my oil keeps getting contaminated with LARGE amounts of fuel. How is this even possible in a rotary engine? No, my injectors are clean as hell. Yes, I have good compression. Yes, the car is fast. Thanks
Sexy James

 

flooded engine, or leaking injectors

anytime a rotary gets flooded the oil should be changed ASAP

 

What do you concider "large amounts", like you can see a visible layer of gas, or it smells like gas?

 

the compression is fine. the engine never floods. the injectors have a zero, read that ZERO, AS IN THE NUMBER 0, leak down. The car does not smoke on start up, which happens within one(1) second of cranking. large amounts mean reaking of fuel and the dipstick "grows" by a quart every 2,000 miles. It can thin 30 weight to the consistency of water in a month. Think about the placement of the injectors in relation to the oil rings and the ports. I want to know how this is even possible without a massive flooding. If there are questions about my injectors, you can call Rich at Cruzin Performance, since you know, he cleaned them less than 6 monthes ago.

 

well, either flooding, or poor compression, or leaking injectors are the only way that fuel can be mixed with the oil, either that or some one is mixing something in with your oil.

 

Sounds like leaking injectors. Fuel contamination will destroy your bearings in little time, if not already.

 

OMG. have you ever plastiguaged a set of bearings? Have you even build a rotary engine? Did you even read my last post? This has been happening ever since I built the engine. The injectors are cleaned as new. How can they leak if they have a zero leak down as stated in the email I recieved from Rich @ cruzin performance less then 6 monthes ago?

 

Re-test your injectors for leakdown, they could be leaking again, its possable.

Also, are you running mega rich?

Did you know that your charcoal canister vents to your 'crankcase?' Observe that your PCV is working properly :O

 

Actually that reminds me:

A stuck check & cut (three way check) valve at the gas tank, and a overfilled gas tank, could dump gas in through the carcoal canister, which could then dump gas through the oil fill.

To check that, don't fill the tank more than half way for a couple of weeks and see if that solves the problem.

Of course if this solves the problem, then I bet you (JamesWade2002) wish you didn't send such a snotty PM to me, or pulled such a crappy attitude.

 

Well that is horrble at $38 an oil change self changed. Grr!

Could a stuck side seal cause this?

Where is the PCV on these cars? My jspec didnt have a EGR on it anyways.

 

If you find your answer let me know. I have the same problem. Put new primary injectors in, cleaned secondary injecters at Marren, and installed a new OEM PCV. Still have bad fuel dilution. I gave up and just change my oil every 1000 miles

 

Wow, you're a dick! You want help? or not

 

I have two theories about this, because it's happening to me too. About a quart every 2K too...

I've heard, and this stuck in my head, that the Viton oil control rings somehow allow this to happen. The ones in the RA kits...

Two, it could be worn side housings. This is my favorite, because we're all (that I know of)putting new side seals on our rebuilds (which are nice and flat) while reusing the side housings (which are NOT worn perfectly flat).

You premix, I presume? That's when mine started, soon after I started premixing. This was way before the rebuild, and even after a complete RA master kit was installed on the rebuild, the blowby was exactly the same. The only parts I didn't change were the side housings...

It could be also that the film of premix all over the side housings (which is a good thing) is causing the side seals to "float" over the side housing surface, allowing the combustion pressures to force minute quantities of premix (and unburnt gas) past the side seals and oil control rings...

I guess that's 3 theories, huh?

I'll know in a year or two whether my theory holds. I'm chomping at the bit to rebuild her again (even though she's only got 25K on her, lol) using new side housings....

 

I've got basically the same engine as WAYNE88N/A (Rotary Aviation full rebuild, used side housings), and see the exact same thing (about 1 quart up per 2k miles).

My personal solution is to use the "1 qt up" mark as my oil change timer.

As for why it happens, I'm not sure. I've just accepted that premixing leads to oil dilution, premixing is good for the engine, and frequent oil changes are good for the engine. The three work together nicely IMHO.

I would tend to believe that the side seals & such "floating" on the oil would be a cause, since the premix is going to be doing a much better job lubricating the side housings than the stock oil injection system. Also, I suspect there's blowby in the stock system, but the oil injection pump draws enough oil out that the level goes down. I'm not sure anyone's figured out exactly how much the MOP flows under normal conditions, but I'd put money on the fact that the amount of oil injected into the engine is significantly greater than the amount that the crankcase drops. With the MOP disabled, you get the "stock" rise, plus any additional rise from the premix.

Just change your oil more frequently. I don't use synthetics because I change my oil every 1.5-2k miles (and don't want to pay through the nose for oil). I suspect my engine is happier for it.

Wayne - when you do your next rebuild, could you spec out the apex seals & side seals & such to find out what kind of wear they've taken? I'm curious as to how much wear occurs on a premix-only engine vs a stock engine. Maybe extrapolate the wear into "mileage until failure" type values for the apex seals?

-=Russ=-

 

Exactly what I thought!

 

okay now we are talking. I am likeing this! Thanks Wayne88N/A!!! While talking to my friend Amishboy a couple days ago when I first posted this thread he said something about the charcoal canister. That doesn't hold up cause I don't have one and the one fuel line that returns for that vents to the atmosphere now cause I forgot to plug it and don't care. The only line going to the oil system is the sump vent in the fill neck, which goes back to my intake manifold. SO.......yes I premix and always have on this motor. I believe it may have viton oil control rings but I'm not sure, it was an adkins rebuild kit. The side housings I used were well used and I missed once with the die grinder and learned a lesson, which may explane my 5psi difference in compression. first motor ever, it happens. Also, one of my side seals has almost double the clearence needed between the side seal and the corner seal, meaning it is too short. I am going with the side seals not seating or sliping too well/ my own beginer builder mishaps. The next engine will be a huge 4 port motor with high compression rotors and a holley. It too will be premix only. we shall see. VERY GLAD TO SEE THIS THREAD GET GOOD!

 

I gain about a quart every 2K miles. I premix and could have compression loss due to leaky side seals. anyone else "gain" oil that stinks of gasoline here? reference this thread - https://www.rx7club.com/showthread.php?t=427817 for more info.

 

Why exactly would you do a 4port motor over a 6?

 

because I don't like the shape of the round/divided intake runners as cast into the 6 port housings and I believe I can make my target output with more area under the curve with a 4 port. plus I wanna do what Racingbeat says cause Jim's the man, and they don't need no stinkin 6 ports.

Ps. Your engine is very similar to mine (sounds great by the way), you premix right? do you find your sump growing?

 

As posted in the other thread, I premix (probably slightly on the heavy side - I err on the side of more 2-stroke oil), and change my oil every 2000 miles or so when it gets a "quart up." I've just accepted it as normal.

-=Russ=-

 

it is normal. good condition housings, brand new side, corner and apex seals and i gain about a quart every 1,000 miles or so.

 

It isn't normal just because you experience. Fuel dilution should be 2% or less over an oil change interval. The only way know exactly what is in your fuel is to pull and oil sample and send it to a lab.

 

This is exactly why I'm "chomping at the bit" to do the next rebuild...

I wrote down specs of everything on the OEM parts coming off of the rebuild, including the wear on the rotor housings (being an aircraft inspector, I have access to some really neat measuring equipment like ultrasonic metal thickness testers and eddy current machines, along with all of the "usual" calipers, hole probes, flatness testers, etc...).

I even determined what the wear rate is on the stock apex seals on an NA engine per thousand miles (I got it written down somewhere, lol)...I figured my stock apex's would have lasted until 237K, then probably rolled out...

SO, when this RA rebuild hits about 50,000 miles, I'm going to tear her down again to see what the wear rate is on 1) the new rotor housings, 2) the RA apex seals, and 3) the difference in the side housing wear per 50,000 miles between a stock OMP engine (which she was until about 150K) and a premixed engine...

At the rate I'm driving, we're gonna have to wait until next year, about June or so

 

Since gasoline is an aromatic hydrocarbon, it takes only the tiniest bit in your oil to smell it, making you think that the oil is saturated with it...

In my case, anyway, it is predominately the excess premix that finds it way into my oil. And as far as I'm concerned, excess premix is a good thing. Doing an oil change 1,000 miles early is a hell of a lot cheaper in the long run than changing rotor housings every rebuild (I have yet to understand why guys reuse worn rotor housings after spending all that money for a rebuild kit- but that's just me)...

 

i accidentally clicked on page 2 and thought this was the whole thread so i missed the part about large amounts of fuel dilution, notice how i was referring to premixing and oil dillution not fuel. fuel dillution is hard to guage how much is actually fuel, premixed oil is saturated with fuel so obviously it will have a lot larger fuel dillution in the oil than a non premixed engine.