oil system, bearing failure, causes and cures

[RussianVR-4]

is our oil system that bad? i went through 2 built motors, each time bearings got fubared. are our oil pumps not good enough? oil passages too small? what can be done to help prevent spun bearings?

[Feral]

Were these 2 or 4 bolt blocks?

[Budweiser®]

I dont know if you have seen this post by ray, but hes pretty knowledgable with our cars

http://www.3si.org/portal/forums/sho...hreadid=172835

[RussianVR-4]

it was the same 2 bolt motor both times, rebuilt twice.

yes i saw the post, but my oil pan was in perfect condition, no dents at all, and i made sure to clean it damn good

[Feral]

I don't believe I've ever heard of a 4 bolt spinning a bearing ... why not just get a new shortblock?? Your heads will bolt right on and then you needn't worry about spinning your bearings anymore ... as for why the 2 bolt is prone to this in high HP applications ... I am not exactly sure but I do know the crank is different.

[RussianVR-4]

plenty of 4 bolts have spun bearings, and now i just bought a OEM 4 bolt block to drop in. it'll take LOTS of persuasion and facts with experience for me to get another built motor. i'll stick with OEM shortblocks for now

[2Mitsus]

I'd say driving with coolant in your oil (after your head gasket incident) would be enough to destroy yours or any year motor.

And a bad oil pump would also be enough to destroy any motor as well.

I don't know if this thread is meant for your car only, or our cars in general. Ray Pampena's info on that thread is priceless, don't throw that knowledge out the window because your oil pan was okay and because you cleaned yours really well. We already know why your motor crapped out on you.

Not meant as a flame or anything, of course, but the reason your motor crapped out had nothing to do with a 2/4 bolt, cast/forged crank, etc.

[JD-01]

See the post by fastmax (Jim) on this thread.

Over the years I've seen many different theories as to why there are so many spun bearings on the 6G72... ultimately, I think it's a combinations of several factors, including things like the oil pan issue mentioned by Ray in the thread above. At one point I believe someone did a survey to determine which bearings failed (similar to the which piston fails most thread), but I can't find it at the moment.

One of these days I'm going to get around to generating a "common problems with the 3000GT/Stealth" list including everything from bearing failures to the nasty habit of the seat belts failing to retract after age/dirt.

-JD

[Chris GTO TT]

There is Currently a pretty good thread in the General section (not rays) that is discussing some of these concers. If this thread is just about your motor issuse then I know the reason that your motor failed both times, you know the first water in oil. The second spun bearing was a direct result of the first one. Your head gasket blew causing water to enter the oil since water is more dense then oil it sinks to the bottom of the oil pan and since thats were the oil pick up is the oil pump was pumping water...boom first motor dies. But what i think you failed to realize is that oil pumps are not desigened to pump water other wise it would be called a water pump

Now unless i am mistaken the oil pump uses oil to lubercate it self (If I am wrong my whole argument goes out the window here In which case this post will magically disappear) with water in the oil the pump isnt getting proper lubercation causing premature wear on the gears and such, extra wear means sooner failure.

Now back to the issue as a whole for as long as i have been a member here there has always been talk of the pump just being adaquit for the job, or being weak, etc. and that was the cause of the spun bearings. Well thats not being good scientests now is it? Bearing spun, cause of spining is lack of oil, lack of oil was caused by poor pump design. well there are lots more variables and factors then just those. if you follow that train of thought you are making huge leaps of faith based on nothing but assumptions and you all know what happens when you assume I personally agree with ray based on the fact that he is a master mitsu tech, he looks at more then just the 3/S he has one of the fastest cars with some of the least mods. Clearly this guy knows his stuff. Now I am not saying that his explanation is for all spun bearings howerver it makes sence that it explains more then 50% cause most of the cars that have had the problem are of an age that the front motor mount would have been pulled and the jack would have to go under the motor.

It is also Important to understand that the onset of spining doenst occure in normal everyday driving it occures when under extream conditions, Launching, cornering hard at high rpms, etc. you won't normally notice the problem until you shut the car down, let it cool off and then restrart it (this is why all the threads are titled "went out and started my car now it has a loud knock"or something to that effect.

I am babaling and probabally being really general and missing some of info but from my knowledge of motors and what i have read this is what i have gleaned Agree with me or not this is what i believe until some hard facts come bouncing along

[Beast]

My stock 4 bolt engine spun rod
bearing number 4 and welded the bearing
halfs into 1 double wide half bearing. I also
spun the 2 middle main bearings but that may have
been from the vibrations from rod 4?

I think it was because of a failing oil pump. Or
possibly too much detonation...mobil one oil?
unorthodox underdrive pully? my hair was not
parted straight?....the list goes on and on.

Im gonna retire from mobil one oil on my new
motor or rebuilt motor. (goin redline baby!)

I dont know but it would be cool to know what
all work was done to allot of the rebuilt engines
that spun shortly after.