Wrangler 392 Blown Head Gasket

[Ron392]

So the work has started, keep you’ll posted. Thank you for your feedback.

 

[Ron392]

It’s been determined both heads our warped, what do you think could’ve caused this? I asked if there was a thermostat failure but that hasn’t been ruled out yet. Could a cold air intake system contributed to this?

 

[stumblinhorse]

It’s been determined both heads our warped, what do you think could’ve caused this? I asked if there was a thermostat failure but that hasn’t been ruled out yet. Could a cold air intake system contributed to this?

No, overheating caused it. Block warped?

 

[Ron392]

No, overheating caused it. Block warped?

He said,
So, It has been determined, both heads are warped ..needs new heads

 

[stumblinhorse]

He said,
So, It has been determined, both heads are warped ..needs new heads

Not sure what that means. I would definitely have them check the block. Usually warped heads means warped block. Get the deck measurement from them to ensure it is still flat.

 

[Fast-n-Furious]

Wondering how did the dealer tech diagnose it’s the head gasket blown even before opening the engine? I find this video very educational:

 

[Ron392]

Not sure what that means. I would definitely have them check the block. Usually warped heads means warped block. Get the deck measurement from them to ensure it is still flat.

Nor do I, but I appreciate your direction. If the block is warped, then do they have to replace the entire motor or will they try to repair it? Obviously I’d prefer it to be replaced.

 

[Ron392]

Wondering how did the dealer tech diagnose it’s the head gasket blown even before opening the engine? I find this video very educational:

They did open the motor, please see my earlier photos. Thank you

 

[Fast-n-Furious]

They did open the motor, please see my earlier photos. Thank you

I saw all. What made them decide to open the motor rather than just fixing the leaking coolant overflow reservoir? That really what I wanted to know.

 

[Ron392]

I saw all. What made them decide to open the motor rather than just fixing the leaking coolant overflow reservoir? That really what I wanted to know.

They inspected the overflow reservoir and they haven’t determined that it is defective yet. But what I do know is they pressure tested the engine and it was not holding pressure. They then where going to replace the blown gasket. Upon disassembling the motor it was determined that both heads where warped. That was all done Thursday, he said they where going to attempt to locate both heads tomorrow. I am going to inquire about the warped engine block. I hope this helps, Thanks for your inquiry.

 

[stumblinhorse]

Nor do I, but I appreciate your direction. If the block is warped, then do they have to replace the entire motor or will they try to repair it? Obviously I’d prefer it to be replaced.

They will do a long block, which is pretty much full replacement. Stellantis spec says not to shave the block, they replace it.

if they mentioned the cold air intake to you as a cause, they are trying to figure out how to void your warranty…. Be careful with what you say if that is the case.

 

[Ron392]

They will do a long block, which is pretty much full replacement. Stellantis spec says not to shave the block, they replace it.

if they mentioned the cold air intake to you as a cause, they are trying to figure out how to void your warranty…. Be careful with what you say if that is the case.

Thank you for the information. You and others have been very informative. Do you think the cold air system, K&N 63-1588 could have contributed to the engine overheating? If so obviously I would want to uninstall it. Thank you

 

[Turboencabulator]

Thank you for the information. You and others have been very informative. Do you think the cold air system, K&N 63-1588 could have contributed to the engine overheating? If so obviously I would want to uninstall it. Thank you

It sounds like there was a failure of the head gasket in-between the cylinder and a coolant passage that pressurized the coolant and caused it to bubble and overflow. Your cold air system would not have been a factor (unless there is a secret turbo hidden in there just kidding) But as @stumblinhorse said the may be grasping at straws to figure out how to avoid covering this, but they should know better. This is clearly a manufacture defect covered under the 5-year powertrain warranty and is 100% Jeep’s responsibility. You didn’t tamper with the odometer, or environmental control system so there is no abuse or negligence. It sounds like they are going to replace the aluminum heads, the block is iron and more tolerant of excess heat, but if there is an issue with the block then they will replace the engine (long block). Sorry this happened to you, but I’m sure you will be back on the trail in no time.

 

[stumblinhorse]

It sounds like there was a failure of the head gasket in-between the cylinder and a coolant passage that pressurized the coolant and caused it to bubble and overflow. Your cold air system would not have been a factor (unless there is a secret turbo hidden in there just kidding) But as @stumblinhorse said the may be grasping at straws to figure out how to avoid covering this, but they should know better. This is clearly a manufacture defect covered under the 5-year powertrain warranty and is 100% Jeep’s responsibility. You didn’t tamper with the odometer, or environmental control system so there is no abuse or negligence. It sounds like they are going to replace the aluminum heads, the block is iron and more tolerant of excess heat, but if there is an issue with the block then they will replace the engine (long block). Sorry this happened to you, but I’m sure you will be back on the trail in no time.

If the head is warped, this failure was caused by heat. when that happens the blocks usually do also warp. I have seen a 5.7 hemi that over heated and 1 head and the block warped and was replaced.

 

[Ron392]

It sounds like there was a failure of the head gasket in-between the cylinder and a coolant passage that pressurized the coolant and caused it to bubble and overflow. Your cold air system would not have been a factor (unless there is a secret turbo hidden in there just kidding) But as @stumblinhorse said the may be grasping at straws to figure out how to avoid covering this, but they should know better. This is clearly a manufacture defect covered under the 5-year powertrain warranty and is 100% Jeep’s responsibility. You didn’t tamper with the odometer, or environmental control system so there is no abuse or negligence. It sounds like they are going to replace the aluminum heads, the block is iron and more tolerant of excess heat, but if there is an issue with the block then they will replace the engine (long block). Sorry this happened to you, but I’m sure you will be back on the trail in no time.

Thank you as well for your detailed response. What your describing is very logical & makes perfect sense. The dealer has confirmed that the block is good & that the repair is covered under my vehicles warranty. Do you think if the gasket & headers our replaced that this should completely resolve the issue? Also could this happen again or is it maybe just a one off? The reason I mentioned the cold air system is because the factory intake system takes air channeled through the hydro-guide only. The aftermarket k&n system takes air in two ways. Both through the hydro-guide & under the hood beneath the mesh grill of the cold air system. I’m just curious if this could effect the engine, since it’s theoretically consuming hot air & possibly effecting the engines ability to keep cool. Please see highlighted area on picture.

 

[Ron392]

If the head is warped, this failure was caused by heat. when that happens the blocks usually do also warp. I have seen a 5.7 hemi that over heated and 1 head and the block warped and was replaced.

Fortunately my engine block is OK, according to the dealer. I’ve been fortunate to be working with a great Jeep dealership and the service manager keeps me well informed. Praying that the truck is repaired soon and done right the first time.

 

[Turboencabulator]

Thank you as well for your detailed response. What your describing is very logical & makes perfect sense. The dealer has confirmed that the block is good & that the repair is covered under my vehicles warranty. Do you think if the gasket & headers our replaced that this should completely resolve the issue? Also could this happen again or is it maybe just a one off? The reason I mentioned the cold air system is because the factory intake system takes air channeled through the hydro-guide only. The aftermarket k&n system takes air in two ways. Both through the hydro-guide & under the hood beneath the mesh grill of the cold air system. I’m just curious if this could effect the engine, since it’s theoretically consuming hot air & possibly effecting the engines ability to keep cool. Please see highlighted area on picture.

Glad to hear that it worked out. I think once they fix the gasket and headers and deal with the coolent/oil you should be all good.

As far as the K&N system I don't know much about it, but pulling air from the engine compartment should not effect the engine's ability to keep the block/heads cool. In fact the factory hydro-guide is actually designed to pull air from under the hood if the primary intake (hood scoop) becomes blocked (see pic below). But pulling hot air from under the hood is far from ideal. Air density is very highly dependent on air temperature. A V8 engine is basically just a big old air pump, the more cold, clean ram air you can feed it the more power that air pump will produce. If that K&N system can effectively utilize all that cold air feed, then supplement as needed with warmer engine compartment air then it's a nice improvement. Personally, I'm just rolling the stock hydro-guide, as my daily driver I think it's a good balance between performance and git-R-done capability.

 

[Ron392]

Glad to hear that it worked out. I think once they fix the gasket and headers and deal with the coolent/oil you should be all good.

As far as the K&N system I don't know much about it, but pulling air from the engine compartment should not effect the engine's ability to keep the block/heads cool. In fact the factory hydro-guide is actually designed to pull air from under the hood if the primary intake (hood scoop) becomes blocked (see pic below). But pulling hot air from under the hood is far from ideal. Air density is very highly dependent on air temperature. A V8 engine is basically just a big old air pump, the more cold, clean ram air you can feed it the more power that air pump will produce. If that K&N system can effectively utilize all that cold air feed, then supplement as needed with warmer engine compartment air then it's a nice improvement. Personally, I'm just rolling the stock hydro-guide, as my daily driver I think it's a good balance between performance and git-R-done capability.
View attachment 25935

I appreciate your response. Luckily the dealer was able to get the gasket & headers quickly. I was told it should be ready next week. As for the intake system your detailed response has shined some light upon the advantages vs disadvantages. Granted the K&N air intake system allows more air through, with a stated horsepower gain of 27 & 35ft. lbs of torque. But like you mentioned it is pulling hot air from under the hood to do so! By installing this system I went from a factory Installed air system with a pleated filter to an after market system that is subpar just to gain some potential horse power. The aftermarket K&N system draws air from both inside and outside the hood. I’d say the oem factory intake system is more of a cold air system then the aftermarket system as air is mostly channeled through the hydro-guide only. I will be removing & reinstalling the oem system.

 

[Turboencabulator]

Luckily the dealer was able to get the gasket & headers quickly. I was told it should be ready next week.

That’s great news!
This whole discussion of intakes led me down the rabbit hole of aftermarket intakes. So just to help myself visualize the impact of air temperature on engine performance here is a graph of that relationship. (I kept it in freedom units )

If the engine compartment runs a 100° F warmer than the ambient outside air temperature (keep in mind folks cook food in there “Car-B-Que” style) on a nice fall day like today I calculate a 17% loss in intake air density. That’s going to have an impact on a naturally aspirated engine like the 392. I’m not sure if the increased airflow of a aftermarket intake would make up for this, but I would reckon things like port polishing are probably more effective than increasing the air filter flow. Also I was thinking if I had just added a fancy new aftermarket airflow setup in my garage the first thing I’d do is take it to a quiet road and gun-it. But that’s with an engine bay that hasn't fully heated up yet so my performance might be better then than in say 30-min when it’s a lot hotter in there. Kinda like running ball bearings without oil, good performance in the beginning, bad results in the end. Anyhow like you I’ve talked myself out of a K&N intake for my Jeep.

 

[Ron392]

If the engine compartment runs a 100° F warmer than the ambient outside air temperature (keep in mind folks cook food in there “Car-B-Que” style) on a nice fall day like today I calculate a 17% loss in intake air density. That’s going to have an impact on a naturally aspirated engine like the 392. I’m not sure if the increased airflow of a aftermarket intake would make up for this, but I would reckon things like port polishing are probably more effective than increasing the air filter flow. Also I was thinking if I had just added a fancy new aftermarket airflow setup in my garage the first thing I’d do is take it to a quiet road and gun-it. But that’s with an engine bay that hasn't fully heated up yet so my performance might be better then than in say 30-min when it’s a lot hotter in there. Kinda like running ball bearings without oil, good performance in the beginning, bad results in the end. Anyhow like you I’ve talked myself out of a K&N intake for my Jeep.

Wow, I appreciate your research, Thank you! Look what’s available now on K&N’s website. An actual drop in high performance air filter, 33-5127. This is an actual game changer folks, this will allow you to keep your factory box & utilize your hydro-glide as it was designed, to pass cold air. I just ordered a filter for myself, hopefully K&N will do the right thing and allow me to send back the previous air intake system I bought, I’ll keep you’ll posted.

www.knfilters.com/33-5127-replacement-air-filter