Jerry,
The idea of using an O-ring is cheap for Rotax, but without lube, the
O-ring is going to squeeze out poorly, and can even roll over themselves
under torqueing. The proper seal would be a flat rubber or compression
washer or design a bolt with a curved recess for the O-ring. There is
nothing in the industry that makes such a bolt for sealing with an
O-ring, only way to seal quickly and inexpensively to a flat surface is
a flat washer. My understanding is that the new bolt is slightly
longer and allows the jet to not bind on the bolt recess as it did on
the older 914s. If you use the O-ring without the fiber washer the bolt
will impact the jet and bind or cut off fuel supply. Other than that,
they are the same.
Just lube the O-ring and torque to spec, then wait a day and torque
again, it holds very well.
My plane is down until Rotax can get me another stainless fuel line.
After numerous removals of my carbs, the right carb compression fitting
no longer seals. $178 bucks and it will be 6 weeks. Lockwood is trying
to locate one or a set in the US.
I think I would be happy with a 912S. Push on barb fittings are a pain,
but hose is fairly cheap, reliable and easily replaced. As I get older,
I like simple. Planes in our shop get the easiest to change fittings
and hoses I can find. I could care less if a hose has to be cut off the
barb and be replaced, as I make sure I have access to all my hoses. I
use quick disconnects from CPC for my fuel filters for rapid and cheap
filter changes. Just keep extra O rings.
Regards,
Bud
----- Original Message -----
From: Jerry Rehn<mailto:rehn@rockisland.com>
To: europa-list@matronics.com<mailto:europa-list@matronics.com>
Sent: Saturday, May 18, 2013 2:56 PM
Subject: Re: Europa-List: 914 rough running
Bud
After about 4 tries the oring has an even fit!
Sent from my iPad
On May 17, 2013, at 8:08 PM, Jerry Rehn
<rehn@rockisland.com<mailto:rehn@rockisland.com>> wrote:
Bud
I have the new float chambers and new orings for the retraining nut
and now see the oring wants to buldge out a bit on torquing down. I
assume the new revised bolt has provisions for the oring that the
current bolt does not. You indicated that yours worked ok. I am hoping
to not have to purchase the new bolts at about $80 each!
But I am not happy with the oring not fitting perfectly. I see you
left the old washers in place as well, I don't see how that will keep
the oring from pressing out. I torqued down to only 46 inch. I didn't
lube them, thought this would make it worse? Tomorrow I will try some
lube but welcome any other suggestions.
Thanks
Regards
Jerry
Sent from my iPad
On May 6, 2013, at 2:41 PM, "Bud Yerly"
<budyerly@msn.com<mailto:budyerly@msn.com>> wrote:
Jerry,
Please note that the 914 is a bugger to troubleshoot, and all the
advice so far is notable and spot on.
Since the engine has two problems: (1) Rough after pulling it back
and (2) TCU Caution light, I will deal with 2 first...
2. The caution light is most probably your throttle pot is not
hooked up electrically or the pot was not set to idle with the throttle
plate closed so check your connections and pot rotation after doing the
carb. Easy mistake, especially since the book doesn't cover it. If not
set properly, the TCU gets the wrong throttle position for the Turbo
boost and pressure sensors.
1. With you having the same hours I have on my engine, I have
noticed that with all the tubing and carb float bowl items operating
properly and no fuel leaks, the engine on power reduction runs very
rough but idles well and runs well above 4000 RPM. I suspect yours is
similar.
It is not uncommon that one of the carb pistons is hanging up.
Once the piston goes up on full throttle, one doesn't want to come down.
I removed the carburetors again. I completely drained and freed both
my carbs of fuel to prevent an explosion. I rigged my vacuum cleaner
and pulled air from the manifold side and noted the movement of the
piston. On the left carb it was clearly hanging up. After much
cleaning, sanding with 1000 and 1500 grit paper, polishing and more
cleaning, the piston is acceptable in its movement and smoothness. If
your carb pistons move smoothly and in unison (checked by noting the
throttle angle vs piston position) then that should make the carbs
balance in the mid range. If the main carb body is worn or scored
badly, some small grit has gotten into the carb and I am afraid you can
save a lot of time and trouble by buying two new carbs. By the way,
that is about the price of a small car down payment.
To Bob Borgers comment, I have found that leaving the float bowl
gasket in place and adding the new extra O ring (with a bit of lube)
allows me to install the original float bowl attachment screw and I
torque it to 48 inch pounds. Be sure to soak your paper gasket in fuel
for a few minutes. Note that the old manual said 5.5 nm or 45 foot
pounds. Obviously 45 foot pounds is going to seriously bend the bottom
of the carb bowl and the pins. Luckily, a quick $100 per float bowl
will fix that. I have found that it necessary to pay attention to the
translation and conversions in the old manual. The new manual has the
torque hidden in the verbage so well that I had to post it to my board
in the shop. Please pay close attention to your brass float pins and
the float bowl. Also make sure your float needle valve and arms are
undamaged.
I have been very disappointed in the fit of the new carb parts
such as the needle fixation screw with the O ring. It sucks.
I hope your carbs just need a little tender love and care and not
replacement. I am at my last straw with my 1/3 side carb, so I may be
spending some big bucks.
Regards,
Bud Yerly
----- Original Message -----
From: Jerry Rehn<mailto:rehn@rockisland.com>
To: europa-list@matronics.com<mailto:europa-list@matronics.com>
Sent: Sunday, May 05, 2013 3:43 PM
Subject: Europa-List: 914 rough running
A little history. Engine has about 450 hours, always ran quite
well, replaced upper ignition module about two years ago.
On recent full boost takeoff, got to about 900 feet leveled off,
pulled throttle back and engine ran severe rough, pulled back to idle
and engine ran ok, didn't stop! Landed. Checked fuel filter, ok, looked
for anything around carbs, nothing. Tried several full run ups, ok.
Tried second take off everything fine, pulled back and again engine ran
severe rough, pulled back to idle, ran rough, landed. Parked plane, got
tools, next day removed carbs looked for issues. Found one of the four
screws that holds down the rubber diaphragm loose, very strange because
I have never removed this before. Anyway figured this was my problem.
Fixed took off all ok. Got home. Next day tried full boost, same issue
again, didn't take off. Got carburetor repair kit and went through both
carbs. Reinstalled carbs double checked. Started right up, as I move the
throttle past 2300 rpm the yellow caution light starts blinking, engine
runs rough, reduce rpm the light goes off, increase the light comes back
on. Seems the engine runs off the idle jet ok but not on the main jet.
I have also checked the waste gate for proper function, fuel
pressure ok, turbo lights come on and go off as they should when master
is tuned on, I have looked at the vent lines. The yellow blinking light
can indicate a sensor failure, seems like it would continue blinking if
there was a failure. Seems odd that it stops at low rpm. Seems I have
some kind of a vacuum or pressure issue, but am running out of ideas. I
am about to go and recheck again! Could a faulty sensor cause this?
Hope someone out there has some wise thoughts on this
frustrating problem. Worse yet, we have beautiful spring flying weather!
Thanks for help.
Jerry
914 Mono XS
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