912 cooling questions

[hihosland]

A question or two

 

1 Where does one source some 17 mm radiator hose for the 912?

 

2 My 80 hp 912 has Evans waterless coolant, Should Evans be changed at certain number of

 

hours or years?

 

3 Are there other coolants suitable for the 912?

 

any and all comments/advice greatly received.

 

 

[rick morawski]

A question or two1 Where does one source some 17 mm radiator hose for the 912?

2 My 80 hp 912 has Evans waterless coolant, Should Evans be changed at certain number of

 

hours or years?

 

3 Are there other coolants suitable for the 912?

 

any and all comments/advice greatly received.

Hi Ho,

Bert Floods in Melb. Have the hose you want or any other Rotax bits.

 

I think Evans coolant is not recommended by Rotax anymore. I always use 50/50 distilled water/glycol.

 

Cheers Rick

 

 

[crashley]

good quality 16mm silicone hose can replace the rotax 17 mm hose or you have to get the 17mm hose from bert floods and as mentioned by rick evans is no longer recommended

 

make sure you flush it out properly before using a good quality glycol mix also as per ricks post I use Castrol and distilled water

 

 

[Ultralights]

Why is evens no longer recommended?

 

 

[maulonir]

Mackay rubber makes 17 mm heater hose thats fits perfect.

 

16mm hose is to small IMHO as the tails on the fittings are18mm diametre. I tried 16mm hose and it just didn't look right to me stretched over the 18m tails.

 

Cheers

 

Rob

 

 

[cscotthendry]

Evans coolant is not approved for 912/914 engines with the new style heads. I'm not sure it has been disapproved for the older style heads...However, your engine will run cooler with a glycol/demineralised water coolant than with the Evans. I used to have the Evans in my Nynja and it always seemed to run quite a bit higher than the school aircraft I hired sometimes. My new aircraft has the new style heads and runs normal coolant and the temps never get much above about 100C, regardless of how long I sustain a full power climb.

 

IMO, do yourself a favor and flush out the Evans and use coolant/water. You can get it pre-mixed from auto supply stores. Make sure it is silicate free and ...(something else free...sorry I forget what it is) but one that complies is the Nulon from SCA.

 

 

[crashley]

I think this is the latest service note it says evans is no longer recommended for si and the new type heads

 

it also says head temps are hotter with evans

 

http://legacy.rotaxowner.com/si_tb_info/serviceinfo/si-912i-001r3.pdf

 

 

[hihosland]

Many thanks for the info forumites

 

 

[DonRamsay]

Water/Glycol works better i.e. dissipates heat better.

 

 

[Blueadventures]

Many thanks for the info forumites

Hi I used the Castrol recommended by Rotax. Got it a Repco store, Supercheap did not stock it.

 

 

[skeptic36]

...(something else free...sorry I forget what it is)

I think it's "traces of nuts"

 

 

[facthunter]

Water is a better "remover" of heat than glycol. Glycol raises the boiling point and lowers the freezing point. It also deteriorates to a corrosive substance, (has a fairly short life) and finds a way to leak through the smallest crevices. The pressure on the cap also raises the boiling point but the cap lets pressure out to a set DIFFERENCE which might be something like 13 psi. At altitude the absolute pressure is reducing as your outside air pressure is lower the higher you go. so your boiling point is dropping. Evans has a few advantages. It doesn't boil so no hot pockets in the engine and you don't rely on the cap pressure. It also lets your engine operate at a higher temp which is more efficient for the engine. Even a raised boiling point of water isn't hot enough without running high cap pressures and risk of coolant hose failure. I'm not suggesting you go against Rotax's recommendations, ever. They would have a reason for their decision and they build the engines. Nev

 

 

[alf jessup]

A question or two1 Where does one source some 17 mm radiator hose for the 912?

2 My 80 hp 912 has Evans waterless coolant, Should Evans be changed at certain number of

 

hours or years?

 

3 Are there other coolants suitable for the 912?

 

any and all comments/advice greatly received.

hiholand

 

Evans never needs to be replaced, your 80hp and my 100hp have no issues running Evans, I found once I changed to Evans on firstly my Trike and then later on my Tecnam it improved both the cly head temp and the oil temp by raising firstly the cly head temp by 30 degrees and the oil temp by about 10-15

 

People think it's great when their oil temp when sitting at cruise is below 90 degrees and a lot of times well below 90 degrees, well it is not good, Rotax recommends 90 deg min for oil temp for a reason

 

My Tecnam when it had glycol in it wouldn't go over 70 deg on the cly and less on the oil temp on a standard temp day

 

Now with the Evans the heads are constantly 95-100 and the oil most times 90 deg

 

I flew out of Yarrawonga at max weight on a 37 deg day awhile back climbing to 8500 ft full noise to cross the divide back to West Sale and both the temps never went out of the green, was close to top of the green but never out

 

I' m not changing it back to glycol as running warmer is better than running colder and Evans will run warmer than glycol

 

Alf

 

 

[OzBirdy]

Oil temp is the nly one you need to regulate.

 

The coolant is only cooling the heads, and the cooler the heads, the more power/efficiancy gained.

 

Iv spent days on end with the coolant never geting over 40c, but i mask the oil cooler to keep the oil temp up.

 

If coolant temp needed to be regulated, rotax would have intergrated a thermostat.

 

Run a few 9xx rotaxs out, never had any problems.

 

 

[Downunder]

I think the faster aircraft benefit from Evans. Those getting very good airflow over their radiators and traveling at 100 or 110 knots plus ( in cruise) can over cool.

 

As I barely get to 100 kts at full song, I'm using glycol/water for best heat transfer.