please let me know if this sounds logical....

[slideways...]

http://www.magnusmotorsports.com/crankwalktheory.htm


its long and somewhat complex but to me it makes sense...
please i would love to hear more experienced thoughts on this

[91 Eclipse]

thats like a chapter book do you think you could summarize it for us.

[david-b]

That is supposed to be one of the best theorys on crankwalk. Complex. Read again. Or searcha round here.

[slideways...]

sort of a summary(i may have missed something but...)

In the case of the 95 after it gets to the main bearing journal, It is also split up to feed the oil squirters (which cool the underside of the piston in case you don't know at this point)
The 93 blocks do not have this, they are squirting oil through a restrictor in a different location (as seen in the previous photo), from the main oil gallery where there is plenty of oil flow and volume.

So here It was, the oil jet. didn't look like a restrictor, such as is featured on the 1g block, but looking down one end it looked like a check valve, blowing air through it proved it was. Taking it apart answered a few questions.

It is a check valve. A damn small one, and it was filled with crud. After more argument we realized that these things could clog real easy. The point being, not that they get blocked, but that they could very easily get hung open.


The check valve squirter was probably a good idea in some office at Mitsubishi HQ, but it didn't look so hot at J+R HQ. With the squirter relocated to the mains you would not want to be squirting constantly at lower oil pressures, like when the car is at idle. Nor would the bottom of the piston need cooling at idle. But in the same regard the fact that it is so small, it could easily fall victim to contamination and allow the ball not to seat properly. When disassembling engines it is commonplace to find some scratches right at the orifice of the oil feed on the bearing surface, this comes from particles that the oil filter has not caught. Remember if an oil filter gets clogged, some have bypass valves which allow the engine to continue to get oil. You get unfiltered oil, but you still have a motor.
The orifice in the check valve appears to be between .030" and .035", without a needle gauge set we won't know for sure. But is that enough to bleed off enough pressure to cause massive thrust failure? Possibly, but what other major differences are there between the two blocks? We found no other major differences between the 93 and 95 block (90-91 have larger main journals). This could explain why there is no actual way to predict thrust bearing failure, some engines could be dirtier than others.
The 1g blocks use an oil squirter from the main oil gallery where there is always adequate volume and flow. The 2g squirters are taking oil from the main bearing journals which share oil with the mains and connecting rods.


Picture this scenario: A particle has wedged itself between the check ball and seating surface of the squirter, the engine is at idle the clutch is depressed, we are now receiving less oil flow and pressure than the main should be getting. Now keep in mind the only way the thrust bearing is fed oil, is from oil that bleeds past the main bearing looking for an escape, it then flows to the thrust. If that check valve is contaminated and stays open, then you are losing some pressure and flow. Today, a day after I posted these findings, I received an email explaining that, they look very similar to ABS unit check valves, which should be kept clean at all times. Those manufacturers put filters in front of them to avoid this sort of thing.

[kjewer1]

There are many possible causes of crankwalk, for any kind of engine. They suggest only a few of them.