Bearings kill two engines inside a year.. Mechanics clueless

[jeepbeep]

Just went through my second 3.7. All the sudden I hear bearings and it eventually gets to sounding like bearings in a soup can; same as last time. Two different low-mile engines inside a year. Great oil pressure and compression when installed and the engine bay is plastered with nothing but brand new OEM parts and there is a better-than-recommended maintenance cycle. The highest RPM I've had either was around 4,950.

Mechanics have no idea what it is. I don't see what can cause it there is no electronics controlling the oil pump and it's synthetic 5w-30 every time with NAPA Platinum or BOSCH filter.. I've posted Torque logs from this '03 sport before and all was normal with trims etc..


Only constant is a small exhaust leak but both front o2s are normal..
Anyone?

 

[Conundrum2006]

Where did the engines come from? And how long did they sit?

Reason I ask is I had some Toyota Japanese cuts outs that were a huge PITA. Cutout motors are from cars too old to be on Japanese roads legally ( some very strict laws with tax penalties behind them)
The motors are literally cut out of the car then sit for years before being exported. Some times they sit in a container on a dock. I had two of these motors go bad because the bearings on otherwise clean looking motors need to be changed before instillation.

This may have nothing to do with you issue, but how long and where the engine is stored may be a factor.
I've had engine sit on a shelf for years with no problem, so I wouldn't necessarily assume it's a storage issue.


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[jeepbeep]

Where did the engines come from? And how long did they sit?

Reason I ask is I had some Toyota Japanese cuts outs that were a huge PITA. Cutout motors are from cars too old to be on Japanese roads legally ( some very strict laws with tax penalties behind them)
The motors are literally cut out of the car then sit for years before being exported. Some times they sit in a container on a dock. I had two of these motors go bad because the bearings on otherwise clean looking motors need to be changed before instillation.

This may have nothing to do with you issue, but how long and where the engine is stored may be a factor.
I've had engine sit on a shelf for years with no problem, so I wouldn't necessarily assume it's a storage issue.


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Yeah I know a little about what you're talking about. Valve seals and gaskets go bad and something probably happens with main-bearings too like oil pulled by gravity then oxidation or gumming. These are cut-outs but they are recent-cut outs from salvaged cars and they passed basic tests.

Both engines went the same on this liberty. Out of the blue I start hearing the main bearings even though I take exceptionally good care of this '03 sport auto 4x4. I even regularly monitor the system with Torque and collect logs just to try and catch this stuff early but this gets past all PCM and sensor stuff and multiple mechanics are lost.

Engines were both around 140k with warranties out of recent salvage vehicles. From reputable used-engine sources like LKQ and another. Compression and oil pressure and coolant pressure were checked on both, and new water pumps and thermostats and belts and oil and oil filters put on upon install; all Mopar OEM.

From what I've seen there is only the oil pump(which is mechanical and inside the front assembly) and the pickup tube then you have the pressure sensor. There is no electronic influence on oil? My temps have never been so hot as to destroy bearings and my oil is fine I check it often. What else can destroy main bearings besides high RPMs and sitting-decay?

 

[Conundrum2006]

Sounds like you did everything right.
A junk yard will not have a clue if the was a headgasket issue that was repaired before they got the car which is what I'd suspect as lead culprit in eventually killing bearings, but it could just be bad luck.






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[renegade 04]

I would recommend always having a oil pressure gauge in every vehicle. You may have had low oil pressure, but not low enough for the oil pressure switch to get triggered.

 

[tjkj2002]

I would recommend always having a oil pressure gauge in every vehicle. You may have had low oil pressure, but not low enough for the oil pressure switch to get triggered.

The oil pressure light will turn on at 3psi.That is the min oil pressure for the 3.7.

 

[JasonJ]

Hmm not sure on the root cause here, but...

Since when is 140,000 miles considered "low mileage"?

How often are you changing oil? I ask not because I suspect you are going too long on OCI's, but perhaps too often.

I had a friend who changed the oil in his Caprice with a 305 using Mobil 1 5w30; he changed the oil every 1000-1500 miles (he was given a monstrous supply of the oil, new in cases).

Well, I suppose it was all of those dry starts, because he wiped out the brand new oil pump on that engine and subsequently destroyed the main and rod bearings within 6 months (he had recently rebuilt the engine prior to using it as a daily driver). I trust his rebuild skill, he's only done about 30 GM small blocks...

 

[CactusJacked]

What else can destroy main bearings besides high RPMs and sitting-decay?[/b]

Poor maintenance and neglect for one. And high rpm's won't destroy the bearings, unless there is an oil supply issue or if the integrity of the bearings are already marginal. Buying an engine with 140k miles on it is a complete crap shoot, it could die in a week, it could go for years/miles. The engine's life span can mostly depend on how well (or not) the engine was treated for those 140k miles.

 

[jeepbeep]

Yeah I know 140k is potential lemon dirt-lot mileage. I'm a second owner and the previous was a person who basically used it as a toy from the looks of it. It has nasty wiring issues and some scrapes and rotted rocker panels on top of a paint job that makes maco look factory. I paid accordingly but expenses from this problem have killed it's value.

It's strange the same problem has happened twice in such a time frame. It's gotta be another variable and not just chance that I got two engines with worn bearings. They actually both did well for hundreds of miles after install.

Problem is I don't see it. As far as I know the only parts are the pump and the pickup. Unless the sensor port is causing pressure leaks sometime after I get good readings. I do oil changes 5k-7k.

I'm trying marvel mystery oil and thicker oil to try and save this one from the loud clinking stage. Most of the engine is new parts and pressure and temp readings have been good since the install.

 

[JasonJ]

Yeah I know 140k is potential lemon dirt-lot mileage.

...

I do oil changes 5k-7k.

I'm trying marvel mystery oil and thicker oil to try and save this one from the loud clinking stage. Most of the engine is new parts and pressure and temp readings have been good since the install.

5000-7000 miles on a GOOD CONDITION 3.7 is just asking for sludge and oil related trouble, on an engine with 140k, I'd never dream of going that long.

Increasing viscosity with MMO and thicker base oil will quiet it down, but it will not stop bearing wear/damage from occurring.

Why not pull the motor, replace the bad bearings on the crank and rods, flush it out and reassemble.. toss it in and see what happens.

 

[TwoBobsKJ]

5000-7000 miles on a GOOD CONDITION 3.7 is just asking for sludge and oil related trouble, on an engine with 140k, I'd never dream of going that long.

Increasing viscosity with MMO and thicker base oil will quiet it down, but it will not stop bearing wear/damage from occurring.

Why not pull the motor, replace the bad bearings on the crank and rods, flush it out and reassemble.. toss it in and see what happens.

Wait a minute...

5000 - 7000 miles on a 3.7 and it would have sludge problems...?

I installed a 3.7 with just under 9000 miles and you'd never know at the time that it had any miles on it at all when looking at the internals. Only visible wear was mud and the usual dirt on the outside. That engine now has 85,000 miles on it and is quiet as the day I put it in. One member here just retired his KJ with 485,000 miles on it and he never did anything but routine oil changes at 3000 mile OCI's.

Can't say I know why the same problem popped up on the OP's engines but first owners' lack of maintenance is a likely culprit. These engines are somewhat old school - take care of them and they last forever. Ignore them and they'll make you pay for it.

My 2 cents...

Bob

 

[HoosierJeeper]

I think he meant 5000-7000 miles oil change interval on a good condition 3.7 will even cause sludge issues.

 

[CactusJacked]

No, no it won't sludge, because....

...and it's synthetic 5w-30 every time with NAPA Platinum or BOSCH filter..

 

[Conundrum2006]

This might be completely wrong, on the Cherokee 4.0 with AW4 automatic transmission some times the bolts for the torque converter to flexplate backs out and makes a horrible sound.
If it's not the bearings but sounds like it, maybe it's a cause on KJs too.


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[JasonJ]

Wait a minute...

5000 - 7000 miles on a 3.7 and it would have sludge problems...?

I installed a 3.7 with just under 9000 miles and you'd never know at the time that it had any miles on it at all when looking at the internals. Only visible wear was mud and the usual dirt on the outside. That engine now has 85,000 miles on it and is quiet as the day I put it in. One member here just retired his KJ with 485,000 miles on it and he never did anything but routine oil changes at 3000 mile OCI's.

Can't say I know why the same problem popped up on the OP's engines but first owners' lack of maintenance is a likely culprit. These engines are somewhat old school - take care of them and they last forever. Ignore them and they'll make you pay for it.

My 2 cents...

Bob

I think he meant 5000-7000 miles oil change interval on a good condition 3.7 will even cause sludge issues.

Correct, I'm not talking about 5000-7000 miles on the engine, total, but as an OCI. Maybe it won't sludge up only changing the oil every 7000 miles.. but everyone always talks about how sludge prone this engine is, so why take a chance?

Oil is cheap, replacement engines and rebuilds are not. That's just me. I change my oil every 3000-4000 with synthetic blend. So far so good, but I don't think I'd want to double that mileage.

 

[Logan Savage]

This might be completely wrong, on the Cherokee 4.0 with AW4 automatic transmission some times the bolts for the torque converter to flexplate backs out and makes a horrible sound.
If it's not the bearings but sounds like it, maybe it's a cause on KJs too.


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I know someone that thought a rod was knocking in their KJ & started parting it out . When they removed the transmission , they found loose torque converter bolts .

 

[JasonJ]

I know someone that thought a rod was knocking in their KJ & started parting it out . When they removed the transmission , they found loose torque converter bolts .

Well, that would indeed suck.

 

[tjkj2002]

I know someone that thought a rod was knocking in their KJ & started parting it out . When they removed the transmission , they found loose torque converter bolts .

That is a issue for CRD's,many reports from CRD owners from the LOST forum,due to trans repairs and not using loctite on bolts,but never heard of it for a gas KJ before.

 

[Logan Savage]

It was a 2002 3.7 .