3.6L ENGINE RELIABILITY

CarbonSteel

Well-Known Member
Joined
Jul 21, 2019
Messages
2,077
Reaction score
2,337
Location
Colorado
Vehicle(s)
2019 Jeep Rubicon Unlimited
Vehicle Showcase
1
Unfortunately, the service center does not know how to tell me what the problem is
They think it's because of the oil
But the strange thing is that they replaced a new engine and again found failures. (the new engine is knocking)
And I am again waiting for a new engine.
Which oil brand and viscosity are you using? What oil filter brand?
Advertisement

 

Nissan

Well-Known Member
First Name
Nissan
Joined
Feb 23, 2019
Messages
60
Reaction score
33
Location
israel
Vehicle(s)
JL
If that's number 2, I'd check the serial numbers on both engines and if produced in close proximity, it would be evidence of a factory defect. If not, then I'd look at the rest of the drive train. The odds are astronomical for the same problem twice with nobody else reporting it, so something external may be causing it.

What oil are you running? Also, are you purchasing fuel mostly from the same vendor? If so, I'd research any possible consumer complaints on that outlet or location. Have you run any fuel or oil additives?

Finally, have any other 3.6 owners in your area reporting similar problems?

Lots to consider when having 2 like failures back to back with an engine that has a stellar reliability and durability reputation in the global auto industry.

I hope your next one does much better for you.
Agree with you in everything you said
I always refuel at the same regular 95 octane stations
Takes care of changing oil every 10000 km (the service center says it is an original oil )
To remind you, the vehicle has been at the service center for six months to this day.
They replaced the engine and went on a test drive.
The tester had to return the vehicle on a tow truck because the New engine started to knock.
I do not perform treatments independently
Only at the service center.

In my opinion, everything that happens is due to a lack of professionalism
But I must be there because it's still under partial responsibility
 

DanW

Well-Known Member
First Name
Dan
Joined
Mar 2, 2017
Messages
7,966
Reaction score
10,284
Location
Indiana
Vehicle(s)
21 JLUR, 18JLUR, 08JKUR, 15 Renegade, 04 WJ
Vehicle Showcase
2
Agree with you in everything you said
I always refuel at the same regular 95 octane stations
Takes care of changing oil every 10000 km (the service center says it is an original oil )
To remind you, the vehicle has been at the service center for six months to this day.
They replaced the engine and went on a test drive.
The tester had to return the vehicle on a tow truck because the New engine started to knock.
I do not perform treatments independently
Only at the service center.

In my opinion, everything that happens is due to a lack of professionalism
But I must be there because it's still under partial responsibility
I'm so sorry you have to deal with that and can't enjoy your Jeep!

If that 2nd engine failed so quickly then it appears to have been defective or damaged immediately, so that would rule out several things, including gas, oil, and the rest of the drive train as causes.

Hopefully the third one will be the charm.
 

Nissan

Well-Known Member
First Name
Nissan
Joined
Feb 23, 2019
Messages
60
Reaction score
33
Location
israel
Vehicle(s)
JL
I'm so sorry you have to deal with that and can't enjoy your Jeep!

If that 2nd engine failed so quickly then it appears to have been defective or damaged immediately, so that would rule out several things, including gas, oil, and the rest of the drive train as causes.

Hopefully the third one will be the charm.
Waiting impatiently for the arrival of the third engine
Thank you very much for your concern, sir
🙏🙏
 

oceanblue2019

Well-Known Member
First Name
John
Joined
Apr 13, 2019
Messages
2,907
Reaction score
4,269
Location
Maryland
Vehicle(s)
2019 JLUR 2.0L Auto
Occupation
Metrology
I know this has been done but maybe we can revisit strictly 3.6 L engine reliability and possibly anything to watch out for that could leave you stranded on a trail. Let’s share any bad experiences people have had with this engine.
E2BC6AA9-5D91-4CB1-A737-480FED9D5D9A.jpeg
Do not mistake the modern 3.6L with the older 3.6L as quite different - they changed around 2018 to get better economy out of them. But the modern version has been used in a lot of applications and therefore hundreds of thousands of them in use worldwide. This means any design issues are likely found and sorted out.

So unless you are unlucky and somehow get a lemon I would have no worries over reliability.

Keep the oil topped up, change it regularly, as well as the other fluids, and be happy for a few hundred thousand miles.

And the good news is if you do have issues post-warranty these engines will be plentiful at the wreckers so picking up a good used one will be cheap and easy to do.
 

DanW

Well-Known Member
First Name
Dan
Joined
Mar 2, 2017
Messages
7,966
Reaction score
10,284
Location
Indiana
Vehicle(s)
21 JLUR, 18JLUR, 08JKUR, 15 Renegade, 04 WJ
Vehicle Showcase
2
Do not mistake the modern 3.6L with the older 3.6L as quite different - they changed around 2018 to get better economy out of them. But the modern version has been used in a lot of applications and therefore hundreds of thousands of them in use worldwide. This means any design issues are likely found and sorted out.

So unless you are unlucky and somehow get a lemon I would have no worries over reliability.

Keep the oil topped up, change it regularly, as well as the other fluids, and be happy for a few hundred thousand miles.

And the good news is if you do have issues post-warranty these engines will be plentiful at the wreckers so picking up a good used one will be cheap and easy to do.
This newer gen, or PUG (Pentastar Upgrade) hit the street about a year before the JL in the Grand Cherokee. They did well right out of the gate. You are right, they should easily hit 300k. But they aren't radically different than the previous gen. The main difference is in the valve train, where they wanted to get some friction out of it and improve low end torque a little. But there is no mistaking that it is still a Pentastar. It's like a fraternal twin.
 

TravisRogers

Well-Known Member
First Name
Dan
Joined
Jun 19, 2018
Messages
213
Reaction score
366
Location
Annapolis, MD
Vehicle(s)
2018 Jeep Wrangler JL Sahara
Mine started knocking around 55K miles. This’ll be the first car I’ve had where the manufacturer needed to address spark knock in the owner’s manual. I can also recognize another JL in the mall parking lot by the screeching and pre-lube clatter startup. Love my JL but I don’t have high hopes for this engine.
 

DanW

Well-Known Member
First Name
Dan
Joined
Mar 2, 2017
Messages
7,966
Reaction score
10,284
Location
Indiana
Vehicle(s)
21 JLUR, 18JLUR, 08JKUR, 15 Renegade, 04 WJ
Vehicle Showcase
2
Mine started knocking around 55K miles. This’ll be the first car I’ve had where the manufacturer needed to address spark knock in the owner’s manual. I can also recognize another JL in the mall parking lot by the screeching and pre-lube clatter startup. Love my JL but I don’t have high hopes for this engine.
The first thing I'd do is swap the spark plugs out, looking closely at the gaps on the old ones to check if they are out of spec. The next thing would be to only run Top Tier gas.

Have you taken it to the dealership to have it diagnosed? Might as well see what they can do since it is under warranty. They might do the plug change and cover the cost.

My JK's 3.8 is supposed to go 100k on spark plugs but I've found around 50k the gaps open up and it makes it prone to knocking. So I now change them at 40k.

Not sure that will help, but worth a try. I'm at almost 55k on the JL's 3.6 and no knocking so far. It's had 99% Top Tier gas. The first little knock I hear will trigger a spark plug change.
 

TravisRogers

Well-Known Member
First Name
Dan
Joined
Jun 19, 2018
Messages
213
Reaction score
366
Location
Annapolis, MD
Vehicle(s)
2018 Jeep Wrangler JL Sahara
The first thing I'd do is swap the spark plugs out, looking closely at the gaps on the old ones to check if they are out of spec. The next thing would be to only run Top Tier gas.

Have you taken it to the dealership to have it diagnosed? Might as well see what they can do since it is under warranty. They might do the plug change and cover the cost.

My JK's 3.8 is supposed to go 100k on spark plugs but I've found around 50k the gaps open up and it makes it prone to knocking. So I now change them at 40k.

Not sure that will help, but worth a try. I'm at almost 55k on the JL's 3.6 and no knocking so far. It's had 99% Top Tier gas. The first little knock I hear will trigger a spark plug change.
Thanks Dan, great suggestions. I’ve been running premium for a while which pretty much takes care of the pinging. It’s going Into the dealership for the steering box and a couple of other things next week (before my extended is up) and I’m saving the knocking for the following appointment. I have to throttle my requests because more than two things at a time and their heads explode. Our dealership isn’t known for their competence. Plugs are cheap and easy enough. Might be worth a swap.
 

DanW

Well-Known Member
First Name
Dan
Joined
Mar 2, 2017
Messages
7,966
Reaction score
10,284
Location
Indiana
Vehicle(s)
21 JLUR, 18JLUR, 08JKUR, 15 Renegade, 04 WJ
Vehicle Showcase
2
Thanks Dan, great suggestions. I’ve been running premium for a while which pretty much takes care of the pinging. It’s going Into the dealership for the steering box and a couple of other things next week (before my extended is up) and I’m saving the knocking for the following appointment. I have to throttle my requests because more than two things at a time and their heads explode. Our dealership isn’t known for their competence. Plugs are cheap and easy enough. Might be worth a swap.
Lol, multi-tasking is hard!

I've watched a few YouTube videos and I think it looks pretty straightforward, although a bit more involved than on my old 3.8 since the big plastic intake manifold has to come off. On the old 3.8, every plug is as easy as pie except for the passenger side rear plug. That one is a real booger.

I'll be doing this one at the first little ping I hear.

Keep us posted on what you find and what works or doesn't work.
 

DanW

Well-Known Member
First Name
Dan
Joined
Mar 2, 2017
Messages
7,966
Reaction score
10,284
Location
Indiana
Vehicle(s)
21 JLUR, 18JLUR, 08JKUR, 15 Renegade, 04 WJ
Vehicle Showcase
2
Thanks Dan, great suggestions. I’ve been running premium for a while which pretty much takes care of the pinging. It’s going Into the dealership for the steering box and a couple of other things next week (before my extended is up) and I’m saving the knocking for the following appointment. I have to throttle my requests because more than two things at a time and their heads explode. Our dealership isn’t known for their competence. Plugs are cheap and easy enough. Might be worth a swap.
I forgot to ask one question....Did it come on or get worse when the shift was made to winter formula gasoline? I've seen that happen with the JK, but I can't remember if it was winter gas or summer gas that made it worse. I think it was winter.
 

Nissan

Well-Known Member
First Name
Nissan
Joined
Feb 23, 2019
Messages
60
Reaction score
33
Location
israel
Vehicle(s)
JL
Which oil brand and viscosity are you using? What oil filter brand?
All the treatments I perform at the service center
The service center tells me that they put the oil according to the manufacturer's requirements.
The oil they fill from the barrel, I want to believe they put 0W-20
 

oceanblue2019

Well-Known Member
First Name
John
Joined
Apr 13, 2019
Messages
2,907
Reaction score
4,269
Location
Maryland
Vehicle(s)
2019 JLUR 2.0L Auto
Occupation
Metrology
Mine started knocking around 55K miles. This’ll be the first car I’ve had where the manufacturer needed to address spark knock in the owner’s manual. I can also recognize another JL in the mall parking lot by the screeching and pre-lube clatter startup. Love my JL but I don’t have high hopes for this engine.
The modern 3.6L has quite high compression ratio - this was one of the changes they made to get better emissions and competitive power numbers. They went from 10.2:1 to 11.3:1.

All the knock and pre-ignition issues revolve around this change; and the way to solve it is higher octane fuel; but that comes with a cost.

As a related point when I was younger I had a Mustang with a 351W with 11:1 compression. It could only run on 93 and was much happier on 100LL avgas. So it is no doubt the EFI brings something to the game.
 

CarbonSteel

Well-Known Member
Joined
Jul 21, 2019
Messages
2,077
Reaction score
2,337
Location
Colorado
Vehicle(s)
2019 Jeep Rubicon Unlimited
Vehicle Showcase
1
All the treatments I perform at the service center
The service center tells me that they put the oil according to the manufacturer's requirements.
The oil they fill from the barrel, I want to believe they put 0W-20
I would seriously consider increasing the viscosity to 5W-30 and would confirm the brand they are using. Bulk oil can contain impurities and many service locations do not maintain bulk oil containers they way they should.

Given that you have had two oil related engine failures, I would either find another service center or start performing my own oil changes--preferably the latter so that you know what is going into the engine.
 

Steve JLUR

Well-Known Member
First Name
Steve
Joined
Apr 29, 2021
Messages
575
Reaction score
1,605
Location
OC, CA
Vehicle(s)
2021 JLUR, 2021 GC Summit
I have power windows and still have to explain it to everyone. The center mounted window switches aren't very common to non-Jeep people.
They are to those of us that had BMW‘s in the 80’s and 90’s…
 
Advertisement

Dwayne Lane's Chrysler Jeep Dodge
 
Advertisement
Top