Oil burning motors; possible cause identified?
07-23-2011, 03:07 AM
#1
JK Super Freak
Thread Starter
Oil burning motors; possible cause identified?
Obviously there's been dozens of threads & hundreds of posts her regarding the propensity of a good number of these 3.8L V6 motors to consume large quantities of oil, often leading to dry sumps & spun bearings, and a lot of conjecture as to the root cause; rings installed incorrectly, incorrectly assembled cranks, bad drain-back valves in oil filters causing dry starts, the specified low-viscocity 5W20 oil not being up to the job with loss of film strength resulting in damaged bearing surfaces, etc.
There was a discussion about this on one of the local forums where I am & one of the members, who is a mechanic at one of the Chrysler/Jeep/Dodge dealerships here, chimed in about something I had not heard before. Apparently there was a known quantity of motors produced in '07 & early '08 that, due to a fault in the manufacturing processes at the engine plant, resulted in the blocks being bored & honed incorrectly resulting in one or more cylinders in the block being noticably out-of-round.
He stressed that the fault was limited to a small number of production runs and the number of motors affected would be statistically small compared to the total quantity of these blocks produced, however he has personally seen two of them go through his shop since the JK was introduced here 4 years ago. The symptoms of these motors sounded all too familiar; higher than normal oil consumption from new, gradually getting worse and then suddenly without warning increasing at a geometric rate, resulting in dry sumps from full within a short period of time, leading to oil pump starvation and spun bearings. Apparantly the out-of-round cylinders cause the oil expander rings to become clogged and siezed and the compression rings to wear quickly & unevenly and to usually lose tension & fail at around, wait for it, 50-60K km or 31-37K miles which is the familiar mileage for the infamous "40K mile spun bearing club".
Apparantly the instruction to dealers here from Chrysler is that if the cylinders are found to be out of round when the motors are torn down to investigate high oil consumption then they are to quickly and quietly replace the short block (or entire motor if required) without question (free of charge if the motor is still under warranty, otherwise a small contribution of like $500-$1000 from the customer is requested) and the faulty block & components are to be shipped off to Chrysler without fail. So without trying to sound like a conspiracy theorist, it appears that Chrysler knows that there is a problem and is trying to deal with it as quietly as possible to avoid the spectre of recalls and class actions.
So, any other Jeep mechanics out there have similar experience with finding some of these oil burners to have cylinders out-of-round? It would go a long way to explaining an issue that has affected some members here first hand and had others (like myself) paranoid about premature motor failure and going into a panic every time they hear (or think they hear) a new tick or rattle coming from under the hood.
There was a discussion about this on one of the local forums where I am & one of the members, who is a mechanic at one of the Chrysler/Jeep/Dodge dealerships here, chimed in about something I had not heard before. Apparently there was a known quantity of motors produced in '07 & early '08 that, due to a fault in the manufacturing processes at the engine plant, resulted in the blocks being bored & honed incorrectly resulting in one or more cylinders in the block being noticably out-of-round.
He stressed that the fault was limited to a small number of production runs and the number of motors affected would be statistically small compared to the total quantity of these blocks produced, however he has personally seen two of them go through his shop since the JK was introduced here 4 years ago. The symptoms of these motors sounded all too familiar; higher than normal oil consumption from new, gradually getting worse and then suddenly without warning increasing at a geometric rate, resulting in dry sumps from full within a short period of time, leading to oil pump starvation and spun bearings. Apparantly the out-of-round cylinders cause the oil expander rings to become clogged and siezed and the compression rings to wear quickly & unevenly and to usually lose tension & fail at around, wait for it, 50-60K km or 31-37K miles which is the familiar mileage for the infamous "40K mile spun bearing club".
Apparantly the instruction to dealers here from Chrysler is that if the cylinders are found to be out of round when the motors are torn down to investigate high oil consumption then they are to quickly and quietly replace the short block (or entire motor if required) without question (free of charge if the motor is still under warranty, otherwise a small contribution of like $500-$1000 from the customer is requested) and the faulty block & components are to be shipped off to Chrysler without fail. So without trying to sound like a conspiracy theorist, it appears that Chrysler knows that there is a problem and is trying to deal with it as quietly as possible to avoid the spectre of recalls and class actions.
So, any other Jeep mechanics out there have similar experience with finding some of these oil burners to have cylinders out-of-round? It would go a long way to explaining an issue that has affected some members here first hand and had others (like myself) paranoid about premature motor failure and going into a panic every time they hear (or think they hear) a new tick or rattle coming from under the hood.
Last edited by JKlad; 07-23-2011 at 03:11 AM.
07-23-2011, 05:20 AM
#2
JK Super Freak
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DAM!! Mine was built in January of '08 and I have 27K on it. I don't seem to be consuming any oil though so maybe mine was not one of the bad runs. lol
07-23-2011, 06:00 AM
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Originally Posted by JKlad
Obviously there's been dozens of threads & hundreds of posts her regarding the propensity of a good number of these 3.8L V6 motors to consume large quantities of oil, often leading to dry sumps & spun bearings, and a lot of conjecture as to the root cause; rings installed incorrectly, incorrectly assembled cranks, bad drain-back valves in oil filters causing dry starts, the specified low-viscocity 5W20 oil not being up to the job with loss of film strength resulting in damaged bearing surfaces, etc.
There was a discussion about this on one of the local forums where I am & one of the members, who is a mechanic at one of the Chrysler/Jeep/Dodge dealerships here, chimed in about something I had not heard before. Apparently there was a known quantity of motors produced in '07 & early '08 that, due to a fault in the manufacturing processes at the engine plant, resulted in the blocks being bored & honed incorrectly resulting in one or more cylinders in the block being noticably out-of-round.
He stressed that the fault was limited to a small number of production runs and the number of motors affected would be statistically small compared to the total quantity of these blocks produced, however he has personally seen two of them go through his shop since the JK was introduced here 4 years ago. The symptoms of these motors sounded all too familiar; higher than normal oil consumption from new, gradually getting worse and then suddenly without warning increasing at a geometric rate, resulting in dry sumps from full within a short period of time, leading to oil pump starvation and spun bearings. Apparantly the out-of-round cylinders cause the oil expander rings to become clogged and siezed and the compression rings to wear quickly & unevenly and to usually lose tension & fail at around, wait for it, 50-60K km or 31-37K miles which is the familiar mileage for the infamous "40K mile spun bearing club".
Apparantly the instruction to dealers here from Chrysler is that if the cylinders are found to be out of round when the motors are torn down to investigate high oil consumption then they are to quickly and quietly replace the short block (or entire motor if required) without question (free of charge if the motor is still under warranty, otherwise a small contribution of like $500-$1000 from the customer is requested) and the faulty block & components are to be shipped off to Chrysler without fail. So without trying to sound like a conspiracy theorist, it appears that Chrysler knows that there is a problem and is trying to deal with it as quietly as possible to avoid the spectre of recalls and class actions.
So, any other Jeep mechanics out there have similar experience with finding some of these oil burners to have cylinders out-of-round? It would go a long way to explaining an issue that has affected some members here first hand and had others (like myself) paranoid about premature motor failure and going into a panic every time they hear (or think they hear) a new tick or rattle coming from under the hood.
There was a discussion about this on one of the local forums where I am & one of the members, who is a mechanic at one of the Chrysler/Jeep/Dodge dealerships here, chimed in about something I had not heard before. Apparently there was a known quantity of motors produced in '07 & early '08 that, due to a fault in the manufacturing processes at the engine plant, resulted in the blocks being bored & honed incorrectly resulting in one or more cylinders in the block being noticably out-of-round.
He stressed that the fault was limited to a small number of production runs and the number of motors affected would be statistically small compared to the total quantity of these blocks produced, however he has personally seen two of them go through his shop since the JK was introduced here 4 years ago. The symptoms of these motors sounded all too familiar; higher than normal oil consumption from new, gradually getting worse and then suddenly without warning increasing at a geometric rate, resulting in dry sumps from full within a short period of time, leading to oil pump starvation and spun bearings. Apparantly the out-of-round cylinders cause the oil expander rings to become clogged and siezed and the compression rings to wear quickly & unevenly and to usually lose tension & fail at around, wait for it, 50-60K km or 31-37K miles which is the familiar mileage for the infamous "40K mile spun bearing club".
Apparantly the instruction to dealers here from Chrysler is that if the cylinders are found to be out of round when the motors are torn down to investigate high oil consumption then they are to quickly and quietly replace the short block (or entire motor if required) without question (free of charge if the motor is still under warranty, otherwise a small contribution of like $500-$1000 from the customer is requested) and the faulty block & components are to be shipped off to Chrysler without fail. So without trying to sound like a conspiracy theorist, it appears that Chrysler knows that there is a problem and is trying to deal with it as quietly as possible to avoid the spectre of recalls and class actions.
So, any other Jeep mechanics out there have similar experience with finding some of these oil burners to have cylinders out-of-round? It would go a long way to explaining an issue that has affected some members here first hand and had others (like myself) paranoid about premature motor failure and going into a panic every time they hear (or think they hear) a new tick or rattle coming from under the hood.
07-23-2011, 04:42 PM
#7
JK Super Freak
Thread Starter
As an addition to my original post, it just occured to me that many people who have had the rings replaced on oil burning motors but have had no other work done on the block (ie: re-boring/honing, replacing the entire short block, etc) have reported that the high oil consumption returns shortly afterwards (often within 5-10K miles). I guess if the cyliders were out of round in the first place then new rings would only mask the problem for a while before it returned.
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07-23-2011, 05:18 PM
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i have no doubt that chrysler knows they have a bunch of fucked up motors out there. My local dealer is also well aware of the problems with the 3.8 they have had to swap a few short blocks. THat dealer is testing a few jeeps with 5-30 weight oil to see how they do.
My jeep was builit real early in 08 and around 40k i noticed i was starting to loose more and more oil between oil changes. The last one i used almost 3 quarts in 3k miles. Brought into dealer to have the PVC valve replaced. After only a thousand miles no oil loss. So guess im one of the lucky ones with the PCV fix.
My jeep was builit real early in 08 and around 40k i noticed i was starting to loose more and more oil between oil changes. The last one i used almost 3 quarts in 3k miles. Brought into dealer to have the PVC valve replaced. After only a thousand miles no oil loss. So guess im one of the lucky ones with the PCV fix.
07-23-2011, 07:25 PM
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JK Enthusiast
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I must have gotten one of the good motors. Haven't used a lick of oil for 75550 miles. But for the trans is another story. Good luck with the engine.!
