Today's Message Index:
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1. 02:30 PM - Rotax 912 Cooling issue / Zodiac CH 601 HDS (Thilo Kind)
2. 05:49 PM - Re: I don't know....... (Dave)
3. 06:06 PM - Re: Rotax 912 Cooling issue / Zodiac CH 601 HDS (Dave)
4. 09:07 PM - Re: Rotax 912 Cooling issue / Zodiac CH 601 HDS (Roger Lee)
Message 1
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| Subject: | Rotax 912 Cooling issue / Zodiac CH 601 HDS |
Hi folks,
got an issue with the cooling system of my Rotax 912 UL: in the past, CHT
temps always were around 100 F and very stable. Water reached 215F during
climb out and dropped back to 140 F during cruise. Also, cooling fluid
always expanded into the overflow tank.
During the last annual I replaced some of the cooling hoses and also
replaced the cooling fluid (50% / 50 %). I'm not sure, what the percentage
was before the replacement.
Now, water runs around 215 F during climb out and 205 F during cruise. CHT's
are very erratic from 100F to 150 F with an increasing tendency during the
flight. Oil was normal as always around 195 F. Immediately after landing, I
checked the engine and everything appeared normal, except there was not more
than the minimum of cooling fluid in the overflow tank. I'm a bit of a loss
and would appreciate your input. My thought right now is, that the glycol
percentage is now higher than before, resulting in less heat transport and
thus higher cooling fluid temps. At the same time, the boiling point is
higher, thus less presuure in the system and now overflow in the overflow
tank. The erratic CHT temps could be caused by air still trapped in the
system.
Any comments are highly appreciated.
Thanks
Thilo
Message 2
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| Subject: | I don't know....... |
I've had no problems with the air boxes and have no lines on the air box
nipples or the drain pan nipples. This is in a Zenith with plenty of
airflow under the cowl.
Dave
-----Original Message-----
From: owner-rotaxengines-list-server@matronics.com
[mailto:owner-rotaxengines-list-server@matronics.com] On Behalf Of Fergus
Kyle
Sent: Wednesday, June 06, 2007 2:44 PM
Subject: RotaxEngines-List: I don't know.......
I tell ya men,
I have this 914 sitting here. I paid cash. It came in one box, BUT
it came without the means to drain the carburettor boxes hanging below. I've
tried to find out what fuelworthy line fits the drain nipple below each box
- since it appears it may tinkle itty bits of fuel down onto the exhaust,
creating an unwanted source of energy.
I have two techinicians and a manufacturer's secretary reading
emails in an attempt to find out:
(a) why it isn't in the parts box, or
(b) where I can find the proper thing once they find out what it
is...........
During my wonderment interval, if you have a suggestion which
doesn't involve impossible manoeuvres of my body, I would be pleased to read
it.........
Cheers, Ferg
Message 3
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| Subject: | Rotax 912 Cooling issue / Zodiac CH 601 HDS |
You have air in the system, more than likely in the underbelly radiator. I
put a valve in the aft end of the radiator (petcock type) and the air bleeds
out very easy now.
Dave 912uls HD
-----Original Message-----
From: owner-rotaxengines-list-server@matronics.com
[mailto:owner-rotaxengines-list-server@matronics.com] On Behalf Of Thilo
Kind
Sent: Thursday, June 07, 2007 4:29 PM
Subject: RotaxEngines-List: Rotax 912 Cooling issue / Zodiac CH 601 HDS
Hi folks,
got an issue with the cooling system of my Rotax 912 UL: in the past, CHT
temps always were around 100 F and very stable. Water reached 215F during
climb out and dropped back to 140 F during cruise. Also, cooling fluid
always expanded into the overflow tank.
During the last annual I replaced some of the cooling hoses and also
replaced the cooling fluid (50% / 50 %). I'm not sure, what the percentage
was before the replacement.
Now, water runs around 215 F during climb out and 205 F during cruise. CHT's
are very erratic from 100F to 150 F with an increasing tendency during the
flight. Oil was normal as always around 195 F. Immediately after landing, I
checked the engine and everything appeared normal, except there was not more
than the minimum of cooling fluid in the overflow tank. I'm a bit of a loss
and would appreciate your input. My thought right now is, that the glycol
percentage is now higher than before, resulting in less heat transport and
thus higher cooling fluid temps. At the same time, the boiling point is
higher, thus less presuure in the system and now overflow in the overflow
tank. The erratic CHT temps could be caused by air still trapped in the
system.
Any comments are highly appreciated.
Thanks
Thilo
Message 4
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| Subject: | Re: Rotax 912 Cooling issue / Zodiac CH 601 HDS |
HI Thilo,
What kind of plane are you flying, is the engine exposed or in a cowling and how
many hours on the engine?
Couple of things here. Let's look at the CHT max temps. They are 266F. You are
running very cool and it would be better running a little hotter (above 200F).
You may be right about the different coolant ratio, but with the temps you are
running don't worry about it. The CHT temps can change 50F from mid-range throttle
at around 4400-4750 rpm and will cool off when at 5000 rpm. Mid-range (4400-4750
rpm) in a 912uls runs hotter CHT's than at 5000rpm. It was set up that
way. If there is a small amount of air in the system then it will work its
way out and that's an "if there is air". Rotax would like to see the oil temps
around 200F-220F so you are a little cool with the oil which is ok. Optimal
running rpm is 4800-5200rpm. My expansion tank never gets overflow. You may need
a new pressure cap or you didn't have enough anti-freeze in the water? Your
running so cool you may want to consider running Evans NPG+ coolant.
Depending on my rpm and the OAT then my GHT will differ 20-50F.
Your old temps were too cool.
Give your engine a few hours and see if things settle down.
You should not have anything to worry about with your temps now.
--------
Roger Lee
Tucson, Az.
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