[Classic Owner]

Your theory is plausible and at least makes sense.
I cannot fathom how a faulty oil cooler could cause a head gasket failure .

It wouldn't unless all the coolant magically leaked out without anyone noticing.
Problem is, coolers don't usually leak coolant anyway. Usually they crack and leak oil.

Either way, cooler leaks are generally caught long before anything overheats anyway.

 

[M0Par]

It wouldn't unless all the coolant magically leaked out without anyone noticing.
Problem is, coolers don't usually leak coolant anyway. Usually they crack and leak oil.

Either way, cooler leaks are generally caught long before anything overheats anyway.

Starting to warm up to this.

 

[Classic Owner]

Honest answer here is it's a head gasket so every immediately jumps to overheating.
An engine needs to get **** hot to warp something enough to blow a HG, even the average oblivious owner will shut it off long before this.

It doesn't however take much added pressure to blow one on a cylinder though. Especially with how close some of the ports are to the combustion chamber:

 

[M0Par]

Honest answer here is it's a head gasket so every immediately jumps to overheating.
An engine needs to get **** hot to warp something enough to blow a HG, even the average oblivious owner will shut it off long before this.

It doesn't however take much added pressure to blow one on a cylinder though. Especially with how close some of the ports are to the combustion chamber: View attachment 54368

I'm trying to follow your post... The average oblivious own will shut it off before the head gasket blows?

So what is it you are stating is blowing instead?

 

[Classic Owner]

I'm trying to follow your post... The average oblivious own will shut it off before the head gasket blows?

So what is it you are stating is blowing instead?

IF it's a coolant related issue, the dash will light up like a christmas tree and it will get shutdown. This isn't generally enough time to blow a head gasket on an engine.

The ignored miss however will slowly eat at the head gasket until it ultimately lets go. This will cause the sudden misfire, coolant loss, etc we're seeing on these engines.

My point is the reason people assume it has to be something coolant related (IE: The Oil Cooler) causing the head gasket to fail is because that's everyone assumes an engine has to overheat to blow a head gasket.
The reality is most head gasket failures in engines have NOTHING to do with over heating.

 

[M0Par]

IF it's a coolant related issue, the dash will light up like a christmas tree and it will get shutdown. This isn't generally enough time to blow a head gasket on an engine.

The ignored miss however will slowly eat at the head gasket until it ultimately lets go. This will cause the sudden misfire, coolant loss, etc we're seeing on these engines.

My point is the reason people assume it has to be something coolant related (IE: The Oil Cooler) causing the head gasket to fail is because that's everyone assumes an engine has to overheat to blow a head gasket.
The reality is most head gasket failures in engines have NOTHING to do with over heating.

This makes a ton of sense and I have seen this play out, although didn't realize it at the time.

However, what explains the slow coolant losses we have seen prior to the misfire?

 

[Classic Owner]

This makes a ton of sense and I have seen this play out, although didn't realize it at the time.

However, what explains the slow coolant losses we have seen prior to the misfire?

The HG that slowly begins leaking into the cylinder as it lets go. It won't cause a misfire until the amount leaking is enough it can't be easily "burned" by combustion.

The HG "blowing" slowly due to excess pressures from minor misfires due to bad plugs seems to point towards something like this even more. That's why there's the slowly increasing coolant use as the gasket is slowly blown more and more as the engine keeps mildly misfiring while being driven. Then eventually it reaches a point where it blows enough that enough coolant gets in to cause the misfire code as combustion can no longer happen.

 

[Jerky_san]

Just to ask.. if replacing just the heads is like 4-5k why would you not just get a new long block for like 6k? Honestly wouldn't that be easier all around? Like I'm not saying this would fit our vans but the below is 5.7k. surely it would be more worth it?

2011 ~ 2019 - 3.6L Long Block Engine Assembly (New) - 68426944AADefault Title

This is a long block engine assembly. It comes with the 3 year/100,000 mile warranty. There is a $600 core charge in addition to the cost with this engine also that is refunded upon the return of the core engine.

www.moparaccessorygiant.com

 

[M0Par]

The HG that slowly begins leaking into the cylinder as it lets go. It won't cause a misfire until the amount leaking is enough it can't be easily "burned" by combustion.

The HG "blowing" slowly due to excess pressures from minor misfires due to bad plugs seems to point towards something like this even more. That's why there's the slowly increasing coolant use as the gasket is slowly blown more and more as the engine keeps mildly misfiring while being driven. Then eventually it reaches a point where it blows enough that enough coolant gets in to cause the misfire code as combustion can no longer happen.

Thanks for that explanation.

Just to ask.. if replacing just the heads is like 4-5k why would you not just get a new long block for like 6k? Honestly wouldn't that be easier all around? Like I'm not saying this would fit our vans but the below is 5.7k. surely it would be more worth it?

2011 ~ 2019 - 3.6L Long Block Engine Assembly (New) - 68426944AADefault Title

This is a long block engine assembly. It comes with the 3 year/100,000 mile warranty. There is a $600 core charge in addition to the cost with this engine also that is refunded upon the return of the core engine.

www.moparaccessorygiant.com

That's a good question and is purely related to cost benefit analysis.

That is 6k for the part alone. Another 4k for labor. You're looking at the difference between 4-5k compared to 10k+ for an entire engine.

 

[Jerky_san]

That's a good question and is purely related to cost benefit analysis.

That is 6k for the part alone. Another 4k for labor. You're looking at the difference between 4-5k compared to 10k+ for an entire engine.

Honestly I was assuming it wouldn't be super high for labor since they'd be pulling and installing.. but yeah guess if it's another 4k for labor yeah.. hosed on the price.

 

[Mexglx]

IF it's a coolant related issue, the dash will light up like a christmas tree and it will get shutdown. This isn't generally enough time to blow a head gasket on an engine.

I will offer another possible explanation that does not require warning lights to get triggered. The oil cooler is cooled by coolant. When it cracks the coolant leaks out slowly onto the hot block and evaporates the water. Some folks notice the sweet smell of coolant in the morning when the coolant that leaked out when the engine was cool starts to boil off. Most people do not check their coolant level. When is goes down enough, I believe it could cause air bubbles/pockets to get into the coolant passages. If one of these air pockets form near the head to block interface then the gasket superheats momentarily until the bubble passes. Repeatedly this could damage the HG. I bring this up becuase when I worked at Cummins, we had EGR cooler failures (air to Coolant) where if the coolant pressure wasn holding 15psi, the coolant going through the EGR cooler would flash boil. Imagine water drops on a hot skillet. Air gets in, the hot exhaust super heats the EGR cooler, the coolant side boils and is no longer touching the tubes in the cooler. There is a gap between the coolant and the egr gas tubes. The tubes get super heated, they lose their solder(brazing) then leak coolant into the EGR gas side of the cooler. Its a similar failure mode. Coolant leak= coolant pressure loss=air can enter the system. No lights get triggered or alarms until the other symptoms, misfires, hg failure, large coolant loss occur. We won know unless someone at Chysler volunteers the information if they ever figure it out. Keep in mind that the failure rate is probably so low that it's cheaper to let it keep happening and just pay for it under warranty or goodwill a little to first owners out of warranty. Thatś what we did at Cummins. We spent years trying to figure out why EGR coolers failed all the time. They even had BS warranty repair procedures like using an off the shelf radiator stop leak product that used cellulose fibers (paper) in it to plg egr cooler leaks long enough to get them out of warranty or until a better solution could be found.

 

[M0Par]

I will offer another possible explanation that does not require warning lights to get triggered. The oil cooler is cooled by coolant. When it cracks the coolant leaks out slowly onto the hot block and evaporates the water. Some folks notice the sweet smell of coolant in the morning when the coolant that leaked out when the engine was cool starts to boil off. Most people do not check their coolant level. When is goes down enough, I believe it could cause air bubbles/pockets to get into the coolant passages. If one of these air pockets form near the head to block interface then the gasket superheats momentarily until the bubble passes. Repeatedly this could damage the HG. I bring this up becuase when I worked at Cummins, we had EGR cooler failures (air to Coolant) where if the coolant pressure wasn holding 15psi, the coolant going through the EGR cooler would flash boil. Imagine water drops on a hot skillet. Air gets in, the hot exhaust super heats the EGR cooler, the coolant side boils and is no longer touching the tubes in the cooler. There is a gap between the coolant and the egr gas tubes. The tubes get super heated, they lose their solder(brazing) then leak coolant into the EGR gas side of the cooler. Its a similar failure mode. Coolant leak= coolant pressure loss=air can enter the system. No lights get triggered or alarms until the other symptoms, misfires, hg failure, large coolant loss occur. We won know unless someone at Chysler volunteers the information if they ever figure it out. Keep in mind that the failure rate is probably so low that it's cheaper to let it keep happening and just pay for it under warranty or goodwill a little to first owners out of warranty. Thatś what we did at Cummins. We spent years trying to figure out why EGR coolers failed all the time. They even had BS warranty repair procedures like using an off the shelf radiator stop leak product that used cellulose fibers (paper) in it to plg egr cooler leaks long enough to get them out of warranty or until a better solution could be found.

Interesting experiential information. Could be more than one cause and this is also plausible.

 

[Mexglx]

It wouldn't unless all the coolant magically leaked out without anyone noticing.
Problem is, coolers don't usually leak coolant anyway. Usually they crack and leak oil.

Either way, cooler leaks are generally caught long before anything overheats anyway.

All the coolant does not have to leak out. Your premise is wrong. Coolant can leak out of the oil cooler. If coolant gets out, pressure is lost, air can get it. If there is pressure loss, boiling point is reached sooner. Leaks can occur either internally or externally. There are reports of coolant in the oil (milky oil) and coolant smell at start up. Here is an excellent video showing the external leak failure mode. Go to minute 5:30.

It is not accurate to say A) the won´t leak externally and B) All the coolant has to leak out and it would be caught by all the hyper vigilant maintenance Pacifica owners all do. It can and does happen. There may be many weak links in the chain. Maybe anyone of those links can start the chain of events for a h.gasket failure.

When the engine company I worked for was having EGR cooler failures (air to coolant) they tried MANY different fixes. They had huge resources to resolve the issue and still took years of work to resolve. Many times they went after a symptom and issued a repair part or procedure only to find out they didn´t get the root cause or there were other weak links they missed. In the end EGR coolers still fail but they were able to reduce the failure rate tremendously and now just live with it and pay under warranty and don´t when its out of warranty. Extended warranty on the semi truck market is just a cost of doing business. The trade-in every 5 years for the major fleets.

 

[Mexglx]

The HG that slowly begins leaking into the cylinder as it lets go. It won't cause a misfire until the amount leaking is enough it can't be easily "burned" by combustion.

What? What about combustion pressure? What about plug fouling? What about combustion gases in the coolant circuit. It´s not just the volume of coolant that gets in a cylinder putting out the fire. Loss of seal means pressure is lost in the chamber too and you don´t have a complete combustion event. Coolant additives can accumulate on the spark plug and foul it making a colder or late spark. It´s not just about a cylinder full of coolant putting out the fire.

 

[Classic Owner]

What? What about combustion pressure? What about plug fouling? What about combustion gases in the coolant circuit. It´s not just the volume of coolant that gets in a cylinder putting out the fire. Loss of seal means pressure is lost in the chamber too and you don´t have a complete combustion event. Coolant additives can accumulate on the spark plug and foul it making a colder or late spark. It´s not just about a cylinder full of coolant putting out the fire.

Tell me you don't know how hydro-locking works without telling me.....

 

[Classic Owner]

I will offer another possible explanation that does not require warning lights to get triggered. The oil cooler is cooled by coolant. When it cracks the coolant leaks out slowly onto the hot block and evaporates the water. Some folks notice the sweet smell of coolant in the morning when the coolant that leaked out when the engine was cool starts to boil off. Most people do not check their coolant level. When is goes down enough, I believe it could cause air bubbles/pockets to get into the coolant passages. If one of these air pockets form near the head to block interface then the gasket superheats momentarily until the bubble passes. Repeatedly this could damage the HG. I bring this up becuase when I worked at Cummins, we had EGR cooler failures (air to Coolant) where if the coolant pressure wasn holding 15psi, the coolant going through the EGR cooler would flash boil. Imagine water drops on a hot skillet. Air gets in, the hot exhaust super heats the EGR cooler, the coolant side boils and is no longer touching the tubes in the cooler. There is a gap between the coolant and the egr gas tubes. The tubes get super heated, they lose their solder(brazing) then leak coolant into the EGR gas side of the cooler. Its a similar failure mode. Coolant leak= coolant pressure loss=air can enter the system. No lights get triggered or alarms until the other symptoms, misfires, hg failure, large coolant loss occur. We won know unless someone at Chysler volunteers the information if they ever figure it out. Keep in mind that the failure rate is probably so low that it's cheaper to let it keep happening and just pay for it under warranty or goodwill a little to first owners out of warranty. Thatś what we did at Cummins. We spent years trying to figure out why EGR coolers failed all the time. They even had BS warranty repair procedures like using an off the shelf radiator stop leak product that used cellulose fibers (paper) in it to plg egr cooler leaks long enough to get them out of warranty or until a better solution could be found.

While I understand your theory, this isn't a diesel, nor is it an EGR cooler that has hot exhaust gases pushing through it and into the cooling system when it leaks. EGR coolers leaking cause bubbles because they have hot exhaust pressure pushing through them and usually pressurize the cooling system.

Flash boiling coolant on an oil cooler isn't going to happen, nor can an oil cooler seeping be compared to an EGR cooler.

 

[M0Par]

Tell me you don't know how hydro-locking works without telling me.....

Specifically regarding?

 

[Classic Owner]

Specifically regarding?

If enough coolant is leaking into a cylinder to stop combustion, it will be enough to hydrolock the engine so it won't turn at all.

 

[Mexglx]

Tell me you don't know how hydro-locking works without telling me.....

You sound like a one trick pony. So you say, if it’s not hydrolocked then you don’t have a HGasket failure? You said oil coolers don’t leak externally, I linked to a video showing they can. Don’t confuse symptoms with failure modes. There can be multiple failure modes leading to HGasket failures as well as the HGasket itself failing. We just had an engine with a 100 hours have an oil leak. Dealer Initially thought all four heads or valve covers were leaking oil. Turns out it was the camshaft cover in the valley of our industrial V8. That is super unusual but gaskets can be misinstalled or defective. These are all higher mileage failures on Pacificas not first 5K miles. I’d love to have the failure data to see how many HGasket issues also had a leaking oil cooler leak. While a HGasket leak can fill a cylinder up with coolant, not all Hgasket failures will fill up and hydro lock a cylinder right off the bat.

 

[Mexglx]

While I understand your theory, this isn't a diesel, nor is it an EGR cooler that has hot exhaust gases pushing through it and into the cooling system when it leaks. EGR coolers leaking cause bubbles because they have hot exhaust pressure pushing through them and usually pressurize the cooling system.

Flash boiling coolant on an oil cooler isn't going to happen, nor can an oil cooler seeping be compared to an EGR cooler.

My point is intercoolers can leak externally and internally. You said they don’t. While my example is an exhaust to coolant cooler, if an oil cooler gets cracked and leaks coolant externally, and slowly, an owner may not see the coolant loss, and subsequently damage the head gasket through lower boiling point of coolant from loss of pressure and air pockets may get trapped at the cylinder head to block interface. Repeated occurrences may be a failure mode.