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Rotax 912UL coolant liquid

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2 years 4 months ago #15266 by przemekmac
Rotax 912UL coolant liquid was created by przemekmac
Hi.
If changing conventional liquid to EVANS npg+ is mandatory on 912UL? I found some documents about certified engines but this is not certified.
Engine is new on guaranty.

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2 years 4 months ago - 2 years 4 months ago #15268 by Roger Lee
Replied by Roger Lee on topic Rotax 912UL coolant liquid
Rotax at one short interval was okay with Evans. Not any more. That's an old document and has been superseded. Don't use it. It also carries with it a 20F-30F heat penalty. Water based coolant does a much better job of heat transfer. Evans was only good at helping a boil over and if your plane does that then it may be time to either change the expansion cap or find out why it boils over and correct that problem.

Roger Lee
LSRM-A & Rotax Instructor & Rotax IRC
Tucson, AZ Ryan Airfield (KRYN)
520-574-1080 Home (TRY HOME FIRST)
520-349-7056 Cell
Last edit: 2 years 4 months ago by Roger Lee.

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2 years 4 months ago - 2 years 4 months ago #15276 by flyhighglider
Replied by flyhighglider on topic Rotax 912UL coolant liquid
According to the latest edition of the Rotax 912 Installation Manual, Ed 2/Rev.1, Feb, 01/2015 makes this statement.

Chapter 75-00-00 - Cooling System,
Page 7
Engine types, Without suffix 01
1.3) Coolant Types
Two types of coolant are permitted.
1. Conventional coolant
2. Waterless Coolant

So to clarify the earlier statement, waterless coolants are permitted which is not the same as saying "was okay, but not anymore".
However, as Roger makes note, waterless coolant will be slightly hotter.
The above reference from Rotax mentions 41-50F hotter which is 5-10 DegC.

Also, Suffix 01 engines are only permitted glycol coolants. (Page 9).
This is important.
Prior to Suffix 01, both Waterless coolant and 50/50% Water/Glycol are permitted.
Suffix 01 changes to only conventional coolants permitted.

See above reference for full details.
Last edit: 2 years 4 months ago by flyhighglider.

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2 years 4 months ago #15277 by Roger Lee
Replied by Roger Lee on topic Rotax 912UL coolant liquid
This is right off the SI. Maybe this will help.


Waterless coolant for engine types 912/914 Series
■ CAUTION: Not released for engine types 912 i Series and 912/914 Series with cylinder head version
Suffix - 01.
An advantage of waterless coolants is their high boiling point which prevents “boiling“ of the cooling system.
However, its specific thermal capacity is lower than of conventional coolant which resulting in slightly higher
running temperatures.
The cooling system of ROTAX® engine types 912/914 Series (without Suffix - 01) is designed for operation with
waterless coolant and thus must not be modified, i.e. drainage or ventilation holes must not be closed.
■ CAUTION: The certification and determination of the correct coolant type must be conducted by the aircraft
manufacturer. As each aircraft type has different characteristics, testing must be done to
determine the most suitable coolant and instrumentation for each aircraft type.
Recommended coolant (100% concentrate)
◆ NOTE: NPG+/NGPR/NPG+C are not available anymore and are replaced by the successor product
Aero Cool 180°.
■ CAUTION: Aero Cool 180° contraction point is approx. -23 °C (-10 °F) . It will not freeze and expand like
conventional coolant. Do not use if conditions expose the engine to non-operational temperatures
below -23 °C (-10 °F).
M n arke/brand Bezeichnung/descriptio
E 0 VANS® Aero Cool 18
4.3.1) Warnings for operating with waterless coolant
- Water or coolant containing water must never be added to the cooling system!
- The max. water content must not exceed 3.6 %; it can be tested using a Brix refractometer.
- Any water present in the cooling system is separated out as vapor. This can cause the cooling system
to fail due to insufficient coolant quantity.
- If Aero Cool 180° is not available locally for servicing the cooling system, a conventional coolant based
on pure 100% ethylene glycol can be used temporarily. However, the coolant must be replaced again
with Aero Cool 180° within the next 15 days.
■ CAUTION: As some conventional coolants are available in a pre-mixed formula (water added) be sure
to add only 100% pure ethylene glycol if Aero Cool 180° is not available.
■ CAUTION: The above warnings are taken from the manufacturer’s users manual, however the
original text and description in the users manual is binding.

Roger Lee
LSRM-A & Rotax Instructor & Rotax IRC
Tucson, AZ Ryan Airfield (KRYN)
520-574-1080 Home (TRY HOME FIRST)
520-349-7056 Cell

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11 months 2 weeks ago #19584 by isapilot009
Replied by isapilot009 on topic Rotax 912UL coolant liquid
Hi Roger. My question is about the 912UL radiator and over flow tank. On my engine I have a clear hose from the radiator down to the overflow tank. On the initial fill I purposely raise the overflow tank with coolant in it to fill up the clear overflow line and fill the radiator cap opening to the top and then I quickly put the radiator cap on and lower the overflow down to its original position. At that point I know the system is pretty much free of air and it any remains it will clear itself on a few engine cycles. Everything works fine. I have a low and high mark on my overflow tank that I monitor at least before each flight to see if the coolant level remains relatively consistent.

Today I had a Rotax approved mechanic doing my annual compliance inspection. He reached over and was going to remove my radiator cap and I immediately stopped him. He could not understand why I was so excited. I told him I would lose the fluid in the hose to the over flow tank and he said that is no problem. He actually said as long as he looks under the cap and there is fluid there that everything is ok. He said that the overflow hose does not have to be full of fluid. Well I strongly disagreed telling him that it is a closed system and that the overflow hose must be full at the top for the radiator cap opening to the overflow tank for the system to cycle correctly between hot and cold cycles. Am I missing something here?

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11 months 2 weeks ago #19586 by Roger Lee
Replied by Roger Lee on topic Rotax 912UL coolant liquid
I just fill the expansion tank on top and fill the reservoir tank to the level I want and don’t worry about the hose. I don’t know anyone that worriers about the hose. The closed system is up the to radiator cap. The reservoir is open to atmospheric pressure. When the expansion tank cap opens to draw coolant up from the reservoir it should not have any issues. If the cap opens to vent hot coolant to the reservoir then it will vent out the air.

Roger Lee
LSRM-A & Rotax Instructor & Rotax IRC
Tucson, AZ Ryan Airfield (KRYN)
520-574-1080 Home (TRY HOME FIRST)
520-349-7056 Cell
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11 months 2 weeks ago - 11 months 2 weeks ago #19587 by Bill Hertzel
Replied by Bill Hertzel on topic Rotax 912UL coolant liquid
Roger is correct!
The system will take care of itself.

There was no point in filling the hose at the first fill because the very first time the coolant came up to temperature it out-gassed all the dissolved air in the water.
It is equivalent to a soda warming up and going flat. Lots of air bubbles.
The first thing that happened was that the radiator "Burbed" the dissolved air and blew all the coolant out of your carefully pre-filled hose.

Water expands about 3% going from room temperature to just below boiling.
Because the radiator is 100% filled, This causes about 4oz per gallon to dump into the expansion/overflow tank.
This refilled your overflow hose without you ever seeing it happen.

When the engine cooled after shutdown, the contracting water pulled coolant from the expansion bottle maintaining the 100% filled condition.
This cycle happens everytime the engine is run and the reason you do Not want to completely fill the expansion/overflow bottle.
A 1/3 to 1/2 full expansion/overflow bottle on a cold engine allows room for the bottle to not actually overflow when the engine heats up.

The system takes care of itself.

Bill Hertzel
Rotax 912is
North Ridgeville, OH, USA
whertzel1@yahoo.com
Clicking the "Thank You" is appreciated by all.
Last edit: 11 months 2 weeks ago by Bill Hertzel.

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11 months 2 weeks ago #19588 by isapilot009
Replied by isapilot009 on topic Rotax 912UL coolant liquid
I agree with what is said about the hose being filled by itself upon a few heat cool cycles of the engine. The part I disagree with is opening the radiator cap to check the coolant before each flight, as removing it will allow all the coolant in the hose to return to the overflow tank. By having a clear overflow line I can visually see the system is full to the high or low level I have marked on my overflow tank with a sharpie. Also by having the system remain closed with the overflow line full should I develop a pin hole leak while flying the water will be immediately drawn from the overflow tank back to the engine and hopefully I would be back on the ground before all the water is drawn back into the engine and out the leak.

Other insight into the clear hose to the overflow tank. I was continually seeing air bubbles in the hose before and after each flight. That is where I attempted to manually fill the hose by raising the overflow tank to back fill the hose and fill the reservoir before replacing the radiator cap. I was very successful in doing this but after a few flights I began getting air bubbles in the clear line to the overflow tank. The fix for it was a new radiator cap. Now the line is always full and it is my belief that I can assume the capped reservoir is full thus eliminating the need to remove the radiator cap before each flight as long as the fluid levels remain constant in my overflow tank.

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11 months 2 weeks ago #19589 by Roger Lee
Replied by Roger Lee on topic Rotax 912UL coolant liquid
I never recommend removing the expansion tank cap each flight. You’ll just wear it out. I do remove them at annual to look.

Roger Lee
LSRM-A & Rotax Instructor & Rotax IRC
Tucson, AZ Ryan Airfield (KRYN)
520-574-1080 Home (TRY HOME FIRST)
520-349-7056 Cell
The following user(s) said Thank You: isapilot009

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11 months 2 weeks ago #19590 by isapilot009
Replied by isapilot009 on topic Rotax 912UL coolant liquid
I appreciate your help and comments Roger. I agree with not removing the cap plus they are about $80 to replace. It is just another thing to put back on incorrectly when you are distracted during a pre-flight check. I always make sure the cap is seated properly with both ears are under the edge of the reservoir and fully turned to the stop. There is no room for error here plus we are hitting the 100F here in Fresno now.

Bill Campbell
Central Valley SportPlanes - Fresno, CA.

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1 month 2 weeks ago - 1 month 1 week ago #22722 by xìng wang*
Replied by xìng wang* on topic Rotax 912UL coolant liquid
Reference S.I, 914-019R10 at para 4.3 mentioned that water less coolant i.e EVANS is not permited for engine 912-915-914?
Last edit: 1 month 1 week ago by xìng wang*. Reason: modify

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1 month 2 weeks ago #22724 by RobSeaton
Replied by RobSeaton on topic Rotax 912UL coolant liquid
-I think because it has a higher viscosity, so it does not flow through the coolant galeries fast enough?
The -01 heads have more gallery area, mostly around the exhaust port, maybe they are smaller diameter requiring a less viscous fluid?
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1 month 2 weeks ago #22730 by Roger Lee
Replied by Roger Lee on topic Rotax 912UL coolant liquid
Evans carries with it a 20F - 30F temp penalty. Water adsorbs and releases heat far better and quicker.

Roger Lee
LSRM-A & Rotax Instructor & Rotax IRC
Tucson, AZ Ryan Airfield (KRYN)
520-574-1080 Home (TRY HOME FIRST)
520-349-7056 Cell
The following user(s) said Thank You: xìng wang*

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1 month 2 weeks ago #22732 by xìng wang*
Replied by xìng wang* on topic Rotax 912UL coolant liquid
on 914 engine, -01 head, we have used EVANS, still found no problem on temperature or CHT.
CAN WE CARRY ON ?

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1 month 2 weeks ago #22733 by admin
Replied by admin on topic Rotax 912UL coolant liquid

Wang Shu wrote: on 914 engine, -01 head, we have used EVANS, still found no problem on temperature or CHT.
CAN WE CARRY ON ?


Sure... if you want to IGNORE the engine manufacturer's explicit service instructions!

"Waterless coolant is not permitted for engine types 912 i, 915 i Series or for 912/914 Series with cylinder head version Suffix - 01."

Pretty sure they didn't go to the trouble of publishing this instruction for no good reason...
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1 month 1 week ago #22799 by Skycat
Replied by Skycat on topic Rotax 912UL coolant liquid
Hi I am Sue and I'm new here, just got my Pilot's licence (whoooeee!) and bought a used but good Skyranger classic. In the past did a lot of motor racing (historic cars) and my own building/making/fixing/running ( helped by my husband) so have some understanding about mechanical things. Now I'm confused about all the
recommendations on Rotax 912 coolants. Some say blue some say pink - and I read that ethylene glycol with
50% water is good, and then propylene glycol undiluted is good or better .Then see that the name Dex-cool is used by all as an advertising ploy. I'm sure that coolant needs to be low silicate and a nitrate free formula. So I need that and pink and available in UK and its hard to be sure which complies. Any ideas?

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1 month 1 week ago - 1 month 1 week ago #22804 by Bill Hertzel
Replied by Bill Hertzel on topic Rotax 912UL coolant liquid
Hello, Sue,
Welcome to the Forum.

Undiluted Propolyene Glycol = Waterless Coolant = Evans NPG = Not Permitted!

You may want to refer to this thread...
www.rotax-owner.com/en/rotax-forum/3-4-s...olers-required#20388

Bill Hertzel
Rotax 912is
North Ridgeville, OH, USA
whertzel1@yahoo.com
Clicking the "Thank You" is appreciated by all.
Last edit: 1 month 1 week ago by Bill Hertzel.

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1 month 6 days ago #22806 by Gasmanjdh01
Replied by Gasmanjdh01 on topic Rotax 912UL coolant liquid
Roger,
So, which coolant does Rotax put in the 912 ULS out of the manufacturer? I am thoroughly confused at this time. My engine came with the "red". What do I use to top off when needed?

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1 month 6 days ago #22809 by Bill Hertzel
Replied by Bill Hertzel on topic Rotax 912UL coolant liquid
Rotax runs the engine at the factory on a test stand for about an hour before draining it and placing it in a shipping crate.
The engine ships from the Rotax factory without any fluids in the engine. Dry!
It will come with the Oil Tank and 4 Liters of Oil but without Oil Hoses or Oil Cooler.
It will have the cylinder Heads plumbed to an expansion tank but will not come with a Radiator, Radiator hoses or Overflow Bottle.

Rotax delivers the engine to the aircraft manufacturer wrapped in plastic and bolted in the box.


It is the Manufacturer that selected the Radiator, Oil Cooler and all the hoses to plumb the installation.
These parts are unique to each aircraft model and their selection is beyond the control of Rotax.
The Manufacturer selected the Cooling Fluid.
Most manufacturers follow Rotax's recommendations.
Some do not.
Whoever installed the engine in the airframe is who you should be asking about what "Red Fluid" you should use to TopOff.

Bill Hertzel
Rotax 912is
North Ridgeville, OH, USA
whertzel1@yahoo.com
Clicking the "Thank You" is appreciated by all.

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1 month 6 days ago #22811 by Roger Lee
Replied by Roger Lee on topic Rotax 912UL coolant liquid
Just use Dexcool 50/50 and don't overthink all the different coolants. If you need to add if the reservoir goes down you can top off with distilled water.
the water in the 50/50 mix does a better job absorbing heat and then releasing it as it cycles through the system and radiator.



FYI:
Red Coolant:
APPLICATION Asian automotive and light duty vehicles requiring an OAT engine coolant.
VEHICLE MAKES Lexus, Toyota, Scion
FORMULATION Ethylene glycol based. Silicate, borate, nitrite and amine free
PRODUCT COLOR Red
SPECIFICATION/PERFORMANCE LEVEL ASTM D3306, JIS K2234
RECOMMENDED CHANGE INTERVAL 150,000 miles* or 5 years of service protection
COMPATIBILITY For best results, do not mix with conventional high pH, borate or silicate based coolants.
PERFORMANCE FEATURE Aluminum Compatible
PRODUCT OPTIONS Concentrate & 50/50 Pre-Diluted

OAT = OAT is an acronym for Organic Acid (Additive) Technolog

www.coolantexperts.com/coolant_overview/oat_coolant

Roger Lee
LSRM-A & Rotax Instructor & Rotax IRC
Tucson, AZ Ryan Airfield (KRYN)
520-574-1080 Home (TRY HOME FIRST)
520-349-7056 Cell

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