Silicone Oil Hoses?

Parker hose sounds good.

I have used Gates for about 15 years. Almost all their hoses have publicly available specifications, so you should be able to find something that meets or exceeds Rotax recommend.

 Below are hoses available in Australia - part numbers may vary with country

Coolant Hose

Note: All are "molded" /shaped - You will have to pick the ones that best suit your application and cut to length.

It may be possible to purchase Gates straight ID 17mm coolant/heater hose in the UK & US

25mm ID radiator hose

 Multi Fit 90 degree  bend, in diffrent "Arm"  length options

• PN 03-0010 ID 25.4mm, Arm 1 125mm, Arm 2 125mm  
• PN 03-0011 ID 25.4mm, Arm 1 300mm,  Arm 2 300mm 

Multi Fit with two bends, a 135 & 90 degree

• PN01-007 ID 25mm Length 550

25 mm OD Gates coolant hose connectors

• Straight PN28606 
• Elbow PN28626 
• Tee PN28638 

Fuel

Gates Barricade EFI (also known as MPI) this is overkill for pressure rating but has slightly better temperature & permeability. This is compared with the Barricade Carburetion Hose, which also meet the Rotax specifications. 

Oil

Gates GTH-8  now appears to be 8GTH

This is classified as a low pressure hydraulic hose and may only be available from hydraulic stores/suppliers.

NOTE: DOUBLE CHECK ID & SPECIFICATIONS BEFORE PURCHASE 

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Roger Lee wrote:

Hi Jeff,

"1/2” oil hose and 12mm are often referred to by resellers as the same, but they are not."

Your correct, but a .5mm shouldn't be an issue. A clamp will easily take care of a .5mm difference. Several hose fittings from different aircraft Mfg's cause things like this. I've never in all my years had an issue with the Parker hose with either fitting. CPS used to sell that hose for both types of fittings.

I’m sure you are right and you have done a LOT more hose replacements than me. But I do feel that the fit of 12mm hose on 12mm fittings is noticeably better than 1/2” hose on 12mm fittings. The 1/2 hose just feels too loose. The other way around is not as noticeable because it’s just a little tighter.  

My personal aircraft (Bristell SLSA) came with 12mm hose fittings and Parker 1/2” hose. It was not initially a problem but after year three I developed a slight leak (ooze) at the lower oil return line on the engine.  I cut the hose back an inch and replaced the clamp with the Oetiker type and that stopped it for another year, then did that again at year four. I always thought the fit was just a little loose. When I did my first five year rubber change I used 12mm hose and the fit was noticeably better. Those hoses went the full five years without any leaks or service required. Coincidence.. maybe. But maybe it’s was just using the correct size hose.  

Hose Fit

All important IF you don't want to go down the doubtful track of "fixing" small leaks by tightening clamps.

I care not the 1/2" or 12mm debate - what I look for, is a firm/tight fit, on the spigot. Anything less and I look for another hose, that may give me what I want.

The hose MUST NOT leak without the hose clamp. The clamp is primarily for security not for making good the wrong hose for the job.

I have found Gates hoses to be excellent in this regard - I have yet to have a loose fit.

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Howdy Jeff and Happy New Year.

Either at the 25 hour warranty inspection or at every other 100 hr / annual I always check clamp tightness because hose after a while settles in. In 25 years I've never had a leak as a mechanic and all the way back to 1980 before I was a mechanic I never had leaks. I do see some engines with oozing from oil hose or the constant compression clamps on the coolant side. The coolant clamp issue is because they don't put the clamp in the right position on the hose and all I have to do is move it. The oil hose issue usually comes from a bad or wrong type clamp on the oil hose. If a clamp is tightened properly there should never be a leak. A .5mm should never be an issue.

You can mess up anything when doing it wrong or fail to pay attention to detail. You can cause issues just by using a screwdriver wrong. In my Rotax classes I cover clamping, proper types clamps, proper installation and most of all paying ATTENTION TO DETAIL I never use the old traditional wormdrive clamp with the serate openings like you'd use on a garden hose. Old school and there are far better clamps out there now.

Hi Sean,

 I use Gate Barricade carb / vapor recovery hose depending on what you want to call it for the 912UL / ULS carb engines. This is rated for 50 psi and we are normally running 3.5 - 5.5 psi for fuel pressure on these two engines. I don't use fuel injection hose here because it has no give and I found at times trying to push it over a mfg's barbed fitting can cause some stripping off of the inner liner and may cause debris. When I do work on the fuel injected engines I do use Gates Barricade fuel injection hose rated for 100 psi, but these are usually going over different fittings.