3.6 Engine - Now I understand the power issue

[ShadowsPapa]

It was screaming just trying to keep up.

So? What's the big deal?
My Silverado with an LS engine had to SCREAM just to keep up towing 5,000-6,000 pounds here in our hills. It had to kick up to 5,000 RPM to make some hills at the speed limit on I80.
And the Chevy guys? They all said "so what, let it scream - it's made for that". In fact, my Silverado's LS had to wind up TIGHTER to pull my cars!
The 3.6 does it with about 500 less RPM.
What's the big deal with the RPM?

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[ShadowsPapa]

Here's my 3.6 after a drive up Donner Pass. The 3.6 motor is a long way from being capable of running that hard all the time.

That's extremely rare. Yeah, it happened to you - but that's one in millions. Not at all common. They'll wind and wind for hours.

 

[ShadowsPapa]

A simple google search will return so many results on the 3.6 overheating issues. It's a frequent thread on the Wrangler Forums and CDJR actually designed their coolant temp gauge to stay center with coolant temps up to 230/235 degrees so people aren't alarmed when it's running hot. lol

Mine has a new engine (16,500 miles on it now, professionally installed by a reputable engine shop. Cost me around 10,500. I have 169k on the chassis), transmission serviced and trans runs great.

You actually believe that's hot? You've missed all of my other threads on engine temps, obviously.
You didn't realize that in the 1970s and 80s a thermostat didn't even fully open until 227 degrees.
The temp gauges from that period - go look in the TSMs about what the real temperatures are on those blank gauges
My 87's 4.0 ran 220 on a regular basis, that was normal (the sending unit placement, however, sort of hid that fact)
230 is NOT hot!

The pressure cap on these is something like 21 pounds, coupled with a 50/50 mix of coolant and the boiling point is over about 270.
If optimal is up around 225, you are hardly overheated at 230.

 

[ericw.]

That's extremely rare. Yeah, it happened to you - but that's one in millions. Not at all common. They'll wind and wind for hours.

Well it lasted 140k which is about the lifespan of an engine according to the manufacturer. I just think the power level and drivability (feeling obligated to watch temps climb) for what it is, sucks. It's a big trade-off for a very capable offroad vehicle, IMO.

The new engine performs the same as the old one, however your experience may differ because our expectations aren't the same.

You actually believe that's hot? You've missed all of my other threads on engine temps, obviously.
You didn't realize that in the 1970s and 80s a thermostat didn't even fully open until 227 degrees.
The temp gauges from that period - go look in the TSMs about what the real temperatures are on those blank gauges
My 87's 4.0 ran 220 on a regular basis, that was normal (the sending unit placement, however, sort of hid that fact)
230 is NOT hot!

The pressure cap on these is something like 21 pounds, coupled with a 50/50 mix of coolant and the boiling point is over about 270.
If optimal is up around 225, you are hardly overheated at 230.

A total of zero people would recommend running it up to 270 degrees. Even Stellantis decided that 260 is in the "red" on your coolant temp gauge. 240 was cause for concern enough to define that as 3/4 of the temp gauge.

This is an aluminum block with iron bore liners and aluminum heads, not your old 1970's/80's iron blocks.

 

[ShadowsPapa]

Well it lasted 140k which is about the lifespan of an engine according to the manufacturer. I just think the power level and drivability (feeling obligated to watch temps climb) for what it is, sucks. It's a big trade-off for a very capable offroad vehicle, IMO.

The new engine performs the same as the old one, however your experience may differ because our expectations aren't the same.


A total of zero people would recommend running it up to 270 degrees. Even Stellantis decided that 260 is in the "red" on your coolant temp gauge. 240 was cause for concern enough to define that as 3/4 of the temp gauge.

This is an aluminum block with iron bore liners and aluminum heads, not your old 1970's/80's iron blocks.

WTF - who said anything about running 270 ???
I was merely stating it's not even close to a danger zone. These systems aren't in any danger even at temps that would mess up engines of a few years ago.

Doesn't matter what you want to believe as a non-tech - 230 is a norm for many modern engines. You'll find some GM people saying 230-240 isn't bad.
For these, 230 is NOTHING.

110C is 230 F - 110 at normal operating temp as shown below.
It wasn't unusual years ago, it's normal today. But people freak out over it. The heat is for efficiency (power) and emissions..

The block is die cast. It's a lot better than before.

 

[ericw.]

WTF - who said anything about running 270 ???
I was merely stating it's not even close to a danger zone. These systems aren't in any danger even at temps that would mess up engines of a few years ago.

Doesn't matter what you want to believe as a non-tech - 230 is a norm for many modern engines. You'll find some GM people saying 230-240 isn't bad.
For these, 230 is NOTHING.

110C is 230 F - 110 at normal operating temp as shown below.
It wasn't unusual years ago, it's normal today. But people freak out over it. The heat is for efficiency (power) and emissions..

The block is die cast. It's a lot better than before.

You seemed to suggest that 270 was acceptable. 250 isn't even acceptable. 230 is riding the line of acceptable, as even in your screenshot it's the "peak" of what MEI suggested operating temp. Both of my 3.6 motors in the wrangler would run the temp up as high as you let it.. well beyond 230.

A properly made iron block is significantly stronger and more durable than even modern aluminum blocks because, even "modern" aluminum suffers from still being... aluminum. it's not even debatable. The switch to aluminum was for weight and economy reason, increasing those MPGs and reducing emissions when emissions standards were being set in the late 80's-90's. lol

 

[ShadowsPapa]

You seemed to suggest that 270 was acceptable. 250 isn't even acceptable. 230 is riding the line of acceptable, as even in your screenshot it's the "peak" of what MEI suggested operating temp. Both of my 3.6 motors in the wrangler would run the temp up as high as you let it.. well beyond 230.

A properly made iron block is significantly stronger and more durable than even modern aluminum blocks because, even "modern" aluminum suffers from still being... aluminum. it's not even debatable. The switch to aluminum was for weight and economy reason, increasing those MPGs. lol

No, I said that with coolant and cap, you didn't need to even consider anything boiling until well over 270, closer to 300 for these with the 21 psi cap. So there's no risk of boiling - which some seem to really be concerned about.

230 isn't riding any line of acceptable - not at all.

These are talking about modern aluminum engines -

120 C is what, about 240F? So, it's not a disaster to be running 230-235. The issue isn't because "these run too hot" because they don't.
It brake, that's bad, a disaster for the person it happens to - but it's not a design or heat issue.

 

[DanW]

Well it lasted 140k which is about the lifespan of an engine according to the manufacturer. I just think the power level and drivability (feeling obligated to watch temps climb) for what it is, sucks. It's a big trade-off for a very capable offroad vehicle, IMO.

The new engine performs the same as the old one, however your experience may differ because our expectations aren't the same.


A total of zero people would recommend running it up to 270 degrees. Even Stellantis decided that 260 is in the "red" on your coolant temp gauge. 240 was cause for concern enough to define that as 3/4 of the temp gauge.

This is an aluminum block with iron bore liners and aluminum heads, not your old 1970's/80's iron blocks.

The lifespan of the engine is 1% mechanical failure rate at 150k. That was the standard at FCA when the PUG Pentastar was designed. Flip it....99% of them still running without a mechanical repair at 150k miles.

I hate that it happened to you, though. When it happens to someone, it is 100% for that person. I don´t like seeing anyone having to deal with that. It ain´t cheap these days.

 

[ericw.]

230 isn't riding any line of acceptable - not at all.

At 235 your temp gauge will be increasing between 1/2 and 3/4. Stellantis' mechanical engineers had reasonable concern, when specifically defining these temperature limits.

Climbing Echo Summit (I50) or Donner Summit (I80), or climbing out of the salt flats between Utah and Nevada, I let off at 245 and it climbs another 2 degrees before coming down. Done these drives so much in the last 5 years that I've memorized it.

 

[ericw.]

The lifespan of the engine is 1% mechanical failure rate at 150k. That was the standard at FCA when the PUG Pentastar was designed. Flip it....99% of them still running without a mechanical repair at 150k miles.

I hate that it happened to you, though. When it happens to someone, it is 100% for that person. I don´t like seeing anyone having to deal with that. It ain´t cheap these days.

Appreciate it, it's water under the bridge. "Without repair", I think that might need to be rephrased but I get what you're saying.

I still don't like how I can't just hand the keys over to someone and let them drive for me. My wife isn't mechanical or technical so she can't drive the Jeep either. Engine failure aside, I don't trust the Pentastar to keep itself alive in the hands of someone inexperienced with it's driving characteristics.

 

[ShadowsPapa]

At 235 your temp gauge will be increasing between 1/2 and 3/4. Stellantis' mechanical engineers had reasonable concern, when specifically defining these temperature limits.

Climbing Echo Summit (I50) or Donner Summit (I80), or climbing out of the salt flats between Utah and Nevada, I let off at 245 and it climbs another 2 degrees before coming down. Done these drives so much in the last 5 years that I've memorized it.

1/2-3/4 is still not overheated. If it was, it would be in the PCM as overheated, and it would state as much. So what if it's 1/2-3/4?
You are interpreting it incorrectly.

 

[ericw.]

1/2-3/4 is still not overheated. If it was, it would be in the PCM as overheated, and it would state as much. So what if it's 1/2-3/4?
You are interpreting it incorrectly.

It's on the way to overheating. That's why there's a gauge with varying levels and marks to watch. lol it's not just a light that pops up when it's overheated. It all means something, so you can prevent a problem before it's a problem, otherwise it wouldn't be there.

 

[biodiesel]

The lifespan of the engine is 1% mechanical failure rate at 150k.

Are you sure it's 1%? The EcoDiesel has a B10 service life of 150,000 miles, which means that 10% of the engines will either fail or require a major repair by 150,000. Life expectancy is on a bell-shaped curve. I'm pretty sure that a B10 service life of 150,000 miles is standard on all light duty engines. My guess is that the Pentastar also has a B10 life of 150,000 miles.

 

[ShadowsPapa]

LOL - like I have no clue having been in the business for so many years, and having dealt with truly over-heated engines

 

[DanW]

Are you sure it's 1%? The EcoDiesel has a B10 service life of 150,000 miles, which means that 10% of the engines will either fail or require a major repair by 150,000. Life expectancy is on a bell-shaped curve. I'm pretty sure that a B10 service life of 150,000 miles is standard on all light duty engines. My guess is that the Pentastar also has a B10 life of 150,000 miles.

Directly from a design engineer of the Gen 1 Pentastar team. The standard they were to meet was 1% at 150k miles.

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