christi

The bearing on the back of the engine..... can that break easily if you spin the tires often?

That night actually before I woke up that Friday morning to do some errands - a friend and I had gone into an empty parking lot (that Inormally do drifting in...) and we spun the rear-wheels a bit and got some video/picture shots.

Anyway - would spinning the tires a bit cause the back bearing on the engine break?

He had talked to his dad who knows a bit about rotaries, and he mentioned this. I'm wondering if I caused my engine to break by doing that. Though, I've done it a few times before, and never showed signs of something breaking; even though we didn't do it hard, or even more than once that night. A few hours after I had gotten home, I went for a midnight snack, and she ran fine going to Walmart and coming home.

I guess I'm just not understanding, or if that's part of the cause.

As soon as I get the 'vert, and hopefully a used/running 13b engine... we'll be tearing down this one and seeing what actually siezed her up.

J-Rat

iTrader: (2)

The only thing that spinning your tires does is get you one step closer to a new set of rubber.

How spinning your tires correlates to an engine bearing failingis beyond me (unless you GROSSLY overrevved). Maybe its just a strange coincedence. Or maybe Kharma is after you... Hit anyones dog lately?

Jarrett

hypntyz7

I can almost guarantee that short of very poor oil change habits, over-revving for a very long period of time such as in race conditions, or oil starvation, bearings in a rotary almost never fail. I have yet to replace a set in a normal rotary engine, even cores with 150k miles appear near new.

I'll tell you what most likely happened to your engine, but first let me go over what happens to most engines when they blow.

You're driving along and everything is fine. When you accelerate or hold a constant speed, the apex seals actually tilt one way. WHen you decelerate, they actually tilt slightly the other way. We all know that stock engines have 3 piece seals...a small triangle piece on one side, and 2 thin, long pieces. The upper piece is what wears. I have seen them worn as low as half of original height. Since the piece is only about 5mm tall when it is new, it can get down to 3mm or less after a 100k miles are put on it.

So what causes blown apex motors? Well, obviously abuse or detonation are factors that can contribute. Aside from that, many of us have been driving along and all at once lose power. Always when shifting gears, or transitioning from acceleration to deceleration. What happens? The top apex piece wears down so thin that finally it tilts and falls right out of it's groove.

But, it doesnt stop there. Since, due to the engine design, the combustion chamber shape varies from very wide to very narrow, this seal breaks into a bunch of pieces. Either right as it falls out of the groove, or on it's trip around the inside of the combustion chamber when it encounters a very tight clearance.

This is how rotors ad rotorhousings get torn up in blown apex motors...the seal wedges against stuff on it's way out. What it wedges against is another tip (where the clearance is the tightest) and thus takes it and the third apex seal out with it. What you wind up with is a fubar rotor and rotorhousing. The pieces are finally pushed out the exhaust. On turbo cars, it is possible for these pieces to hit the turbine or exhaust manifold, and fly back into the *opposing* rotorhousing exhaust port, tearing **** up in there as well. I have seen this a few times. I have also heard of turbos being torn up by apex fragments exiting.

So anyway, this is how 90% of rotaries blow. Then maybe 5% for water seals or misc. problems, and the other 5% or so die like Christi's did. Most people would call it carbon lock. In my experience, it really isnt carbon lock. The same thing that I described above happens upon shutdown or startup as well (think of tilting the apex seal piece when you hit the starter to crank it up, or when you turn off the key and the engine decelerates to stop). Under these **low intertia** situations, the same thing happens to the seal, however the engine doesnt have much momentum built up, so it just locks dead up, adn the seal piece stays at least partially intact and imbeds itself between the rotor and housing. Were the engine running at speed and in gear, it would have broken the tiny seal and threw it out and kept on running. Because you're only dealing with a couple hundred rpms at startup and <750rpm on shutdown, the engine locks up.

Now, Im not saying there is no such thing as carbon lock. I will say that I have only seen one or 2 real cases of it. IT usually happens when an engine is allowed to sit with no lubricant placed inside the rotorhousings (such as atf, MMO, or 2 cycle) for storage. The carbon on the rotor tips and in the apex grooves actually locks onto the apex seals. Since some are compressed and some are extended (apex seals) that means at least one will stick in the IN position. You also stand a good chance that the ones in the OUT position may stick as well, and this means that the engine will not be able to turn, because the seals won't compress in. Carbon lock motors are the ones that are sometimes saved with atf and working it back and forth.

jacobcartmill

iTrader: (6)

dude landers you are a hardass.