DU mechanics: is it unusual for only 1 of 4 rod bearings to go kaput?

[Lance_Boyle]

This is a 2006 Scion tC with the 2AZ-FE engine. Only 80K miles on the car and now a connecting rod bearing is on its way out. Apparently real soon. I guess we won't know until the damned thing is opened up whether there is undue wear on any of the others, but only cyl#4 is making noise about it. How could only one bearing go bad unless it's a manufacturing defect? And no, there is no warranty coverage. :-(

[HopeHoops]

1. I don't know about unusual, but if a rod flies out of the engine and through the hood, that's bad.

[krispos42]

2. I would think it would be odd for several to coordinate their failures

Rod bearings aren't Wall Street, after all. :P

They aren't related, so having only one go out seems normal enough to me.

I had one go out on my Subie a couple of years ago, 5,000 miles before the warranty ran out. I used synthetic motor oil, and the mechanic at the dealer was puzzled at the failure because the oil was clean and the car only had 55k on it. I got a new engine block out of the deal, which was nice.


Get it fixed ASAP. It's not the kind of thing that can run partially-broken forever, but it IS the kind of thing that can take a lot more parts down with it when it goes.

[Throd]

3. No.

[OffWithTheirHeads]

4. Counterfit Chinese parts? Hey, our military has em!

[EnviroBat]

5. Not really.

A rod bearing lives wrapped around the crankshaft where the piston rod connects to the crankshaft. Within all of this there are small holes where oil flows through the crankshaft to these rod bearings and keeps them floating on a thin layer of oil. What usually happens is that the oil gets really dirty and a oil passage gets blocked, much like an artery in a person. The rod bearing becomes starved for oil and the metal begins grinding against the metal of the crank-shaft. If they open up the engine to change one of them, they should change all of them. Frequent oil changes along with the filter will keep an engine running practically for ever. These bearings don't usually go unless someone has been really beating the crap out of the car, (red-lining it through three gears, dumping the clutch at 5000 rpm, typical things a 17 y.o. does when behind the wheel of a Scion)...

[Lance_Boyle]

6. We've only had the car since 58K miles.

Most likely the PO was a real POS. I have stayed on top of maintenance during my time with the car, but yeah - the tC seems in retrospect like a really bad choice to buy used. Never going car shopping with Veruca Salt again!

[Kali]

7. butting in to draw attention to my post in the auto forum

http://www.democraticunderground.com/discuss/duboard.php?az=view_all&address=310x1554

:D

but I can tell you from experience that no they go in singles

[MicaelS]

8. If you have to change one bearing,

I would suggest you change them all. Also make sure your mechanic checks your front and rear main seals.

[dimbear]

9. To look at them, they seem perfectly simple, but they're designed

to absorb a certain amount of grit and live with it.

You may have had some loose metal or excess dirt circulating in the system.

[Mopar151]

10. Not really that unusual

Could be a minor oil starvation, and the one that is barkin' gets starved first - or a gob of sludge or ??? interfered in the oil feed to that bearing - may even be a broken drill inside an oil passage, or one not completely drilled.
I'd consider a rebuilt/exchange "short block", it get shed of any bad mojo with this engine.


Yes, I know from rod bearings..... http://youtu.be/N7969LV_2ZE