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Hi Dave,
Just about the RX8 "No Start" problems. What seems to happen is that they
flood if you are not careful. I don't think this has anything to do with the
seals sticking. Unlike the earlier model engines with peripheral exhausts,
they can't purge themselves when flooded via the side exhaust ports. The
excess fuel is just wiped around the trochoid and wets the plugs. When an
"ordinary" rotary floods, all you need to do is flatten the accelerator to
the floor, the excess fuel is purged directly out the exhaust, and keep
cranking it until it starts. Sometimes, the fuel pump fuse needs to be
removed temporarily to stop the actual flooding.
With the RX8, the only way I can see of purging a flooded engine is to
remove the plugs and crank the sucker over and purge the fuel out the plug
holes.. Being careful, of course, to first disconnect the ignition trigger
to prevent a fire in the engine bay!! I have seen some spectacular engine
bay fires in my time accompanied by that sickening "Whoooomp!" sound, a
bright flash, complete with apprentices with singed eyebrows and absolutely
startled looks!! Most spectacular at night!!
Secondly, just on you recollections of my demented ramblings, I think you
have got what I said slightly mixed up, but then again, it WAS a long time
ago.
You said:
Leon down under sent an e-mail 2 or 3 years ago saying
he'd put an external tank with brake fluid and something else in it
plumbed
to the intake manifold, and would "fog" the engine for a few moments
before
shutdown to "coat rotors and seals" with wet lubricant/compression
enhancer
to make the "next start" easier. I can't find that e-mail - Leon, can you
send your idea again?
There were TWO different issues which I think I addressed at the time:
1. Lack of Compression (usually worn corner seal grooves)
2. Stuck Apex Seals (NOT the same thing as 1)
LACK OF COMPRESSION
What I was talking about with the oil was getting engines started that were
down on compression. The
early twin dizzy Mazda engines (R100 & RX2 & 10A RX3) were notorious for
problems with corner seal groove wear. Corner seal clearances are critical
to compression. So the trick was to set up a winscreen washer bottle with
some engine oil in it.
Just before you shut down, you would squirt a few cc of engine oil into the
carby. As the clouds of oil smoke billowed from the exhaust, the engine
was turned off. This would usually then coat the seals sufficientlly to
give compression for the next start.
If it didn't work, you could then squirt more down while cranking. The
same thing could be acomplished with an oil can. Give the engine a dose of
LIQUID COMPRESSION usually worked wonders!!
NSU Ro80s were also helped by this method (but their problems were far more
serious). Mostly, they also needed hot Falcon plugs as well to get them
going. The stock plugs were VERY prone to fouling even with the CDI
ignition fitted as standard.
If the engine wouldn't start off the key, being towed at 20 MPH usually did
the trick. If that didn't work, then it was time for a new motor!!
STUCK APEX SEALS
As for the brake fluid, that's an entirely different matter. The early
Mazda engines used 6 mm carbon apex seals. If the car was driven slowly in
heavy traffic and never got thrashed, they would eventually stick in the
grooves. Stuck apex seals were evidenced by another symptom. Quite often,
they would still be (relatively) easy to start off the key, but the
compression would "spit back" up the carby under heavy load and make a deep
BRT stuttering noise.
The partial cure for stuck apex seals was to spray a fog mixture of brake
fluid and water into the carb while the engine was running, and especially
under load. The mixture (usually 50/50) was very good at removing obdurate
carbon deposits. ATF will work as well, but it is nowhere as good or as
rapid as the water/brake fluid mixture.
I leaned this trick from my old mentor who used this method to decarbonise
valves and pistons in the days when a "decoke & valve grind" was a more or
less regular maintenence procedure. When the pistons coked up, the engines
would suffer pre-ignition (ping under load no matter where the timing was
set), and also run-on after turning off the ignition (the carbon deposits
glow like a glow plug!!). Give them a decent dose of Dr Ray's "Jungle
Juice" as we used to call it, and a good hard thrashing (known locally as
an "Italian Tune-Up") and the pre-ignition would vanish. Worked
particularly well, among other vehicles, on V12 Jags (which are a
nightmare to do a head job!!).
So I hope that helps clear up the confusion of what I wrote some time ago??
Cheers,
Leon
----- Original Message ----- From: "David Carter" <dcarter@datarecall.net>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Friday, February 18, 2005 3:19 PM
Subject: [FlyRotary] Re: Short motor runs, was I found the power
From: Tom
To: Rotary motors in aircraft
Sent: Wednesday, February 16, 2005 5:40 PM
Subject: [FlyRotary] Re: Short motor runs, was I found the power
Very good to hear Paul you found some power. However, I thought a
person would risk getting apex seals stuck if you ran the motor for short
runs, like less than 5 minutes? I forgot the reasoning behind it.
Then
comes out the bottle transmission fluid or that other liquid and procedure
for creating great clouds of smoke, per previous discussions a few months
back.
Tom
- - - -
David comments:
About "short runs, like less than 5 minutes. . ."
I was in the Mazda dealership's maintenance bay last Christmas season and
an
RX-8 was towed into the shop - "Won't start".
- Service Tech said any engine run that doesn't get the car up to
"operatinig temperature" will result in no start next time you try. They
have a whole procedure to go through to get it started.
- I didn't get any info on "why" and "how".
-I suspect what I heard was only related to the "automobile
installation" with all its computer software and sensor stuff as installed
and designed for the RX-8. Don't know if any of that applies to the basic
mechanical engine assembly that we use in our aircraft with after-market
ECU.
Re: "Then comes out the bottle transmission fluid or that other liquid
and
procedure for creating great clouds of smoke, per previous discussions a
few
months back.". . . . Leon down under sent an e-mail 2 or 3 years ago
saying
he'd put an external tank with brake fluid and something else in it
plumbed
to the intake manifold, and would "fog" the engine for a few moments
before
shutdown to "coat rotors and seals" with wet lubricant/compression
enhancer
to make the "next start" easier. I can't find that e-mail - Leon, can you
send your idea again?
David
>> Homepage: http://www.flyrotary.com/
>> Archive: http://lancaironline.net/lists/flyrotary/List.html
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