17mm coolant hose and 90 degree hose 922192

by Andrew Rowley in 912 / 914 Technical Questions 11 years ago

I am about to do the rubber replacement on my 912ULS engine. I debated about whether the 17mm hose could be replaced with 16mm which is cheaper and much more readily available. I was persuaded by those who say that forcing a smaller hose onto a larger than intended fitting is not best practice, and I purchased the 17mm hose from the local Rotax dealer.

However, I was quite surprised that the right angle formed hose 922192 is smaller than 17mm - by measurement it looks like about 15mm. I haven't pulled the old hoses off yet - are these fittings actually smaller? The description on the invoice says this hose is 17mm.

I queried the part, and was told it was correct, just push a bit harder to get it on. This is what I was trying to avoid by buying the 17mm hose, but if it is OK maybe I should have just gone with the commonly available 16mm?

Can anyone clarify the size of this right angle hose? The part has 922192 marked on it, so I am reasonably convinced I wasn't sent the wrong part.

Is there really any reason not to use 16mm hose rather than the specified 17mm for the other hoses? I have the 17mm now, but I will make a note for 5 years time, and it might help some others decide...

Thanks for any information,

Andrew

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Re: 17mm coolant hose and 90 degree hose 922192

by Roger Lee » 11 years ago

Roger Lee

127 5.21k 4.79k

17mm hose is easy to get on the water tubes out of the heads and on the water pump, but a little tougher on the fill tank. I don't think 16mm would fit. It's just as easy to stick with the 17mm. The 17mm hose that Rotax uses is made for them by one Mfg. I have seen other 17mm heater hose, but it was out of the UK.

Roger Lee
LSRM-A & Rotax Instructor & Rotax IRC
Tucson, AZ Ryan Airfield (KRYN)
520-349-7056 Cell

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Re: 17mm coolant hose and 90 degree hose 922192

by Andrew Rowley » 11 years ago

Andrew Rowley

2 3 0

My question was more related to the 90 degree hose 922192. The part I have received is definitely smaller than the other 17mm hose. It measures about 15mm.

I am concerned whether it will fit. Is this part normally only 15mm ID?

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Re: 17mm coolant hose and 90 degree hose 922192

by MARK JACKSON » 11 years ago

MARK JACKSON

12 332 11

Hi Andrew

You are right about that hose being a lot smaller diameter than 17mm. It will fit because it has to fit, it will just need a good push and a wiggle with maybe a bit of lube to get it on properly.

This also proves that the 16mm will be perfectly OK to use, but 17mm (11/16") hose only costs £5 per metre. It is classed more as heater hose rather than radiator hose. It is made by GATES, and about 80% of 912s have Gates hose on from new.

How much was the 17mm hose from Rotax?

Mark

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Re: 17mm coolant hose and 90 degree hose 922192

by Roger Lee » 11 years ago

Roger Lee

127 5.21k 4.79k

The 17mm coolant hose is not Gates. It is: http://www.contitech-usa.com/

I know because I have talked to them directly. This hose is only made for Rotax and no one else.
17mm (17.06) is 43/64th, 16mm (16.27) is 41/64 and 11/16" is 17.4mm. You can buy true 17mm from suppliers in the UK. Extruded hose like in many of our cars has a different make up from the wrapped 17mm Rotax uses.

Theoretically speaking:
IF I were to swing either way it would be towards the 11/16" and I would not use the spring clamps on the 16mm, too small a diameter and not enough tension on the spring clamp. The clamps won't hold well on the 11/16" either because it is too fat and they won't seal or hold well. IF I used either I would have to use good raised rib worm drive clamps or better yet a fuel injection style clamp. We should never be using the serrated worm drive clamps. Okay for a garden hose, but not for planes. The part of the problem is the expansion and contraction of metals so the spring clamp can adjust and a solid clamp can not. many of our autos use spring clamps now days. I never use lube on a coolant hose. I have seen two people do this and hose have come off in flight.

But I stick with Rotax hoses. As a mechanic I'm not willing to experiment on others planes and accept the civil liability. It only takes one.

Roger Lee
LSRM-A & Rotax Instructor & Rotax IRC
Tucson, AZ Ryan Airfield (KRYN)
520-349-7056 Cell

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Re: 17mm coolant hose and 90 degree hose 922192

by MARK JACKSON » 11 years ago

MARK JACKSON

12 332 11

Roger

It is a rubber coolant hose.

As I said, about 80% of Rotax 912s have GATES rubber coolant hose because that is what Rotax have used for about 18 years or more.

I agree about the serrated worm drive jubilee clips, but the spring clips that Rotax have used for years with the Gates hose that Rotax have used for years is sound. I know Rotax have changed the hose on the newer engines, but I bet its not because there was a problem with the old stuff.

You said " The clamps won't hold well on the 11/16"either because it is too fat and they won't seal or hold well"
This is the correct size to use.

The hose isn't 43/64th" or 17.06mm, it is 17mm.

Mark;-)

I do love reading some of your views, you do make me chuckle :-))

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17mm coolant hose and 90 degree hose 922192

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