skisailbike

It was purchased from a small dealership in Utah, where the owner's wife had driven it for about 6 months. I looked it over very closely, and it had obviously been well cared for. (I actually waited at the dealership while they called her and asked her to bring it by for me to look at it.)

baconrocket

Catastrophic engine failure is unacceptable at that mileage. Kinda confused on the spun bearing/crashed valves thing. It's possible the bolts retaining the bottom bearing surface of the con rod failed?

JKlad

Yeah, that's what I was thinking, that or a dropping valve seat. From what I understand, there are two types of bearing caps fitted to the JK's 3.8L V6 which have different bolts for each type. Apparently these two different types of bearing caps can be fitted in combination to the same crank, but they must have the correct bolts as they are not interchangeable with each other.

The common cause for a spun bearing on the JK's V6 is the motor burning excess quantities of oil due to bad rings and eventually emptying the sump leading to oil starvation to the pump & resultant loss of oil pressure to the bearings. However there have been a lot of "spun bearing" JK motor failures where there were no lubrication issues whatsoever (spun bearings result when the oil film on the bearing surface is broken due to a disruption in the oil supply to the oil galleries, causing the bearing to catch and spin in its shell, leading to rapid wear & destruction). I suspect one of those drunk/stoned workers has been using the wrong bolts on the bearing caps leading to the bolt loosening and either breaking causing sudden catastrophic engine failure as the rod lets go, or causing the bearing's shape to deform & then rapidly destroy itself. These bearings no longer have lead in them so are not as strong & resistant to wear as they once were.

deconstructionist

its actually unacceptable at any milage.... but its an unfortunate fact of life too. But that being said failure can come at anytime. there is 10000000000% NO gurueeentee that a 5 minute old motor aint gonna blow up on the next start up than a 50 year old one properly taken care of aint gonna do the same: somewhere between operator error (orignal engine builder or end user) and structural defect, excessive wear, etc. all come into play and act whenever they hit that magic moment......

I had a BRAND spanking new transmission (non jeep and non-rebuild) go out after only 200 miles-- and it was truly catastrophic-- blowing a chunk on the side, welding the planetary gearset into a blob and threw fluid 30 YARDS in one direction and 10 in the other. Ol' Amco guy I first took it too gave me the sleil 'most people think its worse than it actually is...." I reminded him he said that when he tore it down
I had to actuallyeat the cost as I had also had a new rebuilt motor put in at 40 miles on the new transmission-- both shops pointing fingers at each other an no one wanting to do anything...........

Have 50 more stories from friends and family-- all the same: failure comes when it comes.

Nevertheless this OP's got lucky with the claim and I'm glad they're taking care of him.

Wgrin

Just horrible, that's something I hope I don't have to deal with.

skisailbike

Dealer finished the repair today. Unfortunately, I'm at work in Alaska until next Friday, so it sits at the dealer for another week. Cause of the failure was a broken gear on the oil pump, and loss of pressure. Not sure why the low pressure light didn't come on? Curious...

skibum

Simple really.........as a friend in the industry once told me, those idiot lights are set to go off at such a low pressure that they might as well be called a "your motor just blew up" light.

jpms

Why idiot lights are too late,, I am a SBC guy, yea boo me, but I have built over a 100 of them, anyway a SBC at idle can lube at 10psi, so an idiot light at 10 psi is installed, so what happens when (rule of thumb 10psi per 1000rpms), at 2000rpms requiring minimum 20psi drops to 11psi, no idiot light yet, but the engine is loosing its lube requirements, engine parts getting hot, then bearing goes, engine go boom, and no idiot light. hummmm.....
After typing this, I feel like I need to install an oil pressure gauge now. I scared myself, anyone got good pics for locations of added gauges?????

JKlad

Very interesting! One of the guys on my local forum had a spun bearing (in his case the motor made all the typical knocking sounds prior to a rod letting go) even though the motor wasn't using any oil or showing any other impending signs of catastrophic failure prior to suddenly imploding. The sump was full to the brim with oil, however upon teardown of the motor the mechanics found all the moving components (crank, cam, bearings, rings, valvetrain, etc) to be bone dry. The cause of this was apparantly a failed oil pump too (he didn't state whether it was a broken tooth). The last I heard he was still fighting his case with Chrysler.

So I wonder if there's a batch of bad Chinese oil pumps out there ticking away like time bombs? Chrysler used to make most of its motor components (exhaust manifolds, pistons & cranks, water pumps, oil pumps, etc) in-house at the Trenton engine plant prior to the Daimler takeover 12 or so years ago, when they then closed down the parts production section at the plant and started outsourcing most of the components other than the blocks & heads. Suddenly the 3.8L V6, which previously had a reputation of a reliable workhorse with an excellent record of being able to withstand abuse and lack of proper maintainance in its minivan applications, became notorious for cracked exhaust manifolds, seeping timing covers, noisey valvetrains, early failure of water pumps, excessive oil consumption and spun bearings.

TINMAN080

the 3.8 is only ''notorious'' to those who have had issues. the other 88% on the forum have had good luck with it. So far (knock on wood) I've got 65,000 miles, no issues. Almost all my mileage is a 75mph commute one hour each way to work.