Autopsy of 2.2S, Part Deux - #5 Rod

[KevinG]

Teardown continued through removal of pistons, then came to a stop until I could lay my hands on a star whatchamacallit tool to remove the flywheel bolts. All of the con rods appeared fine - easy movement, no discernable damage - except #5, which seemed to have an extra strong dose of Viagra - stiff to move and stood straight up at attention even when left alone. Since I could, I removed the #5 rod and found this:

The close up shows that the tab on the upper bearing is no longer there - is this what a 'spun bearing' is?

If so, what could be the cause? The con rod bolts were still torqued up - could I have over-torqued them?

Still, this doesn't look like the cause of my problem that led to the teardown - a small handful of thin ferrous metal bits in the oil.

To be continued...

[Ho Hum 74]

Kevin,

Maybe I'm not following you correctly but if the piston has been hitting the valve then I wonder if this abuse was enough to fatigue the tang off the bearing. Are your bearings showing copper or is that the lighting?
What was your oil pressure like?

Tristan

[KevinG]

Tristan -

The exhaust valves on cyl #'s 1&2 were making contact - the rod bearing here is from cyl #5.

Yes - the bearing is showing copper all around, it's not a trick of the light unfortunately. Crank journal looks good, but I'm not looking forward to the machinist's evaluation.

[Ho Hum 74]

Kevin,

I think the bearings can show copper fairly quickly and this isn't too bad. What's bad if, like me, you find some pretty copper flakes sitting in the screen under the oil pump. That means that the copper is giving way to a steel backing (also shows up on magnetic drain plugs). My pistons were not hitting my valves but I had lowish oil pressure and eventually my piston started to make a loud noise as the big end was hitting the crank journal. I had a LOT of play in that #3 bearing. Not sure how it got that way - I only had the car 6 months!

Good luck

Tristan

[konish]

Kevin,
That bearing looks more than just worn down....it looks like it has had some heat damage too, as if the bearing went dry and thats what spun it which in turn led to the scorching. There was a recent thread about overly stiff rods (that just sounds bad) but I can't seem to find it. I do remember there was some binding of a rod that kept it from spinning as freely after the case was reassembled. From what I remember there was some suggestion that the case (not having been align bored) may have been the issue when it was put back together and torqued. Perhaps, although I'm not sure of the likelihood of the 2.2 case being warped, yours needed to be align bored as well...assuming it wasn't done on your initial rebuild. This may explain why the cam timing affected only 2 of the three cyls on that side. Just food for thought...

R/
Dustin

[konish]

Kevin,
Nevermind...I'm an idiot. The warped case should only effect main bearing binding instead of the rod bearings. Did you have your rods reconditioned when you rebuilt last?

R/
Dustin

[KevinG]

Thanks, Dustin

Yep - rods were reconditioned. At this point, #5 appears to be the only one with problems. I wonder if the crank lubrication got plugged somehow. Otherwise I have no clue why this one went south.

[Tyson Schmidt]

Detonation at high rpm is likely the cause. It hammers away at the bearing. You're very lucky you caught it this early, or you would've ventilated the case.

What was the deck height on this motor, and what is the C/R, and total ignition advance.

[Ho Hum 74]

Tyson,

What are the obvious signs of detonation that one should look out for? I have a similar failure with my 2.7 9.8:1 compression I believe.

Tristan

[KevinG]

Tyson -
The motor was rebuilt to stock 2.2S specs, using new Mahle nikasil cylinders and JE pistons. I did not measure deck height, mainly 'cause I didn't know I was supposed to. Ignition advance max @28.

[BURN-BROS]

O.K. I will take a shot at it. If the rod bearing wasn't seated properly or trash was in between the rod and the bearing surface it would not effectively transmit heat away. Was the bearing clearance to spec when the motor was assembled?

Sorry this happened to you Kevin, I hope it didn't set you back too much. I love the 2.2S, good choice.

Aaron

[Wayne 962]

Looks like an oil starvation problem on this bearing to me...

Even extreme detonation shouldn't cause that type of uniform damage.

-Wayne

[KevinG]

Update:

Got the case dis-assembled this weekend. Add rod bearing #2 to the list - this one was really, really bad and it was pieces from it that were captured by the sump screen. No pics yet, but the bearing shells were pounded to crapola. Rod was still torqued, but was loose on the crank. Remains of bearing were pounded paper thin with ends overlapped on the crank journal. Also, a couple of teeth on the drivers side chain gear on the intermediate shaft were broken, cause unknown at this point. This could have caused a chain slip resulting in the valve to piston contact posted earlier, I just don't know. Time to box up everything for a trip to the machinist's for a real evaluation of the damage.

[Tyson Schmidt]

O.K., if it was #5 and #2, then it sounds like high rpm oil starvation.

[KevinG]

Thanks Tyson - but can you speculate on the cause? I haven't a clue.

[TimT]

but can you speculate on the cause?

yeap

high rpm oil starvation

dont know the engines history,

but a good mod for longevity is cross drilling the crank, and modifying the center bearing.....

[TimT]

This makes sure 2&5 are happily oiled

[Tyson Schmidt]

Originally posted by KevinG
Thanks Tyson - but can you speculate on the cause? I haven't a clue.

Well, what TimT posted would've helped a lot. But my guess is that if you are running MFI on that 2.2S, then it may have been fuel dilution of the oil.

If there wasn't any fuel in the oil, then who knows? Did you update the oil pump and do the bypass mod to the case?

[KevinG]

TimT and Tyson - Thanks for the knowledge. I wish I had known about this board before the last rebuild, it would still be the last rebuild.

Tyson -
Yes, I am running MFI on the motor, but the pump (and TB's) were rebuilt about 1.5 years (5K miles) ago. I am assuming that the fuel leakage into the oil only occurs with older, worn pumps here though. Is that the problem that caused you engine failure a few months back?

And no, I didn't do the oil bypass modification - I didn't know about it then and the machinist didn't mention it either. He may have skipped it because I have the older 'pre 76 pump.

[Tyson Schmidt]

Yes, my motor blew in part from fuel dilution of the oil, and high rpm leanness. The car was running extremely rich at low rpm, and extremely lean at high rpm.



Keep in mind that even a brand new MFI system can dillute the oil with fuel. The problem is that because of the high pressure at the injector nozzles and the resulting excellent atomization of the fuel with MFI, they can run surprizingly well at ridiculously rich air/fuel mixtures. These things will still run decent even at 12% CO, and 1000 to 2500 ppm hydrocarbons. Tuning the MFI for good transitional performance and throttle response makes it feel like it runs fantastic, but can make it too rich at other throttle positions and loads, which is where the car may be spending most of it's time. A carbureted car will not get out of it's own way with these readings and will belch black smoke. So just driving around in a seemingly good running MFI car can dillute the oil with fuel after 1000 miles or so. After 3000 miles, the oil may be compromized enough to cause and engine failure like yours if run hard at high rpm for any lenth of time.