sideways-FC

why would both of my rx7s be geting moister in there crank case? I pull the dip stick out and there is little water drops on the dip stick and my oil caps have some sort of foam in them.

thatman

iTrader: (4)

I noticed that too, mainly from the weather. During the summer though, it went away, and I'm guessing its back again. Being that its colder again, though I hadn't checked recently. Condensation mixing with a little oil does that. I wouldn't be too worried, unless someone says otherwise.

bumpstart

1% water contamination in oil = 50% reduction in shell bearing life
( rule of thumb learned at great expense in industry )

while i dont think it is quite so drastic in reality in our cars.. it is something you shouldnt ignore if that water is building up

mustard under the cap is common enough and is accepted by most
.. i run LPG fuel which has its own dew point issues at start up that the rotary engine is prone to recover and mix into the oil
and thus my mustard issue would be worse than most.. provided i didnt already simplify and fix the crankcase breathing system mazda provided

i use an emulation of the high load path that mazda use,, where air flows through the crank space and then towards the aircleaner and is consumed in engine

however mine draws fresh filtered air , has larger hoses ( 5/16 ) and importantly draws through the lid on the top of the filler neck

it requires you to tap in 5/16 nipple into filler neck and into the top of the cap , requires a one way valve and a rocker cover breather filter as seen on old school piston engines

air flows through the rocker filter, through the one way valve.. through the nipple on the filler neck.. out the nipple on the lid ,, and to the aircleaner

zero.. repeat zero .. lung mustard .. in high moisture conditions.. even on LPG fuel..

GrossPolluter

iTrader: (1)

Didn't know that. My friend competes in Time attack events and has water/meth injection and his water is always like chocolate milk. So good chances of his bearings going bad very soon?

bumpstart

i picked that up during my time in industry and it was in relation to shell bearings used in some types of industrial pumps, and the company went to pains to make both the fitters and the operators aware of oil contamination issues having large effect on the bottom line

the shell bearings in a combustion engine have to deal with much worse conditions
than mere water contamination of the oil in a ( pump drive ) application that sees constant speeds and minimal TQ fluctuations

ie.. while water in oil will impact on bearing life,,
the bearings in the auto engine already have a much shorter life than those used in a pump shaft application
as in the auto engine it sees much more TQ fluctuation and is subject to much more acceleration and deceleration forces and varying oil supply pressures

but yes,, most certainly.. with all the current fascination with e85, methanol and water injection.
. those with rotary engines need to be more concerned than others due to the inherent nature of the oil control rings to recover any condensates from the side plate walls
( water and fuel )

ie.. it is important get a hold on the crank case scavenge system .. more than just add a catch can ...and change the oil more regularly

.. and may i add..

.. the frequency of oil changes due to the inherent nature of a rotary engine to recover fuel and water condensates and mix them in the crank oil
may dictate that the argument for use of expensive fully synthetic oil and its supposed longevity is mute

.. as any oil
- no matter where or from what it is made-

.. is still rooted with fuel and water contamination

bumpstart

here you go .. at about the 13th minute there is a chart showing 50% life at just 750 ppm
( less than 1 % )
.. though its not specifically about shell bearings in this instance
.. it will highlight the process in which contamination attack the machine
and some of those process would be much more aggressive in instance of shell bearing and soft metal in particular