gauge for all 6 cylinders or 0% leakage. No evidence of airflow out of exhaust pipe, intake runner, or radiator, however, I did hear a very slight hiss, and was able to just feel air movement out of the oil filler tube on each cylinder.

I rotated one cylinder to just crack one of the valves in order to verify that the tool was capable of reading a difference between the first and second gauge, and it did. I do notice though that when I rotate the tool upside down, it feels like there is something rattling in the second gauge that I don't hear on the first gauge. Do these results seem trustworthy considering that compression readings were about 5-6% difference, and I did hear a slight bit of airflow out of the oil tube? Could the leakdown tester be suspect?

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Are you saying that both gauges remain identical? I have never seen a used engine that doesn't bleed off a little - less than 10% is generally considered good.

If they don't loose any I would say your tester isn't working somehow. Can you get it a little higher maybe - PSI closer to the 100 PSI max on the gauge might make the bleed down more obvious.
 
Are you saying that both gauges remain identical? I have never seen a used engine that doesn't bleed off a little - less than 10% is generally considered good.

If they don't loose any I would say your tester isn't working somehow. Can you get it a little higher maybe - PSI closer to the 100 PSI max on the gauge might make the bleed down more obvious.

Yes both gauges remain identical which would indicate 0% leakage. As I turn the knob starting from 0 psi to 75psi they both travel together right up to 75 psi. I thought maybe there was something wrong with the right hand gauge, so to test it I rotated the crankshaft just to crack one valve and redid the test. As I brought the left hand gauge up to around 60-70 psi the right hand gauge only went up to about 15-20 psi or so. Is it possible that my cylinders are sealing perfectly if I can hear a very slight hiss out of the oil fill tube?

Per the factory service manual you aren't supposed to exceed 80 psi, so I don't really want to go any higher.
 
The complaint of performance is that it will ping on the manual recommended 87 octane fuel and I have to run 89 or 92 to eliminate it. You don't have any concerns about the pitting looking marks in the valves?
The borescope gives a terrible picture and (I believe) erroneously makes the valves look like there is something wrong. I think those are carbon deposits, not pits. Same with the edge of the valve. Not erosion, but more likely to be uneven carbon buildup.

Spark plugs look fine. No issues with oil.

There does not seem to be enough carbon to cause unusual pinging. It may simply be the way your engine is tuned, along with the sensitivity of the knock sensor.

As far as I know, those engines are known for rocker arm failures and oil pump/pressure issues. A few burn valves due to poor valve seats.
 
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Are you saying that both gauges remain identical? I have never seen a used engine that doesn't bleed off a little - less than 10% is generally considered good.

If they don't loose any I would say your tester isn't working somehow. Can you get it a little higher maybe - PSI closer to the 100 PSI max on the gauge might make the bleed down more obvious.

Here is the result of attempting to test functionality of the leakdown tool while allowing the hose to freely vent to the atmosphere. As you can see both gauges read differently as one would expect when the air can escape. Is it possible that this tool is functioning properly, and I have 0% leakage in all cylinders?

Test1.jpg
Test2.jpg
Test3.jpg
 
Here is the result of attempting to test functionality of the leakdown tool while allowing the hose to freely vent to the atmosphere. As you can see both gauges read differently as one would expect when the air can escape. Is it possible that this tool is functioning properly, and I have 0% leakage in all cylinders?

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If you have 0% lookdown on a used engine - send it to the Smithsonian.

You realize valves are metal on metal. THere is no way for them to be 100% air tight.

Rings can be air tight if they have oil between them and the cylinder - so a wet seal. Thats why you do a wet and dry compression test if you have low compression - to determine valves or rings.

I don't see how any engine can't have some valve bleed down.
 
If you have 0% lookdown on a used engine - send it to the Smithsonian.

You realize valves are metal on metal. THere is no way for them to be 100% air tight.

Rings can be air tight if they have oil between them and the cylinder - so a wet seal. Thats why you do a wet and dry compression test if you have low compression - to determine valves or rings.

I don't see how any engine can't have some valve bleed down.

So you think I should return this leakdown tester for a different one? Is it possible that the leakage is so low that the tester just doesn't register it? There is definitely a slight bit of air escaping the oil fill tube on all cylinders, and by sound/feel it appears to be even across cylinders. Unfortunately, I won't be able to retest it for a while because by the time I would be able to get a new tester I'm going to have to complete my repair and button the vehicle back up.
 
Can’t you test the leak down tester by loosening the spak plug adapter? like, with everything hooked up, leave it loose, then start turning out. should start leaking at some point.

Alternatively, rotate the crank, that will change pressure in the cylinder. just a few degrees will do.
 
Can’t you test the leak down tester by loosening the spak plug adapter? like, with everything hooked up, leave it loose, then start turning out. should start leaking at some point.

Alternatively, rotate the crank, that will change pressure in the cylinder. just a few degrees will do.

Yes I mentioned in a previous post that I already tried that and the tool does register leakage. It does seem odd though that at the recommended test pressure it's measuring no leakage on all 6 cylinders when I can hear a slight bit of air sound out of the oil fill tube on every cylinder.
 
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Great thread, but if you keep looking for problems, you'll find them. If you are hankering for a new ride, get it and trade this one in or sell privately to someone that needs a car with a very well researched engine.
 
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